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Experimental analysis of the energy performance of an ACTive, RESponsive and Solar (ACTRESS) façade module
Abstract
Responsive Building Elements (RBEs) are technologies enabling the exploitation of the opportunities offered by the environment and of renewable energy sources at the building scale. Amongst RBE concepts, Advanced Integrated Façades (AIFs) is probably one of the most promising technologies. In fact important players in the field of the façade engineering have started to develop integrated modular façade systems (Multifunctional Façade Modules – MFMs), with a dynamic behaviour interacting with the other building services, to reduce the building energy use and maximize the indoor comfort conditions.
In this framework, a research activity aimed at the development of solar and active building skins was carried out. A MFM has been conceived and a prototype realised for experimental evaluations. The work presented in this paper illustrates the outcomes of the experimental investigation of the MFM called ACTRESS (ACTive, RESponsive and Solar), which has been tested by means of an outdoor test cell apparatus.
In the paper, the ACTRESS module is presented and its performance assessed by means of standardized and non-standardized building performance metrics. The results of the experimental campaign show an overall very good performance of the technology in terms of improved building energy efficiency, although some critical aspects are revealed too. Moreover the façade module shows a very high degree of adaptability, as different strategies and behaviours can be achieved according to the desired performance or requirements.
... Regarding non-concentrating systems with PCMs, Favoino et al. (2016) investigated multifunctional façade modules. Outdoor experiments were conducted. ...
... In light of the issues mentioned above, Favoino et al. (2016) developed a façade-integrated solar system with the following characteristics: ...
... Solar-gain management (in both opaque and transparent configurations). Favoino et al. (2016) highlighted that PV modules combined with thermal energy storage offer an efficient solar-production management, facilitating the matching between energy generation and consumption. The proposed configuration includes three electric-heated foils powered by amorphous silicon PV modules. ...
In recent years there has been an increasing interest in Building-Integrated Photovoltaic (BIPV) and Building-Integrated Photovoltaic/Thermal (BIPVT) systems since they produce clean energy and replace conventional building envelope materials. By taking into account that storage is a key factor in the effective use of renewable energy, the present article is an overview about storage systems which are appropriate for BIPV and BIPVT applications. The literature review shows that there are multiple storage solutions, based on different kinds of materials (batteries, Phase Change Material (PCM) components, etc.). In terms of BIPV and BIPVT with batteries or PCMs or water tanks as storage systems, most of the installations are non-concentrating, façade- or roof-integrated, water- or air-based (in the case of BIPVT) and include silicon-based PV cells, lead-acid or lithium-ion batteries, paraffin- or salt-based PCMs. Regarding parameters that affect the environmental profile of storage systems, in the case of batteries critical factors such as material manufacturing, accidental release of electrolytes, inhalation toxicity, flammable elements, degradation and end-of-life management play a pivotal role. Regarding PCMs, there are some materials that are corrosive and present fire-safety issues as well as high toxicity in terms of human health and ecosystems. Concerning water storage tanks, based on certain studies about tanks with volumes of 300 L and 600 L, their impacts range from 5.9 to 11.7 GJprim and from 0.3 to 1.0 t CO2.eq. Finally, it should be noted that additional storage options such as Trombe walls, pebble beds and nanotechnologies are critically discussed. The contribution of the present article to the existing literature is associated with the fact that it presents a critical review about storage devices in the case of BIPV and BIPVT applications, by placing emphasis on the environmental profile of certain storage materials.
... FIG. 5 Thermal buffer efficiency of the OSM (Favoino et al. 2016) FIG. 6 Efficiency of the LHTES (Favoino et al. 2016) As far as the LHTES (e.g. ...
... FIG. 5 Thermal buffer efficiency of the OSM (Favoino et al. 2016) FIG. 6 Efficiency of the LHTES (Favoino et al. 2016) As far as the LHTES (e.g. PCM layers) is concerned, the analysis was carried out by analysing the energies accumulated/transmitted through the opaque sub module, by means of a first principle analysis of the daily energies exchanged across the solar LHTES system (Q PV , Q IN and Q VIP , as defined in Fig. 2). ...
... A full description of the methodology to evaluate the G-value on a daily basis from non-calorimetric measurement is given in Goia and Serra, (2018). The measurement of the equivalent G-value adopted an innovative measurement method enabling estimates of this metric based on the daily energy balance of the façade (Favoino et al., 2016;Bianco et al., 2017a), although a low accuracy of this measurement was achieved in this case mainly due to the variation in diurnal behaviour of the PCM-filled glazing systems, due to the strong influence of varying boundary conditions (temperatures and solar radiation) (Bianco et al. 2017a). ...
Traditional façade characterisation metrics such as U-value and g-value are of limited value in the design process of buildings with adaptive façades. This issue is particularly important for adaptive façade components that have the capability of controlling thermal energy storage in the construction thermal mass. Building performance simulations can help to analyse the performance of buildings with adaptive façades, but such studies usually only provide information about the energy and comfort performance at room level. Consequently, there is a need for development and testing of new façade-level performance metrics that can be used to compare the performance of different adaptive façade components. This paper presents experiences and lessons learned from four European R&D projects that have introduced novel metrics to capture the dynamic performance of adaptive opaque façades. Characteristics of the different metrics are described, and their similarities and differences are compared and contrasted. The paper highlights the main benefits of metrics that can capture dynamic effects, and concludes by providing directions for future work.
... The separated units (called modules) can be manufactured off-site in factories and then transported and assembled on-site to form an integrated system (Ferdous et al. 2019;Lacey et al. 2018). The literature shows that the modular facades were often designed as multifunctional, besides the typical functions such as energy efficiency improvement (Favoino et al. 2016;Lacey et al. 2018;Lai et al. 2021;Lešnik et al. 2020;Menéndez et al. 2018), integrated ventilation module (Shahrzad and Umberto 2022), enhancement of interior daylight performance (Hosseini and Heidari 2022), there is a growing trend of utilizing integrated photovoltaic (PV) materials in façade retrofits (Fig. 2). ...
... (4) Back layer insulation that fixed mechanically to the back of structural framework to restrict thermal bridge effects. ACTRESS (active, responsive, and solar) was another façade retrofit system was presented and tested by Favoino et al. (2016). Half of the prototype was designed as an opaque part and the other half was designed as a transparent façade module. ...
With the aim to promote carbon–neutral urban development, a number of recent pilot studies and building projects have investigated an innovative building retrofit solution: modular façade retrofit systems that combine photovoltaics products. Due to the novelty of this field, there is a limited systematic investigation of this promising solution. To present the state-of-the-art of this solution and to investigate future promotion needs, this study conducted a systematic literature study. Out of more than 200 relevant articles, 16 closely related papers were selected for in-depth review. Based on the review, the author proposed a definition of modular façade retrofit with integrated photovoltaics (MFRIPV) and summarized the current key focuses of MFRIPV, including energy performance and economic feasibility, system composition, and design process. The PV technologies and modular structural types of representative MFRIPV cases were also categorized. The findings showed that MFRIPV has satisfactory payback time and can be adopted in both residential and office buildings, providing multifunctional improvements such as better energy efficiency, interior daylight quality, solar energy harvesting and even vertical food production. To further promote MFRIPV application, the author suggested that aesthetic guidelines, integrated energy storage system, and design and management from a life-cycle perspective could be the next investigation priorities. The ultimate goal of MFRIPV should be “energy efficient, energy productive, aesthetically pleasing, user-centered design, easy for massive modular manufacture and assembling, easy for maintenance and upgrade, cost-effective’’. This study provided a foundation for advanced MFRIPV study and could serve as a reference for architects, building engineers, researchers, and policy-makers working in the field of sustainable urban renewal.
... The separated units (called modules) can be manufactured offsite in factories and then transported and assembled on-site to form an integrated system (Ferdous et al., 2019;Lacey et al., 2018). The literature shows that the modular facades were often designed as multifunctional, besides the typical functions such as energy efficiency improvement (Favoino et al., 2016;Lacey et al., 2018;Lai et al., 2021;Lešnik et al., 2020;Menéndez et al., 2018), integrated ventilation module (Shahrzad and Umberto, 2022), enhancement of interior daylight performance (Hosseini and Heidari, 2022), there is a growing trend of utilizing integrated photovoltaic (PV) materials in façade retrofits ( Figure 2). using wooden materials and lightweight metal frames (Chen et al., 2023). ...
... 4) Back layer insulation that fixed mechanically to the back of structural framework to restrict thermal bridge effects. ACTRESS (active, responsive, and solar) was another façade retrofit system was presented and tested by Favoino et al. (Favoino et al., 2016). Half of the prototype was designed as an opaque part and the other half was designed as a transparent façade module. ...
With the aim to promote carbon-neutral urban development, a number of recent pilot studies and building projects have investigated an innovative building retrofit solution: modular façade retrofit systems that combine photovoltaics products. Due to the novelty of this field, there is a limited systematic investigation of this promising solution. To present the state-of-the-art of this solution and to investigate future promotion needs, this study conducted a systematic liter-ature study. Out of more than 200 relevant articles, 16 closely related papers were selected for in-depth review. Based on the review, the author proposed a definition of modular façade ret-rofit with integrated photovoltaics (MFRIPV) and summarized the current key focuses of MFRIPV, including energy performance and economic feasibility, system composition, and design process. The PV technologies and modular structural types of representative MFRIPV cases were also categorized. The findings showed that MFRIPV has satisfactory payback time and can be adopted in both residential and office buildings, providing multifunctional im-provements such as better energy efficiency, interior daylight quality, solar energy harvesting and even vertical food production. To further promote MFRIPV application, the author sug-gested that aesthetic guidelines, integrated energy storage system, and design and management from a life-cycle perspective could be the next investigation priorities. The ultimate goal of MFRIPV should be “energy efficient, energy productive, aesthetically pleasing, user-centered design, easy for massive modular manufacture and assembling, easy for maintenance and up-grade, cost-effective’’. This study provided a foundation for advanced MFRIPV study and could serve as a reference for architects, building engineers, researchers, and policy-makers working in the field of sustainable urban renewal.
... The preliminary KPIs, selected in accordance with [6], to experimentally assess the thermal performance of the technology, were the thermal transmittance (U value ) and the total solar heat gain coefficient (g value ). These indicators were calculated from experimental data according to the methodology presented in [25], and are herein referred-to as experimental thermal transmittance (U value,exp ), experimental solar heat gain coefficient (g value,exp ), and experimental solar transmittance (T sol,exp ). As what concerns simulations, U value was calculated from the thermal conductance of the component () and from the conventional external and internal surfaces resistances (R surf,out , R surf,in ) using Equation 1 [26]. ...
... (1) The g value,exp parameter was assessed in situ from the indoor and outdoor air temperatures, internal surface heat flows, and the incident and transmitted vertical solar radiation (I en , I inc ), using Equation 2 [25]. The value of sol,exp was assessed from the incident and transmitted solar radiation via Equation 3 and was discretized by the incident angle. ...
... This concept is termed Responsive Building Elements (RBEs). With reference to a number of excellent studies on this subject, each type of solar façade actually belongs to the RBEs, both for their two main classifications, opaque solar façades and transparent or semi-transparent solar façades [2][3][4][5][6][7][8]. At present, most research has suggested different classifications for the study of advanced building façade systems, in order to assess their thermal behaviour by transient simulations and experimental measurements [9][10][11]. ...
... There has been a considerable amount of research into the field of building envelope energy efficiency. In particular, applications of the AIF systems both at design/commercial and research levels, have taken into account the concept suggested in [1,2] of the envelope as a "dynamic" building element integrated with building plant/services. This means that thermo-physical behaviour of building components may easily change over time and adapt to different • the relevant thermo-physical parameters and the energy performances of the advanced façade systems (taking into account different energy designs, renewable energy integrated uses); • comparison of the energy performance of the integrated building components considered located in different Mediterranean areas, characterized by large hourly climatic fluctuations; • the energy assessment of the façade components studied when integrated with building and plant systems. ...
