RedRhino

Thank you. That looks like a common sense way of interpreting it. if common sense applies!

We have been guided by the government website: https://www.gov.uk/guidance/understanding-biodiversity-net-gain We read: Self-build and custom build applications An exemption applies to this type of development when it meets all the following conditions:   consists of no more than 9 dwellings on a site that has an area no larger than 0.5 hectares    consists exclusively of dwellings that are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015 However, we now also read: 2 April 2024 Removed 'small developments' from the exemptions list as small developments are subject to BNG from 2 April 2024. So our single dwelling is a small development and BNG applies or we are Self build and BNG does not apply? Confused!

We are at the very beginning of our self build so roof sizes / elevations are still to be defined. Why not use the PV panels as an alternative to conventional roof tiles? I appreciate you would still need to tile the non generating roof elevations. The black effect of PV is not at all offensive to me and it could be a simpler, more elegant solution compared to in-roof panels. The size of the array is going to be determined by the size of the roof rather than the KwH we want to generate so could be excessive. But as I say, our roof sizes are yet to be determined so have some chance to influence sizing. comments gratefully received

Thanks for the comments - I agree with @JohnMo that you have to be careful diverting drinking water through anything unclean or that could corrode. FYI I measured the temp of the rising main as it enters our current house. It was 15c. I flushed the loo and it dropped to 10c. The rising main is in our 'tech room' with MVHR / water tanks / gas boiler / washing machine and clothes drying racks. The rising main is beaded with condensation but the room is vented via the MVHR so we have no other damp issues.

I envisage just using the domestic water feed as it enters the house with the option of it going through a heat exchanger (i.e a radiator). No extra water consumption. Every time someone flushes the loo or washes their hands more cold water is drawn out of the ground. How much colder would it make the pantry? Water has a very high thermal mass but I guess there is only one way to find out. Our current pantry is slightly cool in winter, not at all cool in summer. It can’t be worse than that.

Where does the water go? That is a good question. These thoughts are for our next build. Our current ICF house has a pantry on the north wall but it isn’t cold enough. I think the answer would be to have an MVHR extract duct in the pantry. We would have to have some air flow past the pantry door too.

What’s the difference between a large cupboard and a pantry? A pantry is cool, or at least it should be. Reducing refrigeration saves energy and many foodstuffs (e.g. butter, bread, ale) should be cool but not cold. However, Passivhaus requires a continuous airtight, thermal envelope. Nowhere is cool. Here is my idea: locate the rising main in the pantry and T off the supply to a radiator or similar. When extra cooling is required open up the reservoir to divert water at ground temp through the radiator. Simple, low tech and nothing too novel for the trades to scratch their heads over. Smart or is there something I haven’t considered?

"ASHP with UFH is the most expensive option (ours came in at about £9k for everything) but it's the cleanest and most versatile option. Especially if you have a decent solar PV array and you can effectively cool your house for free during the summer. Can't do that with a stove. " This is a good point. In summer PV generates an excess of energy and using it to cool the house is well, cool.

We were fortunate to be given a tour of this Passiv Haus build during its construction: https://www.passivhaustrust.org.uk/news/detail/?nId=1117 Lots of points of interest; for example no heating except an ornamental wood burning stove (in 550 m2) and towel radiators. We have friends about to buy a plot for self-build home. They are near retirement so the house will have high occupancy. What do folks think is best practise for heating and energy mgmt? Here is my view: Prioritise insulation of the total envelope and air tightness. MVHR is essential for air quality Orientation to the sun to get solar gain but with shading from high summer sun to reduce over heating Wood burning stove with external air feed for energy security / aesthetics Solar panels with provision for more if initial funds are limited - charging an electric car will be a continuous demand. Our 3.8 pKW panels heat our DHW for 2/3 of the year with Solar iBoost. Batteries? They will be cheaper in a few years. Heating? if demand is small I think I might forego gas and the associated standing charge, also the installation cost of boiler + wet ufh. Instead maybe just electric ufh on the ground floor. It's more expensive to run but cheap to install. Solar will offset some cost. In the depths of winter burn wood? I haven't said an ASHP. I just feel its a lot of cost and the efficiency is poor when you need it most. I can see the weakness in the above is winter DHW. If you need to run baths in winter that is a lot of electricity cost. I'd be grateful for opinions.

It would be great to see a picture of your self-build

In 2008 we were in Germany and admired the quality of their new-build houses. Why had they got no heating on, in sub-zero temperatures? And yet back in the UK we couldn't keep warm with the boiler and stove on full? That was the start of our first kick up the butt, to get on and build. We built a timber frame low energy house on the site of a 1950's bungalow in Rugby, Warks. Then a one acre site came up for sale with a single dwelling on. We knocked that down and built three brick and block low energy houses. Then 2014 we saw a plot in the Stroud valleys, close to the railway station, with a southerly aspect and couldn't not buy it. We built an ICF house and moved in 2017 and here we are. We always install MVHR, best air-tightness, best insulation - Passiv Haus principles but without the certification. Still we itch for another project and so here we are . . .