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Thermal and energy performance of a building with PV-applied double-skin façade
Abstract
A double-skin façade (DSF) is a passive solar design method for reducing building energy consumption. When a photovoltaic (PV) is applied as cladding for the spandrel area, various heat-transfer phenomena occur on the surface of the PV and consequently reduce the heat transferred into the interior cavity. In addition, air circulation through the top and bottom vents of the DSF cavity promotes the release of heated air inside the double skin, improving building cooling and temperature reduction of the PV. Thus, PV power generation is increased. The purpose of this study was to investigate and compare the thermal performance and energy consumption of a test building with a glass DSF and a PV-applied DSF (PV-DSF). The behaviour of the building and the overall system was evaluated using Trnsys dynamic analysis software. The results showed that heat transferred to the PV-DSF cavity decreased significantly compared with the glass DSF cavity. Although this was disadvantageous in winter, it was advantageous during summer to decrease cooling energy demand. In addition, 1438 kWh of electricity was generated, which corresponded to about 18% of the annual building energy consumption required. Moreover, the building energy consumption of the PV-DSF decreased by 15% compared with the glass DSF.
... Mirzaei and Carmeliet (2015) showed that the stepped arrangement of modules on a pitched roof increases the ventilation rate, improving its performance. Luo et al. (2018), Yu et al. (2017), Wang et al. (2017) studied the performance of naturally ventilated PV-DSF. Yun et al. (2007) found a maximum reduction in the module temperature for natural ventilation. ...
... While for winter season DSF without ventilation performs better in heating load reduction. Among the technologies, perovskite cell with the generation of about 29.7kWh/m 2 year showed better performance than DSSC 15.7 kWh/m 2 year and a-Si of 12.7 kWh/m 2 year (Yu et al. 2017). A simulation was performed to compare the performance of PV-DSF to glass DSF. ...
Integration of Photovoltaic (PV) technologies with building envelopes started in the early 90 to meet the building energy demand and shave the peak electrical load. The PV technologies can be either attached or integrated with the envelopes termed as Building Attached (BA)/Building Integrated (BI) PV system. The BAPV/BIPV system applications are categorized under the building envelope roof and facades as PV-roof, PV-Skin Facade, PV- Trombe Wall, PV claddings, and louvers. This review covers various factors that affect the design and performance of the BAPV/BIPV system applications. The factors identified are air gap, ventilation rate, a tilt angle of PV shading devices, adjacent shading, Semitransparent PV(STPV) glazings design, Cell Coverage Ratio (CCR), transmittance,
Window to wall ratio (WWR), and glazing orientation. Furthermore, the results of the possible factors are compared to building locations. This
review article will be beneficial for researchers in designing the BAPV/BIPV system and provides future research possibilities.Keywords: Photovoltaic,Double skin Facades,Trombe wall,Glazings
... Building cooling energy consumption and reduction in cooling load by applying PV panels as shading devices [9,10,37,38] is studied in EnergyPlus (NREL). The house model is made in SketchupPro (Trimble Inc, USA) by using Euclid Extension to run EnergyPlus. ...
... A model with PV panels at 1 m apart is shown in Figure 13. The cooling load of building decreases with the increase of shaded rooftop [9,10,[37][38][39]. Flat plate PV panels provide maximum reduction in cooling load as shown in Figure 14. ...
PV estimation in an urban environment requires detection of rooftop area, design of PV system based on optimization on PV placement distance and the study of additional benefit of lower cooling load of building by shading provided by PV panels. The study is aimed at policymakers to introduce renewable energy policy towards net-zero energy buildings in urban areas. In this research, the capital city of Pakistan, Islamabad is analyzed for rooftop PV capabilities using deep learning algorithms. The area of the rooftop is calculated by extracting buildings in high-resolution satellite imagery using a deep learning algorithm. The site location is analyzed for available solar energy resources. The distance between the rooftop PV array is optimized based on self-shading losses, coefficient of performance, energy yield, net-zero energy analysis and reduction of cooling load of the building provided by PV arrays as shading devices. The 40 km2 area of Islamabad considered in this research can generate 1,038 GWh of solar energy annually from its 4.3 km2 rooftop area by installed capacity of 447 MW PV panels rows placed at 0.75 m apart. The electricity generated by Islamabad can curtail residential load from the national grid and form a near net-zero energy zone while the electrical energy from the grid can be provided to the industries to enhance the economy and reduce unemployment in Pakistan.