The aim of our present study was to assess and compare the thermo-physical and energy behaviour of different integrated building façades, using a multi-physics simulation approach. Advanced integrated façades composed of opaque modules, one of them with a phase change materials (PCM) layer, the others with multilayer panels, combined with transparent ones, consisting of nano-structured materials and new-generation photovoltaic systems, were investigated. A multi-physics approach was used for the design optimization of the studied components and evaluation of their thermo-physical and heat transfer performance. In particular, computational fluid dynamics (CFD) multi-physics transient simulations were performed to assess air temperature and velocity fields inside the ventilated cavities. Analysis of heat and mass exchange through all the components was assessed during heating and cooling mode of a reference building. The typical Mediterranean climate was considered. Results comparison allowed the dynamic heat transfer evaluation of the multilayer façades as a function of variable climatic conditions, and their flexibility and adaptability exploitation, when different energy strategies are pursued. The multi-physics modelling approach used, proved to be a strong tool for the energy design optimization and energy sustainability evaluation of different advance materials and building components.
... Experiments conducted on a test cell showed that the amplitude of indoor air temperature variation does not decrease significantly at PCM panel thicknesses above 20 mm. Favoino, Goia, Perino and Serra (2016) combined the PCM and VIP layers in the 'ACTive, RESponsive and Solar' façade module, where the VIP is used to thermally disconnect the indoor environment from the air cavity and in which PCM also acted as active thermal energy storage heated by integrated PV modules. VIP panels in multi-layer drywall systems with PCMs also considerably enhanced fire resistance (Kontogeorgos, Semitelos, Mandilaras & Founti, 2016). ...
... Energy use for heating and cooling, as well as indoor thermal comfort conditions, are largely influenced by the building's construction dynamic properties, which were next evaluated for different composite timber façade walls. As stated in Favoino, Goia, Perino & Serra (2016), during the daytime, heating demand in energy efficient office buildings is low or zero due to solar and internal gains, so night-time heat losses ( night q ) were selected as a parameter for evaluation of the dynamic properties. The results of the analysis are presented in Fig. 8 The time lag of periodic heat wave propagation through the composite timber façade walls was determined considering the optimal position of VIP and PCM/VIP panels within the composite timber wall. ...
For the construction of modern energy-efficient buildings, lightweight construction is becoming very popular among designers. EU legislation encourages such design, especially if wood, as a sustainable material, is used. However, lightweight building envelope construction, in general, exhibits poor dynamic thermal properties, which are particularly pronounced in prefabricated metal walls and thin wooden or composite building panels, such as door fillers or opaque parts (parapets) of prefabricated walls with the glazing of the skeleton-built buildings. The aim of this research was the development of a composite timber façade wall, which will not exceed the thickness of building elements, such as doors and windows, and will meet the requirements of energy efficiency and have improved dynamic thermal properties. The composite timber building element with a thickness of 68 mm, which includes two layers of advanced technologies: vacuum insulation panel (VIP) and phase change material (PCM), was developed and optimized. The optimization included a parametric study on VIP and PCM panels’ position in the thin, lightweight building wall. The research has shown that dynamic thermal properties comparable to the heavyweight building envelope constructions (time lag of the heat wave up to 12 h) can be achieved; moreover, the thermal transmittance is considerably reduced.
... Advancements in building technology have facilitated the development of various types of dynamic building elements, aiming to achieve higher levels of sustainability and aesthetics [1,2]. Promising areas of development in adaptive technologies such as phase change materials [3], adaptive solar shading [4], multifunctional facades [5], switchable glazing [6], and double-skin facades (DSF) [7] have been identified. In this research, our focus will be on switchable glazing and dynamic double-skin facades (DSF). ...
The modern movement of architecture has led to a proliferation of buildings featuring transparent facades, which unfortunately amplify the energy needs of these structures. Mitigating this energy consumption necessitates a reevaluation of architectural strategies. Addressing concerns such as overheating, innovative solutions like smart and dynamic double-skin facades have emerged to curtail energy usage while ensuring comfortable indoor conditions. This study focuses on examining the efficacy of smart facades, employing electrochromic glazing, and dynamic double-skin facades, and integrating dynamic shading systems, in reducing energy consumption within office buildings located in hot and arid regions. Parametric simulations were used on a particular office building, comparing scenarios with and without the implementation of smart and dynamic double-skin facades, particularly on south-facing orientations. The simulations varied the wall-to-window ratio (WWR) to gauge energy performance under different configurations. Furthermore, multi-objective optimization (MOO) techniques were employed to analyze and optimize shading device properties. Parameters such as depth, distance from the glass, shade angle, and spacing between shades were optimized as genetic variables to determine the most energy-efficient configuration for office buildings. The study results demonstrate that the use of EC glazing is beneficial in all WWR percentages, achieving 67.65% of energy saving in 90% of WWR., Also it was found that the optimal solution for saving energy is using DDSF with 20 cm of shading depth, 45° of shading angle, and double low-E vacuum in the inner skin, with an energy saving of 70.32% in the case of 90% of WWR compared to the base case.
... Windows of building façades are mainly made of glass, making them one of the most thermally vulnerable building elements [3][4][5]. Various functional façade systems have been developed and applied to actual buildings to compensate for thermal vulnerabilities and to improve the performance of windows [6][7][8]. Recently, insulated tempered glass with multiple glass layers or special films have been developed [9][10][11]. Nevertheless, windows of building façades cause significant heat loss in winter and heat gain in summer. ...
A survey was conducted to analyze the discrepancies of the functional requirements of the façade system in residential units among 605 of the real-life public and 73 experts. Personal and housing information, resident life patterns, public façade usage behavior, and functional requirements were collected from the respondents. Both the public and experts recognized insulation as the main function of façade opening systems. More than 85% of the public and experts opened windows for ventilation, but ventilation was ranked 3rd amongst the public and 4th amongst experts in the main functions list of façade systems. The public cited the inflow of fine dust as the main reason for dissatisfaction with opening windows. In contrast, the experts cited a decrease in thermal comfort due to the inflow of external moisture as the reason for dissatisfaction with opening windows. The results showed that discrepancies exist between the public and experts’ perceptions of the main function of housing façade systems. Analyzing the common points and differences between the public and experts’ perception can help in developing façade system design and control technology.
... In high performance building design, adaptive facades are essential [6]. Smart materials with changing properties that adapt to environmental changes have the potential to significantly impact the built environment and the look of the building [7]. ...
... Likewise, and based on the above-described principles, a number of other researchers also worked on prototype BIPV/T systems, using the air from the cavity of the double façades. Yang and Athienitis (2014) and Favoino et al. (2016) worked on open-loop air-based active building double façades, when Athienitis et al. (2011) and Li et al. (2015), in order to maximize the capture and use of solar energy, coupled building integrated photovoltaic-thermal systems with other systems (such as unglazed transpired collectors). Some researchers worked with semi-transparent BIPV/T systems, thus enhancing the ability of the building to have natural insolation (Kamthania et al., 2011;Gaur et al., 2016;Ioannidis et al., 2020;Zhu et al., 2020;Vats and Tiwari, 2012), when others work with the integration of Phase Change Materials (PCM) into BIPV/T devices, aiming to better understand the behaviour of these systems (Athienitis et al., 2018;Sohani et al., 2022;Bigaila and Athienitis, 2017;Jahangir et al., 2020;Pereira and Aelenei, 2019). ...
The high percentage of energy consumption by fossil fuels in the building sector in combination with climate change across the globe increased the need to move into more sustainable building practices. Thus, the integration of sustainable strategies and active solar energy systems into the design process is becoming a tool for the reduction of the energy demand and improvement of the energy performance of existing and new buildings.
This study investigates the energy performance of an existing residential apartment building in Limassol, Cyprus before and after its energy renovation, using a double skin façade combined with building integration of active solar energy systems. The proposed research starts with the analysis of the existing building energy performance, focusing on the energy loads for cooling, heating, and artificial lighting. Subsequently, the results of the existing situation are evaluated using digital energy simulations, and the process moves on to the renovation and energy upgrade of the building by integrating the aforementioned systems. Energy-Plus simulations are performed where the proposed systems’ contribution to the energy reduction is investigated including their energy reduction potential. The before and after simulations are compared, with the focus to prove whether the systems can be viable in terms of decreasing the energy demands of the building. Finally, a life cycle cost (LCC) analysis is performed, to determine the viability of the enterprise. The performed research proves that the application of the double façade, consisting of three main features — a building integrated photovoltaic system (BIPV), glazing system and rambling planting, can combine the positive effects of each individual system, if there is a combined systematic approach on the architectural design of the building envelope. The combination of the above led to a reduction of 83.5% in the energy consumption of the building, from 94,321 kWh of the existing situation to the 15,563 kWh of the proposed one. This reduction includes the contribution from BIPV system, which amounts to 26,706 kWh/ year of primary energy — thus covering the 63% of the proposed consumption of the building. On the other hand, the LCC analysis sums that a careful combination of bioclimatic design and active solar systems, can have a viable payback period, which in this case is 13 years.
The overall aim of this research is to determine whether the use of a double skin façade combined with integrated active solar systems constitute an energy and cost-efficient solution for the viable refurbishment of an existing building in the south-eastern Mediterranean area.
... The DSF tested could result in heating energy savings due the thermal buffer area, heating energy saving was higher in the lower heights. The experimental campaign used to evaluate the performance of a multifunctional adaptive façade by Favoino et al. [44] showed how the façade components interact. Several systems such as PV panels, PCMs, smart coatings, and operable shadings was used. ...
Enhancing building energy performance has become a focal point in reducing the environmental impacts of buildings to address climate change. Considering the high share of comfort-related energy use in buildings, and the importance of indoor environmental quality (IEQ), a balance between energy conservation and IEQ provision is required. Building façades are the primary boundary controlling mass and energy flow to and from buildings. Dynamic and climate-responsive façades are potential improvements to existing high-performance façades to enhance IEQ in buildings, as they change their functionality with time, in response to changing environmental loads. A multifunctional, integrated, climate-responsive, opaque, and ventilated building façade (MICRO-V) was designed to regulate the flow of heat, air, and moisture into buildings. The MICRO-V façade has a novel design to pre-condition the fresh air and regulate thermal loads in buildings on a daily and seasonal basis. The multiple components of this façade include phase change materials (PCMs), a bi-directional ventilation module and an adjustable insulation system. In this paper, the thermal performance of this façade was evaluated using long-term experimental tests. The real-scale prototype of the façade was constructed and installed in the full-scale BETOP test cell facility in Toronto, Canada. The results of different tests showed how the façade could pre-condition the fresh air acting as a decentralized ventilation module due to a high heat recovery efficiency of 81%. However, it was also shown that the significant impact of solar irradiance, which requires constant adjustment to the operation schedule of the ventilation fans in the façade.
... Research efforts have been focussed on optimising the geometry of shading devices such as blinds (Tsangrassoulis et al. 2006;Tzempelikos 2008;Santos et al. 2018;Konis and Lee 2015;Taveres-Cachat et al. 2019), as well as on actuation mechanisms that allow complex movements and geometries (Hashemloo et al. 2015;Saini et al. 2018), automated operation of new types of shading devices (Mettanant 2013), or the ability to dynamically switch between different materials on their sun-facing sides (Oh et al. 2012) to manipulate the admission of solar energy. E. Finally, novel and optimised concepts have been proposed in which automated shading systems are an integral component within a novel overall façade design (Tzempelikos et al. 2007a;Favoino et al. 2016b;Denz et al. 2018;Aslihan and Eleanor 2006;Chan 2020, 2021) ...
Automated shading systems have the potential to substantially reduce building energy consumption, increase occupant exposure to natural daylight and reduce visual and thermal discomfort. The performance of automated solar shading systems, however, greatly depends on how these screens or slats are operated. Conventional control strategies for automated shading systems, that tend to follow binary close-open approaches, are ill-equipped to respond to the large variety of environmental conditions and shifting performance goals in managing the indoor climate of office buildings. Consequently, they inadequately satisfy the visual comfort requirements of occupants and are frequently associated with user dissatisfaction.
Recently, a series of enabling developments has led to promising comfort-driven control strategies being proposed that seek to maximise the admission of daylight by closing shading devices only to the extent that is necessary to prevent daylight glare or thermal discomfort. If these strategies are to be deployed successfully at scale, however, there are several challenges that need to be overcome. For the development and application of such comfort-driven automated shading strategies there is a need for detailed insight into how control and design parameters can be leveraged to influence building performance trade-offs. Additionally, there is a need for generically applicable and scalable workflows for the development of control strategies and their successful deployment in specific buildings.
