Abstract: In recent discussions on the evaluation methodology of different aspects of building performance, the idea of so-called prescriptive indicators was proposed. These indicators are simple benchmark values of a building, and do not require any complex calculation or simulation. They are regularly based on certain design parameters pertaining to geometric or semantic aspects of the building, such as compactness and mean weighted U-value. Their purpose – amongst others – is to equip building planners with a very quick method to estimate the performance of their building designs in early design stages and to categorize its performance. Moreover, such prescriptive indicators could be considered an alternative concept to the current practice of energy certification in Europe. The energy certificate calculation methodologies in most countries did increase in complexity in the past years. As a result, the issuing of energy certificates has become a time-consuming and cumbersome process. Moreover, the quality of results of energy certificates became questioned in recent years due to uncertainties connected to input data assumptions and widely interpretable guidelines regarding the issuing. Prescriptive indicators, if their derivation is properly documented, can at least mitigate the issue regarding issuing guidelines due to their simple character. A important research question, however, is the relation between key performance indicators, which are the results of energy certification or building performance simulation, and prescriptive indicators. This contribution suggests a methodology based on rank comparison that might help to identify prescriptive indicators that are similar in their sensitivity on design changes as certain key performance indicators are.
Abstract: This study presents a research of envelope systems entailing elements that use and control incident solar energy to deliver renewable thermal or electric energy to the systems providing heating, ventilation and air conditioning to buildings. A simulation model of an office building was developed in the simulation program TRNSYS. A photovoltaic / thermal system was integrated into the building´s southern facade to generate electricity and to increase the temperature of the air flowing through the channel behind the photovoltaic modules. Subsequently, the electricity generated was used to power the heat pump and the warm air was used as the primary fluid for the heat pump to generate thermal energy for space heating in the winter. The useful energy gain and power production increased with increasing length of the photovoltaic modules and the air flow rate through the channel in the periods, when there was enough solar radiation impinging on the facade. In January to April, the benefits of the photovoltaic / thermal system were minor because of the low levels of low solar radiation and insufficient efficiency of the system components.
Abstract: A surface property of building façades, which has implications for thermal performance of buildings as well as outdoor thermal comfort, is visual reflectance. In this paper, the effects of façades’ visual reflectance on buildings' thermal performance and outdoor thermal comfort were investigated. A simulation tool was calibrated via empirical data and deployed to explore the impact of the visual reflectance of typical building façades in Vienna on indoor temperature and heating and cooling loads. The results show that the magnitude of visual reflectance has little impact on indoor temperature and energy demand of insulated buildings, while its effect on cooling load of non-insulated buildings is considerable. Finally, the effect of façades' visual reflectance on outdoor thermal comfort was investigated.
Abstract: This case study is aimed at simulation of dry floor heating system. Heating pipes are inserted in system boards made of thermal insulation. These boards should be supplemented with spreader plates which are installed under the heating pipes. Impact of different thermal conductivity of spreader plates on useful heat flux and uniformity of temperature field is examined. Heat losses are also investigated. These simulations are performed using software CalA with time steady-state boundary conditions. The results show that the dry floor heating system without spreader plates has very low useful heat flux caused by positioning of heating pipes in the insulation material. On the other hand, use of spreader plates causes significant increase of useful heat flux of this system. The higher heat conductivity of spreader plates is, the higher useful heat flux is. The floor surface temperature is also more uniform and the thermal comfort is better. The minimal thickness of additional heat insulation is determined in order that heat losses are lower than ten percent of total heat flux.
Abstract: This contribution presents an ongoing research effort addressing the performance assessment of a number of buildings planned by the Austrian architect Konrad Frey, who is considered to be one of the pioneers of sustainable architecture in Austria. A number of his buildings, planned in the 1970s, consequently integrated principles of modern solar houses. Relevant key projects are subject of an on-going research project. Thereby numeric building simulation was deployed to assess the energy performance of the buildings. In this contribution, we present the intermediate results of a study that focused on one of his latest buildings, namely the prefabricated low-cost loft house. As opposed to architect’s rather complex early designs the loft house concept targeted inexpensive solutions and used simple and commonly available building components and systems. As part of the overall project, the thermal performance of this building was evaluated in terms of the effectiveness of passive cooling via various ventilation schemes (including night time ventilation).
