The Institute for Ecological Economy Research (IÖW) has evaluated the impact of so called heating surveys povided by co2online. co2online compile such surveys based on a short questionaire and the last heat cost billing. They inlcude an estimation of the buildings energy performance and dependent on the results recommendations for energy-efficient refurbishment. In 2010 a houselhold survey was conducted to evaluation whether an which energy-saving measures were initiated. Rougly one third of all dwellings in the survey were modernized including low-investive measures as hydraulic alignment and high-investive measure as facade insulation.