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The digitalisation of the Architecture, Engineering and Construction domain introduced new methods for digital collaboration, i.e. Building Information Modelling (BIM). While this method focuses on building data, the distribution of digital product models is still problematic, complicating uniform product searches and automated product data processing. Existing schemas, such as a subpart of the Industry Foundation Classes or the German VDI 3805, rely on rigid or template-driven schemas, that do not support the description of innovative or multi-functional products or impose a large schema overhead and complexity on manufacturers. Therefore, this article combines flexible and modular product descriptions with Semantic Web technologies and Linked Data. By applying Web-based technologies, the searchability of product data and the applicability of distributed data are expected to be enhanced. More precisely, this article proposes a concept for Linked Building Product Data and introduces the generic Building Product Ontology as a potential core schema of the concept. To demonstrate the feasibility of Linked Building Product Data and the Building Product Ontology, the authors apply both the concept and the data schema to innovative and multi-functional example products that cannot be described with the existing approaches for product descriptions. The evaluation demonstrates the flexibility, modularity and overall suitability of the presented concepts, meeting all collected requirements for digital product descriptions. Hence, Linked Building Product Data may solve existing issues with rigid product description schemas. At the same time, this approach complements the current research trend of Linked Building Data.

The solar protection feature of shading devices is characterized by the Solar Heat Gain Coefficient (SHGC) or g-value. Given their complex light-scattering properties, it is advisable to test innovative shading devices calori­metrically in a laboratory. In the case of an indoor calorimetric facility, a solar simulator is required as the light source. The light beam radiated by commercial solar simulators is not parallel and in general more divergent than direct sunlight. This study analyses the impact of the angular divergence of radiation from solar simulators on the experimental determination of the SHGC of fenestration systems. It is shown that this effect is not negligible in many cases. Two methods are proposed for this purpose: (1) an experimental one based on mea­surements with a luminance camera, and (2) a numerical one based on a digital model of a calorimetric facility. Both methods build on the calculation of contribution coefficients from different regions of the field of view of the sample. The methods can be used to correct the effect of angular divergence on SHGC measurements in the future., + ID der Publikation: hslu_89733 + Art des Beitrages: Wissenschaftliche Medien + Jahrgang: 2022 + Sprache: Englisch + Letzte Aktualisierung: 2022-05-05 09:36:44

This paper first analyses the current exchange of optical and calorimetric data. A large amount of manual work is necessary for manufacturers to supply numerous data formats and for planners to access product data, to check the quality and to use it for building performance simulation. Therefore, this paper proposes a system of databases which use the same specification for their application programming interfaces. This enables fast and cost-efficient building performance simulations and makes it easy for manufacturers to manage their product data. The International Glazing and Shading Database and the European Solar-Shading Database will use the new interface to offer high-quality data for many glazing and shading components.

In order to achieve significant savings in energy and an improved level of thermal comfort in retrofitted existing buildings, specific retrofitting concepts that combine new technologies and design need to be developed and implemented. Large radiant surfaces systems are now among the most promising future technologies to be used both in retrofitted and in new low-energy buildings. These kinds of systems have been the topic of several studies dealing with thermal comfort and energy utilization, but some specific issues concerning their possible use in various concepts for retrofitting are still poorly understood. In the present paper, some results of dynamic simulations, with the transient system simulation tool (TRNSYS) model, of the retrofitted offices equipped with radiant ceiling panels are presented and thoroughly analysed. Based on a precise comparison of the results of these simulations with actual measurements in the offices, certain input data for the model were added, so that the model was consequently validated. The model was then applied to the evaluation of various concepts of building envelopes for office retrofitting. By means of dynamic simulations of indoor environment it was possible to determine the benefits and limitations of individual retrofitting concepts. Some specific parameters, which are relevant to these concepts, were also identified.

We introduce a photonic color concept for integrated photovoltaic modules. Taking up the inspiration from the Morpho butterfly with its brightly colored wings, we developed this photonic concept further to achieve an improved angular independent color effect, suitability for module integration, and compatibility with industrial production processes, while maintaining high module efficiencies. We demonstrate the steps that lead to the optimized photonic structure and explain the underlying optical effects. Using the data from demonstrator modules, we show the outstanding performance in terms of module efficiency and color stability. A power output for the MorphoColor modules of more than 94% compared to the reference module power is shown.

