Due to the recast of the directive on the energy performance of buildings, the Swedish Energy Agency has developed a national strategy that suggests new energy performance requirements at major renovation of apartment buildings. The proposed levels of maximum energy performance strive towards nearly zero-energy buildings (nZEB). The purpose with the present study is to analyze which consequences the proposed nZEB requirements will lead to at major renovations of apartment buildings. Which combinations of different heating systems and packages of energy efficiency measures will be necessary to meet the new nZEB requirements at major renovation? The following four types of heating systems were examined: retaining district heating, complementing district heating with an exhaust air heat pump, converting to a ground-source heat pump or an air-to-water heat pump.

The results show that the shape of the building has little impact on the package of measures in combination with a heating system that will cope with nZEB requirements for major renovation. The larger apartment buildings (low-rise apartment buildings, tower and high-rise blocks of flats) on the whole give the same results. Also age of the building is largely insensitive while the climate is of great importance. In several of the typical buildings for low-rise apartment buildings, tower and high-rise blocks of flats the four heating packages are competitive with each other. Depending on predicts on energy prices and inflation in the future it may be one or the other option that is the most advantageous. Profitability of the different heating packages is also dependent on the district heating price prevailing in the current city. In the study a Swedish mean value has been used.

In the small apartment building the proposed collected package of measures in this impact in combination with retaining district heating, is not sufficient to meet the nZEB requirements during major renovations. For the options being examined here it is only the exhaust air heat pump package or the ground-source heat pump package that can cope with nZEB requirements and profitability.