Christina J. Hopfe

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• Professor
• Professor (Full) at Graz University of Technology

This study evaluates the applicability of two analytical (steady-state) and one numerical (transient) method for estimating ventilation airflow rates based on time-series CO₂ measurements. Over the course of a year, CO2 concentrations were monitored in two Austrian school classrooms-one with natural ventilation and one with a decentralised mechanic...

Providing thermal comfort in office buildings is crucial for maintaining productivity and well-being, especially in free-running offices prone to overheating during heatwaves. Accurate temperature forecasting is essential for predicting and mitigating such conditions. Building on prior research on time series forecasting for indoor temperature pred...

Better indoor air quality is becoming more and more important. Especially in educational buildings such as schools and universities, where many people are in a confined space, it is beneficial if ventilation concepts can be compared with each other. In this paper, cost-effective extract ventilation systems are compared with conventional natural win...

Room ventilation is an important facet of public health. Research has shown that ventilation in classrooms is crucial for maintaining indoor air quality, maximising learning outcomes, and reducing the risk of airborne disease transmission (including measles, Severe Acute Respiratory Syndrome (SARS), and influenza). Despite these well-documented ben...

Beyond building physics" is a newly developed virtual learning environment that was developed from a combination of three technologies: Virtual Reality, Building Performance Simulation and the Internet of Things. The integration of virtual reality in education has emerged as a pivotal focus, driving disruptive advancements in experiential learning....

In recent years, Virtual Reality (VR) has found its way into different fields besides pure entertainment. One of the topics that can benefit from the immersive experience of VR is education. Furthermore, using game-based approaches in education can increase user motivation and engagement. Accordingly, in this paper, we designed and developed an imm...

https://www.rehva.eu/rehva-journal/chapter/can-ventilation-combat-airborne-infection-risks-in-schools

Highlights • 5 classroom ventilation strategies were evaluated using measured and modelled data. • Mechanical and hybrid ventilation were compared to natural ventilation strategies. • Energy, thermal comfort, IAQ and SARS-CoV-2 infection risk criteria were evaluated. • None of the ventilation scenarios could eliminate the risk of aerosol transmiss...

The Erasmus+ project, entitled ‘Digital Erasmus – a roadmap to using building performance simulation to achieve resilient design’ (DesRes), seeks to transform the learning experience of students in built environment disciplines using a continuous digital learning cycle. Three universities play a part in this project: Graz University of Technology (...

Implications for the academic and interpersonal development of children and adolescents underpin a global political consensus to maintain in-classroom teaching during the ongoing COVID-19 pandemic. In support of this aim, the WHO and UNICEF have called for schools around the globe to be made safer from the risk of COVID-19 transmission. Detailed gu...

The rapid escalation of the COVID-19 pandemic has highlighted the importance of efficient ventilation systems in reducing the risk of airborne transmission of the SARS-CoV-2 virus. This study evaluates the energetic performance and viral transmission characteristics of a low-cost mechanical extract ventilation system in comparison to alternative st...

The global COVID-19 pandemic in 2020 has forced universities to completely rethink their teaching concepts to provide safe, remote teaching of students off-campus. One of the challenges of this rapid transition is ensuring that the quality of the learning experience remains high and that students are able to engage and thrive in this new and predom...

Highlights: • Fundamental numerical derivation of thermal radiation properties of common glazing. • Fitting formula for the reflectivity of un-, p- and s-polarized thermal radiation. • Angular dependencies derived for emissivity, reflectivity and absorptivity of glass. • Experimental validation of the numerical derivations shows good agreement....

This Excel-tool can be used to calculate angular/directional emissivity, reflectivity and absorptivity values for common window-glass (i.e. soda-lime glass). The tool can also be used to perform compensated measurements on window glass surfaces with pyrometers or IR-thermography. It features detector related limited spectral bands for pyrometers an...

