New self build design, heat and architect

[Jack757]

We have just started designing our new build with our chosen Architect at stage 1. On meeting we obviously went through all what we wanted, the look etc before he starting drawing ideas. However, one thing was mentioned when I asked for a plant room that I intended to have ASHP, MVHR, Solar and UFH downstairs and rads upstairs, we are going block and brick. He almost jumped on me at the idea of upstairs rads and that I should be having zoned UFH throughout and rads upstairs will not work properly and where did I even hear this could work?  My theory is that hopefully the upstairs rooms won't need as much heating, the majority of all the bedroom floor is covered with bed/furniture, the kids want thick carpet and the extra expense.  I understand the rads need to be bigger than standard and was hoping to position them all under the large windows in each room with a heated towel rail to each bathroom.   Anyone any experience? Is the Architect right? Would my way not work or should I just go with it for now until further down the line when I have the SAP calculation done and discuss then? Bit peeved I was wrote off straight away as you will do it my way!

[SteamyTea]

It is a lot more complicated than it first looks.

Will you want cooling?

Why place radiators against a potentially colder wall

Wil any of the bedrooms be used for other purposes i.e. children doing home work in them.

Will forced ventillation be fitted, with, or without heat recovery.

Will secondary heating be fitted i.e. a wood burner (just don't fit one).

How is the house expected to perform during the day and different seasons i.e. solar gain, or lack of it.

How simple do you want the system.

How controllable do you want the system.

Do you want to take advantage of different, and potentially unknown, time of use tariffs.

 

[Conor]

Is agree. UFH all the way in 1st floor. We bought towel rads as well, still sitting in their boxes. As we had concrete and screed 1st floors, cost of UFH on 1st floor was minimal, 500m of pipe, pump and manifold. rads would have coated way more and compromised the rooms.

[Dave Jones]

fancoils over UFH for 1st floor / bedrooms all day long. free air con.

[joth]

The architect telling you rads won't work is essentially the architect telling you they're going to design a shit house that needs more heating than you would like. Did you talk about levels of insulation and airtightness? You're doing mvhr so I'd start there, figure out some heating (and cooling) demands then decide if you need.

 

IME architects will often speak a pile of bumkin about what is and isn't possible in terms of heating. In most cases this is based on having one bad experience and wanting to have themselves future hassle. 

Passivhaus/ AECB qualified architects are sometimes better, but they can swing the other way and under specify.

 

Also in my experience you can spend many hours and pounds on iterating this at design stage, only for the eventual contractor that gets the job to rip up those plans and do something completely different. Case in point my current project (BMS for a london town house reno), I suggested ashp for heating+cooling, architect said it's not possible in a Victorian terrace, client paid M&E consultant who specified system boiler and multisplit Aircon, that was all thrown out in value engineering and re-tendering (not to mention planning application refusal), eventual contractor is now installing a single Veissman ashp to do everything via a mix of UFH, fan assist and even cast iron rads. 

 

[Jack757]

1 hour ago, SteamyTea said:

It is a lot more complicated than it first looks.

Will you want cooling?

Why place radiators against a potentially colder wall

Wil any of the bedrooms be used for other purposes i.e. children doing home work in them.

Will forced ventillation be fitted, with, or without heat recovery.

Will secondary heating be fitted i.e. a wood burner (just don't fit one).

How is the house expected to perform during the day and different seasons i.e. solar gain, or lack of it.

How simple do you want the system.

How controllable do you want the system.

Do you want to take advantage of different, and potentially unknown, time of use tariffs.

 

We haven't gone into this fully yet as only just started with design. No cooling, Rads under window as frees up other walls that will be utilised with furniture. Children may or may not be in there other than to sleep, they have a playroom/study planned downstairs. No secondary heating, don't like wood burners etc.  We obviously haven't gone fully into the solar side yet, planning back roof to have as many panels as possible/affordable due to sun all day. Simple system, not worried about zoning etc so much, most ground floor is open plan. 

[Jack757]

35 minutes ago, Dave Jones said:

fancoils over UFH for 1st floor / bedrooms all day long. free air con.

Thanks, not interested in cooling though

[Jack757]

26 minutes ago, joth said:

The architect telling you rads won't work is essentially the architect telling you they're going to design a shit house that needs more heating than you would like. Did you talk about levels of insulation and airtightness? You're doing mvhr so I'd start there, figure out some heating (and cooling) demands then decide if you need.

 

IME architects will often speak a pile of bumkin about what is and isn't possible in terms of heating. In most cases this is based on having one bad experience and wanting to have themselves future hassle. 

Passivhaus/ AECB qualified architects are sometimes better, but they can swing the other way and under specify.

 

Also in my experience you can spend many hours and pounds on iterating this at design stage, only for the eventual contractor that gets the job to rip up those plans and do something completely different. Case in point my current project (BMS for a london town house reno), I suggested ashp for heating+cooling, architect said it's not possible in a Victorian terrace, client paid M&E consultant who specified system boiler and multisplit Aircon, that was all thrown out in value engineering and re-tendering (not to mention planning application refusal), eventual contractor is now installing a single Veissman ashp to do everything via a mix of UFH, fan assist and even cast iron rads. 

