Our assignment
The project was procured as a trust-based contract since Bostads AB Poseidon wanted us, with our experience of this type of building, to become involved already during the planning phase.
The developer Bostads AB Poseidon owns 1,600 apartments at Backa Röd, an area that was built during the early 1970s. The building that we renovated is a four-story tower block with four apartments on each floor.
The project’s biggest challenge was to make the building airtight. Consequently, we started by gathering everyone involved with the project and conducted a major review of the project. We also took a field trip with all of the employees to Brogården in Alingsås where we learned from their experiences.
Construction process
We started by enclosing the entire building in order to avoid moisture damage or other work stoppages due to bad weather.
The crawl space, footing and building facade were provided with added insulation.
We also replaced all windows with new, more energy-efficient ones. Achieving a tight seal between the windowsills and the building facade was a difficult task.
The base of the roof was expanded to cover the additional insulation on the facade. Even the attic of the building was given added insulation, and we constructed an entirely new fan room over the attic rafters, above the stairwell, making the building very airtight.
In order to ensure a good indoor air climate, we also installed a new FTX system (exhaust and supply air ventilation with heat recovery).
Combined, these measures have resulted in such low heating requirements that the building only needs supplementary heat during the coldest months of the year, which is achieved using district heating.
Significant upgrades
In addition to the transformation into a low-energy building, we have also conducted significant upgrades to the building. We installed new bathrooms and kitchens and replaced all of the electrical, ventilation, water and sewer systems. Living rooms and bedrooms received fresh, new parquet floors. The apartments also received new surface finishes and security doors.
Previously, the balconies operated like a big thermal bridge so we sawed them all off. New balconies were installed on the outside of the insulation layer, and residents were given the option to glass them in.
The building’s concrete facade was repaired and 20 cm of foam insulation was added.
Effective motivator
In order to assist residents to hold down their hot water usage, we have installed separate hot water meters for debiting each apartment. This allows residents to see the costs directly, which is an effective motivator in lowering usage. Heat and cold-water usage are also metered but are not billed separately to each tenant.
Room temperatures are measured in every apartment. Temperature, moisture content and relative humidity are measured in the crawl space and attic.
The building’s energy use is being monitored on an ongoing basis, with consumption being compared to an identical tower block in the area that has not been renovated.
What our client thinks
“Skanska has capitalized on all of its experience from previous projects and applied that to this project. Consequently, the result has been incredibly successful. This is the first time that we have not had any complaints from tenants regarding draftiness, cold drafts or similar problems during as cold a winter as we had in 2009.”
Cathrine Gerle, Poseidon