... These results further suggest that South facing offices incorporating facades with a g-value of 0.5 and U-value of around 2 W/m 2 K would require minimal heating and cooling during winter. Although this measure will increase energy demand at other times of the year, assuming much of this energy can be derived from various green sources such as photovoltaic modules installed in the spandrel area of the façade (Yu et al, 2017) and/or air source heat pumps, which is a realistic proposition given that irradiation levels and dry-bulb temperatures are higher during these periods, should help reduce CO2 emissions (Wang and Arya, 2016). ...
Office buildings require a significant amount of energy for heating and cooling purposes. A possible strategy for reducing this energy in order to reduce carbon dioxide emissions and operational costs is to specify high-performance facades. However, their benefits remain unclear for UK conditions with mild winters and cool summers. This paper reports on an investigation on the energy demand of offices in London, UK, incorporating facades with U-values between 1·2 and 2·6 W/(m^{2}K) and g-values between 0·3 and 0·5 using the dynamic simulation tool Tas. Other variables considered included climate change (using the Chartered Institution of Building Services Engineers’ future weather data files), low internal gains, long working hours and office orientation. It was found that, apart from the case when internal gains are low, cooling is overwhelmingly necessary and energy usage increases with decreasing U-value and decreases with decreasing g-value. Low-U-value facades act to reduce conduction heat losses, thereby increasing energy use. Conversely, low-g-value facades act to reduce solar heat gains, thereby reducing the energy required for cooling. The results are used to highlight deficiencies in The Building Regulations 2010 and where more advice would be of benefit. The paper also discusses the merits of a number of strategies for reducing energy use in office buildings.
... The integration of PV system shows positively effect on the building sensible cooling energy demands and in increasing the peak production power. Yu et al. (2017) conducted a similar study on a double skin facade with integrated PV panels in R.O. Korea. ...
Advanced building envelope systems can contribute to the reduction of greenhouse gas emissions and improve the energy flexibility of buildings while maintaining high levels of indoor environmental quality. Among different transparent envelope technologies, the so-called double skin facades (DSFs) have been since long time proposed as an effective, responsive building system. The implementation of DSF systems in a real building is highly dependent on the capabilities of the prediction of their performance, which is not a trivial task. The possibility to use whole-building energy simulation (BES) tools to replicate the behaviour of these systems when integrated into a building is, therefore, a crucial step in the effective and conscious spread of these systems. However, the simulation of DSFs with BES tools can be far more complex than that of more conventional facade systems and represents a current barrier. This article is based on evidence from the scientific literature on the use of BES tools to simulate DSF, and provides: (i) an overview of the implementation of DSFs systems in BES tools, with the current capabilities of some selected BES tools; (ii) a comprehensive review of recent, relevant simulation studies, where different approaches to modelling and simulating DSFs are reported; and (iii) the identification of current gaps and limitations in simulation tools which should be overcome to increase the possibilities to correctly predict the performance of DSFs when integrated into a building.
... By simultaneously functioning as envelope material and power generator, building integrated photovoltaic (BIPV) systems can be more costeffective and can provide savings in materials and energy costs, reduce carbon dioxide emissions and add architectural enhancement to the building (Agathokleous and Kalogirou, 2016). The final article (Yu et al., 2017) investigated and compared the energy and thermal performance of a building with a glass DSF and a PV-integrated DSF through dynamic simulation modelling. The results showed that the PV-DSF system was advantageous during summer to decrease cooling load. ...