This pedagogical note presents a novel learning activity (the icebox challenge) that was designed to facilitate deep learning of building physics energy transfer principles through a planning, prediction and analysis process following the Kolb learning cycle. The success of this strategy was evidenced by students relating and collating their knowle...

Domestic Hot Water (DHW) production accounts on average between fourteen and thirty percent of the residential energy consumption worldwide. In UK dewllings, a quarter of the energy is consumed to produce hot water and this proportion is likely to increase as the energy required for space heating reduces over time in order to achieve demand reducti...

It is widely acknowledged that faced with diverse future impacts (including extreme weather events, economic instability, energy supply vulnerabilities and pandemics) buildings and communities’ worldwide need to become increasingly resilient. The work presented in this paper investigates how Community Design and Decision Making (CDDM) processes can...

Prolonged overheating has severe consequences for the future habitability of buildings. Building Performance Simulation (BPS) is increasingly used to identify the propensity of buildings to overheat, however the reliability of this approach has been repeatedly questioned. A new overheating risk-assessment methodology, Technical Memorandum (TM)59 wa...

Prolonged overheating can have serious cumulative effects on human health, resulting in heat exhaustion, heatstroke and even death. The frequency and severity of heatwaves will increase considerably in the future as a result of accelerating climatic changes compounded by increasing urbanisation. A recent overheating risk-assessment methodology, Tec...

In times of crisis (such as climate change, heat waves, and more recently viral pandemics), it becomes apparent that the decisions we have made in the design of our built environment are crucial and can significantly impact our quality of life. Decision making in building performance simulation can add significant support to the design process from...

With the help of building diagnostics, the causes and solutions to complex problems in buildings can be determined. In central and greater London, an increasing number of cases of chronic, year-round, overheating in buildings have been reported. We present three cases of unexpected temperatures in multi-storey residential buildings. Detailed analys...

Scarcity of affordable energy efficient dwellings is a defining characteristic of the global housing crisis. In many countries this problem has been exacerbated by single objective cost-models which favour the homogeneous development of market tenures at the expense of delivering high-quality affordable homes. Despite the obvious environmental and...

The demand for local heat storage to help manage energy demand in dwellings is likely to increase as the electrification of heat through heat pumps becomes more widespread. Sizing thermal energy storage systems has been an important topic in contemporary literature, but the effect of the electrical load shifting tariff and the service the household...

A new set of CIBSE weather files for building performance simulation was recently developed to address the need for better quality solar data. These are essential for most building performance simulation applications, particularly for daylighting studies and low-energy building design, which requires detailed irradiation data for passive solar desi...

Empirical validation of building simulation results is a complex and time-consuming process. A well-structured and thorough experimental design is, therefore, a crucial step of the experimental procedure. A full-scale empirical validation study is planned to take place within IEA EBC Annex 71: "Building energy performance assessment based on in sit...

The housing crisis within the UK continues with growing private housing rental prices and increasing levels of homelessness. This situation has been driven by the homogeneous development of housing tenures under-supplying in-demand social and affordable homes. Previous work has seen the implementation of multi-objective optimisation within a broad...

The latest advancements in glazing technology are driving facade design towards complex and adaptive fenestration systems. Accurate simulation of their optical properties and operational controls for building daylight performance evaluation requires advanced modelling techniques, such as climate-based daylight modelling (CBDM). At the same time, co...

The design of a building is a decision problem with multiple stakeholders and several often conflicting criteria. Multi-Criteria Decision-Making (MCDM) methods are capable of handling decision problems with the abovementioned specific features. This paper focuses on the application and comparison of some of the most well-known and widely applied MC...

Insulated Concrete Formwork (ICF) is a site-based Modern Method of Construction (MMC). As a MMC, ICF has several advantages; increased speed of construction, cost and defect reduction, safety, among others. Moreover, the ICF wall construction method has similar benefits to any other heavyweight structure (such as strength, durability, noise attenua...

