Evidence of an indirect rebound effect with air-to-air heat pump: to have and not to use ?
Résumé
Regional energy efficiency programmes are of particular interest as they tackle local constraints which are not always targeted by national energy policy. In this frame, an energy efficiency programme for existing dwellings has been implemented in a southern European region, providing financial incentives for a combination of energy efficiency actions (reversible air-to-air heat pump combined with insulation and/or solar hot water). Ex-post evaluation results of this pilot programme are reported here. More than 200 households were surveyed regarding their individual energy consumption and building as well as household characteristics. Likewise, the survey highlights household behaviours concerning both space heating and air conditioning, before and after refurbishment. A three years billing analysis is used to calculate the energy savings attributed to the operation. Evaluations are carried out taking into account critical parameter like climate differences between years or direct (enhanced space heating comfort) and indirect (use of air conditioning) rebound effect via a statistical model. Moreover, an uncertainty assessment of energy savings was realized on the basis of three scenarios (low, median and high). Particularly, this study points out the use of air conditioning by households, data rarely found in the literature, whereas this end-use should increase in the residential sector especially in southern regions. These results contribute answering questions about installation of air-to-air heat pump in existing buildings: energy savings and direct rebound effect as well as indirect rebound effect and household motivation for implementing energy efficiency actions.