ZEMCH aims to tackle issues arising in the delivery of socially, economically and environmentally sustainable built environments in developed and developing countries, which accommodate people with different socioeconomic backgrounds, ages and abilities. Annually, the conference brings together researchers and government and industry professionals to discuss the problems and delights of design, manufacturing and marketing surrounding the delivery of low-carbon dioxide and, ultimately, zero-energy houses that are customisable on a mass scale, either built or under construction in developing and developed countries. The ZEMCH network was established in 2010 after a number of international industry-academia collaborative study tours were organised in order to observe the state-of-the-art production and sales facilities of leading low-to zero-energy or carbon dioxide emission sustainable housing manufacturers in Japan, which also practise inclusive design. Presently, the ZEMCH network consists of 667 global partners from academia, industry and government based in over 45 countries. Built upon the success of previous conferences, the fourth conference in the ZEMCH series attracted a large number of submissions from all around the world, which were subjected to a two-stage peer review process. With the objective of producing a high-quality conference, papers were selected for presentation at the conference and publication in the proceedings. The scope of the conference is extensive and 64 oral presentations were delivered. Extended and revised versions of the top articles, which were selected by the ZEMCH scientific committee and the Engineering Sustainability editorial panel, are included in this themed issue to disseminate further the leading research in this field first presented at ZEMCH 2015. The selected papers cover key research topics in the areas of sustainable built environments, including green building rating systems, intelligent building technologies, gamification in the built environment, four-dimensional (4D) building information modelling (BIM), vertical green walls and building-integrated photovoltaics (BIPV). A wide range of 'green' building rating and assessment tools are used around the world to help mitigate the environmental impacts of the built environment through the measurement and recognition of sustainability performance (AlWaer and Kirk, 2012; Haroglu, 2013). Sustainability is now a top priority in the Middle East region and countries like Jordan, Qatar and UAE have developed their own green building rating system to incorporate social, economic, environmental and cultural aspects in modern construction. The first article in this issue (Shareed and Altan, 2017) assessed and compared the different building sustainability rating systems in the Middle East with well-established and leading international green building certification systems such as the Building Research Establishment Environmental Assessment Method (Breeam) and Leadership in Energy and Environmental Design (Leed). The assessment focused on the vision and structure, categories, weightings, levels and certification processes. The study highlighted the importance of developing and employing local green building codes or systems to achieve sustainability targets according to national priorities and regulations. The second article in this issue (Gadakari et al., 2017) focused on finding the relationship between building intelligence and sustainability by developing a predictive statistical model that can estimate the impact of intelligent building technologies (IBTs) on sustainability scores of green building rating tools. The data were collected from 40 Breeam-and Leed-certified buildings in the UK and Europe and were subjected to qualitative and quantitative analysis methods. The work highlighted the numerous benefits that IBTs can provide, and the analysis proved that there was a strong positive correlation between the number of IBTs used in a building and the scores achieved. One of the most important challenges faced by the building sector today is tackling the 'energy performance gap', which is the disparity in energy use of buildings, from predicted performance at the design stage to actual performance in use (Baborska-Narozny and Stevenson, 2017; Johnston et al., 2015; Robinson et al., 2016). The third paper in this issue (Patlakas and Raslan, 2017) discusses the significant role of building users in determining the energy use of buildings and the influence of their behaviour on the 'performance gap'. The authors attempted to addressed the issue by using 'gamification' or game-based tools to help users better understand the issues relating to building performance, post-occupancy evaluation surveys and facilities management. The study demonstrated both the advantages and challenges of gamification which were in agreement with the experiences reported in the literature.
Currently, several façade systems exist to enable sustainable building design. The biggest challenges for façade designers are to identify new technology and effective, sustainable systems that enable high structural and sustainable performance while producing a good aesthetic. Therefore, this paper aims to review the performance of existing façade systems for sustainable building designs and their limitations. Among modern façade systems, Double Skin Façades (DSF) show promise for energy efficiency, indoor air quality, and aesthetics. However, they face challenges like sound transmission between floors, higher initial costs, and outer skin vibrations. Furthermore, adaptive façades gained popularity for their active methods of achieving energy performance and comfort benefits but encountered complexities in design and construction, demanding codes and standards. Green wall systems enhance air quality and aesthetics, while photovoltaic façade systems reduce electricity costs, but both systems face higher initial costs and maintenance challenges. The review indicates that to produce a sustainable building design, architects, engineers, and builders must consider a sustainable façade system that enables high energy efficiency, less cost, better occupant comfort, and fewer environmental impacts.
