Our assignment
Brogården is a partnership between Alingsåshem AB and Skanska, which involves an ongoing dialog and the joint development of solutions.
We have collaborated with Alingsåshem many times before, including when we built four of six renovation phases at Östlyckan in Alingsås. Östlyckan is a million homes program area with 300 apartments and is similar, in many ways, to Brogården.
Sustainability – economic, environmental, social and cultural – is one of the project’s most important concepts. In concrete terms, that means, for example, that we are rethinking the entire residential situation including courtyard environments while also making the buildings accessible both inside and out. Among other things, we have removed thresholds and reviewed the placement of card readers at entryways as well as illumination in the stairwells.
Construction process
Drawing on experiences with the Östlyckan project, Alingsåshem AB and Skanska have applied that knowledge as we transform Brogården. Among other things, we are striving to be as inconspicuous as possible by using empty apartments as offices instead of setting up construction office trailers. In addition, we are preserving the courtyards to the greatest extent possible by using the back sides of the buildings as staging areas and for transports.
We are using a modern project management style. That means that we are capitalizing on everyone’s expertise and experience. To that end, we have morning meetings where we review the entire project as well as charts where we clearly display daily and weekly plans. When everyone is involved and in possession of the same information, then work flows much more smoothly.
New solutions
Converting existing buildings into passive buildings is an extra challenge. Consequently, we have developed various sealing solutions that we have tested at SP Technical Research Institute of Sweden. That effort has resulted in enhanced expertise in the industry regarding passive building construction. We have also invested significant efforts on adding supplemental insulation to the base plate and foundation. The external wall design is entirely new and has also been significantly improved, both in terms of cost and ergonomic implementation.
Since a passive building must be very tight to minimize heat loss, we construct the buildings with extra care. That, in turn, makes it very important to not encapsulate moisture, which can cause mold damage. Consequently, we erect weather barriers over the entire building. This guarantees humidity control while ensuring that work progresses, regardless of the weather.
The buildings are sealed using a plastic layer that ensures that all air leaving the building goes through the ventilation system. In that way, we are able to capture all heat and avoid having warm, humid indoor air escaping into the walls where it could cause condensation and mold problems. Every apartment is then pressure tested to ensure tightness.
Heat losses from a build occur through conduction losses (the heat that escapes through walls and windows) and ventilation losses (the heat that escapes through the ventilation system).
In order to minimize conduction losses, the walls are insulated with 440 mm of insulation and the attic floor with 400 mm of insulation. Windows are replaced with windows that have low U values (the U value is a measure of heat loss) while the base plate and foundation walls are insulated.
FTX system
Ventilation losses are limited by having a high efficiency FTX system installed. These units are shared by the entire building and situated in a common fan room on the top floor.
Thermal bridges have also been minimized by enclosing the former balconies and making them part of the living rooms. New, prefabricated concrete balconies are being mounted on the exterior of the buildings to eliminate the risk of thermal bridges.
In conjunction with the conversion, we are also increasing the number of different types of apartments. Previously, the buildings only had two different layouts of two and three-room apartments. The new buildings have a greater variety and more apartments with disability access including access to an elevator. We have even removed stairs into the entryways as well as throughout the entire courtyard environment to increase accessibility.
Project in figures
Energy consumption will be reduced from 216 kWh per m2annually to 92 kWh. That figure includes not only heating but also household and building electricity.
What our client thinks
”The added value of a Green Workplace for us as the client is that we are contributing to a sustainable society by taking a comprehensive approach, both in what we are building and in how we are building.”
Ing-Marie Odegren, Alingsåshem
