Evaluating the renewable heating and efficiency obligation for existing buildings – insights into the mechanisms of mandatory building requirements

Germany’s third largest state, Baden Württemberg, was the first to mandate the installation of renewable heating technologies in 2008. Owners of a heating system need to employ a minimum share of renewable energy of 15% of the heat demand when the heating system is replaced. Instead of employing a renewable heating system, the building owner can also opt for efficiency measures, including insulation of the building. A part of the obligation can be fulfilled by carrying out an energy audit based on an individual building roadmap.

For the first time, the effects of the Renewable Heating Act Baden-Württemberg have been evaluated in detail, based on statistical analyses of the available verifications, on market observations, interviews with 1000 clients, 150 heating installers, 250 chimney sweepers, 50 building companies, clients of energy audits and various stakeholder workshops and interviews, leading to a model calculation of estimated savings of the law. The paper will present the empirical findings and investigate the various mechanisms of the renewable and efficiency requirement, including direct and indirect effects, trigger effects, windfall effects and wait-and-see attitudes.

Overall, the law provides positive impetus for additional installations of renewable energies, more energy efficiency and advice. This effect results from the sum of different effects: through the explicit requirements, it provides an additional direct incentive to expand renewable energies and substitute measures. Indirectly, the law strengthens the involvement with renewable energies both in the consultation process with heating engineers and planners/architects and in the purchase decision of customers. Additional energy consulting is also encouraged. However, the positive market figures compared to the federal trend are not completely causally attributable to the EWärmeG.The paper will conclude with a set of improvements of the Act itself and the surrounding policy landscape.