Currently, there are several façade systems that exist to enable sustainable building design. The most challenges for façade designers are to identify new technology and effective sustainable systems that enable high structural and sustainable performance while producing a good aesthetic. Therefore, this paper aims to review the performance of existing façade systems and technologies used for sustainable building designs. This review showed that the double skin façade system is the most promising technological solution to improving energy performance and producing sustainable buildings. Furthermore, adaptive façade systems also enhance building performance and occupant comfort through active concepts. However, the lack of design standards, complex design and construction challenges hinder the growth of adaptive façade systems. The review indicates that to produce a sustainable building design, architects, engineers, and builders must consider the sustainable façade system that enables high energy efficiency, less cost, better occupant comfort, and less environmental impacts.
Double skin façades are adaptive envelopes aiming at improving building energy use and comfort performance. Their adaptive principle relies on the dynamic management of the cavity's ventilation flow and the shading device (when available). They can also be integrated with the environmental systems for heating, cooling, and ventilation. In most cases, though, the possible exploitation of the ventilation airflow is not fully enabled, as the adoption of only one or two possible airpath limits the possibility that this façade architecture offers and flexible interaction with the environmental systems is not planned. This work aims to develop, using an existing software tool for building energy simulation, a numerical model of a flexible double-skin façade module capable of fully exploiting the adaptive features of such envelope concept by switching between different cavity ventilation strategies. Leveraging on the Double Glass Facade component available in IDA ICE, a new model for a flexible double-skin façade module was developed, and its performance in replicating the thermophysical behaviours of such a dynamic system has been assessed by comparison with experimental data collected through a dedicated experimental activity using one the outdoor test cells of the TWINS facility in Torino (Italy). The accuracy of the predictions resulted in line with the performance obtained by the Double Glass Facade component to simulate conventional double-skin facades, with mean bias errors lower than 1.5 °C and 4 W/m², for air and surface temperature values and for transmitted long-wave or short-wave heat flux values, respectively. By establishing a new archetype model to study the performance and optimal integration of a large class of double-skin façade modules, including fully flexible ones, this works demonstrated the possibility of modifying existing models in building energy simulation tools to study unconventional building envelope model solutions such as adaptive façade systems.
Building energy efficiency (BEE) is regarded as the key sector in the world for addressing climate change and energy problems, since buildings consume around one-third of global energy and produce a substantial amount of greenhouse gas emissions. It is important to utilise BEE standards (BEESs) to ensure that cost-effective energy efficiency opportunities are incorporated into new and existing buildings. A key question is how the actual performance of BEESs can be measured so that they are developed in a more sustainable way. An effective method that can evaluate BEESs from both quantitative and qualitative perspectives is provided, and it fulfils a dual step: (a) determining a BEES evaluation indicator system, including technological, economical and social indicators, by identification, correction and selection; and (b) establishing the BEES evaluation model: a fuzzy synthetic evaluation model based on the information entropy theory with the analytic hierarchy process. The developed BEES evaluation model and the case study of China‘s ‘Design standard for energy efficiency of public buildings’ could provide a comprehensive framework to understand the energy efficiency performance of BEESs in China. The results will help improve the management of BEESs and ensure more sustainable building practice.
For planning and development and in real-time operation of smart grids, it is important to evaluate the impacts of photovoltaic (PV) distributed generation. This paper presents an integrated platform, constituted of two main components: a PV simulator and a real-time distribution network simulator. The first, designed and developed following the microservice approach and providing Representational State Transfer web services, simulates real-sky solar radiation on rooftops and estimates the PV energy production. The second, based on a digital real-time power systems simulator, simulates the behaviour of the electricity network under the simulated generation scenarios. The platform is tested on a case study based on real data for a district of the city of Turin, Italy. In the results, the authors show possible applications of the platform for power flow forecasting during real-time operation and for detecting possible voltage and transformers’ capacity problems during planning due to high penetration of renewable energy sources. In particular, the results show that the case study distribution network, in the actual configuration, is not ready to accommodate all the generation capacity that can be installed, as, in certain hours of the day and on certain days of the year, the capacity of some transformers is exceeded.