A new controller for office spaces with venetian blinds has been developed to explicitly address both daylight maximization and glare control. Conventionally, systems that operate on these principles require numerous sensors to monitor the visual conditions in the room, leading to expensive, complicated and impractical installations. To address this problem the developed controller substitutes the illuminance sensors with real-time daylight simulations based on the Three-phase method and uses bi-directional scattering distribution functions (BSDF). An optimization engine based on the principles of fuzzy logic has been added to the system in order to evaluate the visual conditions in the room and decide on the optimal shade configuration. A prototype of the controller has been built and tested under real life conditions in a rotatable test facility located in Freiburg, Germany. The accuracy with which the simulation engine predicts horizontal and vertical illuminances in the room has been satisfactorily evaluated against measurements and the operation of the controller has been assessed. A case study has been conducted in order to demonstrate the benefits of the new simulation-based controller over two widely used control strategies.

In this paper, the potential of a facade element with switchable U -value and g -value is investigated. This new switchable facade element consists of a series of air-filled cavities separated by opaque films, that can be rolled up or down between two fixed layers, thus switching the thermal and optical properties from a thermally insulating state to a conducting state. A first prototype has been built and measured in the insulating state and the properties of the facade element have been optimized using a theoretical analysis at the facade level. The U -value can be switched from a value of 0.35 W m −2 K −1 in the insulating state to a value of 2.7 W m −2 K −1 in the conducting state. Building energy simulations using EnergyPlus showed that the sum of the heating and cooling demands could be reduced by about 30% with the switchable insulation used as a window application or in front of an opaque massive wall. Even better performance could be achieved by reducing the frame or edge losses. The influence of the thermal mass, and finally the influence of orientation on the overall performance are also investigated and were found to be non-negligible.

This paper presents a method to evaluate the thermal impact of complex fenestration systems on the energy balance of a building zone based on directional solar heat gain coefficients (DSHGC) and bi-directional scattering distribution functions (BSDF). The proposed methodology is presented as an alternative to layer-by-layer heat transfer models. An example of a layer-by-layer heat transfer model is the ISO15099 as implemented in the EnergyPlus building simulation program. The ISO15099 model relies on a number of assumptions that are not justified in the case of three-dimensional structures, air-permeable layers and deviations from ideal geometries, which are common features in commercial daylighting and solar-control systems. In this paper, the proposed methodology is implemented in the Fener simulation engine and compared with EnergyPlus for systems for which the assumptions of the ISO15099 model are valid. Then, the Fener program is used to simulate the thermal behaviour of a zone with a fenestration system that contains sawtooth-shaped retro-reflecting interior blinds, which cannot be directly modelled with the ISO15099 model. The impact of different control strategies on the thermal performance of the zone is demonstrated for this case study.

Based on an analysis of building processes to date, this paper proposes two ways to make Building Information Modelling (BIM) and with it complex building processes less expensive and more reliable. First, existing experience with building processes that include building-integrated solar systems is analysed, as they are one example for buildings with high energy-saving goals. Based on the analysis, the authors propose to include a new property set and functions in machine code in the next version of the Industry Foundation Classes (IFC). For the machine-code functions, several formats are proposed and the advantages and disadvantages of the proposed IFC extensions are discussed. For simple conventional building components, the existing IFC version 4 seems appropriate. Buildings with innovations that add complexity to the building process can profit most by the savings generated by exchanging machine-code functions. In building processes to date, much information is not shared because of proprietary matters. Functions in machine code can provide the necessary confidentiality so that more capabilities can be exchanged between the stakeholders. Models based on machine-code functions can be updated much faster than detailed models with many parameters. With machine-code functions, advantage can be taken of the greater accuracy of detailed models, as long as they are fast and easy to use. The modularity of the functions stimulates competition between alternative approaches, which makes simulation models less expensive. Finally, exchanging a closed, validated simulation model in machine code introduces a much lower risk of error than exporting and importing complex simulation models.

