Furnace

Yup. The PHPP consultant (he's built his own PH) has been on top of this and advising the architect on that point from the word go. It's very easy to run into overheating problems. We've got some fin walls to block the late summer west sun, and overhangs for the summer midday heat. First cut of the architect's design passed PHPP so we're on a reasonable footing I think. Do you mean the heat effect of having PV on the roof, thus raising the heat gain through the roof?

I've been following @TerryE's insightful blog and I notice you are a regular contributor, so I take your comment as a glowing endorsement of my findings 😉

I'm hoping to build a passive house next year. Planning application is due to be submitted in the next few weeks. I have a PHPP consultant in the mix working with the architect. In the meantime I've been assessing energy requirements and on the basis that the cheapest energy is the one you don't use, I've spent some time in learning where it appears to be worth spending time, money and energy. I started with Jeremy Harris' spreadsheet to understand the orders of magnitude of the heat losses. Many people have different ways of wanting to look at data and I'm no different, so I wanted to break the losses into discrete areas: Walls Windows Doors Roofs Air via the MVHR Air via infiltration (leakiness) Jeremy's spreadsheet appeared to address air energy losses, but based on an ACH and MVHR efficiency. That doesn't seem right to me. I've modified the sheet (attached to this post) so it has 2 sources of air heat loss - one that uses 30m3/h per person and a heat recovery efficiency ratio (MVHR); and another that uses the air tightness ACH factor and no heat recovery (leakiness). Using this approach suggests that the air leakiness losses are about equal to the sum of all losses from roof, walls, windows and doors. If my calcs are correct, it would make sense to focus even greater efforts on air tightness. I understand that Justine Bere's recent build had a blower test result of 0.15 - that makes a big difference to the heat loss - far more than speccing better windows, for example. Does any of that make sense to you folk? Kind regards Mark Drag files here to attach, or choose files... Accepted file types: bmp, svg, jpg, jpeg, gif, tif, pdf, txt, png, odt, mp3, mp4, mov, qt, xls, xlsx, ods, doc, docx Max total size: 5.86 MB Uploaded Files Heat loss calculator.xlsHeat loss calculator.xlsx

The design and location on the plot is coming along quite nicely and planning will likely be submitted in a few weeks. In the meantime, I'm trying to shortlist suppliers/manufacturers of the more expensive items that will be needed. Main timber frame Windows/doors Timber external cladding Any and all suggestions and experience would be most welcome. Mark

Sound advice. I've given the architect guidance that I'm not looking for something that looks good on Instagram- I'm looking for comfort, ease of build, ease of use and maintenance, low energy use and very few bells and whistles (that will likely cause headaches down the line). I think they get my drift. I'm not wedded to a build system, but am drawn towards MBC for the assurance of air-tightness and experience. But there are a plethora of other decisions to be made, which is daunting. I should compile a list, but even that's daunting....

Thanks. It's quite daunting since I'm single, children have left home so I'm flying a bit solo. I'm in no rush, so will be taking it slowly. Just as well since there are SO many decisions to make!!

The journey has started, but I'll need plenty of support. Currently working with architect for a design to submit for planning. I'm intending to employ a PHPP consultant to assist and advise on the design, and have a planning consultant to help navigate the local planning shenanigans (Green Belt, but we already have a Class Q approval). I'll be back!