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C. Berger, H. Teufl, U. Pont, A. Mahdavi:
"Uncertainties in Building Energy Certification: Two Case Studies Pertaining to Zoning";
Applied Mechanics and Materials, 12th Envibuild - Buildings and Environment - From Research to Application Proceedings of the 12th International EnviBUILD Conference (7th & 8th September 2017) (2019), 887; 156 - 164.

Building energy certification is stipulated by law in the majority of the European countries. The intention of these regulations is to offer key performance indicators (KPIs) to relevant and interested stakeholders. Another motivation for implementing these calculation schemes was to compare the energy performance of different buildings. However, existing guidelines for building energy evaluation do not comprehensively outline the input data collection process and the derivation of substantial KPIs. Furthermore, practitioners do not share a common understanding of the approach to energy certificates, resulting in different practical methods and different interpretations of the calculation guidelines. As a result, the envisioned comparability between buildings is not ensured, as a number of studies illustrated in the past.
This contribution focuses on a specific uncertainty in building energy evaluation input data, pertaining to zoning and usage assumptions. Toward this end, two case studies are presented. A number of existing buildings (typical Viennese building stock) were subjected to the Austrian normative energy certification calculation. Thereby, different scenarios regarding the zoning and usage profiles of the buildings were developed. On the one hand, the calculated performance of individual (residential) units was compared with the calculated performance of the whole building. On the other hand, calculations considering different usage assumptions in different zones within the building (detailed calculation) were compared to results based on generalized assumptions for the whole building. The evaluation of the case study buildings showed significant differences in KPIs, given different input data (depending on the case study, heating demand showed deviations up to 50%). The results emphasize the importance of a clear documentation of input data assumptions for building-related energy assessment.

(no german abstract)
Building energy certification is stipulated by law in the majority of the European countries. The intention of these regulations is to offer key performance indicators (KPIs) to relevant and interested stakeholders. Another motivation for implementing these calculation schemes was to compare the energy performance of different buildings. However, existing guidelines for building energy evaluation do not comprehensively outline the input data collection process and the derivation of substantial KPIs. Furthermore, practitioners do not share a common understanding of the approach to energy certificates, resulting in different practical methods and different interpretations of the calculation guidelines. As a result, the envisioned comparability between buildings is not ensured, as a number of studies illustrated in the past.
This contribution focuses on a specific uncertainty in building energy evaluation input data, pertaining to zoning and usage assumptions. Toward this end, two case studies are presented. A number of existing buildings (typical Viennese building stock) were subjected to the Austrian normative energy certification calculation. Thereby, different scenarios regarding the zoning and usage profiles of the buildings were developed. On the one hand, the calculated performance of individual (residential) units was compared with the calculated performance of the whole building. On the other hand, calculations considering different usage assumptions in different zones within the building (detailed calculation) were compared to results based on generalized assumptions for the whole building. The evaluation of the case study buildings showed significant differences in KPIs, given different input data (depending on the case study, heating demand showed deviations up to 50%). The results emphasize the importance of a clear documentation of input data assumptions for building-related energy assessment.

building energy certification, zoning, key performance indicators, usage profiles