This paper deals with the state of the art of advanced solar control devices for buildings, with the comparative evaluation of solar-control systems and with guidelines for the development of new solar control systems. It includes multifunctional systems with building integrated photovoltaic (BIPV) and/or building integrated solar thermal (BIST) energy conversion. In order to facilitate and to structure the understanding of solar control systems two multidimensional spaces are introduced: the design space and the evaluation space. The design space contains the design parameters which are to be selected by the designer when solar control devices are to be chosen for specific buildings or when new systems are to be developed, such us the color of the slat of a venetian blind or the fraction of holes (direct transmittance) of a fabric for a roller blind. The evaluation space contains the performance parameters or evaluation criteria, which indicate the design‘s ability to satisfy the functional and aesthetic requirements, such us passive solar gain control or visual comfort. All the design parameters and evaluation criteria are explained in detail in the paper. A chapter with examples of advanced solar control systems completes the overview of the state of the art of solar control systems.

Solar building envelopes are attracting increasing interest. Building-integrated solar thermal (BIST) systems are one of the subgroups of solar building envelopes. This paper summarizes the most important contributions of recent years and extends them. First, BIST elements are defined and available BIST elements are presented. Then, the general functions which BIST systems can provide are presented and the conflict between the constant U and g values of simple planning software and the variable g and U values of BIST elements is discussed. Measurements to characterize BIST elements are presented as well as a design parameter space in which the current BIST elements are located and which can be used when developing innovative new components. Methods to evaluate and compare BIST technologies are presented. The substantial cost savings which were achieved in three building projects between 2002 and 2009 are discussed. Roles within the building process are presented, as well as the general methods and challenges for economic BIST calculations and one economic calculation as an example. Based on existing building processes, a vision for future BIST building process integration is presented. Simple BIST models, which need no programming, are provided with easy-to-use equations. The challenges of standards and regulations are outlined and future research topics are presented. This paper summarizes important recent contributions to BIST research as a basis for future progress in building-integrated solar thermal systems. Instead of aiming to cover all recent BIST developments, the focus is on BIST research findings which are relevant for cost reduction of BIST components and therefore necessary for the economic success of BIST technology. These are discussed, together with proposals for future research.

The generated electricity of a rather complex building-integrated photovoltaic system, installed in the main building of the Fraunhofer Institute for Solar Energy Systems, is analyzed in detail. For this purpose, the measured irradiance on the tilted surface, the temperatures of the PV modules, the DC power and the AC power are compared with the results of an advanced electricity yield simulation program that has been developed at the institute. The chosen building-integrated photovoltaic (BIPV) system allows detailed investigation of complex shading patterns, improved electrical cell connection and the temperature characteristics of building-integrated photovoltaic modules when they simultaneously function as insulating glazing units with a low U value. The comparison of simulated and measured AC power shows that the consequences of partial shading, the consequences of the integration as a thermally insulating component of the building envelope and the electrical properties of the PV system are understood well.

This paper addresses the definition of a new criterion Ra out-in to evaluate the color rendering of objects in a room viewed by an observer who is outdoors. This is not only relevant when outdoor observers are viewing persons in the room. It is also frequently taken into account when the color of internal solar-control or glare protection systems is selected so that they have a pleasing appearance for both indoor and outdoor observers. The relation of the new criterion to the general color rendering index R a as applied for daylight transmitted through glazing is discussed and several solar control systems are assessed with respect to R a and Ra out-in . Both color rendering indices are based on an evaluation of the color rendering of eight moderately saturated test colors illuminated with the reference illuminant D65 and the illuminant under consideration (e.g. the same illuminant transmitted through a spectrally selective solar-control glazing). A discussion about an extension of the range of test colors by addition of strongly saturated test colors is also included in the paper.

