The Potential of Descriptive Building Specifications as an Alternative To Detailed Normative Calculations

Abstract

(no german abstract) Abstract. Energy performance calculations are stipulated by law in most European countries. Thereby, different calculation schemes have been developed in the past years in different countries. The physical processes in buildings were simplified in terms of normative calculation routines in most of these schemes. A major idea behind these simplifications was to enable different stakeholders (practitioners, engineers, and architects) to issue energy certificates without being simulation experts. Moreover, the simplifications needed to be described thoroughly in corresponding guidelines to ensure and facilitate the comparability of the energy performance of different buildings. However, neither of these objectives can be considered to be fully met. Regarding the former, the normative calculation procedures increased in complexity in the past years, so that the issuing of energy certificates requires not only the stakeholder's expertise but also a comprehensive knowledge of the standards that form the calculation method. Regarding the latter, recent research efforts revealed that many guidelines do not fully cover every aspect of the calculation procedures and the assumptions regarding required input data. Thus, the comparability of energy certificates has to be strongly questioned, as a number of relevant calculation parameters are dependent on the interpretation of the corresponding issuer. Given this background, alternative approaches to building performance evaluation would be of interest. Previous approaches by different researchers suggested so called prescriptive indicators, which can be derived by basic building data (for instance, geometry and thermal quality of the building envelope components). This contribution is based on this concept. In the framework of a master thesis, a number of prescriptive indicators were considered. These indicators were derived for a set of sample buildings. In a parallel effort, energy certificates (encompassing Key Performance Indicators KPIs) were calculated for the sample buildings. It is clear that the prescriptive indicators cannot act as a 1:1 replacement for KPIs in terms of a numeric value. However, their usefulness can be expressed by the relation of the prescriptive indicator and the corresponding KPIs of a building. Thus, the results of the described calculation efforts were ranked. Subsequently, the lists of buildings ranked by the different indicators were compared in order to identify prescriptive indicators, which result in the same or at least similar ranking as the normative key performance indicators. Within this contribution, the suggested prescriptive indicators, the sample buildings, and the results of the analysis are presented and discussed.

Abstract. Energy performance calculations are stipulated by law in most European countries. Thereby, different calculation schemes have been developed in the past years in different countries. The physical processes in buildings were simplified in terms of normative calculation routines in most of these schemes. A major idea behind these simplifications was to enable different stakeholders (practitioners, engineers, and architects) to issue energy certificates without being simulation experts. Moreover, the simplifications needed to be described thoroughly in corresponding guidelines to ensure and facilitate the comparability of the energy performance of different buildings. However, neither of these objectives can be considered to be fully met. Regarding the former, the normative calculation procedures increased in complexity in the past years, so that the issuing of energy certificates requires not only the stakeholder's expertise but also a comprehensive knowledge of the standards that form the calculation method. Regarding the latter, recent research efforts revealed that many guidelines do not fully cover every aspect of the calculation procedures and the assumptions regarding required input data. Thus, the comparability of energy certificates has to be strongly questioned, as a number of relevant calculation parameters are dependent on the interpretation of the corresponding issuer. Given this background, alternative approaches to building performance evaluation would be of interest. Previous approaches by different researchers suggested so called prescriptive indicators, which can be derived by basic building data (for instance, geometry and thermal quality of the building envelope components). This contribution is based on this concept. In the framework of a master thesis, a number of prescriptive indicators were considered. These indicators were derived for a set of sample buildings. In a parallel effort, energy certificates (encompassing Key Performance Indicators KPIs) were calculated for the sample buildings. It is clear that the prescriptive indicators cannot act as a 1:1 replacement for KPIs in terms of a numeric value. However, their usefulness can be expressed by the relation of the prescriptive indicator and the corresponding KPIs of a building. Thus, the results of the described calculation efforts were ranked. Subsequently, the lists of buildings ranked by the different indicators were compared in order to identify prescriptive indicators, which result in the same or at least similar ranking as the normative key performance indicators. Within this contribution, the suggested prescriptive indicators, the sample buildings, and the results of the analysis are presented and discussed.