Under the GrowSmarter project, the City of Stockholm has implemented energy retrofitting actions for the 6 tertiary buildings owned by Stockholmshem. In this retrofitting, external insulation is added to the whole building envelope in an ambitious manner and new windows and balcony doors have been installed with the best possible U-values for the project. This way there is control over incoming air. The only air intake is under the windows right behind the radiators to warm the air up before it continues into the apartment. The air exits by exhaust ventilation and the heat is recovered by a heat pump on the roof.
The plumbing system has undergone significant improvement, and all new pipes are properly insulated and a system for wastewater heat exchange installed.
Instead of installing a traditional system with a circulation pipe parallel to the water pipe, the project uses a solution where the two are installed one inside the other, to minimize the surface where heat may escape and keep the water temperature high.
New substations and heat exchangers for district-/geothermal heating are installed in every building. This way decreasing prior culvert losses is possible and users have enhanced control of heating, hot water and ventilation heat recovery in each building.
The new modern elevators are more effective and lighting fixtures in common spaces have been replaced with more efficient ones with motion control. In addition to this, PV-cells have been installed on the roof to provide renewable local energy for the building.
These smart installations combined make the building require less energy and the consumed energy will be recovered in the best way possible.
Following are the measures implemented:
Climate shell refurbishment of Valla Torg:
- Additional insulation by 80 mm to façade and 200 mm to basement walls.
- New type of construction for the roof with added insulation.
- New four glass windows with U-value 0,7 W/(m2K).
New installations of Valla Torg:
- Separate heat exchanger in every building for district- /geothermal heating.
- Heat pumps recovering heat from the exhaust air and transmitting it to produce heat and hot water
- Wastewater heat exchange system to preheat fresh water.
- Installation of “pipe in pipe” system to reduce hot water circulation losses
- Water-saving tap water fixtures to reduce water consumption
- Electricity saving measures -Low energy lighting fixtures for common spaces -Modern and more effective elevators
- Renewable energy: PV cells to produce electricity