lakelandfolk, on 23 January 2016 - 02:14 PM, said:
Hi, We are are retired couple who self build approx 19 years ago at a time when the local builders and merchants in our beautiful Lakeland area were non plus when I engaged them in conversations about things like, reduced carbon footprint, U values etc
We went ahead and I took a year out from my work to build the house myself, 5 bedrooms, 3 bathrooms etc.. Conventional cavity block work etc . Insulation levels above building regs at he time ( look pretty week now ), Underfloor heating, MHRV. Inbuilt VAC, Solar Thermal, Solar PV etc.
We now propose to self build again, but this time in SIPs and to Passivehouse standard ( not going for the certified route). At 76 I don't feel up to all that heaving about of concrete so will project manage and undertake various internal fitting out. Kitchen, Bath rooms, plumbing, joinery etc etc to ensure that we come in on budget.
We look forward to picking up lots of tips and recommendations from fellow members in the coming months as we plan our downsize to a super energy efficient home.
Quite a few here have built, or are building, self-builds that are passive houses (be wary of using the term "PassivHaus" or using capitals, as the PassivHaus Institut has trade marked the term!). There area lot of passive houses being built now, but very few bother to get certification, as it is very expensive.
I'd be cautious about SIPs, as it isn't easy to get a cold-bridge free solution for the wall to floor junction. There has been a lot of discussion here on this, including input from the largest UK SIPs supplier, Kingspan, so a search on the forum for SIPs builds would be time well spent. You can get a SIPs house to passive house performance levels, but it takes additional insulation and careful detailing, and may add to the cost such that other construction methods start to look more cost effective.
You also need to be aware that very few trades people are familiar with passive house construction, particularly the importance of not penetrating the airtight layer and so decreasing the air tightness. Attention to detail is critical when you have first fix trades working in the house, as it is very easy for them to just makes holes in the air tightness or vapour control layer without realising the importance of maintaining the integrity of these.
Finding an architect who understands passive house design can also be a struggle, as it is critical that things like glazing area, orientation and shading are taken into account at the design stage, which means the architect has to have a fairly good understanding of the engineering of the building, and this isn't something many architects have, as it isn't a major part of their training.
Finally, be cautious about accepting advice from "consultants", as there are very few people in the UK who have an in-depth understanding of designing and constructing a passive house. My blog on this forum (have a look in the blogs section, there are several low energy builds there) may be useful, as I've tried to highlight the trials and tribulations of building this type of house here.