Guideline for energy upgrading of buildings for low energy class 2015 and building class 2020

Two buildings containing a dormitory, day-care centre and a hall were successfully transformed to up to date nearly-zero energy residential apartments. Only the concrete structure and the insulation of the roof (the latter in one building) were preserved. The preservation saved both money and CO2. The renovation has resulted in up-to-date affordable apartments which can be rented out by the housing association (there is a waiting list to get an apartment). Furthermore, the renovation has improved the architecture and indoor climate of the buildings and the buildings now have a new sewer system, new cold and hot-water system and new electrical system. There are new lighting in the staircases, new kitchens and bathrooms, balconies for some of the apartments, elevator to the upper apartments in block A and improved surroundings. The users are very content with the quality and layout of the apartments, the indoor climate, the improved architecture and the surroundings.

The renovation was financed like new social housing, i.e. not subsidized. The rent of the apartments is comparable with other apartments of the same quality in the area. The experience of the housing association – Boligselskabet Sjælland – is that it is a good idea when performing deep energy renovation to strip the building down to the loadbearing constructions and add a new thermal envelope instead of trying to improve the original thermal envelope. However, they also learned that it is a challenge to upgrade existing buildings to contemporary and future-proof apartments especially if the new design uses other module lines etc. than the original design.

The concrete structures (including decks) were maintained, however, this made it difficult to comply with modern requirements regarding acoustics. PCB, asbestos and paint containing lead had to be removed from the building and safely deposited. The housing association also experienced difficulties in obtaining approval from the municipality to change the status of the buildings from dormitory/daycare centre to residential. The new improved apartments and architecture has been very well received by the tenants. There is at the moment a waiting list for people who would like to rent an apartment in the buildings. The indoor climate and the energy use of the buildings will be followed closely in the coming years and the results will be utilized for promoting deep energy renovation of multifamily buildings in Denmark.