When the block as a whole was inventoried in part of our work with energy and climate, it became clear that the windows had a long technical lifespan left. At the same time, there was a clear potential to improve their energy performance.
Instead of replacing entire windows, we therefore chose to work with what is already there, while the glass has been upgraded for better airtightness and lower U-values.
"This is a good example of how we can save energy by developing what we already have instead of replacing fully functional building components," says Jonas Forell, former energy engineer and project manager at Akademiska Hus (now at Legera Syd).
Clear effect in both energy and comfort
Measures have been carried out on Buildings A, B, C, D and F – buildings rented by the Faculty of Medicine – and a total of about 2,700 windows have been overhauled and improved. The energy savings are a total of about 450,000 kWh per year, mainly for heating due to improved U-values, but also for cooling because sun protection glass has been installed there appropriately. Discarded glass has been taken care of for recycling, as part of a more resource-efficient design. On the inside, the cold draught in the winter next to the windows in the work rooms has also decreased, which has further strengthened the working environment for the staff in addition to the sun protection in the summer.
Quick action with little impact
The window measures have been carried out with a combination of two construction techniques. One method has been to replace the window cassettes themselves with the glass part, and this as whole units. The frame and window frame have been retained, and maintenance has been carried out on sealing and fittings, as well as new window cassettes being installed.
The other method has been to install a so-called climate pane, an extra insulation pane or energy glass on the existing window package, see picture below. This method is particularly suitable for older windows, where extra consideration can also be given to the appearance of the inside, due to different choices of decorative strip.
Both construction methods have been time-efficient per room, with a large proportion of pre-assembly and relatively few disruptions to operations.
"The installation is usually quick per room, about 30 minutes, and then there is thorough cleaning," says Rikard Enehill, subcontractor at Grundels Klimatruta.
Custom calculations
To deal with updated U-values, impact on heating and cooling, choice of glass, determination of sun protection levels, status of airtightness, etc., energy simulations have been performed on three selected buildings. With the help of energy consultant Aktea, the IDA ICE program was used to draw up and calculate energy models, and the parallel detailed inventory provided a basis for this for the premises.
"The calculations clearly show that targeted improvements in the building envelope provide measurable energy savings and improve temperature stability in the buildings. The analyses produced thus provided robust decision support for planning energy-efficiency measures going forward," says Charlotta Gibrand, Office Manager at Aktea.
Careful planning in complex environments
The project has been carried out in buildings with ongoing operations, including sensitive laboratory environments. This has placed high demands on planning, coordination and dialogue. By working with pre-inspections, clear foresight and close collaboration with the business, the working method has been able to be developed gradually during the course of the project.
"At an early stage, a clear methodology was established characterised by close dialogue with the business, with proactive foresight and a distinct way of working to minimise disruptions and risks," says Emilia Sandström, construction project manager at Hifab.
For the project, a contact organisation was built up between the actors involved: the contract with Akademiska Hus, the various activities in the buildings, and the Division of Premises Planning and Support within the Faculty of Medicine. In the final stage, this dialogue resulted in zero inspection remarks and a high level of customer satisfaction.
"Tobias Kristensson and I have appreciated the good cooperation we have had with project management and the contractor group. They have really been responsive to the needs of the operations and made adjustments accordingly," says Mariana Johansson, Head of Division of Premises Planning and Administrative Support at the Faculty of Medicine.
"We got together a cohesive working group with an open discussion climate, which in turn made for a successful project," adds Jonas Forell.
Left to right: Jonas Forell, project manager Akademiska Hus; Emilia Sandström, construction project manager Hifab; Tobias Kristensson, Technical Manager Premises Planning Operational Support; Mariana Johansson, Head of Division Premises Planning Operational Support; Paul Raso, CEO, entrepreneur Paras; Rikard Enehill, subcontractor Grundels Klimatruta.