This doctoral dissertation investigates how computational analyses and optimisation can be used to support the development and application of comfort-driven shading strategies. More specifically, the objective of this research is to develop and test a computational framework for performance evaluation and optimisation of advanced automated shading strategies. Firstly, this framework consists of a virtual test bed (VTB) aimed at analysing the performance of (i) advanced shading controls, (ii) materialisation and shading design features, and (iii) applications of dynamic solar shading systems within performance-driven façade design processes. Secondly, this framework encapsulates a set of computational support methods, aimed at performance analysis, optimisation, and quality control in the application of the VTB.
Because of the fragmented façade design and delivery process, the design and control parameters that define the building performance effects of automated shading systems are specified by various decision makers at different positions in the supply chain. In addition, these design and control parameters vary in their physicality and scale. The requirements for the computational framework are therefore investigated through an iterative process involving four application studies. This process includes feedback from stakeholders in the shading industry. In each application study, the computational framework is developed and tested by applying it to analyse and optimise a series of design and control aspects that are specific to a particular type of shading system and decision-maker perspective.
A literature review identifies the needs and possibilities for applying building performance simulation (BPS) effectively to support decision making in this domain. Based on the identified needs and possibilities, and the findings of the four application studies, a set of requirements for the computational framework were obtained.
The main contribution of the research is the developed computational framework. This framework consists of a VTB for analyses and optimisation of automated shading systems and a set of computational support methods that facilitate the effective use of this VTB. The VTB is designed for multi-domain and multi-scale simulation of automated shading systems. It employs a co-simulation approach between high-resolution domain specific tools using middleware software. These domain specific tools are used for transient thermal building simulation, daylighting and glare simulation, and control system simulation. Additionally, the VTB uses a stepped approach where sub-system simulations are used to describe the physical behaviour of shading materials, shading devices, and the overall fenestration system. The emergent physical behaviour predicted by subsystem simulations at the lower levels of scale is used to define input parameters for models that describe the fenestration system at a higher level of abstraction and predict performance effects on the building level. The VTB also includes multiple features for modelling energy systems at varying levels of detail.
Each VTB module is individually verified and validated throughout the four application studies. In addition, the four application studies show that the modular structure of the VTB allows it to be configured to fulfil various simulation objectives and describe a variety of shading systems. Furthermore, these studies illustrate fit-for-purpose application of the VTB and provide guidance in the selection of model complexity and resolution. Through these studies, this research contributes to the knowledge on performance modelling of complex fenestration systems.
The analyses and optimisation support methods that are developed in this research use statistical classification techniques to identify high performance sensor configurations, detection algorithms and control parameters. The support methods contribute to the body of knowledge on the simulation-based development of advanced shading strategies. Their novelty can be found in the beneficial trade-off between (i) their replicability, (ii) their effectivity in finding control strategies that optimally exploit non-intrusive and non-ideal sensors, and (iii) the time, effort, and skill that are required of developers in their application. Many existing approaches tend to perform particularly well in only a subset of these three aspects. Because the support methods place due emphasis on all three aspects, however, they allow the creation of control strategies that are potentially more scalable in the current context.
The computational framework has gone through usability testing in a broad variety of representative applications that illustrate the most significant ways of it. The application studies address: optimisation of design and control aspects on the five most relevant levels-of-scale (i.e.: sensor deployment strategy, control strategy, shading material, shading system, façade configuration), various types of shading systems (e.g., sun-tracking roller shades and vertical blinds), and the perspectives of various decision makers that are positioned at varying places within the façade design and delivery process (e.g., control developers and façade designers).
Finally, this research contributes insights into the causal relationships between solar shading design and control features and building performance effects. These insights give reason to reconsider the often thermally driven approach to the design of facades, the specification of solar shading devices and the development of control approaches.
... More specific information related to the DSF prototype are provided in the next sections. This prototype was installed in a South-exposed facade of the TWINS outdoor test cell facility ( Fig. 1) of the Politecnico di Torino (Favoino et al., 2016), with the aim to perform a yearly experimental campaign (currently ongoing) in order to (i) characterise the performance of the DSF in different configurations (different operable shading devices and different ventilation paths), (ii) to calibrate the building simulation models of the DSF, (iii) to implement real-time rule-and model-based control strategies and demonstrate them in a real-world application. ...
... The design of the system was then improved with the application of several ideas, which led in some cases to improved thermal efficiency by about 10%. Another open-loop air-based active building façade is investigated by Favoino et al. [30]. Here, modular façade made of both opaque and transparent elements is tested, showing interesting benefits by the energy point of view. ...
Solar building integration, differs from everyday active solar energy systems on a building envelope, because the active system replaces building elements and are integrated into the architectural envelope and structure. This article aims to present a comprehensive review and analyse the geometrical and architectural characteristics
and design possibilities offered by the building integration of active solar energy systems.
The literature studies are separated into double and single façade solutions, as well as solutions where the active system performs as an independent architectural element of the building. It is concluded that the majority of the researchers preferred the single façade solutions, followed by the double façade systems since the second one offers a
cavity which can be used as an air duct for the BIPV (Building Integrated Photovoltaics) and BIPV/T (Building Integrated Photovoltaic / Thermal) solutions. This work provides an overview of the state of the art systems and geometrical solutions emerging by the development, research, and applications of the BISS (Building Integrated Solar Systems).
... Nevertheless, when a maximum transparent appearance has a lower architectural priority, including an opaque area within the AIF system could enable to achieve very high energy and comfort performances, while promoting RES integration and energy independence for the façade operations at the same time. This is achieved by means of plug-and-play façade systems, such as the ACTRESS AIF façade concept (Favoino, Goia, Perino, & Serra, 2016) and the 'solar window block' (Andaloro, Avesani, Belleri, & Machado, 2018). These are prefabricated and energetically autonomous fenestration system, which can provide a high level of IEQ and energy saving, by balancing a transparent part devoted to view out, daylight and solar control with an opaque one embedding high performance insulation, PV panels, electrical and thermal storage for autonomous operations, decentralized ventilation units and control system (Andaloro, Minguez, & Avesani, 2020;Minguez, Gubert, Astigarraga, & Avesani, 2020) (Fig. 5.15). ...
Advanced fenestration systems (AFS) can respond to baseline functionalities and requirements in the remit of the transparent part of the building envelope (eg, reducing heat transfer, solar control and providing view out) and can combine these to a higher level of functionality aimed at providing an occupant with excellent indoor conditions while improving building performance toward building sustainability objectives. This full set of possible wished functionalities include providing view out/privacy; managing solar radiation; managing glare/daylight; managing and/or controlling heat transfer; increasing thermal storage; managing airflow; and facilitating energy generation. The present chapter provides an overview of different market available advanced fenestration components and systems highlighting (1) the main features while providing some examples of commercial products and solutions still in the R&D stage; (2) the increased building performance and functionalities achieved; and (3) the challenges for broader market adoption. Finally, an overview is provided regarding the challenges and requirements for performance evaluation of AFS, with the aim to support decision-making for design and operation of AFS.
... In this study the inverse design problem was addressed by means of integrated thermal and lighting simulations carried out in EnergyPlus, coupled with a systematic parametric search and data-postprocessing that recreates a continuous function for the problem variable starting from a relatively small number of simulations. The findings of this investigation supported the development of an integrated, modular façade system (a multifunctional façade module) capable of dynamically interacting with the other building services to reduce the building energy use and maximize the indoor comfort conditions (Favoino, Goia, Perino, & Serra, 2016). ...
Inverse problem approaches are relatively new and are growing in popularity in research in natural sciences and engineering. Inverse problem solving (or inverse design) comprises a rather heterogeneous collection of methods that are characterized by first setting the performance requirement(s) and then obtaining the optimal configuration of a material, geometry or process through a search targeting the selected performance.
In this chapter, we present the concept of inverse design applied to R&D in the field of façade engineering for new systems and optimal operations. By discussing recent research activities, we provide an overview of the methods and tools for inverse design problems and the potential of this approach for the development of advanced building envelopes. The process of inverse design is further exemplified through a case study that aims to identify optimal combinations of static and dynamic shading systems for high-performance building skins to provide optimal daylight utilization and minimal risk of daylight glare discomfort.
... These systems, allow to reversibly adjust their properties in response to external stimuli in order to adapt their [4]. Different promising fields of development in adaptive technologies such as Phase Change Materials [5], adaptive solar shading [6], multifunctional facades [7] and switchable glazing [8] were identified. Switchable glazing is one of the technologies that is getting major attention thanks to the key role played by transparent envelopes in the energy flow controlboth in summer and winter conditionsand thanks to their high retrofitting suitability. ...
During last decades, many efforts have been made to address challenges regarding building energy consumption. A particularly interesting and effective field of development in the building domain is represented by responsive technologies applied to transparent envelopes. Among these technologies, the electrochromic (EC) glazing is one of the most developed solutions thanks to its capability to dynamically modulate daylight and thermal radiation, simply applying a controlled external voltage. The aim of this study is to provide a methodology to analyse smart responsive technologies and optimize the properties of an ideal switchable glazing to find the best configuration for a medium office in different climatic zones. The genetic optimization considers a 5-elements genome, constituted of the following genes: i) solar heat gain coefficient in bleached (SHGCB) and ii) coloured state (SHGC C ), iii) visible light transmittance in bleached (VLT B ) and iv) coloured state (VLT C ) and v) thermal transmittance (U). Moreover, different European cities were selected as representative of different climatic zones and results obtained give a set of ideal EC glazing configurations in the case of EC window controlled by daylighting sensors.
... For this purpose, applying internal (Mangkuto et al., 2019) and external (Saifelnasr, 2016;Vera et al., 2017;Attia and De Herde, 2009) shading devices have been identified as an acceptable method to achieve this goal. Moreover, applying a dynamic skin façade (Favoino et al., 2016;Chi et al., 2017;Juaristi et al., 2018) was regarded as a solution to control energy consumption in office buildings Manu et al., 2019;Wong et al., 2012). Given that most Iranian territories experience hot-arid climates, the studies being conducted in various fields tend to focus on reducing energy consumption for cooling and heating purposes in the country (Korsavi et al., 2018;Hosseini et al., 2016). ...
Purpose
The modular dynamic façade (MDF) concept could be an approach in a comfort-centric design through proper integration with energy-efficient buildings. This study focuses on obtaining and/or calculating an efficient angle of the MDF, which would lead to the optimum performance in daylight availability and energy consumption in a single south-faced official space located in the hot-arid climate of Yazd, Iran.
Design/methodology/approach
The methodology consists of three fundamental parts: (1) based on previous related studies, a diamond-based dynamic skin façade was applied to a south-faced office building in a hot-arid climate; (2) the daylighting and energy performance of the model were simulated annually; and (3) the data obtained from the simulation were compared to reach the optimum angle of the MDF.
Findings
The results showed that when the angle of the MDF openings was set at 30°, it could decrease energy consumption by 41.32% annually, while daylight simulation pointed that the space experienced the minimum possible glare at this angle. Therefore, the angle of 30° was established as the optimum angle, which could be the basis for future investment in responsive building envelopes.
Originality/value
This angular study simultaneously assesses the daylight availability, visual comfort and energy consumption on a MDF in a hot-arid climate
... As a result, an adaptation of their behavior to climate fluctuations is achieved, and, consequently, users' comfort requirements can be more efficiently met [1,2]. Currently, the most promising results of adaptive envelopes [3] are related to wall-integrated PCMs [4,5], switchable glazing [6][7][8][9], adaptive solar shadings [10][11][12], dynamic insulation [13,14], and multifunctional facades [15,16]. ...
Featured Application
Reduction of energy consumption in residential and office buildings through the improvement of latent heat storage in active and passive strategies.
Abstract
Among the adaptive solutions, phase change material (PCM) technology is one of the most developed, thanks to its capability to mitigate the effects of air temperature fluctuations using thermal energy storage (TES). PCMs belong to the category of passive systems that operate on heat modulation, thanks to latent heat storage (LHS) that can lead to a reduction of heating ventilation air conditioning (HVAC) consumption in traditional buildings and to an improvement of indoor thermal comfort in buildings devoid of HVAC systems. The aim of this work is to numerically analyze and compare the benefits of the implementation of PCMs on the building envelope in both active and passive strategies. To generalize the results, two different EnergyPlus calibrated reference models—the small office and the midrise apartment—were considered, and 25 different European cities in different climatic zones were selected. For these analyses, a PCM plasterboard with a 23 °C melting point was considered in four different thicknesses—12.5, 25, 37.5, and 50 mm. The results obtained highlighted a strong logarithmic correlation between PCM thickness and energy reduction in all the climatic zones, with higher benefits in office buildings and in warmer climates for both strategies.
