What drives the impact of future support policies for energy efficiency in buildings?

Policy makers face the challenge to design and test support policies for nearly zero energy buildings (nZEB) - and in general energy efficiency policies - in a real-life laboratory. Model based scenarios are expected to reduce the uncertainties. However, rather than trying to exactly predict the future or the impact of a certain instrument, the core objective is to understand the drivers affecting the impact of policies on future energy demand in buildings. We will draw nearer to this objective by a comparative analysis of policy scenarios in 9 EU Member States (MSs) and EU-28 as a whole. Thus, the key research questions of this paper are: (1) What impact on energy demand, CO2-emissions and public costs do various policies trigger in scenarios for EU MSs and the EU-28? (2) What drives the differences between the scenarios in various countries and policy settings? (3) How do the policies compare in terms of their consistency with long-term targets of energy savings and CO2-reductions? We build this research on three policy sets which were developed in the IEE project ENTRANZE in a discussion process with policy makers: one policy set reflecting current policy instruments and two others with more innovative and ambitious approaches. The potential effect of these policy sets was analysed with the bottom-up model Invert/EE-Lab. The model is based on a disaggregated description of the building stock, and its building and HVAC components. The investment decision for various retrofit measures and HVAC systems is modelled under consideration of the characteristics of various country specific agent groups (e.g. low-income households, elderly people, ownership types etc). The results show a wide range of energy savings for space heating, hot water, cooling and lighting of less than 10% to more than 30% from 2008-2030. Remarkably, the highest energy savings were not achieved in those scenarios and countries with the highest public expenses. It turns out that at least a minimum level of regulatory measures increasing ""nZEB renovation"" activities and renewable heating (RES-H) systems should be added to economic incentives and strong supply - side measures