Photographer: Tove Lauluten

Lessons learned in the Økern retrofitting project

The Økern nursing home in Oslo, Norway, is a successful retrofitting project nearing its completion. An important lesson learned during the project is that energy efficiency renovation does not have to be more difficult or complicated than a standard renovation.

The project used known and well-tried techniques and products, while the innovative part of the project was the process itself and a novel collaboration with research institutes during the design and execution of the work.

Flemming Roggbif Idsøe, technical coordinator at Omsorgbygg Oslo, gives us an update on the renovation process of the Økern nursing home in Norway.

The Økern Sykehjem demonstration project is soon to be completed – which were the major activities that were performed? Which products and techniques make the major contribution to the energy efficiency of the building?
The Økern Sykehjem demonstration project has been completed and the tenants are moving in these days. The official opening of the nursing home takes place on October 9th as a part of the 10 year anniversary conference of Omsorgsbygg. We are very pleased with the results so far; the nursing home is completely transformed and is more architecturally adapted to its environment. Major activities have been additional insulation, minimizing of thermal bridges and the construction of a building with a lower air infiltration rate. These measures have reduced the energy demand for heating by 80%; and all energy for heating now comes from district heating rather from direct electricity as previously.

We have also changed the entire HVAC system and introduced variable-air-volume control in relevant spaces and a heat recovery of 85% and a maximum SFP of 1,5 kW/(m3/s). This has reduced the energy demand for ventilation (except heating) by 70%. In addition to this we changed the lighting system to a system with low energy consumption and motion sensors, reducing the energy demand for lighting by 38%.

The total energy demand for Økern Sykehjem is reduced by 66 % from 357 kWh/m2year to 120 kWh/m2year. The techniques and products used to achieve this are not that innovative, rather they combine a series of known and well-tried measures within the same project. The innovative part of this project has been the process and the manner in which we have collaborated with research institutes during the design and execution of the work. This particularly applies to the PV plant we installed on the roof of the building. The PV plant is Oslo’s largest, and Norway’s second largest, plant. It is expected to produce 105 MWh annually and will cover 10% of the buildings energy demand. In order to achieve this we have had a close collaboration with the research partners of the ZenN project and we used their input for quality assurance during the design and execution stage. During a number of workshops, knowledge has been transferred from researchers to the designers and contractors in order to ensure that we will reach our goals in an optimised way. 

What turned out to be the greatest challenges you encountered? There have been several challenges during this rehabilitation, but it is important to emphasise that it has not been the energy efficiency measures or the PV plant that has proven to be challenging. Rather, the greatest challenge has been the rehabilitation of an old building from a very poor shape. There are many unknown parameters in an old building and surprises that just wait to be revealed during demolition works. The amount of asbestos in the existing building was a lot higher than we managed to uncover before the demolition works started. We made the decision to remove all asbestos from the building, also in places where we didn’t plan to do any work.

Another challenge has been to do a deep retrofitting of a building attached to another building (also a nursing home) in full operation, where some of the areas in the building being retrofitted needed to be accessible by the adjacent building. This required intense detailing and coordination with all the different actors involved.

Økern is a nursing home for senior citizens; in what manner did that influence the renovation process? In what manner were the tenants involved in the project? During the design phase we involved the tenants in regular planning meetings in order to enable them to impact on design choices so that the building would be as user friendly as possible and cover their needs.

Lessons learned! What are the major lessons concerning innovative energy efficiency renovation that you have learned during the course of this project? The major lesson learned so far is that energy efficient renovation really is not that complicated. It is in fact not any more difficult than a standard renovation. We are very excited about the monitoring phase that we are starting now. We are expecting to learn a great deal from this.

For more information, please contact:Flemming R. Idsøe, Omsorgsbygg Oslo KF, e-mail:

Updated: 2015-05-07


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