Jane W

I think you hit the nail on the head- start with what you want and compromise just as much as necessary to get through. We have no glazing North or South, but would like double height glazing in the entrance to the East, all other east facing rooms have standard sized windows, and we're hoping to have almost wall to wall windows on the West facing elevation ground floor( living kitchen and sitting room) and standard windows upstairs. It is the new room by room calculation that make it more difficult to pass. The standard calculation also doesn't account for mvhr which we really hope to have. Not sure if you or anyone else knows how much difference that makes? I'm thinking that to reduce the compromise I'd rather go a/c cassette...

Thank you, that setup is of interest. Have you any thoughts on a diversion to heat the supply air in the mvhr, similar to Denby Dale. I know it was used to reduce short cycling there but presumably it could also work with an ashp. I wonder how effective that would be?

I agree. I have actually had a quote that is cheaper than the rest for triple, also significantly cheaper for double glazing. But when talking to the sales people about airtightness and thermal bridging they seemed a bit dismissive so wondering about their fitters also being dismissive about the important detailing...🤔

I've read little about thermal stores so far...is it really just a larger cylinder?

1.8kW is very low minimum output, that's so much better than I expected.

It hasn't been calculated yet as I'm at the very beginning of the process but really want to get the options considered so it's not a rushed decision. Looking at full fill cavity, 150mm on short sides (north and south) and 200mm on long sides east and west facing. Floor and roof as close to 0.1 as possible but dormers might compromise this. Would like triple glazing but costs seem so much higher than high performance double so probably end up with double. Going for good level of airtightness but style details like 1.5 storey with dormers might make this tricky in places. Taking inspiration as far as possible from Denby Dale case study but I understand that having dormers and 1.5 storey detailing will likely compromise overall airtightness. We're really keen to include mvhr.

The only thing that seems very clear to me atm is that there are SO many possible options. Having learnt a great deal by reading various threads, but not enough yet to make a good well-informed decision I'm still considering gas but with a system boiler and UVC. Use the solar pv to feed into heating dhw or maybe solar thermal as an alternative to pv. In the Denby Dale House they prevented some of the cycling by diversion to heat incoming air supply in mvhr. I'm not exactly sure how that works but I like that idea. I may also need ac cassette to pass part O and of course this could be used to heat as well, as suggested on here somewhere. If I'm not careful I'll have an unaffordable selection of heating methods that may not be needed very much because of (hopefully) a fairly low heating demand. Some of the total heating and hot water mvhr solutions also seem pretty good and I haven't yet discounted the idea of an ashp🤷‍♂️

Apologies...not so much a post and dash, more of a busy-life-read-replies-slow-responder🤦🏼‍♀️ I like the idea of using the PHPP although having briefly looked, it seems quite a task. Think I'll definitely try to use it for modelling once all of my fairly random and unorganised ideas come together to create a more fully assembled and organised design. Being able to model and adapt the vast number of variables in all adpects of the build will be very useful if not slightly overwhelming. My rookie thinking in terms of part O is that if glazing choice and mvhr is not enough to prevent overheating then some type of canopy or ac cassette would be the backup plan. From what I've read so far it seems that the more complicated calculations required to take account of things like mvhr would need a professional to help.

We have been planning a 150sqm house with lots of fairly large windows including glazed gables facing north and East, and 2 or 3 sets of bifold doors covering almost all of the ground floor west facing elevation. Looking at how others have had to reduce the size of windows etc I'm guessing this is no more than a fantasy now. Not done any calcs as only just secured land and playing with possibilities of what we could fit on the plot . But thinking lots of light, lots of big windows is impossible. Could anyone who is further on, with designs or calculations in place give any advice or comment on how part O has affected their design, especially if your plans have large expanses of glazing. Thanks

Agreed, to a great degree. I thought you were thinking solar pv but I realise now you mean passive solar🤦🏼‍♀️

What are the benefits over a heat pump cylinder given similar initial costs?

I think batteries are probably the way to go with solar Pv and take advantage of low demand electric tariffs from the likes of Octopus energy, but again the upfront cost is very high...

Unvented cylinder, heated by ASHP to 47 to 50 degs. And then topped up with immersion to prevent the bugs?

This is exactly what I had in mind. So if going with an ashp if you were to do it again how would you do dhw? Do you still use gas atm or have you installed a cylinder?

Because you think I'll end up with a heat pump anyway? Looked at Viessman micro chp boiler for previous house but why Viessman in this case (I'm a bit clueless!)

I haven't looked into these or fan coils tbh, what considerations made you go that route?

Heard good and bad about Eddies, had solar pv on previous house with FIT tariff, do you think they are worth the capital outlay now with cheap overnight tariffs?

Definitely agree with kitchen, this will be 3rd time buying a kitchen and budget getting lower each time!

I'm considering how to supply heating and hot water to a 150 sq m 1 3/4 storey self build. I'm going round in circles. I can't get past the cost effectiveness of a gas boiler and the ability to provide instant heat. Capital cost is definitely a primary driver in the decision. At the same time eco friendly options appeal because it will future proof the build and help getting planning I think. Could anyone share what they are planning or have had installed recently. I'm interested in the complete system you have chosen for heating and hot water solutions and why, particularly where capital costs were a primary consideration. Thanks