Estimating cooling and heating energy requirements is an integral part of designing and managing buildings. Further, as buildings are among the largest energy consumers in cities, the estimates are important for formulating effective energy conservation strategies. Where complex hourly simulation models are not favored, such estimates may be derived by simplified methods that are less computationally intensive but still provide results that are reasonably close to those obtained from the more complicated approach. The equivalent full load hours (EFLH) method is a simplified energy estimation method that has recently gained popularity. It offers a straightforward means of evaluating energy efficiency programs. However, to date, easily accessible EFLH data exist only for a very limited number of countries in North America and Europe, but not Asia. This current work provides previously unavailable monthly EFLH data for building cooling and heating in three large Asian cities, viz. Hong Kong, Seoul and Tokyo. To assess the effects of changing temperature over the course of decades on building cooling and heating energy consumption, EFLH data are calculated for three time periods: past (1983–2005), present (2006–2014) and future (2015–2044). The projections for the future time period are based on the climate scenarios Representative Concentration Pathways (RCPs) 4.5 and 8.5 of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report. RCP-4.5 assumes a stabilization of future greenhouse gas (GHG) emissions followed by a reduction, while RCP-8.5 assumes their further increase. From the EFLH data, considering just the effects of ambient temperature changes, it is projected the total energy required to heat and/or cool residential dwellings in Hong Kong, Seoul and Tokyo to increase by 18.3%, 4% and 10.4%, respectively over 62 years from 1983 to 2044 in the case of RCP-4.5, and by 23.3%, 9.3% and 15.8%, respectively in the case of RCP-8.5. This shows that even with future stabilization and reduction of GHG emissions, as per scenario RCP-4.5, the energy needs of the three cities for building heating and cooling combined can be expected to increase over the next few decades. This has significant implications, namely increased demands for additional primary energy, which will result in further GHG emissions. These effects, however, can be controlled with adjustments to the electricity fuel mix of each location, and also by use of more efficient heating, ventilation and air-conditioning (HVAC) devices. [Full text available at: http://dx.doi.org/10.1016/j.apenergy.2016.12.039]
This paper addresses the simulation of a partially transparency, ventilated PV facade integrated into the envelope of an energy efficient building. Such an arrangement exploits the heat transfer between cavity air, the PV façade and the primary wall of the building for the purpose of PV cooling in summer (with natural convection) and heat recovery in winter (mechanical ventilation). A simplified physical model of the system is proposed for the summer operating configuration, which is more challenging from a numerical perspective. The model describes the active envelop in terms of a simplified geometry, and includes parameters such as density of PV cells, relative coverage of degree of transparency/opaque surfaces, and the ratio of height/width of the double-skin. For a given set of meteorological conditions, the surface and air temperatures, mass flow rate and PV power output are obtained by solving a system of thermal and aerodynamic balance equations. Validation of the model was undertaken using experimental data from a full scale prototype system installed in Toulouse, France as part of the RESSOURCES project (ANR-PREBAT2007). Coupling of the system to a simulated building was achieved with the aid of TRNSYS, and this combined system was evaluated in terms of heating and cooling needs for a range of French climates. It was found that the cooling needs are marginally higher for all locations considered, whereas the impact of the façade on the heating needs is weak as these needs are already low for these all locations.
