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I think it's fair to say that this thread has been a lively experience for all. To summarise: 1. Bit of an impasse reached on the "Passivhaus (and current airtight + MVHR approach in particular) = problems" question. Personally I'd like to see some real hard data one way or the other. All of the research I read before making my own decision was very positive, but we do have a different winter climate in the UK compared to that in the countries where most of the research was done. 2. Planning is a bit of a mess and most people would like to see some changes one way or the other. If people want to continue the planning conversation, may I suggest that they start a new topic in the relevant area? If anyone thinks there's still useful discussion to be had on the Passivhaus air quality question given where we got to in this thread, I suggest starting a new topic with a new focus. I can link this thread to it if that happens, so the information remains linked.

New video on Sunamp from the guys at Fully Charged:

The structural engineer may not want to advise as it's a finishing screed not structural. That happened me on a few jobs and the contractor won't make any decisions in case something goes wrong and has to dig it out and redo it. They'll give advice but you can be sure they won't take any responsibility for its design. It's left to the architect but they may not have experience with them. What's the thickness of the polished concrete and what are you using to reinforce it. Don't use steel mesh unless the whole project is very carefully planned and I've seen the metal fibres show in the finish a bit. If using the plastic fibres then cut the slab at every 6 meters and under all doors the day after pouring about 30mm deep into the slab with an angle grinder. They can be filled later with mastic. Keep the cut areas square and large. Long thin ones can crack in the middle and small squares can rock like paving slabs. Do you have any columns or other structural walls protruding into the space. You may need additional crack joints near or inline with these. Also are the walls smooth? We had one project with rough stone walls so the edge perimeter insulation has to be thicker to allow for the undulating surface and avoid cracking. Make sure the perimeter insulation isn't rigid too as it needs to be able to compact and move if required.

Hey, size isn't everything.

Feck! Will guests be presented with a map when they arrive or are you using GPS?

My pleasure, glad you're happy with him

Looks great, like it's always been there! 4 months? That's overnight by my standards of doing anything!

@daiking No particular politics ... just attempting to interrogate the implications of your proposed Right to Housing wrt the numbers. Supply, demand and how to build that supply are relevant. So is demand management but if it is to be a genuine Right to Housing then demand management is mainly moot. There are two main drivers of the houses you are going to have to build, which are net immigration and household size falling. Others would be for example restrictions on HMOs and the numbers of students living away from home as University attendance has gone from 10% or so to 40% or so. We need to look at demographics because e.g. more one person households will be adding perhaps 100k-200k+ a year to the demand for some sort of Housing. Do they have a Right to Housing? What sort of Housing? Who decides? We need to talk about immigration because the main element of demand for more houses is population increase, and in the period 2000-2015 Uk population is up by around 5m and approx 70-75% (estimate but roughly right ) of that increase is net immigration (I make it about 3.7m net immigration). This is a report from the Govt on household formation in England published in 2010 looking at the period 2008-2033 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/6395/1780763.pdf Reported in summary by the Beeboids here: http://www.bbc.co.uk/news/magazine-15400477 That came up with a number of new households of 6-7 million between 2008 and 2015. Add another million for SNiW. THese numbers were reduced from the previous 2006 report. Their high projection for immigration was 217k a year. In fact since 2004 to now the average is around 250k, and we may be heading for more like 9-10 million than 8 million new households. Ironically Brexit may help. That is an extra 40%, so pro rata 1.4-1.5 million new households in London for example. And then we need the local authorities who have been trying to build fewer houses than requested by a strong central policy for a decade to pretty much double their allocations, under your proposal for a 'local service'. How would that work? Would you abolish eg the Planning Inspectorate as an unwelcome central body? (There is also the question of LPA competence and politics. When we applied for our Housing Estate PP there were councillors on the Planning Committee - this in a DC with a 100k population- who did not know where the community development boundary was.) Not trying to go in too hard on you here, but we have had too many years of non-joined up policy ideas. Since we are slightly of topic too suggest we wrap this up quite soon. I have 2 lofts to insulate this w/e. Ferdinand

We did this. Our ASHP is on the north wall of our attached garage, which is on 300mm insulation (no idea why - easier to work to the same level across the site I guess). I made two trenches in the middle layer (of three) by cutting some EPS pieces. I then foamed in some 60mm (from memory) polypropylene pipe. The next layer of EPS held it all in place. We then got some 28mm (I think) pushfit barrier pipe and some long rolls of stick-on 3 or 4mm thick nitrile insulation tape. This was just wide enough that two parallel runs covered the outside of the barrier pipe. I greased it up with a little washing detergent and it pulled straight through the duct. There seems to be very little temp drop over the 8 or 9 metres the pipe travels to the plant room, even when running at 55 deg C. The temperature at the top of the UVC gets to exactly 55 deg C every morning throughout winter. The one thing that worried me a little was that we had to go through the ring beam. I used some foil-covered rockwool sleeves wrapped in DPC plastic to protect the pipe and insulate it from the ringbeam. Seems fine. The area where it comes through is one of the lowest stress points of the house, and the heat going through the pipes every day, at least in winter, should avoid condensation (I hope!)

Yup, that's my current plan. One doesn't cover our worst usecase. Plus in 4 years time when the planning conditions have lapsed, I'll put a load of PV on our roof. I did look a at ASHP boost but again, it just doesn't make sense. In a few weeks I'll put my design up for critique.

I for one would like to hear about the alternative way of doing it.

Not having a telly, I did not recognise Robert Llewellyn at first He has changed a bit. Has he had surgery?

I have been following but not contributing to this thread (it appears to have become a bit heated in a nice way), however this is my plan: I need 472.92 m3/h of vent for my house (yes it is large see my blog), so I am working on 495 m3/h as my working figure (for various reasons). I am looking at MVHR units in the range 675-945m3/h so that it is running at 50-70% capacity normally. I am also massively over specifying ducting, flow rates never to exceed 2m/s and most planned much less. This then gives me the following: The unit will be running slow so quiet and more efficiently (heat exchange efficency drops off towards the upper levels of capacity). If I have condensation/mold problems I have the capacity to increase flow rates relatively easily (some re-balancing required). But that is my design and I won't touch house builders and people designing to the minimum limit!