This paper reviews and analyzes technological design options, which have become available to date for BIPV systems on roofs and facades, independently of specific products or building projects. This means that this survey does not analyze existing products or realized buildings, but provides an overview of the technologies for BIPV. The starting point is an analysis of the relevance of BIPV technologies for the decarbonization of energy systems, providing energy for direct use of electricity and sector coupling together with an analysis of the German BIPV market. The paper presents the wide range of technical design options for BIPV systems and categorizes and analyzes them to provide a structured overview. This comprises a detailed analysis of the design options for BIPV modules, in which not only the design options for the PV cell layer were comprehensively investigated, but also the different variants of embedding materials, front and rear cover materials, additional interlayers and electrical module layout. Two fundamental module-level design options were investigated in particular detail: The use of PV cells as basic elements of patterns and the use of color to conceal the PV cells. Subsequently, options for the design of complete electrical systems are reviewed, ranging from sub-module level design parameters to building energy systems. Design options for the constructional integration of BIPV modules in the building envelope complete the review of technological design possibilities.

International audience; In this contribution, a new model of switchable insulation element is introduced. This element essentially consists of a double glazing unit with a translucent insulating panel mounted inside. Switching of the U-value is achieved by control of an internal convective flow around the insulation panel. The element can be in an insulating state with a low U-value, or in a conducting state with a high U-value. First the new model of the element, based on numerous thermal, hydraulic and optical assumptions, is introduced. The airflow rate is calculated by balancing the pressure drops and the buoyancy driving force. The model is validated against U-value measurements, showing a reasonable accuracy. Finally, the model is used for a parametric analysis, where the influence of different thermophysical properties on the U-value and g-value of the element in insulating and conducting state is investigated.

Building-integrated solar thermal systems (BIST) outperform building-added solar thermal systems (BAST) due to smaller heat losses at the back of the collector. BIST offer economic advantages, too. The insulation behind the collector can be used to reduce the heating demand of the building as well as to increase the solar thermal yield. Therefore, less material and labour are needed. Of course, the energy flux to the building interior needs to be considered. This energy flux depends in general on the operation of the collector as well as on the irradiance. Several innovative solar thermal building skins have been modelled in detail to analyze this coupling between the active building skin and the building. However, planners need an easy approach to include BIST into their calculations. Often, there is not enough budget to measure and model the new facade. This paper presents several new and simple models which are more accurate than neglecting the coupling to the building and which are less complex than detailed physical models.

This study presents and demonstrates a methodology for calculating the economic potential of photovoltaic installations in urban areas including the previously often disregarded potential on building facades. The analysis of a 2 km2 urban area has shown that building facades there provide almost triple the area of building roofs. However due to non-optimal inclination and orientation, they receive only 41% of the total irradiation. From this, the economic potential under present market conditions was calculated, resulting in 17% of all analyzed building surfaces, i.e. 0.3 km2 of roof surfaces being economically exploitable for photovoltaic installations already now which corresponds to an installed capacity of 47 MWp. Considering further a material substitution from the building integration of the photovoltaic installations, an economic potential of up to 56 MWp or 0.4 km2 results, of which up to 6 MWp or 0.04 km2 are economically installable on building facades. Facade-mounted installations would then account for 13% of the economic potential. The calculation of an economic potential and additionally considering the material substitution from building integration both constitute an extension to many existing renewable energy potential studies just focusing on the technical potential. However, only the economic potential allows forecasts of the future diffusion of this technology.

In this study, we evaluate established and newly developed metrics for predicting glare using data from three different research studies. The evaluation covers two different targets: 1. How well the user’s perception of glare magnitude correlates to the prediction of the glare metrics? 2. How well do the glare metrics describe the subjects’ disturbance by glare? We applied Spearman correlations, logistic regressions and an accuracy evaluation, based on an ROC- analysis. The results show that five of the twelve investigated metrics are failing at least one of the statistical tests. The other seven metrics CGI, modified DGI, DGP, Ev, average Luminance of the image Lavg, UGP and UGR are passing all statistical tests. DGP, CGI, DGI_mod and UGP have largest AUC and might be slightly more robust. The accuracy of the predictions of afore mentioned seven metrics for the disturbance by glare lies in the range of 75-83% and does not confirm findings from other studies stating a poor performance of existing glare metrics.

