Name of organisation: KBAB - Karlstads Bostads AB
Stage of development: completed
Year of finalization: 2009
Type of project: refurbishment
Area: suburban
Scale: group of buildings
Type of building: Apartment in a block of six to ten stories
Number of units/dwellings: 630
Tenure: social rental
Street: Babordsgatan
Postcode:
City: Karlstad
Region/ County:
Country: Sweden
Last Update: 06.04.2010
The project "Orrholmen Façade Renovation" had the objective of removing comfort problems such as uneven temperatures, draughts from windows and balcony partitions in the apartments, at the same time as reducing energy loss in the area. This objective was achieved by the removal of unnecessary electrical equipment and including seven large fan units which supplied the garage with preheated exterior air. The façades were decontaminated of PCB and existing joints removed. The space in the joint was then filled with foam right into the space between the edge of the floor structure and the precast concrete unit. This also provided, besides sealing against wind loads, improved soundproofing and air-tightness between the apartments. The existing precast concrete units were also provided with supplementary insulation of 70 mm expanded plastics board. The balcony partitions were additionally insulated and the balcony doors were prepared to increase accessibility. New windows were also installed.
Certification
An Energy Declaration was conducted during the autumn of 2009.
Funding
A small charge supplement has been added to the rent, but according to KBAB’s estimates, the energy measures are profitable. Considering energy price increases and annual reduction of energy and power costs this means that there is a repayment period for the measures of about 12 years.
Thermal Insulation
In order to preserve the character of the buildings, precast concrete units on balconies have not been removed, although they do comprise a thermal bridge. The balconies’ curtain walls have been supplied with new glass partitions and doors with good U values. Supplementary insulation has also been fitted to the partitions and an outer sheet of plastics laminate added. A supplementary insulation of 25 cm loose insulation fibre has been fitted to the roof. Supplementary insulation has been fitted to the precast concrete units of the façades with 70 mm foamed plastic and rendering.
Air Tightness
The soft joints, which contained PCB, were exchanged on half of the buildings about 20 years ago. Notwithstanding this, the concrete around the joint is still contaminated. The joint and the concrete closest to the joint were therefore removed and the waste carefully collected for disposal.
The space in the joint was then filled with foam right into the space between the edge of the floor structure and the precast concrete unit. This also provided, besides a seal against wind loads, improved soundproofing and air-tightness between the apartments. The façade insulation and the mounting of the new windows are otherwise the most important items affecting air-tightness.
Electricity Saving Products
Unnecessary electrical equipment was removed when renovating in order to reduce energy use.
The most important indicator that the project has succeeded is that the use of energy has reduced from 225 kWh/m2 per year to 150 kWh/m2 per year after the unnecessary electrical equipment was removed. This figure reduced further, after the façade renovation was conducted, to 90 kWh/m2 per year excluding, property electricity. Another positive aspect with the project is that the air-tightness has improved.
A strong aspect of the project is the use of partnering contracts as a form of working, which resulted in the same contracting company and craftsmen being able to renovate all ten buildings with a focus on quality and good craftsmanship. New mistakes were therefore not made for every building, as the feedback of experience was utilised. This method of working could also be refined, even if renovation of the first building was very successful. Another strong point with the project is that the entire shell around the building was renovated. With this, no part of the shell was missed.
KBAB does not see any direct weaknesses with the project; possibly further things, for instance solar panels or trimming of control systems, could have been included in the project. However, this would have resulted in it not being possible to complete the project in the time that it was. It is easy to do these things in the next step.
In the current situation there are no firm plans for future work with Orrholmen, but measures that may be considered for implementation include: more energy efficient exhaust air fans, solar panels and individual measurement of cold and hot water/energy efficient mixers.
Orrholmen is the most cost effective project that KBAB has implemented, which results from the partner procurement conducted.
Study visits by other property owners and housing companies have been made in the area, but KBAB cannot express its views on the extent to which similar ideas have been used with other projects.