Current practices show that the goals of energy saving and CO2 reductions for creating an energy-neutral building stock can only be reached by strict and supportive governmental policies. In Europe the Energy Performance of Buildings Directive (EPBD) and the Energy Efficiency Directive (EED) are driving forces for member states to develop and strengthen energy performance regulations both for new buildings (via building approval procedures) and the existing building stock (via energy performance certificates or labels). The effectiveness of these current governance instruments and their impact on actual CO2 reductions are found to be inadequate for ensuring actual (not hypothecated) energy performance is achieved. To realize the very ambitious energy-saving goals a radical rethink of regulatory systems and instruments is necessary. Building performance and the behaviour of the occupants is not well understood by policy-makers. Alternative forms of governance are needed that have more impact on the actual outcomes. Supportive governance to stimulate near-zero renovations in combination with performance guarantees is a promising approach. Furthermore, engagement with occupant practices and behaviours is needed. To ensure accurate outcomes-based governance, a better understanding of building performance and behaviours of occupants must be incorporated.

The register of the Dutch social housing stock was analysed, containing 300.000 dwellings, renovated between 2010 and 2013. The main objective was twofold: to evaluate the performance gap in these dwellings before and after the renovation and to establish what renovation measures achieve the highest reduction of consumption, particularly in practice (actual savings). The results showed large performance gaps in dwellings with low R and high U values, local heating systems, changes from a non-condensing into a condensing boiler and upgrades to a natural ventilation system. Regarding the actual effectiveness of renovation measures, replacement of old gas boilers with more efficient ones yields the highest energy reduction, followed by deep improvements of windows. Installing mechanical ventilation yields a small reduction compared to other measures, but still much larger than theoretically expected. The paper shows once more that the calculation method currently in use cannot be considered accurate if compared to actual consumption. The study demonstrated that unrealistic theoretical efficiencies of heating systems and insulation values are causing a part of the performance gap. Nowadays, large datasets of buildings thermal performance and actual consumption offer an opportunity to improve these misconceptions.