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January 15, 2013

Swegon Air Academy in Tallinn on renovation of multi-residential buildings – Part 3: We only get ONE chance to do this right!

This article is a final part of three articles about Swedish experiences with renovation of multi-residential buildings and the application of the right measures at the right time. Åsa Wahlström has presented her research and practical experiences in Tallinn on November 22 about multi-residential buildings in Sweden. And here is the final message from Åsa.

Backa Röd is a shining example for low-income tenants. The building was built in 1971 with 1,357 m2 as one of the smallest type buildings to try out the system. Originally, the building had low air tightness qualities, many thermal bridges in balconies, original sewage system in white plastic pipes in bad conditions, water supply pipes needed to be changed, and the old exhaust system with  air intakes above windows needed upgrade. The measures were taken such as external walls were insulated 200 mm (U-value improved from 0.31 to 0.12 W/(m2.K)), windows were changed from 2.4 to 0.9 W/(m2.K), attic floor was insulated and leaky crawl space was made air-tight and insulated. The central unit for heat recovery air-to-air was replaced with central rotating heat exchanger placed in new ventilation room built in old attic where they have increased the height in the attic. Also the cooker fans in kitchen were furnished with a separate exhaust fan.

The result is that the building´s consumption is nearly down to passive house standard. In this case the building owner has also decided to keep some district heating with new upgraded radiators. The detailed results show that the hot water consumption was not much improved as the time for the show is the same as it was before renovation. The heating consumption decreased from 133 to 25 kWh/(m2.a). Total consumption for district heating (covering heating, electricity, hot water, culvert losses and electricity excluding domestic) was decreased from 178 to 60 kWh/(m2.a).

According to Åsa the economical evaluation is one of the major points for the building owners: “In this case, the renovation with energy efficiency measures requires extra costs of about 27,000 EUR per each apartment. Renovation result in decrease of energy costs of about 755 EUR/year, yet the rent will not pay for the renovation as the tenant association in Sweden will allow a slight increase in rent if you get better level of living, but the association will allow no increase in rent for energy efficiency measures. In future, when they do the renovation, they will add on extra floor which would allow them to get the extra rent to pay for renovation measures.”

Åsa concluded with important message: “We only get ONE chance to do this right! The renovation is efficient only when it is done when it is needed. And if we don’t do it right now, it will take another 40 years when we get the chance to do it!”