OVERHEATING RISK IN BUILDINGS: A CASE STUDY OF THE IMPACT OF ALTERNATIVE CONSTRUCTION SOLUTIONS AND OPERATIONAL REGIMES Andreas WURM , Ulrich PONT, Farhang TAHMASEBI, Ardeshir MAHDAVI Department of Building Physics and Building Ecology, TU Wien, Karlsplatz 13, 1040 Vienna ulrich.pont@tuwien.ac.at

Table of Content Introduction Method Results Conclusion & Future Research

Summer Overheating Climate Change Heat Periods Tight Constructions Lightweight Constructions HVAC / Operation Cost User Comfort Recommendations for Planners Recommendations for Occupants

Number of heat wave days increases year Number of Kyselý days Fig. 1 Annual number of Kyselý days in Vienna, Source: ZAMG 2015 [1]

Worldwide produced amount of electricity 1990 - 2013 Fig. 2 Worldwide produced amount of electricity 1990 – 2013, Source: IEA, Statista 2016 [2]

Can passive measures help maintaining comfortable conditions? Thermal mass Orientation Window ventilation and shading Each construction is evaluated with all orientations in all scenarios. For each evaluation we have 72 possible performance indicator combinations Evaluation: ArchiPhysik [3] Simple normativ method based on ÖNORM B8110-3 [5] Energyplus [4] Numeric thermal simulation

6 constructions (thermal mass) 3 operational scenarios (ventilation and shading) Fig. 3 Selected building constructions Fig. 4 Operational scenarios for window ventilation and application of shading devices

Case study building – floor plan Fig. 5 Case study building floor plan [6]

Operational scenarios (Ventilation, shading systems and internal gains) Ventilation summer Fig. 7 Minimum ventilation during summer [6] Fig. 8 Day & night ventilation (open windows) [6] Fig. 6 Overview of operational scenarios [6]

Operational scenarios (Ventilation, shading systems and internal gains) Internal gains summer Fig. 9 Thermal output of persons in summer [6] Fig. 10 Thermal output of equipment in summer [6] Fig. 6 Overview of operational scenarios [6]

Operational scenarios (Ventilation, shading systems and internal gains) Internal gains winter Fig. 11 Thermal output from persons and equipment during winter [6] Fig. 6 Overview of operational scenarios [6]

Results ArchiPhysik Fig. 12 Cumulative frequency distributions of operative indoor temperature [6] Fig. 13 Cumulative frequency distributions of operative indoor temperature for south and west orientation [6]

Results ArchiPhysik Fig. 14 Overheating tendency (over 25°C) [6]

Results ArchiPhysik Fig. 14 Daily temperature profiles, west orientation, scenario 1 (left), 2 (middle), 3 (right). Fig. 15 Boxplot daily temperature, west orientation, scenario 1 (left), 2 (middle), 3 (right). [6]

Results energyplus Fig. 16 Cumulative frequency distributions of operative indoor temperature for the period April – September [6] Fig. 17 Cumulative frequency distributions of operative indoor temperature for the heat wave period [6]

Results energyplus Fig. 18 Cumulative frequency distributions of operative indoor temperature for all scenarios during the summer period. [6] Fig. 19 Cumulative frequency distributions of operative indoor temperature for all scenarios during the heat wave. [6] The order of the curves from left to right are scenario 3 (leftmost line of each construction method), scenario 2 (middle line of each construction method), and scenario 1 (rightmost line of each construction method).

Results energyplus Fig. 20 Heat wave temperature distribution for all evaluated construction methods, west orientation, scenario 3 [6]

Results energyplus Fig. 21 Temperature difference [K] between different constructions and the reinforced concrete construction (CC_nFC) in scenario 3, west orientation during heatwave. [6] Fig. 22 Summarized average and maximum temperature differences, west orientation, scenario 3 [6]

Conclusion Operational regimes can significantly influence the room's thermal performance. Failure to apply passive cooling methods in the operation cannot be offset by the applied construction method alone. Especially during heat waves, the construction method with the highest thermal mass (reinforced concrete) performs better than the other construction methods. Additional elements of high thermal mass, such as concrete screeds in the floor construction can reduce overheating. An opposite effect – albeit to a smaller extent – could be observed with regard to facing shells. The assessment method does influence the estimated magnitude of overheating.

Future research Forward planning: - Simulation with future weather data (climate change) - Innovative Construction methodes and materials Case study building - Different use case buildings and a wider set of constructions. The constructions should be evaluated in view of their optimization potential. - Variance in the size and orientation of transparent parts of the building envelope. - The existing case study shall be extended to examine attic space. Are the results from the simulation close to the reality? - Cupboards in front of surfaces with high thermal mass - Influence of the material of floor surfaces

References [1] ZAMG: Zentralanstalt für Meteorologie und Geodynamik, Hitzewellen: 2015 eines der extremsten Jahre der Messgeschichte, 13.08.2015 WWW:<http://www.zamg.ac.at/cms/de/klima/news/hitzewellen-2015-eines-der-extremsten-jahre-der- messgeschichte> [2] Statista 2016, 15.06.2016 WWW:<http://de.statista.com/statistik/daten/studie/166918/umfrage/stromerzeugung-weltweit-seit-1990/> [3] A-Null Development GmbH. Archiphysik 12 (Version 12.0.46) Available via www.archiphysik.com [4] US - Department of Energy. Energy Plus 8.1. (Version 8.1.0.009) Available via http://apps1.eere.energy.gov/buildings/energyplus/ [5] Austrian Standards Institute: ÖNORM B 8110-3, 2012-03-15. Thermal protection in building construction – Part 3: Prevention of summerly overheating Object. Austrian Standards Institute, Heinestraße 38, 1020 Vienna, Austria [6] Wurm, A. 2016 Sommerliche Überwärmung – Ein Vergleich zwischen unterschiedlichen Bauweisen und Nutzerverhalten. Master Thesis, TU Wien, 2016 WWW:<http://repositum.tuwien.ac.at/obvutwhs/download/pdf/1018552?originalFilename=true>

!Thank you for your attention! OVERHEATING RISK IN BUILDINGS: A CASE STUDY OF THE IMPACT OF ALTERNATIVE CONSTRUCTION SOLUTIONS AND OPERATIONAL REGIMES Andreas WURM , Ulrich PONT, Farhang TAHMASEBI, Ardeshir MAHDAVI Department of Building Physics and Building Ecology, TU Wien, Karlsplatz 13, 1040 Vienna ulrich.pont@tuwien.ac.at