Hi,
I've been renting investment type property (single glaze) as well as old houses (leaks everywhere) in East Gippsland. We are cold in winter and over it. My partner is sensitive to cold. And we are both sensitive to energy bills and impact on the environment.
The good news: we are building!!
We found a builder that builds prefab houses which are transported to the site. They look stunning, better than most houses in our suburb. Modern look, great floor plans, open spaces. The build are timber framed based with batt insulation. They comply with 6 star rating. However I understand the rating is projected and not the actual since it's measured via a computer software.
Their inclusion for R rating is 2 for walls and 4 for walls. But they say this can be increased.
I've read the "Design For Climate" http://www.yourhome.gov.au/passive-design/design-climate
And I've done a fair bit of reading on passive houses.
Our block of land is huge and I have the opportunity to maximise glazing north and avoid east and west glazing as per government's recommendation.
While passive house is too expensive, can I still achieve energy efficiency and great comfort with:
- ask the builder to increase wall and ceiling insulation as they offer it. I don't know the cost. How much rating should I get for zone 7?
- Sanden heat pump for hot water
- dry floor heating (can't have slab heating as this is transportable home so as dry suspended floor). A dry floor heating: http://univenta.com.au/product/dry-floor-heating/. Alternatively radiator/panels if floor heating falls through
- heat pump to feed the hydronic floor heating
- double glaze thermally broken windows everywhere
- energy efficient fire heater for the look and the very cold days and if can get cheap wood
- external permanent shading for summer
What else can I ask? How can I be sure the house is not leaking? Can I get someone external to audit or should I just trust them?
Am I on the right track? Does this have the potential to provide a comfortable cost effective house? Or is it not going to happen with timber frame at all. Unfortunately not much thermal mass as there is just no concrete/brick in this build.
The cost of the house is less than $2,000 per square meter with this prefab builder. As they build in factory, their cost are pretty good.
I looked at SIP panel based builder tells me cost will be near $3,000 per square meter. It just blows the budget and I doubt I'll get my money back with loan interest and so forth.
What is your opinion?