passive house and ufh

[Iceverge]

@jonM

 

Have you investigated cooling with the rads? I'm aware condensation be more of an issue than with UFH. 

 

Obviously the greater the surface emitter area to the lower the flow temps and the better COP. Fan assisted rads may be an option but the complexity increases there again. Are yours truly massive? 

 

 

 

[jonM]

19 minutes ago, Iceverge said:

Have you investigated cooling with the rads? I'm aware condensation be more of an issue than with UFH. 

 

Obviously the greater the surface emitter area to the lower the flow temps and the better COP. Fan assisted rads may be an option but the complexity increases there again. Are yours truly massive? 

 

Very good question and what you say makes sense both in terms of lower flow temps and cooling. I have however been able to keep room temperatures below 25oC all summer by venting the house overnight and my heating bills are already low, so a small increase in COP will not lead to material savings. The house is fully passive but not certified. 

[joth]

1 hour ago, ADLIan said:

 

Photographic evidence of build quality (insulation levels, dealing at junctions, preventing thermal bridging etc) is now part of the Building Regs. Requirement of the 'new' 2021 Approved Doc L, effective mid 2022, for all new dwellings.

So I guess in about, I don't know, 20 years RICS will start suggesting surveyors could review and advise buyers based on this documentation. 🙄

[joth]

45 minutes ago, Iceverge said:

@jonM

 

Have you investigated cooling with the rads? I'm aware condensation be more of an issue than with UFH. 

 

Obviously the greater the surface emitter area to the lower the flow temps and the better COP. Fan assisted rads may be an option but the complexity increases there again. Are yours truly massive? 

 

 

 

Someone on this forum made a great explanation why cooling via radiators basically doesn't work: the inlets and outlets are at the bottom of the panel, so the cold water just flows along the bottom of the rad and the majority of it just sits there at room temp.

If the inlet is at the top of the rad it might have a bit more chance to work.

 

[JohnMo]

1 hour ago, jonM said:

but therein lies the problem. If something does go wrong either with the installation or the operation, the pipework is under screed

Each loop is a single length of pipe, buried in concrete, once installed and covered in concrete very little to go wrong.  During the concrete pour the pipe will be pressurised with air or water, so not likely to get damaged.  Manifold is just a series of flow meter and either a manual or actuated valve for each loop - all pretty simple stuff.

 

Much more likely to put a screw through a pipe hidden in a wall than a pipe under 50 plus mm of concrete.

[ProDave]

3 hours ago, Kelvin said:

From memory you have a relatively small output ASHP?

Yes, 5kW which is about twice the worst case heat loss.

[ProDave]

2 hours ago, joth said:

So I guess in about, I don't know, 20 years RICS will start suggesting surveyors could review and advise buyers based on this documentation. 🙄

I recall Jeremy saying he improved his previous house and when selling it he presented the surveyor with all the details and evidence of the extra insulation added including photographs, and the surveyor promptly ignored it and and made the standard assumptions.

 

I wonder if in > 10 years time (the life of an EPC) we choose to sell if the new surveyor would believe the full sap done and issue the same EPC or would he make assumptions and issue something worse?

[billt]

20 minutes ago, ProDave said:

I recall Jeremy saying he improved his previous house and when selling it he presented the surveyor with all the details and evidence of the extra insulation added including photographs, and the surveyor promptly ignored it and and made the standard assumptions.

AIUI the assessors are only allowed to take officially documented information into account, so BR certificate for insulation improvements would be acceptable, evidence supplied by the homeowner wouldn't. This seemed to be the case when we had an EPC done several years ago, may have changed since.

 

Of course insulation has very little impact on the EPC anyway.

[Nickfromwales]

4 hours ago, ADLIan said:

 

Photographic evidence of build quality (insulation levels, dealing at junctions, preventing thermal bridging etc) is now part of the Building Regs. Requirement of the 'new' 2021 Approved Doc L, effective mid 2022, for all new dwellings.

Strange that nearly every BCO AND warranty provider that I’ve been around over the last 4 years or so gave this lip service at best. Most of those projects were / are well-insulated / airtight dwellings, or PH, and even ZEB, but at that level most BCO’s are just way out of their depth. 

Written practices aren’t always practiced. 

[ADLIan]

33 minutes ago, Nickfromwales said:

Strange that nearly every BCO AND warranty provider that I’ve been around over the last 4 years or so gave this lip service at best. Most of those projects were / are well-insulated / airtight dwellings, or PH, and even ZEB, but at that level most BCO’s are just way out of their depth. 

Written practices aren’t always practiced. 

 

+1 to that. It is now down to the SAP assessor to police this, not something they signed up for as this is a Building Control function. In the absence of this photographic evidence assessors must revert to default SAP numbers at which point the house will probably fail under Appr Doc L and the assessor is the messenger (who probably will be shot!). Because of this, and a whole raft of other admin procedures, I will let my SAP assessor status lapse in the next few months.

[SuperJohnG]

@JohnMo @ProDave @Russdl @Nickfromwales @jack

 

I thought you were talking just pure electricity costs.

 

I was also forgetting about the cop, and solar gain...oops.