 

Nothing has been mentioned about airtightness or insulation yet. Presumably as only at first drawings and he wasn't going to put a plant area in, that this emerged about the ufh/rads.  Is it worth getting a contractor under my belt around stage 4 for the construction drawings rather than let the architect go all the way through to the spec/schedule stage 5? From what I understand by their stages the SAP calculations etc won't be carried out til near stage 4 anyway?

[Jack757]

47 minutes ago, Conor said:

Is agree. UFH all the way in 1st floor. We bought towel rads as well, still sitting in their boxes. As we had concrete and screed 1st floors, cost of UFH on 1st floor was minimal, 500m of pipe, pump and manifold. rads would have coated way more and compromised the rooms.

That's interesting from what I have been reading etc, cost of UFH was considerable more to install upstairs over rads... Still got the thick fluffy carpet issue though too!!!

[joth]

23 minutes ago, Jack757 said:

Presumably as only at first drawings and he wasn't going to put a plant area in, that this emerged about the ufh/rads. 

Haha so literally, the architect omitted about the need for plant room space, but when you suggested your ideas for heating he rubbished those plans and asserted the need for something else that requires more plant room space? Smh

 

25 minutes ago, Jack757 said:

Is it worth getting a contractor under my belt around stage 4 for the construction drawings rather than let the architect go all the way through to the spec/schedule stage 5?

 

There's a really awkward circular dependency you need to pick your way around. Ideally you get the eventual installer in before tender pack is created, as heatpump installers are trained (and obliged to provide) design services as part of their industry certificated supply and install package.

But obviously you can't tender the work until you have a tender pack. And if you're going for a single principal contractor to run the whole build (this sounds like custom build rather than self build so i very much assume you will), many principal contractors have their own tame subbies they much rather work with and will slap a hefty P&A surcharge on dealing with anyone else you foist on them. (And/or use it to play the finger pointing game when issues occur).

 

My own suggestion would be to specify the thing that's cheapest in professional fees that you could definitely live with if the install price is right, e.g. UFH everywhere, and be very upfront during tendering that you're open to engage in constructive value engineering on anything that is adding undue build cost, and flag that as one such candidates. A good builder will come back with their own suggestions or loop in their preferred installer to participate in that decision. And yes, you'll have full SAP figures by then so it'll be a more substantiated discussion.

 

To your other points,

1. ufh can work fine with thick carpets, so long as all the building exterior is much more thickly insulated, and you run the ashp low and slow (as is best for it anyway) the ufh heat will warm the fabric of the building and make its way to where you need it rather than being lost outside.

2. Even if you're 100% set on not having cooling, I'd still recommend running the numbers to confirm exactly what your overheating risks are, do some stress testing of it based on increasingly warm summers, and also do a little bit of future proofing thinking on what you'd do if retrofitting it proves necessary in the future.

Considering window placements and external shuttering to minimise overheating is even more important at the earlier design stage than stressing over active cooling. 

[G and J]

1 hour ago, Jack757 said:

Thanks, not interested in cooling though

We moved into our new pad just as the first heatwave hit.

 

We are epc A, well insulated, good airtightness, mvhr, ashp that cools the ufh (downstairs). We passed part O (overheating) with flying colours......our experience is that we should have put WAY more thought into our cooling strategy beforehand.....we are in the process of changing track ...(a2a rather than fan coils from ashp), so not sure whereabouts you are but..........

[Bancroft]

1 hour ago, Jack757 said:

Thanks, not interested in cooling though

Two thoughts:

1. If designing from scratch the additional cost of adding cooling will be minimal in the overall scheme of things so put it in at the start.

2. Why on earth would anyone building a new house in 2026 NOT want to add cooling?

[Indy]

2 hours ago, Jack757 said:

We have just started designing our new build with our chosen Architect at stage 1. On meeting we obviously went through all what we wanted, the look etc before he starting drawing ideas. However, one thing was mentioned when I asked for a plant room that I intended to have ASHP, MVHR, Solar and UFH downstairs and rads upstairs, we are going block and brick. He almost jumped on me at the idea of upstairs rads and that I should be having zoned UFH throughout and rads upstairs will not work properly and where did I even hear this could work?  My theory is that hopefully the upstairs rooms won't need as much heating, the majority of all the bedroom floor is covered with bed/furniture, the kids want thick carpet and the extra expense.  I understand the rads need to be bigger than standard and was hoping to position them all under the large windows in each room with a heated towel rail to each bathroom.   Anyone any experience? Is the Architect right? Would my way not work or should I just go with it for now until further down the line when I have the SAP calculation done and discuss then? Bit peeved I was wrote off straight away as you will do it my way!

I've heard this concept from a lot of people on here and discussed at length with our builder and architect/designer.

 

In the end, went with UFH on both floors as I hate rads and would not have them. In the bathrooms, gone for electric towel rads with a shelly relay wired in. The thing that swung it for me was a question from the builder - would you buy a property that did not have a heating source on the 1st floor where you and your family sleep? 

 

You may trust the solution where heat from downstairs keeps the whole house warm but a subsequent buyer will not be able to wrap his head around the concept and simply look at it as something that needs to be fixed/money that needs to be spent to clean up the mess. 

[torre]

@Indy we followed almost exactly the same line of thought, would add that the UFH should give some moderate cooling benefit too, not as much as fan coils but without the visual intrusion.