The CIE illuminant D65 is widely adopted as defining the standard spectral power distribution (SPD) for 'average' daylight. Thus daylight indoors is generally assumed to approximate the SPD for D65. The weight of research on the non-visual effects of light now suggests that a key consideration for the long-term health and well-being of occupants sh...

Enhanced fabric performance is fundamental to reduce the energy consumption in buildings. Research has shown that the thermal mass of the fabric can be used as a passive design strategy to reduce energy use for space conditioning. Concrete is a high density material, therefore said to have high thermal mass. Insulating concrete formwork (ICF) consi...

The insertion of climate-based daylight metrics as a requirement in several design guidelines calls for a better understanding of their effectiveness. This paper draws attention to the sensitivity of annual daylight metrics to changes in input reflectance values. The uncertainties related to the choice of guidelines and of simulation techniques wer...

It is widely acknowledged that faced with diverse future impacts (including climatic changes, economic instability and energy supply vulnerabilities) buildings and communities' worldwide need to become increasingly resilient. The work presented in this paper investigates how Community Design and Decision Making (CDDM) processes can be enhanced thro...

The evolution of building facades towards increasingly smarter and more complex fenestration systems required an evolution in simulation capabilities too. While simulation software can reliably reproduce the system's optical behaviour, the climate-based daylight evaluation of entire buildings needs to efficiently combine accuracy and computation sp...

Airtightness and thermal conductance of the fabric play a key role in constructing low energy buildings. These two factors might minimise the building's heating demand in winter but contribute to its overheating in summer. This study focused on a building using Insulated Concrete Formwork (ICF), a site-based Modern Methods of Construction (MMC). IC...

Low carbon housing policies embody visions of the future that shape and constrain current choices between different technological pathways. These socio-technical imaginaries include expectations around new ways of living and interacting with technology, with implications for everyday lives. This paper investigates existing expert visions of low car...

In previous papers we have presented a continuous learning cycle that includes exposure to theories and the application of tools from the start for effectively teaching BPS and we have described the course we have developed based upon this cycle. The important role played by the simulation autopsy in this cycle is the focus of the current paper. Th...

Low-energy buildings have a major role to play in achieving carbon emission reduction targets. The Passivhaus standard is driven by improved thermal comfort and has stringent targets for limiting energy consumption. Such constraints can be difficult to achieve with aesthetically pleasing results. In early stage building design, decisions are often...

Insulating Concrete Formwork (ICF) walls consist of cast in situ concrete poured between two layers of EPS insulation. The system can achieve very low U-values and high levels of air-tightness. This paper investigates the inconsistency in simulation results provided by nine widely used Building Performance Simulation (BPS) tools when calculating th...

Reducing energy consumption and managing energy supply/demand responses are key challenges facing the future built environment. The use of de-carbonised electricity to deliver space heating will make significant impact on CO 2 emissions for the UK. A likely technology in UK homes is to replace conventional gas boilers with heat pumps. A high coeffi...

The design and construction of a building is inherently complex and a myriad of decisions must be made during the design and planning process. No single stakeholder (architect, client, building physicist) has complete knowledge and visibility of the consequences of each decision and each stakeholder group is driven by different objectives. Those as...

During the past decades building performance simulation (BPS) tools have become complex. Alternate methods are offered for resolving many of the significant heat and mass transfer processes and energy conversion systems. At the same time, modern user interfaces allow users to quickly ascend the learning curve to operate tools in order to produce si...

Passivhaus is the fastest growing energy performance standard in the world, with almost 50,000 buildings realised to date. Applicable to both domestic and non-domestic building types, the strength of Passivhaus lies in the simplicity of the concept. As European and global energy directives move ever closer towards Zero (fossil) Energy standards, Pa...

During the past decades building performance simulation tools have become complex. Alternate methods are offered for resolving many of the significant heat and mass transfer processes and energy conversion systems. At the same time, modern user interfaces allow users to quickly ascend the learning curve to operate tools in order to produce simulati...

