SBMS

Nod - agreed and we are pretty well insulated to be honest. 200mm cavity, blown beads etc. I know your last build you put radiators and never used them but I can’t bring myself to put no heating upstairs. Cold wife and cold children.

Planning our upstairs heating for our build. Downstairs is wet UFH, ASHP. We’ve got a first and second floor (attic rooms). Some small risk from overheating due to a fair bit of glazing so would like some active cooling upstairs. Trying to decide what to put upstairs. UFH upstairs on two floors is coming out expensive. Mainly labour costs (we are not going to fit it ourselves). Seems that it’s overkill if heat requirement is low? And we can’t cool. I thought about putting split AC units in each of the 5 bedrooms and using them for heat as well. But not sure about having to remember to turn them on if it gets nippy, fans running etc? But cooling would be fine. I therefore thought about a ducted AC system upstairs (maybe a couple of zones) that could do heat and cooling? Other option is fan coils. I don’t quite understand the condensation risk - does all pipe work need to be lagged? Do I need condensate drain off at each unit? Are they as effective at cooling as an AC system? Would appreciate peoples throughts: Upstairs options option 1 - UFH + split AC option 2 - radiators + split AC option 3 - split AC (heat and cool) option 4 - ducted AC (heat and cool) option 5 - fan coil units (heat and cool)

Thanks @JohnMo - I have done the heat loss calculations. I might be missing it but where in the spreadsheet does it show a ‘peak energy input’ requirement that would help me size the heat pump? I can only see total monthly losses.

I think that’s what I’m trying to work out - what size do I need? Is the SAP calculation accurate enough to size the heating or does an MCS installer (which they are) produce a more accurate figure?

Sorry @JohnMo you’re suggesting I need a 6kw unit not a 16kw? am I right in thinking that January heat loss rate figure of around 4kw is a peak figure based on -9 outside? So a 6kw unit would comfortably cope? sorry @SteamyTea for miscapitalisation of the Ks and the Ws on my phone typing

is 35w/sq m good? Average? It’s masonry 200mm cavity with eco bead. 304mm posi rafters with blown in cellulose and external 22mm wood fibre sarking. 175mm PIR in the floor. Glazing averaging around 0.85 but a fair amount of it to be fair. aiming for 1.0 on airtightness. House footprint is 190 sqm PA ratio of 0.35.

One thing with this.. I might be misunderstanding but am wondering if we need UFH upstairs (we have a first floor and rooms in roof as well - So UFH on both floors). This adds quite a bit of cost. But if I wanted to minimise radiators upstairs I would need to work on a certain value for sizing the wet UFH loops in the slab to ensure it provided the right amount of output?

Thanks @JohnMo. Yes MVHR. Have found the heat loss in my sap for January: That figure is what’s confusing me as it seems the supplier has come up with a much higher figure. We’ve got a fairly standard form factor…

We have had our SAP rating done. It’s come out with a primary energy rate of around 23kWh per sqm. One of the ASHP suppliers has come back and intimated we might need a 1 x 12kW & 1 x 7kW system. They’ve calculated a 35 W/m2 requirement - so 16kW (over 450sqm - this includes a potential future extension). This has been done based on the worst case -2 outside +20 inside. We are trying really hard for good u values - 0.14 walls, 0.1 Roof and floor etc. Does this calculation sound correct? I appreciate this is the ‘worst case’ so the average will be better but can anyone comment on this W/m2 calculation? Is it our floor area that’s pushing us to two units?

I know someone whose husband died and because he didn’t put his wife’s name on the application they’re now chasing for CIL because he hasn’t lived in the house for 3 years. Outrageous.

No reason to think traditional can’t be energy efficient.

I think you’ll struggle. The self build exemption specifically states Individuals benefiting from the exemption must own the property and occupy it as their principal residence for a minimum of 3 years after the work is completed. In this instance YOU don’t own the property. This is why you are required to submit title deeds at completion to prove you own the property. A limited company owning it doesn’t pass this test, I suspect they would reject your application.

There’s a few suppliers that do oversized glazing: https://www.iqglassuk.com/news/how-to-incorporate-oversized-glass-in-your-design/bp170/ https://www.precisionglassltd.co.uk/oversize-glass/ not sure if this includes framing

Ah okay thanks @JohnMo I was asking because my wife didn’t want timber internally (chunky) and we’ve had quotes from norrsken, rationel etc that are all more than the pure aluminium system. It seems like a bit of a no brainier for me but wasn’t sure if I was missing something

It’s the Uw. Had the values back from local fabricator.

Have done. Largest privately owned fenestration company in UK turning over 53 million so would hope their claims and testing were robust. What do you think: https://www.seniorarchitectural.co.uk/wp-content/uploads/2023/01/PURe®-Casement-Window-System-Technical-Datasheet-28.10.2024.pdf

Would be interested in why many favour timber alu clad over pure aluminium? Thermal efficiency for us is on a par (0.75 u value eg for aluminium windows). For me the internals of aluminium are preferable to more chunky timber. But would be really interested to know if I am missing something?

Stone slips? Just trying to visualise that.. we are using stone copings on top of the flat roof area..

We are looking at some column and beam casings for some aluminium columns and beams on a canopy. We’ve had a quote from guttercrest which was reasonable. But just struggling with what fixings are needed to attach the square column and beam casings to the steels? Guttercrest weren’t terribly helpful and just pointed us to an installer who wants to charge an arm and a leg. Anyone got any ideas how you’d go about fixing these column/beam casings: https://www.columncasing.co.uk/square-column-casings/

Our architect has designed an open canopy structure that will have a glass/plastic roof and open sides. The beams and column are steel. We’ve had a price to clad these in aluminium which is very expensive. We might have to end up with this as an option but wondered if anyone has any ideas for alternatives? Potentially using composite cladding or anything similar? Be interested if anyone has a similar design. Steel bits numbered in red:

Once plannings approved sort out any pre commencement conditions if you have any - another 10 weeks for us! Depending on your planning this will usually involve getting a drainage design done, construction management plan (ask chatgpt to write one) etc. Depends on your conditions obviously. Whilst this is happening get full building regs compliant drawings done by architect along with any drawings by structural engineer. As part of this you might end up getting a design done for any engineered floors / roof. I would recommend Pasquill for this, they’ve always been good. YMMV. Make sure you get your CIL self build exemption and issue any commencement notices for when ready to start. Next get your SAP and Part l over heating work done. You need to ensure your build is compliant. You’ll need to start thinking about windows, doors etc so you know the u values and thermal bridging details. You’ll need to try and achieve these so your as designed sap aligns with your as built sap. Utilities next. Sort out how you’ll get gigabit internet to property as required for building regs. Easiest is to submit application to openreach. Worst case use starlink. Get quotes for water and electric connections as required. Next step is to organise any self build warranty and site insurance. Then appoint your building control and get your architect to act as principal designer for building regs and submit everything on your behalf. At this stage I think you’d be ready to start although I might have missed something. Obviously you’ve got the appointment of a contractor or if you’re self managing your subbies. Think that’s it!

Sorry @JohnMo I thought you were saying all aluminium units were ‘rubbish’ u value.

Yes this is the Uw value with triple glazed units. Some aluminium units were dreadful - 1.6 Uw and triple not much better. These are Senior’s systems with a polyurethane thermal break.

Our quoted aluminium sliding doors are 0.9 u value. Windows are 0.76 u value. That’s not rubbish?

As someone who went rigid (ahem) with the association attenuators etc, couldn’t agree more. Ridiculous amount of extra kit and complexity for no real benefit in my opinion.