Die Diskrepanz zwischen Energiebedarf und -verbrauch bei Nichtwohngebäuden - ein empirischer Ansatz

The gap between calculated energy demand and measured consumption for non-residential buildings - An empirical approach.

The research project "Teilenergiekennwerte von Nichtwohngebäuden (TEK)" (partial characteristic energy values of non-residential buildings) within the EnOB research program of the German Federal Ministry for Economic Affairs and Energy (BMWi), delivered a database consisting of 93 existing non-residential buildings. The database contains detailed information on properties of the building envelope, energy efficiency of technical installations, user behaviour, measured energy consumptions and calculated energy demands. With these data the commonly observed gap between calculated energy demand for heating and domestic hot water and actual energy consumption will be examined. Generally it is observed, that for energy efficient buildings, the calculated demand tends to underestimate the actual consumption, whilst it tends to overestimate the consumption for older buildings not yet refurbished. This tendency, arising by simple linear regression, however is superimposed by a significant distribution. Hence an extended examination approach seems to be necessary. As further important impact factors for energy demand calculations, usage parameters will be examined by use of the methodology of multiple linear regression. The identified impact factors describe the observed distribution better, although still not completely. Based on the obtained insights of the regression analysis, functions for an estimated energy consumption with standard error are derived in order to diminish the gap towards the actual energy consumption with a certain probability. This methodological approach is suitable especially for the energy assessment of building portfolios or districts, but also for empirical correction of energy saving predictions of individual buildings.