 

It's not capped imo at 50p/kWh..the government is paying the gap between the 50p/kWh and the 34p and that will end at some point I think. 

 

I'm with Octopus standard variable at the moment I've attached my tariff at the moment. 

 

We have achieved 0.8 ACH at the mid build stage I hope to be even closer to 0.4 when they do the completion test. It's a SIPS house with 50mm added internally, no thermal bridges nearly and our roof is 270mm thick and walls 220mm thick. 

 

 

Edited February 9, 2023 by SuperJohnG
Added image

[ProDave]

Why are you paying so much? commercial tariff?

 

This ends in a couple of weeks, then I will be onto the capped rate of about 33p, no fixed rate deals on offer at the moment.

[SuperJohnG]

2 hours ago, ProDave said:

Why are you paying so much? commercial tariff?

 

This ends in a couple of weeks, then I will be onto the capped rate of about 33p, no fixed rate deals on offer at the moment.

No this is the normal now. 50p/kWh and the government brings it back to 34p.

 

 

Edited February 9, 2023 by SuperJohnG

[ProDave]

Ah so you are not actually paying 50p, that is what confused me.

[eandg]

19 hours ago, jack said:

 

I believe the term being discussed at the time was  "eco" house.

 

If I ever sell ours, my focus will be on getting our energy bills in front of potential buyers. Passivhaus doesn't mean as much to most as very low bills.

Our valuation surveyor (mid-build) said "eco-houses" should do very well going forward. Maybe an outlier as there's still some dinosaurs but I definitely think the cost of energy will be changing people's views on sustainable housing and adding an extra few grand to what they're willing to pay. 

[SteamyTea]

14 hours ago, eandg said:

Our valuation surveyor (mid-build) said "eco-houses" should do very well going forward.

Two things there that would make me walk away.

"eco-houses"

"going forward"

[JohnMo]

15 minutes ago, SteamyTea said:

"eco-houses"

I am afraid that's what the general public think and need a is simple Tag to associate low running cost houses with.  Passivhaus - what's that, very small group of people have heard of them and understand them, most no clue, if they have heard of them they're airtight and must be stuffy and mouldy. That was the feedback I had from people I spoke to when I was building our near Passivhaus.  

 

Building education is very low in this country, with the general public and building professionals. Picking up on another thread, Tado sell smart thermostats to rest of the world, they degrade them for this country to on/off thermostats

[ProDave]

5 minutes ago, JohnMo said:

Building education is very low in this country, with the general public and building professionals. 

Dead right there.  While watching last nights "dream homes" a friend of SWMBO sent a message along the lines "Are you watching this? .....  It's just made of wood, no brick anywhere, it must be freezing"

[JohnMo]

Sad but true

[SteamyTea]

1 hour ago, JohnMo said:

1 hour ago, SteamyTea said:

"eco-houses"

I am afraid that's what the general public think and need a is simple Tag to associate low running cost houses with.

To some people it will mean looking like it is made from timber, other may think it means it has a wood burner, some may say as it is old, it has low energy cost as it has been around for decades.

Another may say that they grow their own vegetables, or it has a green roof.

 

Probably the most environmentally friendly housing is city centre, very high rise, flats.

Try putting an "eco" tag on those.

[Kelvin]

59 minutes ago, ProDave said:

Dead right there.  While watching last nights "dream homes" a friend of SWMBO sent a message along the lines "Are you watching this? .....  It's just made of wood, no brick anywhere, it must be freezing"

I’ve had this as well. Both from a it will be cold angle and it will blow down in the wind and they then reference the granite and sandstone old Scottish houses with their big thick walls. Just at Christmas i was in such a house where this comment was made. They had the oil boiler on running nearly all day and a stove in the evenings. They also used electric space heaters in some of the rooms. They commented how warm their house was. I didn’t get into a discussion about it but these were smart people who just don’t understand how buildings work at a basic level. 

[Iceverge]

24 minutes ago, Kelvin said:

didn’t get into a discussion about it but these were smart people who just don’t understand how buildings work at a basic level. 

 

It's amazing isn't it. I lived most of my life without even considering it. 

 

Something so simple as form factor never occurred to me which is amazing since I was always good at maths and physics and the sums are very basic. 

 

I think it has to do with decades of houses been sold as "homes, assets, fashion statements, investments, tax vehicles, inheritance, status pieces, heritage" etc etc. Anything other than machines to keep us safe from the elements. 

 

Nobody can make any ongoing cash from building a house that has very low running costs, is low maintenance and durable. 

 

People, even smart people, are just a product of their environment. 

Edited February 10, 2023 by Iceverge

[ProDave]

15 minutes ago, Kelvin said:

and it will blow down in the wind

Will have to ban the three little pigs from childhood reading.

[Iceverge]

2 minutes ago, ProDave said:

Will have to ban the three little pigs from childhood reading.

 

It's a conspiracy by "big concrete"

 

 

[Iceverge]

@jonM

 

Back on topic, you mentioned having different rooms at different temps which I can see some benefit in. 

 

Maybe bathrooms at 23, living room at 22, kitchen at 21, circulation spaces at 20 and bedrooms at 19. 

 

Have you actually done something like this in practice, does it create drafts?