Domestic Hot Water (DHW) production can account for a quarter of the energy consumed in UK dwellings and this proportion is likely to increase as the energy required for space heating reduces in order to achieve demand reduction targets. As the margins for improving the performance of heating system technologies diminish, the need for improving mod...

In a changing climate and with ever increasing energy standards that lead to low and zero energy buildings, the provision of hot water in buildings will become more significant in relation to the overall energy consumption. Higher demand on the provision of hot water consumption has been documented and will occur around activities such as laundry,...

Insulating Concrete Formwork (ICF) is classified among the site-based Modern Methods of Construction (MMC) and consists of hollow insulation blocks and cast in-situ concrete. ICF construction elements can achieve very low U-values and high levels of air-tightness. The aim of the study was to examine the inconsistency in the simulation results provi...

There is a plethora of dynamic Building Performance Simulation (BPS) tools on the market, that use different methods in terms of how they calculate the effect of thermal mass in buildings. This paper analyses the ability of six widely known BPS tools to calculate the thermal mass potential in whole BPS. The first stage is focused on the analysis of...

In an effort to minimise the energy consumption in buildings, designers currently use a variety of energy simulation programs. However, despite the fact that those programs can make a significant contribution to the design of low energy buildings during the early design stage, the lack of detailed design information at that phase results in uncerta...

In the past 30 years, much effort has been directed to make building performance simulation become inherent in architectural practice. Anecdotal evidence however shows that it still a long way for this goal to be achieved. This paper presents the outcome of a survey conducted in Australia, India, the US and the UK, to investigate difficulties that...

The recent development of climate-based daylight modelling (CBDM) and its application in various com- mercial tools, as well as its introduction in building simulation guidelines, created the need of more com- mon procedures and quality checks on input values. Between these, the optical properties to be assigned to the modelled building can be very...

The process of building design is currently undergoing some major changes. In an attempt to mitigate climate change, the design of more sustainable buildings is advocated by the UK government. Furthermore, standalone design methods are being replaced with the concept of Building Information Modelling (BIM). The adoption of BIM has been documented t...

The Passivhaus Designers Manual is a comprehensive technical guide available to those wishing to design and build Passivhaus and Zero Energy Buildings. As a technical reference for architects, engineers and construction professionals The Passivhaus Designers Manual provides: State of the art guidance for anyone designing or working on a Passivhaus...

With the construction industry moving rapidly towards Building Information Modelling (BIM), it is essential that various analysis tools used in the Architecture, Engineering and Construction (AEC) domain are interoperable with a non-proprietary open BIM schema such as the Industry Foundation Classes (IFC). The UK government will be requiring fully-...

Decarbonising housing is a key UK government policy to mitigate climate change. Using discourse analysis, we assess how low carbon housing is portrayed within British broadsheet media. Three distinct storylines were identified. Dominating the discourse, Zero carbon housing promotes new-build, low carbon houses as offering high technology solutions...

In response to UK government policy Mandating the construction of 'zero carbon' homes by 2016 there have been significant changes in the way dwellings are being designed and built. Recent years have seen a rapid uptake in the adoption of the German Passivhaus standard as a template for ultra-low energy and zero carbon buildings in the UK. Despite g...

Building performance assessment is complex, as it has to respond to multiple criteria. Objectives originating from the demands that are put on energy consumption, acoustical performance, thermal occupant comfort, indoor air quality and many other issues must all be reconciled. An assessment requires the use of predictive models that involve numerou...

Driven by climate change legislation and high rates of fuel poverty, the UK faces multiple challenges both in new build and upgrading the existing stock. How these challenges are addressed will have long-term impacts on the building fabric, occupant comfort and wellbeing. Building performance simulation has an important role to play in this process...

Building Information Modelling (BIM) has many benefits, and can be used throughout the building lifecycle. At the initial planning stage building performance simulation (BPS) can be used to inform design decisions. Data can be exchanged between BIM and BPS tools using data transfer schemas such as the Industry Foundation Classes (IFC). The IFC sche...

