A typical Irish / UK house fitted with the Climawin system alone will reduce its annual energy bill by 20% to 24%.
This is based on research at Fraunhofer Institute and University of Aalborg where the system was modeled/ installed in a reference test house in the field and the affects of Climawin on its heat requirements over a period was studied. The method used complied with EN/ISO 13790 (1).
This was done in 3 ways (computer model, building lab, and in a real field test house). The reference house was a 2 storey pitched roof home of 140 sqm area, with 10 windows (each 1.48m(h) x 1.23m(w)), 4 facing south, 1 north and 5 east/ west. U values are assumed as following; W = 0.28, roof= 0.2, windows (before)= 1.01 and door 1.8 (all W/msqK). Airflow through the Climawin was assumed to be 4 Pascals (about 3.6litres/sec through Climawins vents) and an air change rate of 0.4 ac/h was the assumed target for the house. It was assumed that the occupants desired an internal temperature of 20 deg C, that normal heating and ventilation devices/regimes were operating and scientifically accepted typical climate days in Dublin (it was also done for Copenhagen) were taken to represent the external temperature and conditions.
The Climawin glazing arrangement (a number are possible) was the variation shown to produce optimal results; it has a layer of double glazing externally, the air space (where a blind can be fitted) and a single glazed layer facing the interior. Various coatings and fills (argon etc) are applied to different surfaces/cavities within this assemblage.
This house was estimated to use 16,571kW/yr putting it on the borderline between a DEAP B2 and B3 rating in Ireland. The average house in Ireland is much worse than this.
The studies and trials showed that simply fitting Climawin to this better than average Irish house would reduce its annual energy demand to 13261 or 19.9 % less. Other versions of the tests and models indicated it could be as much as 24%. These test of course also take into account energy required to cool the buildings in warm months.
They also showed that even on an overcast day or where walls face other than south, Climawin can recover 57% of the heat needed to make outside air comfortable (20 deg C) on its way in. This rises on a south facing condition to be meet 100% of the air heating needs and can even become a net energy gain in sunny conditions – where Climawins bypass and cooling functions could be utilised. In terms of air temperature increase, on a overcast winter day the tests showed that incoming air could be increased in temperature by 11.5 degrees and on a sunny day (even in winter) by 20 degrees celcius plus.