... As stated by Faviono, Goia, Perino and Serra [26] the technologies that promote the relationship between the production of renewable energy and the load construction profile are fundamental, since they make use of the responsive elements of buildings. These are elements of buildings that act with a dynamic and active behaviour that improve the exploitation of available natural energy sources. ...
An educational building must integrate smart building strategies to ensure indoor environmental quality. Thermal, acoustic, visual comfort and indoor air quality are to be considered, otherwise they can develop the sick building syndrome. Smart buildings solve this potential problem by providing a highly efficient living ambience that includes safety, comfort and a good quality of living/learning/working experience, that helps the users achieve their best possible performance. These buildings should integrate advanced technologies such as automated systems and the implementation of architectural skins, well and functional designed spaces and architectural features that act as active bioclimatic solutions. The following is a case study of an architectural project for an elementary and junior high school academic campus in the state of Nuevo León, Mexico that has to deal with the extreme climate conditions of the location, while applying the best alternative and bioclimatic strategies through the implementation of inmotics, a responsive architectural skin, sustainable construction systems and native vegetation. In doing so, a comprehensive environmentally friendly building is created, taking advantage of the surrounding natural conditions, using the latest environmentally oriented systems and technologies. The result is a healthy, safe, and productive space for its users that greatly benefits the teaching-learning process.
... The glazed structure that can use solar energy and meets the requirements of building lighting and thermal insulation has become a new glass system [4]. Recently, PCM (phase change material) filling in glazed envelopes is recommended as an exciting innovative solution for solar energy storage devices [5][6][7][8] since this technique enables absorbing part of solar energy in latent heat form in the glazing unit during the day and releasing it to the indoor environment during the evening through phase change, which ultimately enables reduction of energy consumption of buildings and improvement of indoor thermal comfort [9,10]. As the implementation of PCM into building components increases the thermal storage capacity of buildings [11][12][13] and the accumulation of the energy storage and the acceleration of the photothermal conversion in the glazing unit, PCM-filled sandwich glazed structure is considered one of the prospective technologies to improve the solar energy utilization of buildings [14][15][16][17]. ...
... The glazed structure that can use solar energy and meets the requirements of building lighting and thermal insulation has become a new glass system [4]. Recently, PCM (phase change material) filling in glazed envelopes is recommended as an exciting innovative solution for solar energy storage devices [5][6][7][8] since this technique enables absorbing part of solar energy in latent heat form in the glazing unit during the day and releasing it to the indoor environment during the evening through phase change, which ultimately enables reduction of energy consumption of buildings and improvement of indoor thermal comfort [9,10]. As the implementation of PCM into building components increases the thermal storage capacity of buildings [11][12][13] and the accumulation of the energy storage and the acceleration of the photothermal conversion in the glazing unit, PCM-filled sandwich glazed structure is considered one of the prospective technologies to improve the solar energy utilization of buildings [14][15][16][17]. ...
The paraffin incorporation in device of glass envelope allows the thermal regulation, increasing the thermal comfort and energy efficiency of buildings. Addition of nanoparticles has an advanced application prospect in the field of solar energy collection and storage capacity of glass envelope systems filled with paraffin. The present study conducts an experimental and numerical investigation in order to study photothermal properties of the paraffin incorporated ZnO or CuO nanoparticles. An experimental and theoretical model is also established to analyze the effect of nanoparticles on the thermophysical and optical properties of nano-enhanced paraffin. The results show that due to the presence of the nanoparticles, the transmittance of nano-enhanced paraffin decreases. On the other hand, temperature increment results in a small rise in the transmittance of nano-enhanced paraffin. The results also indicate that the utilized nanoparticles exhibit a higher attenuation to light, and the scattering effect cannot be avoided, where the maximum scattering proportion is 6.3%. Improvements of 5.87 and 13.12% in thermal conductivity of nano-enhanced paraffin at the volume fraction of 5 × 10 − 4 vol% are obtained using ZnO and CuO nanoparticles, respectively. The evaluation of the photothermal performance based on the temperature variations shows that the CuO/paraffin can absorb more solar energy. The optimum pho-tothermal performance can be satisfied by the nanoparticle volume fraction ranging from 5 × 10 − 4 to 1.5 × 10 − 3 vol%.
... The following large-scale glazing of façades fulfilled these requirements, but also introduced new building physical problems, such as excessive solar gains in summer and unwanted heat losses in winter. Besides the development of new constructive solutions such as double façades, this critical window to wall ratio, as also identified by Favoino, Goia, Perino, and Serra (2016), led to an increasing mechanisation of the building, resulting from the idea that the energetic disadvantages of the glass façade can be compensated with technology. In the course of expanding the functional scope of façades and the additional integration of technologies and building services, the complexity of façades increase. ...
New technologies and automation concepts emerge in the digitalization of our environment. This is, for example, reflected by intelligent production systems in Industry 4.0. A core aspect of such systems is their cyber-physical implementation, which aims to increase productivity and flexibility through embedded computing capacities and the cooperation of decentrally networked production plants. This development stage of automation has not yet been achieved in the current state-of-the-art of façades. Being responsible for the execution of adaptive measures, façade automation is part of hierarchically and centrally organised Building Automation Systems (BAS). The research project ThinkingSkins is guided by the hypothesis that, aiming at an enhanced overall building performance, façades can be implemented as cyber-physical systems. Accordingly, it addresses the research question:
How can cyber-physical systems be applied to façades, in order to enable coordinated adaptations of networked individual façade functions?
The question is approached in four partial investigations. First, a comprehensive understanding of intelligent systems in both application fields, façades and Industry 4.0, is elaborated by a literature review. Subsequently, relevant façade functions are identified by a second literature review in a superposition matrix, which also incorporates characteristics for a detailed assessment of each function’s adaptive capacities. The third investigation focuses on existing conditions in building practice by means of a multiple case study analysis. Finally, the technical feasibility of façades implemented as cyber-physical systems is investigated by developing a prototype. The research project identifies the possibility and promising potential of cyberphysical façades. As result, the doctoral dissertation provides a conceptual framework for the implementation of such systems in building practice and for further research.
... Between the most innovative solutions there is an ACTive, RESponsive and Solar multifunctional façade module presented by Favoino et al. (2016), and also the smart control of buildings glazing's transmittance in function of solar radiation wavelength for optimizing daylighting and building's energy efficiency (TaiKima and Todorovic, 2013). ...
... Windows are indispensable parts of buildings since they enhance the buildings' aesthetical architecture, provide passive solar energy gain and air ventilation and increase natural lighting [1][2][3]. However, due to their poor thermal resistance, low thermal inertia and high transmission of solar radiation, they usually have poor thermal performance compared to those of opaque parts of the building envelope such as roofs and walls. ...
Filling window units with phase change material (PCM) improves the thermal performance of windows, but on the other hand it has a deteriorative effect on the optical performance due to poor heat conductivity of PCM. A novel method to tackle this drawback of PCM is to disperse nanoparticles in the PCM. In this study, a model was developed to evaluate the thermal and optical performances of window units filled with nanoparticle enhanced PCM (NePCM). The effect of different types of nanoparticles, volume fractions of nanoparticles and sizes of nanoparticles on the thermal and optical performances of windows such as temperature, heat flux, solar transmittance, absorptance and reflectance were numerically investigated and compared with the referent case (i.e. pure PCM). The results showed that the optical and thermal performances of window units filled with nanoparticle dispersed paraffin wax are improved compared to that of with pure paraffin. However, the improvement is nearly the same regardless of nanoparticle type. The effect of volume fraction and size of nanoparticle is significant during the sunset and sunrise periods. Considering both thermal and optical performances of window units, it is recommended to disperse CuO nanoparticles with the volume fraction of below 1% and nanoparticle size of below 15 nm in PCM.
... An active and responsive solar façade module with integrated PV panels and PCMs was developed by Favoino et al. [24]. In summer, the PCM was used as a passive thermal storage, and a ventilated cavity was used as an outdoor air curtain. ...
... The façade becomes an integral part of the climate concept and building services components can be integrated into it (Klein, 2013). An increasing interest in the application of advanced building envelope solutions can be seen both in research activities and in industrial developments (Favoino, Goia, Perino, & Serra, 2016;Loonen, Trčka, Cóstola, & Hensen, 2013). The potential of 3d printing technology to generate complex geometries for integrating multiple materials and functions should be investigated in this respect. ...
Currently, several research projects investigate Additive Manufacturing (AM) technology as a possible construction method for future buildings. AM methods have some advantages over other production processes, such as great freedom of form, shape complexity, scale, and material use. These characteristics are relevant for façade applications, which demand the integration of several functions. Given the established capacity of AM to generate complex geometries, most existing research focuses on mechanical material properties and mainly in relation to the load-bearing capacity and the construction system. The integration of additional aspects is often achieved with
post processing and the use of multiple materials. Research is needed to investigate properties for insulation, thermal storage, and energy harvesting, combined in one component and one production technology.
To this end, the research project “SPONG3D” aimed at developing a 3D-printed façade panel that integrates insulating properties with heat storage in a complex, mono-material geometry. This paper gives an overview of the panel development process, including aspects of material selection, printing process, structural properties, energy performance, and thermal heat storage. The development process was guided by experiments and simulations and resulted in the design and manufacturing of a full-scale façade element prototype using FDM printing with PETG. The project proved the possibility of the integration of functions in 3D-printed façades, but also high-lighted the limitations and the need for further developments.
... In this paper, a non-calorimetric method for the characterisation of in-situ thermal transmittance and solar factor of glazed systems is reported. This procedure has been previously adopted in experimental campaigns on triple glazed units with an integrated shading system (Favoino et al., 2016) and on triple glazed units with/without smart glass panes (Bianco et al., 2017a(Bianco et al., , 2017b, to assess both the in-situ thermal transmittance and solar factor; and on a double glazed system (Goia et al., 2014b) to assess the in-situ thermal transmittance, and on thermotropic glass panes (Bianco et al., 2015). Furthermore, parts of this methodology have also been previously used for assessing the different energy performance of advanced glazed façades in office buildings (Bianco et al., 2013;Goia et al., 2014a). ...
The performance of glazing systems is usually assessed through the thermal transmittance and the solar factor, two metrics characterised either through calorimetric laboratory tests or calculations. In this paper, the analysis of the performance of a non-calorimetric method for obtaining the in-situ thermal transmittance and solar factor of glazing systems is presented. This method, developed as a trade-off between accurate (and expensive) laboratory tests (which characterise the systems under standardised, “averaged” conditions), and easy and less expensive tests on systems installed in real buildings (under real operative conditions), has been previously adopted for the characterisation of different glazed systems, but never presented and discussed in full detail. The method, suitable for full-scale glazing systems installed in buildings or in test cells, is based on the acquisition of temperature, heat flux, and solar irradiance values. Experimental data are then processed through simple equations and linear regressions to determine the thermal transmittance and the solar factor under real boundary conditions. In this paper, a detailed description of the method, the experimental test rig, and the related expected accuracy is reported. The method is then applied to a case study (a conventional double glazed unit) to give an example of the proposed procedure and to validate it. The results of the case study show the capability of the assessed in-situ thermal transmittance and solar factor to replicate the thermophysical behaviour of the glazing system within a satisfactory degree of accuracy. An in-depth discussion on the observed outcomes from the case study deepens the understanding of the method's performance and the results’ significance.
... Recently, there has been a noticeable work on filling the glass envelope with paraffin, for optimizing the shortcomings of window with small thermal inertia [4][5][6]. This technique absorbs the solar thermal energy directly, which will reduce the heat loss and enhance thermal comfort in building. ...
The present work is to experimentally investigate the optical properties of liquid paraffin contained with Al2O3 nanoparticles for application in glazed envelope. Paraffin-based Al2O3 nanofluids were prepared through two-step method and its transmittance spectrum was measured by a TU-19 FTIR spectrometer. Based on the optical properties of liquid paraffin contained with Al2O3 nanoparticles obtained by model calculation, the changes of optical properties of liquid paraffin filled with and without Al2O3 nanoparticles are compared. The results show that compared with pure paraffin, the presence of Al2O3 nanoparticles decreases the transmittance of liquid paraffin by 15.7% in 5 mm optical path when the concentration is 0.001 vol%, and the nanofluids absorption coefficient is about 20.07 m⁻¹ in the visible spectrum, which is almost 4 times that of pure paraffin. Meanwhile, the addition of Al2O3 nanoparticles makes the reflectivity of paraffin increase by 0.022. This conclusion is useful in analyzing glazed envelope contained Al2O3/paraffin nanofluids and provides a method of solar energy harvesting.
