The inter-relation between heating systems, ventilation systems, insulation, energy price growth rates and discount rate for different dwelling types in Flanders (Belgium): a cost and E-level analysis

Enhancing energy performance of buildings remains key in order to achieve the European Union climate and energy objectives. In this context, Europe produced the Energy Performance of Buildings Directive (EPBD). This directive is converted in Flanders into the “Energy Performance and Interior Climate” (EPB). Taking into consideration the EPB requirements, this study will investigate the profitability of insulation of facade, roof, floor and glazing (moderate, high and very high insulation level), energy price growth rates (for gas, oil and electricity) and discount rate in combination with different heating systems (condensing gas boiler, non-condensing gas boiler, oil boiler, and heat pump) and ventilation systems (C and D) for three representative types of dwellings in Flanders (terraced, semi-detached and detached). To this purpose, we will compute the net present value of all related costs with respect to each scenario as well as the E-level. The analysis clearly reveals that the condensing gas boiler with heat exchanger performs best in terms of E-level and net present value of the total costs for all dwelling types. The insulation costs to obtain higher insulation levels are largely compensated by the decrease in energy costs. The discount rate largely influences the total costs and a rise in the energy price growth rate of gas or oil might cause a switch in the gas boiler or oil boilers to be the cheapest heating system in terms of total costs. The total costs in the event of using a heat pump always significantly exceed the total costs of the other heating systems, although being the second best in terms of E-level. Finally, the E-level and U-values/K-value are not aligned in the current EPB policy, resulting in too stringent E-levels.