New build, upstairs heating options (or none at all?!!)

tobdom

So we're currently about to go to tender for our new 'self-build' having gotten planning over a year ago and recently gotten mortgage AIP.... and I have a query about our heating options, mainly for upstairs.

With the current building environment (everything seemingly having drastically increased in price in a relatively short space of time - detailed costing estimate is +20% since this time 2 years ago), we're looking to make savings where possible but without being silly and scrimping......

The plan at the moment is to go with an A2W heat pump with UFH downstairs (+ fairly high-spec of insulation, triple-glazing etc.). Upstairs we have just one big ensuite bedroom, an office + the landing. As a means of looking to save, I'm thinking that we'll go with a 'standard' timber joist 1st floor rather than slab/hollowcore. With that, I'm not sure how advisable UFH is upstairs without hollowcore?

My main question is: What are people's thoughts on not putting any heating upstairs, no UF, no rads (heat rises at the end of the day....)? Is it a mental thought or would it be something that some people choose to do?

If we do (and I hope we can) install MHRV, could this potentially be a 'heat source' for the upstairs room or would there almost be too much demand from those rooms for the system to satisfy it?

Any thoughts/advice would be appreciated......

Calahonda52

Dropping out the H/C floor is a decision you will regret every time you walk up stairs.
Leaving out the MHVR in a highly spec insulation wise house is another decision you will regret every time you open a window...

Explore inline electrical heating in the MHVR system.

The ensuite bathroom is extract....

Calahonda52

Dropping out the H/C floor is a decision you will regret every time you walk up stairs.
Leaving out the MHVR in a highly spec insulation wise house is another decision you will regret every time you open a window...

Explore inline electrical heating in the MHVR system.

The ensuite bathroom is extract....

Metric Tensor

Don't drop the hollowcore for timber. The difference isn't huge compared to a lifetime of listening to every plop from the upstairs en-suite!!!

tobdom

Thanks for the replies, appreciate the input.

I also appreciate the wisdom around hollowcore, but if the main thing we're losing by not having it, is better sound proofing, then it's something we'll have to live with in order to be able to proceed with the house; obviously along with making some other sacrifices/savings, but no really short-sighted ones hopefully.

Will look into "inline electrical heating in the MHVR system" not something I had yet heard of, thanks Calahonda.

Dudda

If the house is very well insulated you can drop the heating upstairs but you need near passive house standards. If all of downstairs is kept at 21 degrees then having 19-20 upstairs is acceptable which the MVHR will help maintain. The one thing I'd suggest to install a cheap electric underfloor heating mat which is put under tiles in the ensuite. Tiles can feel very cold in winter even if the air temp is 19 degrees.

tobdom

Thanks Dudda, interesting suggestion re electric UFH mat.

Not sure how near passive we'll be getting, and being honest I wouldn't know enough about it to understand/appreciate the difference between say an A1 & passive. If we were in the A's from a BER perspective would that be sufficient? Perhaps that's far too simplistic a way of looking at it in terms of feasibility.

BryanF

It's difficult a lot of the time to offer a meaningful response to these type of questions. OP, I say that with the greatest respect to all home builders. In order to answer the question posed, we need the following things answered amongst many others, your designer will have considered during the tender / design phase.

What is the air-tightness (ACH) specified and itemised in the tender and forming part of the contract conditions?
How confident are you of the insulation & fabric details? Will they for example meet the lower thermal bridge (psi) factor in the BER or better?
Is the mvhr system designed and shown on the tender drawings?
What is the heating requirement (kWh/m2/yr) ?
Will the mvhr push sufficient air around the house/upstairs?
Would a low temp rad on landing/en-suite/wc be enough?

Starting asking your construction designer these questions

tobdom

Thanks very much Bryan, appreciate the guidance/prompting and indeed I expected (almost hoped ) to be asked such hard questions in response to my post!

I don't have these answers at the moment, but expect to have them relatively soon after sitting down with the Engineer to go through all of these details and forge a path forward! I'll feel better equipped for such conversations due to this thread and boards in general.

Question on a couple of your questions!
Will the mvhr push sufficient air around the house/upstairs? What determines this, purely a correctly designed/executed system for the house, with a sufficiently 'powerful'(?) ventilation unit?
Would a low temp rad on landing/en-suite/wc be enough? What would heat this if I have A2W HP with UF downstairs? Would we need to have a buffer tank system to feed those rads? My thinking around a MHRV solution for upstairs instead was because I'm assuming it might be a cheaper option (as opposed to rads with the required implementation off an A2W system)