1) Were bricks used for the supporting structure, or was it a wooden skeleton?
Not sure what you mean, the foundation is concrete; beam & block with a screed on top. The actual structure is pretty much all I beams with some glulam beams where needed.
2) I'm sorry, but to me the amount of insulation doesn't seem all that much, not for passive standards anyway. 140 mm with warmcell is only about half to one third of what is needed for the house to be truely passive. The few months in which you claim only to need heating also seem very optimistic to me. In my case: we used 100 mm polyurethane which has a better lambda value than warmcell (so it insulates better per mm) The R value (larger is better) of our insulation is (thickness in meters / lambda value) 0.1/0.023= 4.34mēK/W. The lambda value of warmcell is 0.035 (best value) to 0.040 (worst value). In this example I'll use the best value. So your R value is 0.14/0.035= 4mēK/W. Conclusion: our house is still insulated a tad better with our 100 mm of polyurethane than yours is with your 140mm of warmcell. For the k value, you need to do 1/R, so for my insulation that's 0.23W/mēK and for your insulation that's 0.25W/mēK. (smaller is better here) Of course, to be completely correct, you need to add all the materials in the entire wall. In your case this means I would have to add the k values of the 40mm fibreboard and the 18mm OSB and most likely 15 mm of plaster on the inside as well.
In any case, our houses are insulated about the same, and they are built in areas with similar environmental conditions. Still, we could never go without additional heating from October to April/May. Granted, we use a low kW heat pump, but there's no way we could do without. I simply cannot imagine you needs so much less heating... maybe it is different for you if you haven't used bricks but used all wood? (just guessing here?), or maybe you can tolerate cold better than I can, but still... ?
I guess we'll find out once we move in, it's pretty much all wood, I can't remember the U & R values but we paid a lot of attention to avoiding cold bridging and air leakage. We're hoping to move in in November, yesterday morning (frosty) it was warmer in the new house with heating off than in the old house with heating on.
3) Did you use triple-layer glass for the windows? Maybe even the so-called 4-season glass which has a special filter, which decrease your g-factor a lot?
Yes, all triple glazed, some with an extra pane outside for the blinds. I don't think it was special glass.
4) I really can't get my head around the building style. Don't get me wrong, I like the look personally, but it seems very inefficient for a passive house. For passive, best is to have a boring square or rectangular house with a normal roof (a 'compact' house). I find the shape of your house, with all the sections like the garage and the living room jumping 'out' (I don't know really how to put this, I hope you'll know what I mean) like they do really inefficient because they all are extra surface that is in contact with the air outside the house. All this extra surface inevitably means more loss of heat through the walls and roof. Naturally it's imperitive this should be avoided at all cost in a passive house. Flat roofs can be done, but also are more difficult to insulate. I can see you did the homework on your windows though ; small to no windows on the North side, most other windows in the South side of the house. Were this factors you took into account, but let the look of the house be decicive in the end? (I could understand that)
It was a VERY difficult house in terms of targeting passive house, too many corners, too much external wall to volume. The form was dictated by the floor plan, we wanted all of the house to be used, and for it to be flexible in it's accommodation.
We were aware that we were making things more difficult from a detailing point of view but there's not much point building your own house if you don't optimise your living space. One of the reasons there's more glazing than you'd expect to the N is that our kitchen is on the N of the building and we wanted to make full use of natural daylighting.
5) Did you do a
blower door test to test the airtightness of the house? If so, what was your g (small g) value? (just for my curiosity
) Did you have a thermal image scan of your house done?
Yes, but I don't have the figures. I'll dig them out. We haven't had a thermal scan done.
6) For ventilation, you say you use a MVHR system. What unit did you use? Is the inlet simply pulled air from outside, or does the air get pre-treated via the heat in the soil outside the house? (I don't know the correct name of these devices in English, but literally translated they should be called "Soil Heat Exchanger" or something like that)
It's a PAUL unit, it has an electrical frost protection circuit but just takes in fresh air through the wall, the engineer did originally spec a ground loop but changed his mind, can't remember why.
7) What is the kW value of your gas boiler? I suppose you also heat your hot tap water with this gas boiler? Or did you install a solar boiler? (can't really tell from the photos, but I think not?)
I'll see if I can dig out the spec, we have solar thermal for hot water.
[8) Did you install photovoltaic panels?
No
I hope all my questions don't overwhealm you, but for me this is very facinating stuff.
I'm glad you find it interesting. I did a presentation on it with my architect at the
AECB conference this year and will be doing another at
EcoBuild next year.
Previous Topic
Index