The paper describes procedures for the direct calorimetric measurement of the solar heat gain coefficient g in detail. g is also called SHGC, solar factor, g-value or total solar energy transmittance TSET. All these terms are used synonymously in this document although there are some differences in the details of the definitions of these properties (e.g. different reference wind conditions or reference solar spectra). The document aims to summarize more than 25 years of experience in g-value testing at Fraunhofer ISE, Freiburg, Germany, which includes many different transparent and translucent building materials ranging from transparent insulation materials to daylighting and solar control systems and active solar energy harvesting facade components like building-integrated PV systems (BIPV) or building-integrated solar thermal collectors (BIST). The document focuses on methods for the calorimetric measurement of g under steady-state laboratory conditions. Transient outdoor measurements are beyond the scope of this paper. It also describes the corresponding error analysis and methods to correct experimentally determined values gexp to reference conditions, if it is not possible to reproduce the reference boundary conditions exactly in the laboratory.

Nowadays buildings are being designed with large glazed areas mainly due to aesthetics considerations but also to achieve daylit spaces. However, large glazed facades are prone to cause glare problems for building users. To mitigate this risk, it is important to predict existing glare metrics dynamically and reliably in the early stages of the design of a facade. Current evaluation methods for dynamic glare are either computationally too expensive or not suitable for operable facade systems. In this study, a new method is proposed to calculate the Daylight Glare Probability (DGP) index in a computationally efficient fashion, while allowing the fenestration system to switch states during the annual simulation. The method is based on a matrix formalism to calculate the vertical illuminance at a view position, and also on the calculation of a luminance map of the field of view solely from the direct component of the light sources. A first validation of the proposed method is presented. An office setup in Freiburg is monitored with a luminance camera for different weather conditions and different facade systems. Additionally, the calculation of the DGP index by the proposed method is compared with the calculation of the DGP by backward raytracing with high rendering parameters. The proposed method has been implemented in a building simulation program, called Fener. A case study is presented to illustrate the new possibilities offered by the Fener tool. The glare risk of three different textile roller blinds, with similar visible transmittance but different openness coefficient, is assessed.

A field of transparent solar thermal facade collectors (TSTC) was installed in a pilot building in Ljubljana, Slovenia. This paper presents the first measurement results from the installation. During the heating season, the transparent facade collectors contribute to the heating of the pilot building, while they provide heat to an adsorption chiller during the cooling season. Despite the different loads and surrounding conditions, the monthly solar gains of both seasons are similar. The heat flux between the collector and the interior as well as the temperatures seem comparable to a conventional solar control facade.

Transparent solar thermal collectors (TSTC) represent a new development. An adequate model is needed to predict their performance. This paper presents a collector model with an advanced calculation of the transmission of diffuse radiation and a connection to the building which allows analysis of the collector gains and of the g value, also called “solar factor”, “solar heat gain coefficient (SHGC)” or “total solar energy transmittance”. The model is implemented as a TRNSYS Type and a coupled simulation between a collector and a room is presented for different facade constructions. Facade areas with glazing and venetian blinds are simulated with a second new TRNSYS Type which introduces high modelling accuracy for facades with solar control systems. An HVAC system is presented together with a first estimate of possible reductions of primary energy. It indicates primary energy savings of about 30% by replacing opaque walls with transparent collectors. The g values prove to depend not only on the irradiation, but also on the operation of the solar collectors and vary e.g. between 0.04 and 0.21. Detailed modelling of active facades like TSTC is therefore essential for accurate predictions of the collector gain, the heating and cooling loads and the thermal comfort.

U radu se ocjenjuje unutarnja okolina renoviranih ureda koji su, kao pokusni primjer, opremljeni naprednim stropnim isijavajućim pločama koje se primjenjuju za grijanje i hlađenje. Obavljene su opsežne analize na bazi raznih nizova stvarnih mjerenja kako bi se ocijenila djelotvornost i prikladnost predložene koncepcije za adaptiranje prostora. Ustanovljeno je da čitav sustav za temperiranje uredskih prostora funkcionira na prikladan način, te da raspon unutarnjih temperatura zraka omogućava postizanje najviše razine udobnosti., The indoor environment in retrofitted pilot demonstration offices, equipped with advanced radiant ceiling panels that were used for heating and cooling, is evaluated in the paper. Comprehensive analyses based on various sets of real case measurements were carried out in order to assess the efficiency and adequacy of the proposed retrofitting concept. It was established that the entire system for tempering the offices operates well, and that the range of indoor air temperatures ensures the highest level of comfort.

