Full-scale test of an old heritage multi-storey building undergoing energy retrofitting with focus on internal insulation and moisture

• We energy renovated an old heritage multi-storey building with internal insulation.
• We examined the moisture safety of a solution with 200 mm gap in the insulation.
• Full-scale tests and theoretical investigations are carried out.
• Energy-savings of 39–61 % was obtained strongly influenced by occupant behaviour.
• A 200 mm gap in the insulation result in increased heating consumption of 3 kWh/m2/yr.

The hypothesis investigated in this article is: it is possible to carry out moisture safe energy renovations in the old existing multi-storey buildings with heritage value and still save 50% of the building's energy consumption by use of existing technologies. A holistic energy renovation on an old multi-storey building with heritage value was carried out. Focus was given to energy-saving measures that would preserve the original architectural expression of the building, such as internal insulation. Comprehensive measurements were performed on the energy consumption before and after the renovation to document the obtained savings. Numerical simulations were validated with the measurements in order to explain the savings and to carry out parameter variations on the energy saving measures. Since internal insulation was applied the durability and robustness were investigated and measurements of the temperature and relative humidity were performed in the wooden beams-ends embedded in the masonry brick wall. A solution where the insulation was stopped 200 mm above the floor was investigated. This increased the heat flows through the wall compared to a fully insulated wall, and calculations showed that the difference in the space heating consumption was 3 kWh/m2/yr. The measurements showed the proposed solution should have no risk of moisture problems. The measured energy consumption was reduced with 47% whereas the theoretical reduction could be reduced with 39–61% depending on the room set-point temperature (20–24 °C).