Abstract: This contribution concerns the reproducibility of energy certificates. To examine the impact of different input data assumptions on the results of energy certificates, sensitivity analysis was performed. Conducting such sensitivity analysis manually is not only time consuming and error-prone, but is also typically limited in view of input-data/result combinations. This can be a problem, as a number of input data combinations can have contradictory influences on corresponding KPI (key performance indicator) results. For instance, transparent building components increase not only solar gains, but also transmittance losses. As an alternative to manual modification of input data, the parametric algorithm-editor, Grasshopper (an Add-on to the CAD/CAM-environment Rhino) was utilized. The calculation standards of the Austrian energy certificate procedure were implemented in this environment. Input data values can be modified via a graphical user interface (rulers), and the impact of the change is instantly generated by the environment. Past research regarding planners' usage of energy certificate tools identified usability and overall user acceptance of such calculation tools as a weak spot. Thus, the implementation of calculation routines within a widely used drafting/parametrization tool could result in increased acceptance by planners. In a first methodological approach, the impact of input assumptions regarding building typology and window properties on solar gains, transmittance losses, and heating demand were considered. The contribution illustrates the method and the results of a number of case studies, which show that the concept can be usefully deployed in energy evaluation of buildings. Thereby, the approach can accommodate two requirements: On the one hand, it can result in a tool to evaluate building concepts in early design stages. On the other hand, it can serve as a conceptual vehicle to explore and evaluate calculation methods, such as the standardized energy certification procedure.
Abstract: Simulation tools have been suggested to have the potential to support the design of high-performance buildings. However, sophisticated simulation environments are frequently utilized in the later stages of building planning. This might be due, in part, to the lack of sufficient and reliable input data during the early stages of design. Moreover, advanced tools appear to be geared toward consultants and specialists (expert users) rather than primary building designers. In recent years, tools in the CAD and BIM areas have introduced new features for parametric design and interfaces to different calculation and simulation engines. If properly deployed, such tools could offer effective early-design performance evaluation support, for instance via pre-rationalization of building forms and morphologies. Surprisingly, few studies have assessed the usefulness and usability of these new opportunities. In this context, the present contribution documents the background, method, and results of a tool potential assessment study regarding two specific environments, namely Ladybug and Honeybee. These are plugins for the parametrization environment grasshopper. The outcome of this effort provides not only a specific snapshot of the standing of these tools in the context of realistic performance assessment scenarios, but provides also a detailed framework for future critical evaluation of the usability and usefulness of computational solutions for early stage design optimization.
Abstract: This contribution reports on the progress in the EVA project. This project was started in 2017 based on past experiences made in the framework of workshops and design studios at the University of Applied Arts in Vienna. Within these workshops different concepts toward energy-active and reactive architectural concepts was conceived and realized into scale models. The major design goal was to provide a built structure that is not only energy efficient, but also comfortable for occupants, and can display dynamic behavior in response to stimuli from the surroundings and the occupants. To construct the designs into scale models, different supportive tools and techniques were deployed, such as numeric thermal building simulation, parametric design programming, electronic control loops and mechatronic systems. Moreover, the different designs and concepts were inspired by a wide range of ressources, such as biology, bionics, natural phenomena, and traditional architectural concepts. Partly, these concepts (e.g. the photosynthesis of algae plants) were integrated in the scale models. As such, the workshops and design studios could be considered a success. New, challenging, and exciting designs were developed, and engineered in terms of scale models. However, the proof of concept in terms of real life implementation is missing. This gap will be bridged by the EVA project, which targets the evaluation of different concepts and the realization of the most promising project as a fully functional full scale mock-up. Needless to say, the level of complexity increases by the scale: Aspects of structural and dynamic stability have to be considered, mechatronic elements have to be constructed, and intelligent and reliable building control modi have to be implemented.This paper describes the first phase of this project, which is the collection, description, and structured evaluation of a number of design studies from the past years. Thereby, it was decided not only to assess projects that were designed in the framework of the University of Applied Arts, but to investigate similar design studies from professional and academic backgrounds worldwide The contribution concludes with an outlook of the project’s next steps.
Abstract: The aim of the paper is to explore and establish a base for a possible development of a more holistic and spatially-inclusive method for evaluating energy performance of buildings. This is to be achieved by envisioning building envelopes as arrangements of spatial zones, which could improve the overall energy balance of buildings but at the same time reduce the usage of construction materials and thus consumption of production energy and built-up space. The wall deconstructed in spatial zones, as shown e.g. in Antivilla by Brandlhuber-+, opens a series of questions about the future of existing building codes and certification tools. The potentials are discussed based on the aspects of flexibility, responsiveness, adaptability, replaceability and affordability. The analysis outlines the benefits of the inclusion of those paradigms in the definition of sustainable architecture, and at the same time exposes the lack of possibility to reflect their potential by the established certification criteria. The paper aims at opening the discussion about the limits and traps of quantifying architecture and calls for rethinking of established schemes of sustainability in building sector.
Abstract: Organisations are becoming more intensively conscious about energy related-topics. The overall societal recognition, changing legal requirements and cost reduction pressure results in increasing interests in holistic energy management activities well embedded into the overall facilities and asset management context.This paper aims to specify the information requirements for setting-up energy management system. Such a system aims to ensure that owners, tenants and operators of buildings can deliver facility and energy management services in compliance to the relevant legislative, technical and environmental standards. Initial information requirements for such a system were developed over the past nine months and are presented in this paper.