Pre building renovation measurements and efficient decision-making. Danish case study

Efficient renovation of residential buildings is a cornerstone to achieve the 2020 to 2015 European energy strategy. However, the gap between the actual and estimated energy savings is a challenge, since it jeopardizes the refurbishment´s credibility to both the investors and building end users. In this study, a prerenovation measuring concept was investigated as a solution to reduce the energy savings gap through identifying the building baseline and evaluating the occupant’s behavior and its influence on the energy performance. The concept was tested on two Danish social housing apartments in Aalborg city where dynamic measurements of indoor environment and energy use were conducted for two weeks. Linear regression relations between the measured indoor and external temperatures were developed and linked to a dynamic building model developed in TRNSYS to predict the heating profiles for the heating season. Short-term measurements before the renovation and the regressed relation to outdoor conditions reduced the difference between expected and actual energy consumption to 3%. The method did not perform well in the renovated apartments where added insulation and improved air tightness decoupled the indoor and outdoor conditions.