... To improve the behaviour of the system during winter and to exploit its heat storage potentials also in colder period, one envisageable solution is to realize different layers of dynamic shading hosting PCMs characterised by different melting temperatures. A similar approach was used by the Research Group in the development of a responsive opaque façade [61] and in another research project [62]. In this work, due to the aims of the research framework, the system was conceived to manage just the cooling loads. ...
Large transparent surfaces in building façades can be a cause of high energy demand and discomfort conditions in buildings. Since standard static solutions for glazing and shading devices are not sufficient to overcome these drawbacks, a new dynamic shading device based on the integration of phase change materials (PCM) in an alveolar polycarbonate panel was proposed. The concept of the innovative translucent shading is to act as a self-controlling device able to reduce and modulate both light and solar heat gain in the indoor environment and to improve the thermal inertia of the envelope. To provide input data for energy and daylighting computational tools on a building scale, a complete thermal and optical characterisation of the PCMs and of the dynamic shading systems was carried out. Different typologies of PCM (paraffin waxes, salt hydrates and bio-based PCMs) with different melting temperature (in the range of 26–44 °C) and different colour of the polycarbonate panel (blue, green, opal and crystal) were investigated. Specific experimental protocols were implemented to compare the properties of various configurations of the new technology. Results show that the preferable PCMs are the paraffin waxes, due to their stable thermal properties, high latent heat of fusion and narrow melting temperature range. With regard to the thermal resistance of the system, a slightly better performance was measured with the bio-based PCM. According to the optical characterisation, it can be stated that the preferable colours of polycarbonate are green and crystal. The outcomes are promising, but several limits still need to be overcome at the technological and architectural level.
... Moreover, referring to recent research on this subject [20] some performance indices, i.e. efficiency of pre-heating (Eq.1), thermal buffer (Eq.2) and dynamic insulation (Eq.3), were also calculated, as following: ...
The aim of this paper is to study an advanced semi-opaque active façade using a multi-physics modelling approach. The studied façade is to be understood as an integrated energy system as designed with innovative materials and system solutions. It is an envelope building component composed of opaque modules combined with transparent ones, in which multilayer panels are integrated, consisting of nano-structured materials and new-generation photovoltaic systems. The multi-physics approach used for simulations allowed consideration of fluid-dynamics and thermal behaviour of the components, including the phase change material (PCM) occurring in one of the system elements under external microclimatic stress, modifying its heat capacity over time. Numerical modelling based on RANS-turbulence models was implemented to simulate the multi-layer components. In particular, numerical solutions of buoyancy / forced driven flows and temperature fields were developed by means of an energy equation, taking into account the enthalpy variation in the solid/liquid computational domain connected with the phase change process. Simulation results show the airflow and thermal map computed in a chosen constraint configuration of the integrated system façade.
... This can be achieved by the generation of electricity through integrated PVs, the control of solar heat gains and by the extraction of heat from the PVs and the shading device by the air flowing within the cavity. In order to improve the energy and comfort performance of DSFs, diverse effective system geometries and airflow concepts [8] as well as novel integrated designs [13] have been recently investigated. The available studies on the DSF performance show that faç ade design, building and site parameters are identified to be the most important parameters influencing the performance of the DSF [14]. ...
A numerical model is developed for simulating a single or multi–story Double Skin Façade integrating Photovoltaics (DSF-PV). The DSF-PV can co-generate solar electricity and heat, while it also allows daylight to be transmitted to the interior space. The buoyancy-driven air flow inside the cavity may be assisted by a fan to cool down the photovoltaics while providing natural or hybrid ventilation to adjacent zones. Automated roller shades are also implemented in the model and help regulate heating and cooling loads but also control the daylight levels in the indoor space. A parametric analysis for different control strategies for the airflow within the cavity and the roller shading devices is performed with the purpose to apply the proposed methodology to minimize the heating and cooling demand of the DSF-PV system. In addition, a parametric analysis for different adjacent zones floor areas is performed. The simulations show that a DSF-PV system can supply approximately 120kWh/façade area/year covering the yearly electricity demand of the adjacent office if the floor area is approximately less than 3 times larger than the floor area.
... The solar-thermal arrays to be integrated in active solar-thermal facades differ from a regular assembly of solarthermal collectors through specific architectural design prerequisites (colors, shapes), safety in construction, easy maintenance and efficiency, [3]. Recently, several solutions were reported, as those with internally extruded pin-fin flow channels, [4] that offers high efficiency but does not approach the overheating issue, or the ACTRESS façade, [5], based on rectangular solar-thermal collectors ...
The Solar Heating and Cooling Roadmap (2014) set a main focus “on increasing the share of solar thermal energy for the domestic hot water and space heating demand per building, from about 25% to about 60%” with installed systems on or near the buildings. The suitable implementation area at building level is limited, and optimally oriented facades have to be considered. Facades integration adds pre-requisites to the design specifications of the solar thermal collectors, mainly related to the architectural acceptance and good conversion efficiency. A novel solar-thermal collector was developed to specifically address the main challenges brought by facades implementation. The collector with trapeze shape (0.67m² active area, 69.42% nominal efficiency) is used as building block in arrays with various surface areas, shapes and colors, well matching the variety of the buildings facades. A comparative analysis of the solar-thermal arrays of three trapeze collectors and traditional rectangular collectors is presented in the paper. Three facades of single- and three of multi-family houses are comparatively analyzed considering architectural acceptance, functionality, durability (limited tracking) and thermal power output.
... Favoino et al (2014), and others in the field of design and development, have proposed a new approach to the development of new technologies, by means of a method to define the ideal / optimum range of adaptive thermo-optical performance of a glass façade with different reaction times, in order to evaluate the potential of future adaptive glass façades. Among the existing studies, some focus on built-in solutions and prototypes, such as ACTRESS (ACTive, RESponsive and Solar Façade), or user interaction in control systems (Favoino et al, 2016). Goia and Cascone (2014), on the other hand, present the results of an investigation to evaluate the advantages of an ideal adaptive building skin based on the systems of construction of conventional claddings. ...
Sun exposure is a variable phenomenon that forces to conceive building façades as an architectural component that must vary accordingly. On this premise several concepts have been developed that aim to give a dynamic character to the interior-exterior relationship that façades must mediate. In this line, the concept of a Variable Facade is proposed, which corresponds to the application of these ideas in the Chilean context, where the technological and industrial realities do not allow to think of motorization as a unique market solution for variability. Variable Façade is a technical and architectural design concept that ranges from the absence of sun protection to fixed and mobile, mechanized solutions, applied in the control of sun radiation and light transmission with the objective of reaching the best balance between energy performance and environmental comfort for the users of the buildings. The development of this concept is proposed through the combination of 1:5 scale prototype measurement campaigns and simulation processes to bring the experimental results to annual performance analysis. This methodology is proposed as an approach being compatible with the iterations of the architectural design, since it allows to test a greater number of options, avoiding in the prototypes most of the construction variables that the 1: 1 scale forces to solve. We present in this paper the Laboratory of Sun Protections, LAPSO (Spanish acronym for Laboratorio de Protecciones Solares) a measurement platform that will allow the development of the concept of Variable Façade., initial submissions should fulfil the final layout assuming that no revisions shall be necessary
Water-flow glazing (WFG) adaptive facades can significantly enhance the energy efficiency of glazed buildings. Although the energy potential of WFG has already been studied, there remains a research gap between this potential and the control strategies needed. This study evaluates the performance of a smart controller designed to manage active WFG adaptive facades by executing programmed algorithms. These algorithms consider both internal and external ambient conditions in two reduced-scale test cells. The influence of the intelligent controller on the internal cell ambient, the stored water temperature, and the heating energy consumption is examined. The results indicate that the smart control enables the active WFG adaptive facade to reduce the indoor temperature of the test cells during solar radiation hours by absorbing a portion of the internal ambient energy. The stored energy can be used later within a specific time delay, thereby reducing heating energy consumption.
Technological advances in robotics have enabled us to see the concept of kinetics in architecture. Responsive Facades, an example of kinetic architecture, are multifunctional in terms of energy efficiency. The façade system improves thermal and visual performance with less energy in the interior. Various responsive facades are being developed according to changing environmental impacts and spatial conditions. This study aims to comprehensively review recent thermal and daylighting performance studies of responsive facades in the literature. The study aims to use the results of such existing studies to guide future studies by providing feedback on responsive facades. This can help to improve the technical development of such facades and make them suitable for construction or retrofitting. Therefore, in this sense, it contributes to the literature. Studies in the literature are tabulated and interpreted. The study concludes that there are indoor thermal and daylight parameters that designers should consider during building design and that the building should be designed to provide the building with physical conditions for the users to perform their actions most comfortably. It was also found that a responsive façade design can provide indoor thermal visual comfort by using the optimization method more frequently.
Proposing new materials and systems to improve buildings' performance and energy efficiency often requires testing their performance in the field. Experimental performance characterization of new and existing building systems is crucial to understanding their behaviour. Full-scale experimental test cell facilities have been at the forefront of experimental performance evaluation in building-related research, as they provide a realistic representation of buildings, including environmental conditions, assembling challenges, and operational characteristics. In this paper, trends in the design and construction of outdoor testing facilities are first discussed. Then, based on the current literature and the knowledge gained through visits to multiple facilities, the new test cell facility “BeTOP”, located in Toronto (Ontario), is described. BeTOP is a full-scale experimental facility with the capacity to perform multiple experimental tests simultaneously. This paper describes its characteristics, including structure details, testing capabilities, system details, current monitoring campaigns, and future testing potential. The paper concludes by showing that the design of a full-scale testing facility is crucial to observe the long-term performance of new systems under variable boundary conditions in a continental climate with cold winters and hot and humid summers.
Proposing new materials and systems to improve the performance and energy efficiency of buildings is often followed by performance evaluation to monitor how they perform and contribute. Experimental performance characterization of new and existing building materials and systems is crucial to understanding their behaviour in relation to indoor environmental and conditional changes, in addition to outdoor environmental changes. Full-scale experimental test cell facilities have been at the forefront of experimental performance evaluation in building-related research, as they can provide a realistic representation of buildings, which includes environmental conditions, building structure, and operational characteristics. In this paper, the new test cell facility of BeTOP, located in the city of Toronto, Ontario, is introduced as a full-scale experimental facility with the capability of multiple practical tests simultaneously. This paper describes the characteristics of this test cell, including structure details, testing capabilities, system details, previous testing campaigns, and future testing potential. The design of such a full-scale testing facility is shown to be crucial in a continental climate, such as Toronto, to observe the long-term performance of new systems under variable boundary conditions with cold winters and hot and humid summer seasons.
Building energy simulation (BES) tools offer the possibility to integrate double skin façade (DSF) technologies into whole building simulation through dedicated modules or possible workarounds. However, the reliability of such tools in predicting the dynamic heat and mass transfer processes within the DSFs is still to be determined. Therefore, this paper aims to assess the performance of four popular BES tools (i.e. EnergyPlus, TRNSYS, IDA-ICE and IES-VE) in predicting the thermal behaviour of one-storey naturally ventilated DSF in three different ventilation modes. To evaluate their capability to predict thermophysical quantities, we compared the simulation results with experimental data. The results show that it is not possible to identify a tool that outperforms the others for all the analysed quantities, especially for the cavity air temperature, which is the least accurate parameter in all software due to underestimation of the daytime peak. IES-VE seems to be most accurate for Supply Air and Thermal Buffer modes when shading is deployed, while EnergyPlus appears most accurate for Outdoor Air Curtain mode. When it comes to surface temperatures and transmitted solar radiation, TRNSYS appears to be the best-performing software. In addition, this study investigated the challenges that designers may face when modelling a naturally ventilated DSF using whole-building simulation tools. Moreover, the investigation elucidates the challenges that have a more significant effect on the performance of the BES tools in order to reinforce their reliability.