Colored Module glasses with high angle tolerance can be achieved by using the photonic effect discovered on high transmission is demonstrated. In a BIPV module, a homogeneous appearance with saturated color will be achieved by using a black back sheet and black interconnect wire or back junction cells. Fig. 2: Demonstration of the color effect for a mini module. The glass panes are applied with a water film. For large area demonstration, the functional layer was applied to glass panes of the format 109 x 112 cm2 (Fig. 3). These glass panes will be used for PV module lamination and installation in a demonstration facade at Fraunhofer ISE (installation planned in autumn 2016). Fig. 3: Large area demonstrator on an area of more than 1 m2. In the bright green area the strong color is visible since a black screen was positioned behind the glass. In the surrounding areas the high transparency can be seen. In the center and at the bottom reflections of the flashlight are visible.

Es wurde ein allgemeines Verfahren zur realistischen Leistungsbewertung von Sonnenschutzmasnahmen fur Fassaden entwickelt. Das Verfahren eignet sich insbesondere fur Jalousien und kann entweder unabhangig oder innerhalb von Gebaudesimulationsprogrammen eingesetzt werden. Das neue Verfahren hat sich in der Praxis bereits bei der Planung groser Burogebaude in Deutschland, Osterreich und der Schweiz bewahrt. Dieses Verfahren wird in [4] ausfuhrlich dargelegt. Es kann entweder unabhangig (ohne Gebaudesimulation) zum Vergleich verschiedener Fassadensysteme oder innerhalb von Gebaudesimulationsprogrammen eingesetzt werden. In dieser Veroffentlichung wird die Erweiterung der Methode auf Fassaden mit in einer Isolierverglasung integrierten Sonnenschutzsystemen vorgestellt. Bestimmte Teil e des Verfahrens konnten innerhalb von Normen (z. B. EN 13363) oder zur Verbesserung der Genauigkeit von Gebaudesimulationsprogrammen verwendet werden. Praxiserfahrung mit der neuen Methodik fuhrte zu neuen Erkenntnissen, die die Grundlage fur zwei neue Produkte bilden. In [5] werden diese neuen Produkte auf der Grundlage der neuen Methodik mit Produkten auf dem Stand der Technik verglichen. Im Rahmen eines von der Veluxstiftung finanzierten Projekts wird das neue Verfahren z.Z. in das Gebaudesimulationsprogramm ESP-r integriert. Sun control: General evaluation method (also suitable for integrated systems) and two new blind types. A general method for realistic performance evaluation of solar control properties of facades with sun-shading or other solar control systems has been developed. It is particularly designed to be used for venetian blinds. It can be used ‘stand-alone’ or within building simulation programs. The new method has proven to be of great practical value to planning teams of huge office buildings in Germany, Austria and Switzerland. The method is presented in detail in [4]. It can be used either ‘stand-alone’ (without building simulation) for comparisons of different facade variants or within building simulation programs. In this publication the extension of the methodology for the case of facades with solar control systems between the panes of an insulating glazing unit (IGU) is presented. Some parts of the proposed methodology could be used in standards (e.g. EN 13363) or to improve the accuracy of building simulation programs which are currently on the market. Practical experience with the new methodology led to insights which are the basis for the design of two new products. These new products are compared with state of the art products in [5] on the basis of the new methodology. We are currently linking the new method with the building simulation program ESP-r in a project which is funded by the Veluxstiftung.

