A proposal to go beyond the rebound effect: how to evaluate the financial value of comfort after retrofitting?

Panel: 8. Monitoring and evaluation: building confidence and enhancing practices

This is a peer-reviewed paper.

Authors:
Stanislas Nösperger, EDF - RD, Département TREE, France
Dominique Osso, EDF R&D, France
Maxime Raynaud, EDF R&D

Abstract

Evaluations of energy savings of retrofitting programs are relativized due to the rebound effect. Moreover, their economic relevance (i.e. NPV calculation) is questioned because of the discouraging paybacks. The underlining question of both problems is a missing consideration of comfort improvement, often hidden behind the concept of rebound effect.

Yet, it can be considered that some potential energy savings in an initially uncomfortable dwelling are assigned to achieving decent comfort. In this case, the household sets aside some of the potential savings to improving thermal comfort and thus part of the rebound effect is simply to catch up. It therefore imports to distinguish within the so-called rebound effect between the share of legitimate comfort improvement and the energy “wastage”.

We propose an approach embodied in a formula to monetize the comfort catch-up relying on the comparison of ex-ante and ex-post energy savings. This approach has been applied to regional energy efficiency programs. These case studies are located in 3 different regions with different climates (oceanic, continental and Mediterranean). After refurbishment, we evaluate the level of comfort catch up according to the set-temperature and the difference between the real consumption and its potential value at a conventional set-temperature.

The methodology turned out to be quite easily applicable providing that some essential data are available (energy consumptions and set-temperatures before and after retrofit). Quantitative results of comfort catch up are in the same order of magnitude of energy savings.