David Taquet

Thanks a lot. Actually after I posted this message last night, the architect sent me the first draft of the floor plans and told me it would be an option to substitute blown in rockwool for the blown in glass fiber, for a price which I don't know yet.

I think both companies use vapor barrier (sheets I guess). I need to check more on that too.

As far as the EPS vs polyurethane, I agree I am kind of iffy for both. I will push them further and see what other options they have. Being a foreigner, and having a slightly original design (as far as "regular" Japanese clients is concerned) they really want to build my house and use it as an open house to promote their companies. That should give me some leeway to negociate better materials for the same price.

Hi! First of all, let me say that I am a total beginner and am not even confident I can explain my question using the proper technical words. I live in Japan and am about to have a passive type house built. Reaching the real passiv haus standards would cost a fortune here so I am doing my best to match my budget.

Before choosing between 2 house builders, I asked them what kind of wall insulation they recommend in order to reach a 0.3 U-value withing the house. Provided they use the same windows, ceiling and floor insulation I would like your advice on 2 kinds of wall insulation.

1. 105mm glass wool as interior insulation, plus 120mm EPS exterior insulation.

or

2. 105mm urethane board interior insulation. Each company is assuring their material will not loose any of their insulation power even after 50 years, but I find that hard to believe. Also I have heard bad things about chemicals in EPS. ] All things equal (including prices) which is better? Which is more reliable in the long run?

Thank you, David