The author has developed two new sun-shading systems together with two different companies. These systems are compared with state of the art products on the basis of the new general evaluation method for facades with venetian blinds or other solar control systems that has been prestented in detail in [T.E. Kuhn, Solar control: a general evaluation method for facades with venetian blinds or other solar control systems to be used ‘stand-alone’ or within building simulation programs, Energy Buildings, in press]. The main advantage is that the method can take into account realistic user behaviour (different utilisation modes). Without the new methodology, it would not have been possible to recognise the weaknesses of products which are currently on the market. This recognition was the basis for the design of the two new products: • The new stainless steel blind s_enn® selectively shields certain regions of the sky. This leads to a transparent appearance while direct insolation of the room and the associated glare is prevented in most cases. • The special shape of the ‘Genius slats’ of a new venetian blind ensures good sun-shading properties which are relatively independent of the actual setting of the slats over broad ranges, which ensures robust performance despite so-called ‘faulty operation’. In other words: The performance of the new venetian blind is relatively insensitive to different utilisation modes.

A general method for realistic performance evaluation of solar control properties of facades for facades with sun-shading or other solar control systems has been developed. It is particularly designed to be used for venetian blinds. It can be used used ‘stand-alone’ or within building simulation programs. The new method has proven to be of great practical value to planning teams of huge office buildings in Germany, Austria and Switzerland. The method is presented in detail in this paper. It can be used either ’stand-alone’ (without building simulation) for comparisons of different facade variants or within building simulation programs. Some parts of the proposed methodology could be used in standards (e.g. EN13363) or to improve the accuracy of building simulation programs which are currently on the market. Practical experience with the new methodology led to insights which are the basis for the design of two new products. These new products are compared with state of the art products in [T.E. Kuhn, Solar control: comparsion of two new systems with the state of the art on the basis of a new general evaluation method for facades with venetian blinds or other solar control systems, Energy and Buildings, in press] on the basis of the new methodology.

To prevent the overheating of a well-insulated building in summer, facade elements with switchable U -value are a possible solution. A new translucent element with switchable U -value is presented. The convection around a translucent insulation panel is controlled by moving this panel vertically within the double glazing unit. Measurements of such elements show a possible switching of more than +100% of the U -value between the insulating and conducting state. Various geometries have been measured, and the influence of CO 2 in the cavity has also been investigated. Based on the experimental results, TRNSYS simulations have been performed to investigate the overall performance of such a new element integrated in a real building. An optimized element could lead to a reduction of the cooling demand of up to 29.6% of the useful energy and to large improvements in the summer comfort.

Sun-shading systems have to provide thermal and visual comfort both reliably and economically. At the same time, they should prevent unwanted solar gains in summer and permit high solar gains in winter. This paper describes a method to assess the overheating protection offered by different types of sun-shading systems together with the associated control strategy. The objective of the new method is to provide a simple but reliable and realistic approach to evaluate the effectiveness of internal and external shading devices in combination with glazing, which is independent of the building type. The new method consists of the angle-dependent determination of the total solar energy transmittance, g, based on ray-tracing methods, which has been validated using calorimetric measurements. Combination with annual irradiance distributions allows for the evaluation of different control strategies. This paper shows that it is essential for the reliability of calculated cooling and heating loads, that the calculation is based on a control strategy, which reflects the priorities of the users of the building.

New facades of high-rise buildings often include renewable energy converters to allow "green building" operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTCs) aim at decreasing the non-renewable primary energy demand and increasing the visual transparency at the same time. On the one hand, this paper presents the main modelling challenges that arise when considering building facades and especially integrated TSTC systems. New transient systems simulation (TRNSYS) [Beckman, W. A., L. Broman, A. Fiksel, S. A. Klein, E. Lindberg, M. Schuler, and J. Thornton. 1994. "TRNSYS The Most Complete Solar Energy System Modelling and Simulation Software." Renewable Energy 5 (1-4): 486-488] types have been especially developed for this purpose. A simplified model is presented for comparison purposes. On the other hand, the overall performance for a building with facade-integrated TSTC, as measured by its non-renewable prima ry energy demand, is treated. This is achieved by considering a complete simulation model coupling the TSTC, building and heating, ventilation and air conditioning operation. Possibilities for primary energy savings are investigated using the building mass as additional thermal storage.