Research in buildings has lately focused on tackling two main issues: reducing energy use and building better and faster to cope with the expected expansion of cities. The building industry has struggled to adapt to these changes as it is one of the world's largest industries yet one of the least digitalized. One of the challenges is that buildings are becoming more complex to meet these goals and integrate more technologies like renewable energy systems. As a result, there is a need to adopt new methods and tools for designing buildings.
This PhD thesis focused on the design and development of Advanced Building Envelopes (ABEs), which are also sometimes referred to as smart, intelligent, or adaptive building envelopes. ABEs are innovative systems that intend to balance multiple performance aspects such as sustainability, aesthetics, and comfortable indoor environments using new technologies and design approaches. Examples of ABEs may be shading systems that slowly adapt their shape during the day following the sun's path or envelope components specifically designed to optimize energy flows and indoor comfort while harvesting solar energy.
This thesis aims to increase the uptake of ABEs in real-world projects by contributing to characterization systems of new envelope technologies and demonstrating the use of performance-based design approaches. Additionally, it also provided robustness assessments and developed best practice guidelines. This work includes simulations of a specific type of ABE that was an external Venetian blind system with integrated photovoltaic modules. The work developed for the case study used a combination of co-simulation, parametric design, and optimization. The actual performance of the system was also verified in a full-scale experiment.
The thesis' findings highlight that using a performance-based approach had several advantages in addition to providing accurate results. Parametrizing the system's design allowed searching and evaluating many more design alternatives, where eclectic designs could be considered and assessed in a much more efficient manner. Using optimization and co-simulation also allowed generating a set of higher-performing solutions from which one could select a suitable alternative. Finally, this work underlines that new design and evaluation methods can be integrated with initiatives aiming to digitalize building processes and increase collaboration across different engineering fields. However, the types of approaches also require users to develop inter-disciplinary skills and challenge the traditional separation of tasks between architects, engineers, and data scientists.
The demand for tall buildings has increased over the past decades for cultural, financial, and technological reasons. Such slender structures are more flexible and vulnerable to wind-induced vibrations. Additionally, wind speed exponentially increases with height, resulting in larger wind loading on higher levels and complex turbulent regimes. Such effects call for more innovative approaches to enhance the resilience of tall buildings while accounting for the sustainability implications. Current methodologies to control the vibrations using auxiliary dampers are typically limited in their applicable bandwidth. The aerodynamic modifications are specific to a particular wind direction and characteristics and cannot adapt to the changing climate or that of flow regimes due to the new construction in the proximity of the target building. There have been major advances in using secondary façades to achieve sustainability through ventilation and energy-saving applications around the world. These advances have resulted in the development of adaptive facades for architectural and energy applications. This review paper discusses the available approaches and potential opportunities to utilize the existing adaptive façade system capabilities (for energy applications) to alter building aerodynamics. For this purpose, the paper concisely discusses aerodynamic modification, surface roughness effects, available bio-inspired approaches, and potential morphing material capabilities to provide valuable insights into understanding the flow-control mechanism of such systems, potentially leading to innovative designs of façade systems. Opportunities have been identified to combine this concept with smart technologies to develop smart façades with the aerodynamic performance that leads to mitigating wind-induced vibration in tall buildings. The review of existing research on this topic opens up opportunities for enhancing the use of facades as active, dynamic, and smart systems that not only enhance the performance of the tall buildings under wind-induced vibrations but also can result in long term energy saving, leading to more resilient and sustainable communities.
Advanced building envelopes (ABEs) are innovative integrated systems that aim to increase the sustainability of buildings by providing flexible and efficient energy management solutions while safeguarding healthy and comfortable indoor environments. These building envelopes operate at the cross-section of architecture, engineering and data science, and often involve transient multi-physical parameters and advanced material properties. The development of ABEs has increasingly relied on building performance simulation (BPS) tools to improve the understanding and management of their complex interrelationships. However, this complexity has sometimes shown to constitute barriers for their real-world implementation, in part caused by the limitations of monolithic legacy BPS tools. One of the most promising alternatives to overcoming these difficulties has been to use co-simulation. Co-simulation allows modelers to use multiple sub-models and link them to enable simultaneous data exchange during simulation runtime. This approach provides added possibilities for implementing advanced control strategies, integrating innovative data-driven inputs, and creating collaborative interdisciplinary and evolutive workflows for building envelopes at different stages and scales in projects.
This article provides a critical overview of the possibilities that co-simulation approaches offer to improve performance assessments of advanced building envelopes. This article also presents current barriers to co-simulation and discusses critical elements to overcome them. Ongoing trends in BPS and information and communication technologies are highlighted, emphasizing how these are transforming the field and creating new opportunities for modelers working both in research and in the industry.
The present article provides an overview about photovoltaic/thermal systems categorised by the temperature of the working fluid: Low-temperature (lower than 60 °C), medium-temperature (between 60 and 90 °C) and high-temperature (higher than 90 °C). Concerning photovoltaic/thermal-air systems for low-temperature use, the majority of studies involve building-integrated non-concentrating systems with phase change materials and working-fluid temperatures at around 30–55 °C. Concerning low-temperature photovoltaic/thermal-water systems, a large number of studies are about non-concentrating configurations appropriate for building-integrated and, in general, domestic applications with working fluids at approximately 50–60 °C. Regarding non-concentrating photovoltaic/thermal systems for medium-temperature use, a large number of references are appropriate for industrial and domestic applications (working fluids: air; water) with around 60–70 °C working-fluid temperatures. The literature review about medium-temperature concentrating photovoltaic/thermal systems shows that the majority of investigations concern photovoltaic/thermal-water systems with concentration ratios up to 190X and working fluids at approximately 62–90 °C, appropriate for domestic and water-desalination applications. As for high-temperature concentrating photovoltaic/thermal systems, most of them have concentration ratios up to 1000X, involve parabolic concentrators and use water (as the working fluid) at around 100–250 °C. Moreover, in the field of high-temperature photovoltaic/thermal systems, most of the configurations are appropriate for building and industrial applications, and consist of triple-junction or silicon-based photovoltaic/thermal cells. In light of the issues mentioned above, a critical discussion and key challenges (in terms of materials, efficiencies, technologies, etc.) are presented.
1791 و 6112 انرژی نهایی مصرف کل 6 از جهان 464 / 4 خام نفت ادل م بشکه میلیارد 3 به 555 / 7 ادل م بشکه میلیارد سال این در بزرگ کننده مصرف دومین مسکونی بخش است. رسیده خام نفت سال در که بوده ت صن از پس ها 6112 مسکونی بخش 64 مصرف کل از درصد است داده اختصاص خود به را جهان انرژی نهایی [ 68 ]. سال در بین انرژی جهانی مصرف رشد اخیر های 1 تا 6 رشد این ایران در که حالی در بوده درصد 5 تا 8 می درصد است جهان در انرژی مصرف رشد متوسط برابر پنج که باشد [ 9 ]. هم چنین سال انرژی ترازنامه به توجه با 1374 مصرف ، از انرژی نهایی 7 / 791 سال در خام نفت ادل م بشکه میلیون 1382 به ، 4 / 1158 درسال 1374 سال در است. رسیده بخش بین در دارد. مصرف افزایش از نشان این و بوده ودی ص انرژی نهایی مصرف روند موال م اخیر های ه ای بخش انرژی، کننده مصرف بیشترین همواره اری ت و عمومی خانگی، های مصرف بین در را سهم داشته انرژی کنندگان طور به و اند سال بین میانگین 1382 تا 1374 بخش این ها 32.62 % داده اختصاص خود به را انرژی مصرف کل از اند [ 14 ] .
La exposición solar es un fenómeno variable que obliga a concebir las fachadas de los edificios como un componente arquitectónico que debe adaptarse a esta variación. Sobre esta premisa se han desarrollado varios conceptos que apun-tan a dar un carácter dinámico a la relación interior-exterior que las fachadas deben mediar. En este artículo se propone el concepto de Fachada Variable, que corresponde a un concepto de diseño técnico y arquitectónico que va desde la ausencia de protección solar a soluciones fijas y móviles mecanizadas, aplicadas para el control de la radiación solar y de la transmisión lumínica con el objetivo de alcanzar el mejor equilibrio entre rendimiento energético y confort ambien-tal para los usuarios de los edificios. El desarrollo de este concepto se basa en la formulación de un método que combina campañas de medición de prototipos en escala 1:5 y procesos de simulación digital para llevar los resultados expe-rimentales al análisis de desempeño anual. Este método es compatible con las iteraciones del diseño arquitectónico, ya que permite probar un mayor número de opciones, evitando a través del uso de prototipos a escala la mayoría de las variables de construcción que la escala 1:1 obliga a resolver con mayor costo y demora. Presentamos en este trabajo el Laboratorio de Protecciones Solares, LAPSO (Laboratorio de Protecciones Solares) una plataforma de medición que permitirá el desarrollo del concepto de Fachada Variable.
The growing demand for both building energy efficiency and indoor environmental comfort is leading to a substantial evolution of the traditional concept of the building envelope. The future building skin is required to be responsive and dynamic, actively regulating the flows of heat, light, air and water from outdoor to indoor and vice versa, in order to effectively respond to ever-changing climatic conditions, occupant comfort and energy efficiency requirements. In the framework of a decade-long research activity on Advanced Integrated Facade, AIF, a new Multifunctional Facade Module called ACTRESS has been conceived: the ACTive, RESponsive and Solar envelope is designed to play different roles through its ability to change its thermo physical behaviour in order to suit the different environmental conditions. This paper briefly illustrates the ACTRESS MFM concept and its functional strategies, focusing on the simulation and the assessment of the performance of such a dynamic envelope. The numerical study was conducted in order to evaluate the potential energy savings achievable with such a facade and to evaluate different design functional strategies and options. The evaluation of the performance in terms of energy savings was done at both component and whole-building level. Moreover this work presents an example of the applicability of Building Performance Simulation tools to the design of an innovative and dynamic facade system, discussing the capability of BPS software in simulating and evaluating the performance of such systems. The results show that the ACTRESS MFM can effectively reduce the total primary energy consumption of an office building up to 55% compared with a reference facade complying with national regulations. On the other hand modelling assumptions and simplifications are needed in order to evaluate the performance of such a system with BPS software, representing a barrier to the design and the adoption of advanced facade systems in the building industry.
The development of dynamic building envelope technologies, which adapt to changing outdoor and indoor environments, is considered a crucial step towards the achievement of the nearly Zero Energy Building target. It is currently not possible to evaluate the energy saving potential of innovative adaptive transparent building envelopes in an accurate manner. This creates difficulties in selecting between competing technologies and is a barrier to systematic development of these innovative technologies.
The main aim of this work is to develop a method for devising optimal adaptive glazing properties and to evaluate the energy saving potential resulting from the adoption of such a technology. The method makes use of an inverse performance-oriented approach, to minimize the total primary energy use of a building. It is applied to multiple case studies (office reference room with 4 different cardinal orientations and in three different temperate climates) in order to evaluate and optimise the performance of adaptive glazing as it responds to changing boundary conditions on a monthly and daily basis. A frequency analysis on the set of optimised adaptive properties is subsequently performed to identify salient features of ideal adaptive glazing.
The results show that high energy savings are achievable by adapting the transparent part of the building envelope alone, the largest component being the cooling energy demand. As expected, the energy savings are highly sensitive to: the time scale of the adaptive mechanisms; the capability of the façade to adapt to the outdoor climatic condition; the difference between outdoor climatic condition and the comfort range. Moreover important features of the optimal thermo-optical properties are identified. Of these, one of the most important findings is that a unique optimised technology, varying its thermo-optical properties between a limited number of states could be effective in different climates and orientations.
The key role of the building envelope in achieving building energy efficiency and indoor comfort for the user has been long established. The most promising-and innovative-strategy for the building envelope of the future is based on a dynamic, active and integrated solution, that is able to optimize the thermal performance, integrate the active elements and systems, and exploit energy from renewable sources. This paper illustrates the most relevant results of a decade-long research activity carried out on active and integrated building envelopes at the Politecnico di Torino, in which numerical analyses and experimental campaigns, involving test cells and field monitoring, have been performed. The overall performances of different façade modules and the thermo-physical behaviour of various components, under different operating strategies, are presented and discussed. The analysis provides information on the contribution of each subsystem, e.g. glazing, sun-shading devices, natural and mechanical ventilation,... to the achieved energy efficiency and the overall performances of different typologies of Double-Skin Façades (DSFs) and Advanced Integrated Façades (AIFs).
