rebenstorf-1
2014-04-10 22:22:25
- #1
Hi guys, I need some advice from you. Our detached new build house is currently being calculated and the person doing the calculations called me and said that the house does not reach KfW 70 and I was shocked because I actually thought we would almost reach KfW 55. Now to the house data: 186m² living space Underfloor insulation 8cm XPS 0.04 WLG Exterior wall 1.5cm gypsum plaster, 24cm Poroton T16, 18cm 0.035 WLG mineral wool, 2cm air layer, 11.5cm clinker Windows triple glazed UG 0.7 Roof 6cm insulation above rafters, 24cm 0.035 WLG insulation between rafters, 6cm insulation below rafters WLG 0.035 Heating system Buderus GBH172 T75S 14KW with 750L buffer tank, 5SKS 4.0 collectors at roof pitch 45° south-facing no shading Underfloor heating on the ground floor and upper floor I hope I haven’t forgotten anything. So according to the transmission heat losses it should be close to KfW 55, but the heating is also taken into account. Although it is a gas condensing boiler, it should still reach KfW 70. Since I naturally got offers from several house manufacturers and construction companies, I know what they do to achieve KfW 70 and there wasn’t even a ventilation system included and usually only gas condensing boilers with hot water preparation. As far as insulation is concerned, not a single house matched what we had planned. My question to the experts is, is my calculating person right, which would actually mean that almost all house providers are cheating or did they make a calculation error. I understand that opinions here can’t replace an actual calculation but a rough assessment should be possible. Many thanks in advance!