Climate change will affect the performance of our building stock. As buildings can have a lifespan of 50-100 years, designing for this condition is now a key challenge for the building industry. This study focuses 011 predicting current and future behaviour of a folly air-conditioned office building in Wales. UK probabilistic climate projections ar...

The sensitivity of low energy and passive solar buildings to their climatic context creates a requirement for accurate local climate data. This situation takes on increasing importance in the context of modelling Passivhaus buildings where the absence of conventional oversized heating and cooling systems implies a greater reliance upon fabric and s...

The process of Building Information Modelling (BIM) is slowly replacing traditional design methods. The use of BIM has been documented to produce many benefits, both on- and off-site. BIM authoring tools create the building model, and this can be further analyzed by downstream applications. Currently, one of the main data transfer schemas, the Indu...

A rapid transition to ˜zero carbon" building was announced by the UK Government in December 2006 as a key step forward in reducing the Green House Gas (GHG) emissions from the domestic and non-domestic sectors. This paper elaborates on whether the revised definition of "zero carbon" dwellings in the UK (2009) and the approach to implementing this p...

Buildings account for nearly 40% of the energy consumption in the UK, producing almost half of the CO2 emissions at a national level. Using appropriate insulation is a cost-effective way to substantially improve the energy efficiency of any building and reduce the overall contribution to global CO2 emissions. This chapter focuses on cavity insulati...

Building performance simulation (BPS) has the potential to provide relevant design information by indicating directions for design solutions. A major challenge in simulation tools is how to deal with difficulties through large variety of parameters and complexity of factors such as non-linearity, discreteness, and uncertainty. The purpose of uncert...

Experimental data is presented for the dry and saturated steady state thermo-physical properties, and also the dynamic thermal properties, of 180, 120 and 65 mm target slump mix designs for Plain Rubberised Concrete (PRC) with varying %wt rubber substitution and aggregate replacement types (fine, coarse, and mixed). The composites had significantly...

According to the Passivhaus Institute (PHI) the verification of a Passivhaus design must be carried out using the Passivhaus Planning Package (PHPP). A number of methods are now available for designers to access climatic data for use in PHPP design predictions. The original climate data provided for design and certification in the UK was derived fr...

Amongst a large range of passive energy conservation measures (ECMs), building integrated vegetation (BIV systems) is witnessing a rapid growth in both research and market development (Bass and Baskaran, 2003). Unfortunately, their uptake remains limited in the UK, although the existing non-domestic building stock is in urgent need of energy conser...

26 million homes1 (Killip G., 2008) in the UK are traditional and 'hard-to-treat'2 dwellings that need urgent attention in order to meet the government's carbon reduction targets. Most of these homes are situated in villages without mains gas. A computational methodology will be used to formulate energy retrofit and renewable energy technology (RET...

Several construction-related information portals have been commissioned and developed by various institutions at a European and national level. The information published by these portals is in many cases redundant, overlapping, specialised, and not easy to locate and access. Furthermore, these portals do not provide user-friendly and effective sear...

Proceedings of the conference

The paper provides a critical and evolutionary analysis of knowledge management (KM) in the AEC (architecture, engineering, construction) industry. It spans a large spectrum of KM research published in the management, information systems, and information technology (IT) disciplines. An interpretive (subjectivist) stance is adopted so as to provide...

The research explores factors influencing knowledge value creation of virtual teams in the construction industry. Collectiveness and conscientiousness emerge as important socio-cultural enablers for value creation. Collectiveness represents the degree of cohesiveness and social relationships between virtual team members and conscientiousness repres...

Through a comprehensive review of the relevant literature, this paper considers the development of information communication technology (ICT) and the demand for better, well-organized, and more effective government; governments have pursued eGovernment initiatives to offer services and information online to citizens, government organisations, and b...