In order to evaluate the energy saving performance of various windows on a common basis, three conceptual window models are presented, and an energy consumption index is defined as the ratio of the energy consumption of a given window to the corresponding value of the perfect window. A building energy analysis program, “BuildingEnergy”, was used to evaluate the energy consumption value of different window models. The following results are obtained: the energy saving potential of regulating the emissivity of the window is greater than that of regulating the solar transmissivity, the optimized phase transition temperature of the ideal near infrared solar spectrum regulating window is between 16 and 21 °C, and due to the high absorptivity in the metal state, the single vanadium dioxide (VO2) glazing discussed here behaves differently than the ideal near infrared solar spectrum regulating window, and it shows no obvious solar control advantage in energy savings over the ordinary window, and the phase transition process has no contribution to the energy saving effect of the single VO2 glazing in the summer.
This paper deals with the search for the optimal window-to-wall ratio (WWR) in different European climates in relation to an office building characterized by best-available technologies for building envelope components and installations. The optimal WWR value is the one that minimizes, on an annual basis, the sum of the energy use for heating, cooling and lighting.By means of integrated thermal and lighting simulations, the optimal WWR for each of the main orientations was found in four different locations, covering the mid-latitude region (35° to 60° N), from temperate to continental climates. Moreover, the robustness of the results was also tested by means of sensitivity analyses against the efficiency of the building equipment, the efficacy of the artificial lighting and the compactness of the building.The results indicate that although there is an optimal WWR in each climate and orientation, most of the ideal values can be found in a relatively narrow range (0.30 < WWR < 0.45). Only south-oriented façades in very cold or very warm climates require WWR values outside this range. The total energy use may increase in the range of 5-25% when the worst WWR configuration is adopted, compared to when the optimal WWR is used.
This paper deals with the development and use of innovative glazing systems that utilize Phase Change Material (PCM) to achieve dynamic and responsive behaviour. The coupling of a PCM and glass panes could be a way of improving the low thermal inertia of fenestrations and could be an effective way of collecting, storing and exploiting solar energy at a building scale.
In the present work, a simple prototype of a PCM glazing system has been proposed and its energy performance has been analysed and compared with a conventional fenestration. The two glazing technologies were installed on an south facing outdoor test cell, in a temperate sub-continental climate. The surface temperatures, transmitted irradiances and heat fluxes of both the PCM glazing and the reference fenestration were measured during an extensive experimental campaign. Summer, Mid-season and Winter days were considered during the analysis, in both sunny and cloudy weather conditions, in order to assess the energy performance of the PCM glazing under different boundary conditions.
The experimental results have highlighted a good ability of the PCM glazing to store solar energy and to smooth and delay peak values of the total heat flux. In summer the PCM prototype allows the energy gain to be lowered by more than 50%, compared to the traditional fenestration. In winter, a suitable reduction in the heat loss during the day can be observed, but the direct solar gain is also drastically reduced and the application of this technology for passive solar heating purpose might not always be effective. The obtained results have pointed out the promising performance of PCM glazing, even though a careful integration of the PCM glazing component with the control strategies of the indoor air temperature (e.g. night cooling) is necessary.
Responsive building elements (RBEs), renewable energy sources (RES) and energy storage within the building are considered as a key issue for the development of zero energy/emission buildings. The exploitation at the building scale of RES and of the opportunities offered by the environment can be achieved through the ability of the RBEs to dynamically adapt to changing environmental conditions. Among various concepts, advanced integrated facades (AIFs) are probably one the most promising technologies, due to the important role that the building envelope plays in controlling the energy and mass flows between the building and the outdoor environment. In the framework of a research activity on AIFs, a new multifunctional facade module (MFM), called ACTRESS (ACTive, RESponsive and Solar) has been conceived and a prototype built for analyzing the energy performance and the potentialities of such envelope components. The work presented in the paper introduces the MFM features and illustrates the results of an experimental campaign performed for the winter (heating) season.
Progress in the development of energy-efficient coatings on glass has led to the study of smart glass with special functional coatings that can regulate solar energy in response to an external stimulus. Thermochromic smart windows are considered attractive because they are visibly transparent and can intelligently control the amount of solar heat (mainly in the near-infrared region) in response to changes in ambient temperature. Discovered over 50 years ago, VO2 is the most promising thermochromic material; however, related materials have not been commercialized because of problems related to cost-efficient preparation, stability and performance. To date, gas-phase deposition methods, such as sputtering and chemical vapor deposition, are the most common methods for the fabrication of VO2 films, but these methods are still dependent on innovative technologies to meet the requirements of practical applications and are excluded from the topic of the current paper. This paper reviews the state-of-the-art solution processes used to prepare VO2 films, with a special emphasis on polymer-assisted deposition methods. The VO2 films prepared by these methods show controllable morphology and thickness and complex optical properties compared with those prepared by gas-phase methods. In fact, single-layered films exhibit the highest integrated visible transparency (43%) and solar-energy modulation ability (14%). These studies suggest that chemical preparation is inexpensive, easy to scale up, and best suited for the practical applications of the fabricated materials.
The term Net ZEB, Net Zero Energy Building, indicates a building connected to the energy grids. It is recognized that the sole satisfaction of an annual balance is not sufficient to fully characterize Net ZEBs and the interaction between buildings and energy grids need to be addressed. It is also recognized that different definitions are possible, in accordance with a country's political targets and specific conditions. This paper presents a consistent framework for setting Net ZEB definitions. Evaluation of the criteria in the definition framework and selection of the related options becomes a methodology to set Net ZEB definitions in a systematic way. The balance concept is central in the definition framework and two major types of balance are identified, namely the import/export balance and the load/generation balance. As compromise between the two a simplified monthly net balance is also described. Concerning the temporal energy match, two major characteristics are described to reflect a Net ZEB's ability to match its own load by on-site generation and to work beneficially with respect to the needs of the local grids. Possible indicators are presented and the concept of grid interaction flexibility is introduced as a desirable target in the building energy design.
The building enclosure plays a relevant role in the management of the energy flows in buildings and in the exploitation of solar energy at a building scale. An optimized configuration of the façade can contribute to reduce the total energy demand of the building.Traditionally, the search for the optimal façade configuration is obtained by analyzing the heating demand and/or the cooling demand only, while the implication of the façade configuration on artificial lighting energy demand is often not addressed.A comprehensive approach (i.e. including heating, cooling and artificial lighting energy demand) is instead necessary to reduce the total energy need of the building and the optimization of the façade configuration becomes no longer straightforward, because non-linear relationships are often disclosed.The paper presents a methodology and the results of the search for the optimal transparent percentage in a façade module for low energy office buildings. The investigation is carried out in a temperate oceanic climate, on the four main orientations, on three versions of the office building and with different HVAC system’s efficiency. The results show that, regardless of the orientations and of the façade area of the building, the optimal configuration is achieved when the transparent percentage is between 35% and 45% of the total façade module area. The highest difference between the optimal configuration and the worst one occurs in the north-exposed façade, while the south-exposed façade is the one that shows the smallest difference between the optimal and the worst configuration.
This paper presents the results of a numerical and experimental study on thermally efficient windows. An experimental investigation using spectrophotometry was realized on simple and composite glass windows filled with air or PCM. The transmittance and reflectance tests indicate large reductions in the infrared and ultraviolet radiations while maintaining good visibility. The number of glass sheets, their thickness and the gap between them were also investigated. The numerical model is based upon a one dimensional formulation of the composite window. The program was optimized, and the predicted results were compared with experimental measurements.
An all-solution process was developed to prepare VO2-based double-layered films containing SiO2 and TiO2 antireflection layers. These double-layered films were optimized to improve luminous transmittance (Tlum) and switching efficiency (ΔTsol). The substrate/VO2/TiO2 double-layered structure showed the largest improvement of 21.2% in Tlum (from 40.3% to 61.5%). Tlum could be further improved to the maximum of 84.8% by combining film thickness optimization and antireflection layer deposition. ΔTsol (usually below 10% for single VO2 films) could be improved by adjusting the position of antireflection peaks (the highest ΔTsol was 15.1%). A sample with balanced Tlum and ΔTsol showed Tlum of about 58% (20°C) and 54% (90°C), and ΔTsol of 10.9%. This work is an important technical breakthrough toward the practical application of VO2-based smart windows.
Smart window coating is fabricated by using vanadium dioxide (VO2) thin film. The VO2 thin film is nanocrystal structured and has low phase transition temperature which is about 35°C. This kind of thin film is infrared-optically transparent in the semiconductor phase at low temperatures and highly reflective in the metallic phase at high temperatures. Based on the VO2 thin film, a multilayered structure for smart window is designed and fabricated. The multilayered structure is optically transparent for visible light whether at low temperatures or high temperatures, and is transparent at low temperatures and opaque at high temperatures for infrared light, which is smart for adjusting infrared transmittance. This type of multilayered structure is potential to be applied to green smart windows to realize energy saving function.
Subject of our recent investigations is the utilization of a reversible thermotropic material for a self-regulating sun protection glazing that controls the solar energy input in order to avoid overheating. Based on the well-established UV curing technology for laminated glass a superior thermotropic material with tunable switching characteristics and of low material costs was developed. The polymer layer contains core/shell particles homogeneously dispersed in a UV-cured resin. The particle core in turn consists of an n-alkane mixture that is responsible for the temperature-induced clear/opaque switching. To obtain particles of well-defined size and with a narrow size distribution, the miniemulsion polymerization technique was used. The visible and solar optical properties (normal–normal, normal–hemispherical, and normal–diffuse transmittance) in the off (clear) and in the on state (opaque) were determined by UV/Vis/NIR spectroscopy. Samples containing particles of high median diameter (>800nm) primarily scatter in the forward direction. However, with smaller particles (300–600nm) a higher backscattering (reflection) efficiency was achieved. The largest difference in the normal–hemispherical transmittance could be found with a particle amount of 6% and a median scattering domain diameter of ∼380nm.
The control of sunlight can be achieved either by electrochromic or polymer-dispersed liquid crystal (PDLC) smart windows. We have recently shown that it is possible to homeotropically align fluid mixtures of low molecular mass liquid crystal with a negative dielectric anisotropy, and a liquid crystalline monomer, in order to obtain electrically switchable chromogenic devices. They are new materials useful for external glazing. In fact, they are not affected by the classical drawbacks of PDLCs. In this paper we present a new self-switchable glazing technology based on the light-controlled transmittance in a PDLC device. The self-adjusting chromogenic material, which we obtain, is able to self-increase its scattering as a function of the impinging light intensity. The relationship between the electro-optical response and the physical–chemical properties of the components has been also investigated.
This paper describes the results of experimental tests and computer simulation modelling aimed at evaluating the performance of an electrochromic (EC) window with respect to solar control in buildings. The research is carried out by a test-cell equipped with a small area EC double glazing unit (EC-DGU) where one pane consists of an EC device and the other of a clear glass. The performance of the device on global light transmittance control, internal temperature control and solar heat gain control, is investigated in summer-time under real sky conditions as a function of time, test-cell orientation and switching strategies (static and dynamic). Both experiments and numerical analysis show that the decrease of the heat load affecting the test-cell, normalized respect to a clear float glass, is maximum when the EC-DGU is set to its lowest transmitting state and amounts to about 50% for west orientation and about 60% for south orientation. In this latter, thermal load reduction registered when the EC DGU is driven in the dynamic mode (31%) is similar to that of a reflective low-e glazing.
Several studies have shown that the use of switchable windows could lower the energy consumption of buildings. Since the main function of windows is to provide daylight and visual contact with the external world, high visible transmittance is needed. From an energy perspective it is always best to have the windows in their low-transparent state whenever there are cooling needs, but this is generally not preferable from a daylight and visual contact point of view. Therefore a control system, which can be based on user presence, is needed in connection with switchable windows. In this study the heating and cooling needs of the building, using different control mechanisms were evaluated. This was done for different locations and for different combinations of switchable windows, using electrochromic glazing in combination with either low-e or solar control glazing. Four control mechanisms were investigated; one that only optimizes the window to lower the need for heating and cooling, one that assumes that the office is in use during the daytime, one based on user presence and one limiting the perpendicular component of the incident solar irradiation to avoid glare and too strong daylight. The control mechanisms were compared using computer simulations. A simplified approach based on the balance temperature concept was used instead of performing complete building simulations. The results show that an occupancy-based control system is clearly beneficial and also that the best way to combine the panes in the switchable window differs depending on the balance temperature of the building and on the climate. It is also shown that it can be beneficial to have different window combinations for different orientations.
