During much of the year warms the school only by solar radiation and the heat generated from people, lighting and appliances. In the winter additional heat is supplied via a hydronic heating systems that are supplied by means of so-called passive geothermal heat. In the school building plot there are 28 boreholes in 250 meters. The drill holes also help cool the building on hot summer days.
In June 2015 the school was awarded the International Passive House certification.
Air tightness test report, or Lufttäthestprovningsrapport (link here). February 2015. Report by IG Passivhus is in Swedish. A passive house school in Knivsta needs to have a good air tightness (n50<0.6 h-1) to be certified as a passive house according the Passive House Institute and German definition of a passive house. Blower door equipment is used to test the air leakage. The results show that air leakage at 50 pa is q50 = 0,06 l/(s.m2) and air permeability is n50 = 0,07 oms/h. The report shows locally occurring small air leaks at the provisional seals at the unfinished details. The shortcomings should be addressed through adjusting the frame / sash and seal between the frame and the wall. The assessment for the building as a whole is that it is very tight and no air leakage is expected to cause defects in the thermal climate.
Thermography test report, or Termograferingsrapport (link here). February 2015. Report by IG Passivhus is in Swedish. Report describes the procedure how to test the house with thermographic camera including the evaluation of results and images, and the floor plans of school where the images were taken. In the three lower floors the exterior walls are made of the concrete which means there is a temperature inert material. No leakage of air or cooled surfaces could be noted for this type of wall. On the 4th floor is exterior walls of lightweight construction with a stud frame and mineral wool insulation, air and vapor-proof barrier on interior and wind shield on outside. Exterior walls are then lined with sheet material. No leakage of air or cooled surfaces could be noted for this type of wall. Roof images are generally satisfactory surface temperature and temperature distribution. No air leakage was observed onto adjacent walls. Windows are generally well sealed and no abnormal air leaks between the sash and frame or between the frame and the adjacent walls. On the single window are local minor shortcomings, that should be addressed. In summary, the building as a whole performed well regarding air tightness and insulation.
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Images by IG Passivhus.