Cost optimality - brake or accelerator on the way towards nearly zero energy buildings

Art. 5 of the recast Energy Performance of Buildings Directive (EPBD, Directive 2010/31/EU) requires EU Member States to take into account cost optimality when defining energy per formance requirements by considering initial investment costs, running costs and replacement costs over the life-cycle of a building. In March 2012 the European Commission published the Delegated Act No. 244/2012 (including explanatory guidelines), in which the methodological approach of cost optimality calculations as to be applied under the EPBD is described. Although this regulation includes harmonised standards for some important input parameters, it leaves considerable degree of freedom to the Member States for selecting input parameters according to their choice. As a result, calculations on cost optimality will play a crucial role in setting the energy performance levels in the Member States and may act as brakes or accelerators on the way towards nearly zero energy buildings. Based on long-term experience in life-cycle cost assessment of buildings and on selected examples of available cost opti-mality calculations from the Member States under the EPBD regime, the paper analyses – in a first step – the impact of the most important input parameters on the results. In a second step an approach of a quick “top-down” plausibility check of cost optimality calculations is developed. This approach aims at increasing transparency of cost optimality calculations and follows several assessment steps “from general to particular”, as follows: • Check 1: Plausibility of the shape of the cost curve (e.g. flatness respectively steepness in certain energy performance areas); • Check 2: Plausibility of the most important input parameters and their relation among each other; • Check 3: Completeness of the methodology applied. The paper concludes that a large share of cost optimality assessments which are available – including those presented in this paper – suggest that considerable tightening of minimum energy performance requirements can be argued not only from an energy performance but also from an economic point of view. On the other hand, since the EU regulation offers a high degree of freedom on the actual implementation of cost optimality calculations, very different results cannot be completely excluded