The poly-O-anisidine (POA) electrochromic film was obtained by cyclic voltammetry method. The optical properties of the electrochromic film were investigated by UV–vis spectrophotometer and FT-IR spectroscopy. The results show that the different colors of the electrochromic film can be achieved, which exhibit as light yellow-green, light dark green and blue. The maximum difference of the UV–vis absorption of the film is about 40% between −0.5V and 0.9V and the biggest different average emissivity dynamic of the film is 0.553 in the wavelength of 8–14μm regions.
An interior sun protection system consisting of vertical slats filled with phase change material (PCM) was monitored from winter 2008 until summer 2010. While conventional interior sun protection systems often heat up to temperatures of 40°C or more, the monitoring results show that the surface temperature on the interior side of the PCM-filled slats hardly ever exceeded the PCM melting temperature of 28°C even in case of long-term intense solar radiation. As long as the PCM is not fully melted, the latent heat storage effect reduces the solar heat gain coefficient (g-value) of the sun protection system to 0.25 for a totally closed blind, and 0.30 for slats set at 45° (the g-values of the same system without PCM are 0.35 and 0.41, respectively). This reduced the maximum air temperature in the offices by up to 2K in contrast to a reference room with a comparable conventional blind. The sun protection system with PCM therefore considerably improves thermal comfort. In order to discharge the PCM, the stored heat must be dissipated during the night. In climates with sufficiently low outside air temperatures, this is best achieved using a ventilation system in combination with tilted windows.
This paper focuses on the performances of flexible all-polymer electroemissive devices as active materials for thermal control of satellites. These devices are made of a semi-interpenetrating network of poly(ethylene oxide) and poly(3,4-ethylenedioxythiophene) (PEO/PEDOT) where PEDOT is embedded within the PEO network and swollen with an ionic liquid. The reflectivity at 2.5μm and the emissivity in the infrared region between 5 and 50μm were measured at room temperature as well as the stability in vacuum. It was thus pointed out that these films exhibit interesting switching properties as notably a maximal emissivity contrast of 0.31 with a switching time less than 3min. Moreover a low energy was required (473Jm−²) to modulate the emissivity of the devices.
Active transparent façades constitute a building envelope component that is becoming more and more common in high-rise office buildings. Many designers have opted for a ventilated façade, claiming that this technology is sustainable, reduces energy consumption and enhances indoor comfort conditions, but these claims have often proved to be wrong. From the thermofluid-dynamic analysis point of view, few design procedures or sufficiently detailed, reliable and easy to use simulation software are available for ventilated façades. A numerical model that has been developed to simulate the thermal behaviour of mechanically ventilated active transparent façades is presented in this paper. The model, developed in the Simulink/Matlab® environment, simulates the façade in both steady-state and transient conditions and provides the temperature of the different layers of the façade structure and the corresponding heat fluxes as output data. The model has been validated by comparing the simulation results with experimental data obtained in the laboratory. A test has also been performed on a real façade under actual operating conditions. The model performance has resulted to be quite promising. The accuracy of the prediction of the temperature is good, while the simulations of the heat fluxes are slightly less reliable for some operative conditions.
The results of an extensive experimental campaign on a climate façade with a mechanically ventilated air gap, carried out at the Department of Energetics at the Politecnico di Torino, are presented. Measurements were performed utilizing the TWINS (Testing Window Innovative Systems) test facility, which consists of two outdoor cells, one used for reference purposes, and the other which adopts different active façade configurations. The energy efficiency of the façade and the thermal comfort implications have been evaluated considering the ability to pre-heat the ventilation air in the winter season, and the ability to remove part of the solar load during the summer season; the normalized daily energy passing through the façade and the normalized surface temperature of the inner glass were analysed. The improvement in performance obtained by varying the configuration and operative conditions (changing the air flow rate, the shading device and the internal glazing) has been investigated.
Electrochromics is introduced as a key “green” technology for producing massive energy savings in the built environment, jointly with indoor comfort and financial benefits. The paper discusses basic electrochromic device designs, useful oxide materials and their nanostructures, and elements of a theoretical description of the electrochromic phenomenon. It also surveys critical manufacturing technologies and their pros and cons. Focus is then put on electrochromic foil technology, which is shown to be capable of mass fabrication via roll-to-roll web coating and continuous lamination.
Latent heat thermal energy storage (LHTES) is becoming more and more attractive for space heating and cooling of buildings. The application of LHTES in buildings has the following advantages: (1) the ability to narrow the gap between the peak and off-peak loads of electricity demand; (2) the ability to save operative fees by shifting the electrical consumption from peak periods to off-peak periods since the cost of electricity at night is 1/3–1/5 of that during the day; (3) the ability to utilize solar energy continuously, storing solar energy during the day, and releasing it at night, particularly for space heating in winter by reducing diurnal temperature fluctuation thus improving the degree of thermal comfort; (4) the ability to store the natural cooling by ventilation at night in summer and to release it to decrease the room temperature during the day, thus reducing the cooling load of air conditioning. This paper investigates previous work on thermal energy storage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermophysical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. and heat transfer enhancement are discussed. We show that with suitable PCMs and a suitable incorporation method with building material, LHTES can be economically efficient for heating and cooling buildings. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.
From the thermal point of view, windows represent the weak link between the internal and external ambients of a room. In cold climates, they are responsible for 10–25% of the heat lost from the heated ambient to the external atmosphere. In hot climates, the excessive solar radiation entering the internal ambient through the windows leads to increasing the cooling load of the refrigeration system. The use of absorbing gases filling the gap between glass sheets appears to be an alternative solution for thermally insulated glass windows. The other options one may incorporate filling materials such as silica aerogel or a PCM. In this work, a comparison between the thermal efficiency of two glass windows one filled with an absorbing gas and the other with a PCM and exposed to solar radiation in a hot climate is done. To model double glass window filled with infrared absorbing gases, a CW real gas model is used. A radiative convective conductive model and a radiative conductive model were investigated. Three mixtures of gases were used; a strongly absorbing gas mixture, an intermediate absorbing gas mixture and a transparent to infrared radiation mixture. To model the double glass window filled with a PCM, a relatively simple and effective radiation conduction one dimensional formulation is used. Heat transfer through the window is calculated and the total heat gain coefficients are compared and discussed.
In recent years the use of thermal energy storage with phase change materials has become a topic with a lot of interest within the research community, but also within architects and engineers. Many publications have appeared, and several books, but the information is disseminated and not very much organised. This paper shows a review of the latest publications on the use of phase change materials (PCM) in buildings. The paper compiles information about the requirements of the use of this technology, classification of materials, materials available and problems and possible solutions on the application of such materials in buildings.
One of the most important methods of saving energy in a building is by carefully designing its facade. A 'double skin façade' is optimally one of the best options in managing the interaction between the outdoors and the internal spaces. It also provides some architectural flexibility to the design. Recently it has received much attention as opposed to the more typically glazed curtain wall. This is because of its ability to efficiently reduce energy and therefore saves cost. The amount of energy saved depends on the climate and the design chosen. The design of the DSF involves decisions on geometric parameters, glass selection, ventilation strategy, shading, daylighting, aesthetics, wind loads, and maintenance and cleaning cost expectations. DSF has an impact on several aspects of the design phase of a building. For example, thermal properties, acoustic characteristics and daylighting are affected in the exploitation phase of the building. In addition, in terms of building safety point of view, fire propagation maintenance or glazing thermal break must be taken into account. Currently, little work has been done on the behaviour of DSFs in hot and humid climates. This paper shall review previous studies made on double skin façade systems (DSFS) in buildings.
A survey on prototype and currently commercial dynamic tintable smart windows has been carried out. The technologies of electrochromic, gasochromic, liquid crystal and electrophoretic or suspended-particle devices were examined and compared for dynamic daylight and solar energy control in buildings. Presently, state-of-the art commercial electrochromic windows seem most promising to reduce cooling loads, heating loads and lighting energy in buildings, where they have been found most reliable and able to modulate the transmittance up to 68% of the total solar spectrum. Their efficiency has already been proven in hot Californian climates, but more research is necessary to validate the products for colder climates, and to improve furthermore the commercial products in order to control the indoor climate in a more energy efficient way by reducing both heating and cooling loads.
Phase change materials (PCMs) are regarded as a possible solution for reducing the energy consumption of buildings. By storing and releasing heat within a certain temperature range, it raises the building inertia and stabilizes indoor climate. Within this work, a state-of-the-art review is given on the knowledge of PCMs today for building applications.
Double glazings combined with phase change materials (PCM) result in daylighting elements with promising properties. Light transmittances in the range of 0.4 can be achieved with such facade panels. Compared to a double glazing without PCM, a facade panel with PCM shows about 30% less heat losses in south oriented facades. Solar heat gains are also reduced by about 50%. This results in calculated Ueff-values of −0.3 to −0.5 W m−2 K−1, depending on PCM used. For an optimised panel, we calculated an Ueff-value of −0.6 W m−2 K−1. Although the Ueff-value of a double glazing is −0.8 W m−2 K−1, the PCM-systems may prove advantageous in lightweight constructed buildings due to their equalised energy balance during the course of day. Facade panels with PCM improve thermal comfort considerably in winter, especially during evenings. In summer, such systems show low heat gains, which reduces peak cooling loads during the day. Additional heat gains in the evening can be drawn off by night-time ventilation. If a PCM with a low melting temperature of up to 30 °C is used, thermal comfort in summer will also improve during the day, compared to a double glazing without or with inner sun protection. A homogeneous appearance of the PCM-systems is achievable by use of a concealment, like a screen-print glazing.
A comprehensive review of various possible methods for heating and cooling in buildings are discussed in this paper. The thermal performance of various types of systems like PCM trombe wall, PCM wallboards, PCM shutters, PCM building blocks, air-based heating systems, floor heating, ceiling boards, etc., is presented in this paper. All systems have good potential for heating and cooling in building through phase change materials and also very beneficial to reduce the energy demand of the buildings.
Results of an extensive measurement campaign performed on an active transparent façade during actual operating conditions are presented. The main aims of the research were: to assess the actual façade performance, both in terms of energy savings and enhanced comfort conditions, to obtain more detailed knowledge of its thermofluid dynamic behaviour and to highlight the weak points of this relatively new technology that still requires further improvement. The analysed component consists of a transparent mechanically ventilated façade integrated with an HVAC system. The façade is used as the exhaust outlet of the HVAC system. The temperatures, heat fluxes and air velocities in the ventilated façade were continuously monitored, over a period of 2 years, using a monitoring system with 34 sensors. In the paper, attention is focused on the measurement techniques that were adopted and on the critical analysis of the experimental data.
Over the last decade, artificial intelligence technology has moved from being an obscure research project within NASA to being an important tool for NASA mission controllers who operate spacecraft such as the Mars Exploration Rovers and the International Space Station. This achievement is in part due to advances in artificial intelligence, but a critical part is due to the development of a good understanding of mission controllers needs and how they interact with computer software. This talk presents the development of these interactive software tools, with focus on user involvement and how lessons learned were applied to improve the technology.
Modelling the air infiltrations in the second skin façade
- F Dimaio
- A H C Van Paassen
DiMaio, F. & Van Paassen, A.H.C., (2001). Modelling the air infiltrations in the second skin façade. In the 4th IAQVEC
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Conference Proceedings: pp. 873-880. Changsha, China.
Thermal insulation --Building elements --In-situ measurement of thermal resistance and 1021 thermal transmittance --Part 1: Heat flow meter method
ENISO 9869-1:2014, 2014.Thermal insulation --Building elements --In-situ measurement of thermal resistance and
1021
thermal transmittance --Part 1: Heat flow meter method.
Building components and building elements --Thermal resistance and thermal transmittance --1023 Calculation method
ENISO 6946:2007, 2007.Building components and building elements --Thermal resistance and thermal transmittance --1023
Calculation method.
Integrating Environmentally Responsive Elements in Buildings
IEA -ECBCS Annex 44, 2010. Integrating Environmentally Responsive Elements in Buildings, Design Guide -Vol. II.