Go to Forum Home General Board PassivHaus building cost

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    • #31322
      Anonymous

        I would be interested to know if anybody has any information on the building cost per square metre for the PassivHaus standard.

        I realise this may be asking how long is a piece of string but with regard to 'normal' building practices, I tend to have in mind a cost of £1000/sqm.

        Does anybody think or know if a PassivHaus building will be much different?

        My motivation for asking this question comes from my hope to have a PassivHaus home built for my family.

        Rob.

      • #37244

        I always advise people to be very wary of outline build costs because their are so many variables. £1000 per sq mtr is very low. It also depends on how much you plan to do yourself. having said that The Denby Dale House built by Green Building Store quotes figures of
        £141K build costs
        118m2 three-bed detached house.
        But the figure you need must be based on the exact house you are building. So many people underestimate the costs. How many times have you seen a grand design come in ahead of time and under budget. The big variable is the site development, foundations etc. Also the passivhaus market is not well developed yet so many of the products need to be imported.

      • #37245
        SimmondsMills
        Participant

          UK lack of experience means to answer this is nigh on impossible, but £1000 is prob too low. However – simple design (or rather, 'simplified' designs) can save thousands! This is a pact between you and your architect. Also try for sponsorship from companies at this early stage in the game for passivhaus. I do recommend aiming for passivhaus (or at least somewhere on the continuum from AECB silver to Passivhaus) from experience – as a way to build VERY comfortable buildings with low running costs and if you follow AECB CarbonLite guidance as well, low GHG emissions.

        • #37246
          Anonymous

            £1000 to what stage? We're miles from that even having gone through 2 tenders and extensive “value engineering”

          • #37247
            Anonymous

              £1000/sqm to a finished state.

            • #37248
              Nick Grant
              Participant

                Rob this is a subject close to my heart.

                If the Passivhaus approach is embraced rather than bolted on then it leads to savings in cost and energy. The form and construction becomes simplified. Excess envelope (walls, floor, roof) area that does not deliver useful floor area means wasted energy and less chance of hitting the PH target but also means wasted cost.

                The need to design for airtightness mans that this must be designed in rather than dealt with by hundreds of hours with silicon. Airtightness of under half the PH requirement is hardly news these days where this has been designed in whilst conventional buildings still struggle to hit 10m/h

                Simple windows with less frame mean more solar gain and daylight with less heat loss and less cost. We want opening windows but in out non passivhaus many never get opened because they are hard to reach or just don't need opening. Fixed lights are cheaper and more energy efficient than opening ones and can have nice slim frames.

                Our house has a PH style foundation slab floating on insulation that also serves (after quick polish) as our finished floor. A nervous contractor might charge a premium never having done this before but we found it easy and cheap for DIY. Others on the forum have seen it and can say if they think it looks OK.

                Then there are opportunities for value engineering (not cost cutting) that are nothing to do with Passivhaus or energy saving. Simple kitchen fit out, avoidance of a bathroom in every bedroom etc. The Glasgow School or Art is full of examples of low cost finishes and 'decoration' that look expensive but aren't. I've seen gorgeous Architects kitchens made out of softwood shuttering ply for example (Ikea probably cheaper though!).

                Then the bad news! All the above is win win but at some point you have to factor in high quality windows with high performance triple glazing and a high quality (efficient and quiet) MVHR with ducts (kept short by clever layout).

                Both of these add value in terms of health and comfort (I wish we had proper controlled ventilation and warm glazing) but are an undeniable additional cost.

                The other reality is that sliding and double doors are difficult to make airtight (and durable) so if you really can't live without them expect to pay a lot for German or Austrian ones. And on the subject of doors, how many do you really need. We seem to have a lot in the UK.

                Remember, whatever the cost, it will be far less than if you try and add the performance later so don't miss the opportunity to do a great job now.

                Hope this helps

                Nick

              • #37249
                Tom Foster
                Participant

                  Neat little essay, Nick

                • #37250
                  Nick Grant
                  Participant

                    Thanks Tahir and Tom

                    I forgot to say that if I applied what i know now about Passivhaus to our building, the cost of the envelope would be less and it would have gone up quicker. We did mostly DIY and cost was about £45k a few years ago but we did go OTT with floor to ceiling travertine bathroom, local oak doors, heavy grass roof etc. Treated Floor area would take me a little while to measure properly but I think it is around 125m2.

                    I'd love to have a go at building a very low cost Passivhaus. A very inspiring guy on this wavelength is Bjorn Kierulf in Slovakia http://www.createrra.sk/?EPD_energeticky_pasivny_dom . Google does a good job of translating but I'm not sure what details he has on his website.

                    Gave a great presentation at the Passivhaus conference this year on very cost efficient design. Unfortunately one neat idea, unvented flat roof, is unlikely to work in UK climate because of moisture issues.

                    Nick

                  • #37251
                    Anonymous

                      Wolf Passive Homes (IOM) Ltd. is currently completing the last stage of TRADA Q mark approval for the Wolfbloc passive foundation system. We are currently working with the architects Sustainably BY Design on our first build for a private client in the Island. In that our certification is for a complete foundation system and would come complete with NHBC approval we are with our innovative passive timber frame design looking to build at the £1000 per square metre. Within the next two months we will have full costings in place and be able to validate that figure. Given that this is a construction process more akin to a factory operation on site than our current labour intensive methodology my belief is that once we have a network of accredited installers in place (we already have the training packages in place), we will be able to improve on the £1000 per sq metre. Obviously solid gold taps will be an extra.
                      John sheppard (director)

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