This paper describes a new general method for building simulation programs which is intended to be used for the modelling of complex facades. The term ‘complex facades’ is used to designate facades with venetian blinds, prismatic layers, light re-directing surfaces, etc. In all these cases, the facade properties have a complex angular dependence. In addition to this, such facades very often have non-airtight layers and/or imperfect components (e.g. non-ideal sharp edges, non-flat surfaces, …). Therefore building planners often had to neglect some of the innovative features and to use ‘work-arounds’ in order to approximate the properties of complex facades in building simulation programs. A well-defined methodology for these cases was missing. This paper presents such a general methodology. The main advantage of the new method is that it only uses measureable quantities of the transparent or translucent part of the facade as a whole. This is the main difference in comparison with state of the art modelling based on the characteristics of the individual subcomponents, which is often impossible due to non-existing heat- and/or light-transfer models within the complex facade. It is shown that the new method can significantly increase the accuracy of heating/cooling loads and room temperatures.

Transparent facade collectors can provide solar heating and cooling and lead to primary energy savings even compared to an opaque wall. They can be simulated with a detailed physical model based on laboratory measurements. The demonstration installation in Ljubljana will provide extensive measurement data of transparent facade collectors in an outdoor environment. This allows a comparison with simulations performed with the model validated by laboratory measurements. This paper presents the demonstration installation and the measurement system, which are based on the new modelling abilities and focused on the outdoor validation of such models.

Within the Aktifas project, a road map is being developed for research and development of facade-integrated solar thermal systems. The road map is based on an analysis of the barriers for facade-integrated solar thermal systems as well as a market overview of existing components. This paper presents the methodology for creating the road map as well as first results. The final road map will be published on http://bit.ly/Z0hkso at the beginning of 2015.

Rule-based control logics have proven to be efficient for automation of shading and lighting systems. However, successful commissioning of these systems for multiple stores non-residential buildings, regardless of the control logic, requires time-consuming programing and fine-tuning of numerous parameters. In this article, a control approach is suggested to overcome the limitations of the rule-based control systems: i) necessity for extensive information on the office room, ii) costly adaptation of control parameters to a new environment, and iii) no feedback to the control system in the case of mal-function. A novel self-commissioning approach is proposed: a set of open-loop geometry-based rules are enhanced with a supervised learning module for fine-tuning seven tunable parameters. This approach was validated through an in-situ experiment for 22 days in a daylight testbed equipped with internal venetian blinds, dimmable electric lighting system, a miniaturized accurate High Dynamic Range vision sensor to evaluate Daylight Glare Probability (DGP), horizontal illuminance meters and a pyranometer. The goal was to command the shading and electric lighting system to keep the DGP and horizontal illuminance in a predefined visual comfort zone. A novel visualization method is proposed to demonstrate the performance of the automatic system in leading the indoor environment to the visual comfort zone. After 11 days, the learning module reached the convergence state. Afterwards, the controller was capable of successfully confining the indoor illumination conditions to the visual comfort zone for 96% of the working hours while actuating the shading system efficiently; on average 2.54 times a day.

Current discomfort glare prediction metrics usually account for at least one of the two categories of effects that induce discomfort glare – the saturation and contrast effects. Saturation-driven metrics (overall illuminance on the eye) are suited for brightly lit scenes in general. On the contrary, contrast-driven metrics (luminance ratio in the field of view) usually perform better in high contrast conditions such as with small-sized bright glare sources. Only a few existing metrics consider both effects, such as the Daylight Glare Probability (DGP). However, even these “hybrid” metrics may underperform in conditions other than those considered when they were developed, such as in dim scenes with high contrast glare. This paper investigates the ability of current glare indicators to predict perceived discomfort glare in user-evaluated scenes depending on two different adaptation levels. Towards this end, we used a composite dataset of six laboratory studies performed previously and separately in various parts of the world. According to Receiver Operator Characteristics (ROC) findings and complementary statistical research, the hybrid metrics DGP and Eccologit perform best in both investigated ranges (dimmer and brighter scenes). For the single-effect metrics, the contrast-driven metrics appear to perform better than saturation-driven metrics in lower adaptation levels (dimmer scenes), while the reverse is seen in higher adaptation levels (brighter scenes). As a result, metrics that only consider one effect should be used with caution. Although hybrid metrics continue to perform well in the investigated scenes, further research is needed to extend their applicability to a larger variety of lighting conditions that may be observed in work environments.