Evaluation of the impact of energy renovation measures

Name: Evi Lambie

Dirk Saelens

Introduction / Objective
In order to decrease greenhouse gas emissions in the battle against climate change, energy use needs to be decreased worldwide. Although the renovation of residential buildings holds a large opportunity to decrease energy use, previous research reports significant lower energy savings from energy renovation measures than expected, which is caused by an energy performance gap between actual and expected values. In this context, the main aim of this research is to assess how the most efficient energy renovation measures can be identified for a sample of twenty case study dwellings.

Research Methodology
In order to achieve this main aim, the building energy performance is evaluated using an elaborate data set of in-situ measurements per case, complemented with theoretical calculations following the Flemish energy performance regulations (EPB-software). Three sets of secondary research questions are answered.

• First, this work focuses on bringing the results to the same comparison basis. Hereto, the impact of occupant behavior, outdoor climate and temperatures in adjacent zones is analyzed by means of linear regressions, correlations and a parametric study. Moreover, a model is developed to decrease the energy performance gap by normalizing the measured energy uses and correcting the theoretical energy uses identified with the EPB-software.

• Second, the impact and efficiency of the renovation measures of the case study dwellings are identified, focusing on three performance aspects: indoor environmental quality, building envelope quality and energy use

• Third, to proceed towards a consolidated approach to quantify and predict the renovation impact , this work formulates a basic monitoring campaign and a five-step methodology to predict an occupant-specific post-retrofit final energy use 

Results & Conclusions
Some of the key findings are the following:

• The average gap between the theoretical and measured energy uses of the sample of cases is decreased from 64% to 35%.
   
• The most efficient renovations of our sample of cases could be selected: roof renovations, complete building envelope renovations and deep renovations. However, some of these measures did not improve all building performance aspects, which illustrates the need for a comprehensive assessment.