The prime goal of professionals in the built environment is to build cost-effective, environmentally sustainable
buildings. This work focuses on the viability of passive solar design strategies of conservatories in the UK in
mitigating the impact of future climate change. It further shows that passive solar energy utilisation in building
design can contribute to the reduction of dwelling energy consumption and enhancement of indoor thermal
comfort. Synergetic passive design strategies that optimise solar energy gains through thermal simulation analyses
of varying future climatic conditions, occupant behaviour, building orientation, thermal mass, advance glazing,
appropriate ventilation and shading, which influence the potential thermal performance of the conservatory, are
devised. The balanced energy benefits of reduction in energy consumption through the application of passive solar
design principles for space heating in winter and the challenge of reducing excessive solar gains in summer are
analysed using the Cibse TM52 adaptive thermal comfort criteria. The results show that judicious integration of
passive solar design strategies in conservatories, with increasing conservatory size in elongated south-facing
orientation with an aspect ratio of at least 1·67, could decrease energy consumption, enhance thermal comfort and
help to mitigate the impact of climate change when the conservatory is neither heated nor air conditioned.
The construction industry has made considerable energy-saving efforts in buildings, and studies of energy-savings are ongoing. Shading is used to control the solar radiation transferred through windows. Many studies have examined the position and type of shading in different countries, but few have investigated the effects of shading installation in Korea. In this study, the case of the shading installation according to the standard of Korea, and variations of the heating and cooling load in the unit area on the performance of the windows were examined. This study compared the variations of the heating and cooling load in the case of horizontal shading and the changing position of venetian blinds. This study confirmed that horizontal shading longer than the standard length in Korea saved a maximum of 13% energy consumption. This study confirmed the point of change of energy consumption by the Solar Heat Gain Coefficient (SHGC) variations. The exterior venetian blinds and those between glazing were unaffected by the SHGC. On the other hand, in the case of a south façade, the interior venetian blinds resulted in 24% higher energy consumption than the installation of horizontal shading in case of Window to Wall Ratio (WWR): 80%, U-value: 2.1 and SHGC: 0.4.
With the global target to promote energy saving in buildings, various studies draw attention to the role of environmentally benign building envelopes. In this regard, double-skin façades (DSFs) have been proposed as a promising passive building technology to enhance the energy efficiency and improve the indoor thermal comfort at the same time. A comprehensive analysis of the current design of DSFs, and their technical aspects is presented in this paper. Construction characteristics of DSFs are also reported. The impacts of DSFs on the energy efficiency and thermal performance are discussed by looking at measured and simulated performances. Findings confirm that significant benefits result from using DSFs. Finally, research opportunities are outlined for further investigation.
This article presents the state of the knowledge on the thermal analysis of double skin facades with integrated photovoltaic (PV) panels called the Building Integrated Photovoltaics (BIPV) in terms of the published studies carried out on these systems. The idea of integration of the PV panels by replacing building elements, increase the prospects of the renewable energy systems. Taking also into account the need to use more renewable energy systems in buildings, the investigation of the BIPV systems to improve their performance is of a great importance. The literature studies are separated into experimental and theoretical for naturally ventilated systems and mechanically ventilated with external means e.g. fan use. It is concluded that most researchers studied the systems with mechanical ventilation rather than the systems with natural ventilation because the latter are more complex in terms of the air flow behaviour in the air duct. Additionally, various researchers proposed Nu number correlations and convective heat transfer correlation under several assumptions and conditions every time, for different range or Ra number which are presented and compared in this paper.
Windows are one of the thermally weakest parts of a building envelope and climate change is becoming an increasingly important parameter in evaluating the energy performance of buildings. This study investigated the effect of various window configurations on the energy behaviour of school buildings in three cities in Turkey based on climate change, orientation, glazing type and window size. Detailed parametric simulations were used and the results were compared in accordance with ISO 18292. The simulations indicate that the contribution of windows to cooling loads is highest when the value of the solar heat gain coefficient (SHGC) is high and its contribution increases due to climate change. The U-value of glazing is not as significant as the value of the SHGC for cooling. Orientation and window size are other important parameters that affect the energy performance of windows. In addition, in terms of energy costs and performance, it is more efficient for a building to be orientated in south or north directions.
