Air-to-air heat pumps in real-life use: Are potential savings achieved or are they transformed into increased comfort?

This paper deals with individual air-to-air heat pumps in Danish dwellings and summerhouses and the question of to what extent they actually deliver savings of energy consumption. Results show that 20% of the expected reduction of electricity consumption is converted into increased comfort in the homes, including extended heating areas, keeping a higher temperature and a longer heating season and using the heat pump for air conditioning. Data include electricity consumption in 185 households before and after installation of heat pumps together with survey results of 480 households. Furthermore, 12 households were selected for in-depth analysis including technical inspection and qualitative interviewing. Especially for summerhouses, results indicate that on average there is no reduction in electricity consumption, as energy efficiency is counter balanced by increased comfort and changed heating practices. These results have to be taken into account when making long-term energy planning for a sustainable energy system.

► Meter readings, survey and interviews of households having installed an air-to-air heat pump.
► A rebound effect of 20% indicates that 20% of expected reduction is used for increased comfort.
► In summerhouses on average there are no reductions because of increase in heating during wintertime.
► Changing heating practices: higher temperature, longer heating season, used for air-conditioning.