Ventilated building-integrated photovoltaic (BIPV) facades can not only generate electricity at the locations of buildings themselves but if designed optimally, such facades can also reduce the respective heat gains and heat losses in summer and winter via the building envelope. The development of a novel ventilated BIPV double-skin facade (DSF), constituted by a see-through amorphous silicon (a-Si) PV module and an inward opening window, is reported in this paper. In order to enhance ventilation, an air-flow duct, 400 mm in depth is situated between the outside PV module and the inside window. This ventilation design can remove much of the waste heat generated by the PV module energy conversion processes, and thus bring down the operating temperature of the solar cells. Infrared thermal imaging was adopted in relation to the ventilated PV-DSF to visually demonstrate this ventilating effect. It was found that the air temperature at the outlet louver is higher than that at the inlet louver by 2.2-2.3 degrees C. The thermal performance of PV-DSFs operating in different modes was studied and compared. The results showed that the ventilated PV-DSF provides the lowest solar heat gain coefficient (SHGC), while the non-ventilated PV-DSF better reduces heat loss. Based on the experimental results, the optimum operation strategy for the PV-DSF under different weather conditions has been determined and proposed. This novel PV-DSF is more suitable for sub-tropical climates because it results in a much lower SHGC than that of a low-e coating DSF.
Building integrated photovoltaic systems are fast becoming a feature of urban landscapes in France and other countries tackling similar pressures to improve the energy footprint of residential and commercial building sectors. As active components of building envelopes, the technology represents a promising solution to the local electrical and thermal demand. However, despite significant recent interest and investment into the technology, few studies have been undertaken to study full-scale installations operating under real conditions.
To mitigate the overheating problem in the warmer seasons, and thereby improve thermal performance and energy efficiency of the double-skin façade (DSF) system, this study introduced an innovative design approach involving the integration of passive thermal mass technique with the air channel of the conventional DSF. To assess the contribution of this integration to energy efficiency of the system, a numerical model was developed, capable of determining the thermal performance of the conventional DSF. The numerical model is composed of airflow and thermal models. This paper briefly describes the development of the models as well as the models’ verifications. Models were then used to carry out a series of parametric studies to investigate the effect of thermal mass on the energy performance of the integrated system.The simulation results revealed that mechanically ventilated DSF can save energy based on configuration from 21% to 26% in summer and from 41% to 59% in winter as compared to conventional DSFs without thermal mass. The results also showed the total saving for a naturally ventilated DSF is negligible year-round.
Developments in the design and manufacture of photovoltaic cells have recently been a growing concern in the UAE. At present, the embodied energy pay-back time (EPBT) is the criterion used for comparing the viability of such technology against other forms. However, the impact of PV technology on the thermal performance of buildings is not considered at the time of EPBT estimation. If additional energy savings gained over the PV system life are also included, the total EPBT could be shorter. This paper explores the variation of the total energy of building integrated photovoltaic systems (BiPV) as a wall cladding system applied to the UAE commercial sector and shows that the ratio between PV output and saving in energy due to PV panels is within the range of 1:3–1:4. The result indicates that for the southern and western façades in the UAE, the embodied energy pay-back time for photovoltaic system is within the range of 12–13years. When reductions in operational energy are considered, the pay-back time is reduced to 3.0–3.2years. This study comes to the conclusion that the reduction in operational energy due to PV panels represents an important factor in the estimation of EPBT.
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.
Energy consumption in the residential and commercial sector accounts for over 25% of the total in Japan. With the information technology revolution and the improving requirement for indoor air environment, energy consumption for household air conditioning is increasing. In this research, a double skin facade is proposed for a two-story house in Kitakyushu of Japan. The stack effect in the double skin space during the summer, the green house effect during the winter and the availability for free air-conditioning during the autumn have been studied. The temperature distribution, thermal performance in the double skin space and its impact on air-conditioning load in rooms have been measured. Results show that the double skin façade leads to about 10–15% energy saving for cooling in the peak of summer because of heat exhausted by natural ventilation, 20–30% energy for heating in winter because of the green house effect, and the temperature adjustment is quite large with the different operation mode of the double skin system during the intermediate seasons. Therefore the double skin system is proved to be effective in energy conservation in residential buildings.