UFH for cooling upstairs - what I wish I had known for our new build

[RedRhino]

We knew our new house would be very well insulated and air tight so the heating demand would be low. 
Our rational response to that was to only put UFH on the ground floor because bedrooms should always be cooler and heat rises. 

Now we are thanking our lucky stars that our ASHP can cool, I wish I had put UFH in the bedrooms. 
During the current heatwave our ground floor is lovely and cool: 22c /  max 24c, that coolness doesn't reach upstairs except via the MVHR mixing. 
I think if I had my time again I would put UFH (or rather Under Floor Cooling) in the bedrooms to aid sleep during heatwaves. 

Edited 10 hours ago by RedRhino

[Spinny]

I think many with underfloor heating would be interested in using it for cooling.

 

I don't have a heat pump.

What temperature water are you circulating to provide your cooling ?

[RedRhino]

23 minutes ago, Spinny said:

I think many with underfloor heating would be interested in using it for cooling.

 

I don't have a heat pump.

What temperature water are you circulating to provide your cooling ?

16c - no condensation since we started running (although that might be tested in high humidity)
And 7KWH of solar / battery for 24 hours of cooling which we would otherwise export at 10p / KWH (in other words it cost us 70p for 24 hours). 
The solid line is the temperature of the hall thermostat - not the bedroom thermostat alas. 
 

[Mr Blobby]

We put ufh loops on the first floor for exactly this reason. 

 

Not yet sure how effective it will be.  UFH loops are in screed which is on insulated screed on bison slabs.  If we go ahead as planned and install engineered timber on top of the screed then I am concerned that it may be too insulating and defeat the purpose of the FF UFH.  (anyone installed porcelain fake timber planks on the FF?)

 

I suggested to the builder to shutter out sections of the insulated screed so that the cooling from the ufh loops would get to the bison slabs to cool the problem rooms below.  Like most of my other crazy suggestions this was ignored 😕

[JohnMo]

1 hour ago, RedRhino said:

UFH in the bedrooms

Really depends on floor covering - carpets maybe not so good for cooling.

[saveasteading]

54 minutes ago, Mr Blobby said:

anyone installed porcelain fake timber planks on the FF?)

No, but it's just tiling, which is standard practice. The only issue would be using long tiles on a floor which might flex. Do you feel any suggestion of movement when jumping on the middle?

[Mr Blobby]

Just now, saveasteading said:

No, but it's just tiling, which is standard practice. The only issue would be using long tiles on a floor which might flex. Do you feel any suggestion of movement when jumping on the middle?

 

No, the floor is solid, its hollow core slabs so the only thing that flexes when I jump on it is my ageing knees.   

Thermally porcelain tiles may help the cooling, but aesthetically I'm not sure if SWMBO will accept pretend wood.  I think I need to get her to a tile showroom.

[JohnMo]

14 minutes ago, Mr Blobby said:

I'm not sure if SWMBO will accept pretend wood.  I think I need to get her to a tile showroom.

That's went my plan started to unravel - ended up with nice thick wool carpet in bedrooms - nice insulation for low temp UFH. If there was a next time fan coils for bedrooms and maybe elsewhere

[Redbeard]

18 minutes ago, Mr Blobby said:

Thermally porcelain tiles may help the cooling, but aesthetically I'm not sure if SWMBO will accept pretend wood.  I think I need to get her to a tile showroom.

 

I thought it would look pretty naff but I did some over a dodgy concrete floor for a relative and it looked fine.

[Russdl]

@RedRhino do you have external shading for your windows/doors?
 

External shading and a (very manual) ventilation strategy is without a doubt what does the trick for us in keeping the house at a comfortable temperature throughout these little heatwaves that keep turning up.
 

We only have heating downstairs and no cooling of any description.
 

No heat pump either so the cold UFH utilised by many here is not an option for us but, fortunately, that has not been a requirement either.

(So far 🤞🏻)
 

 

[JohnMo]

18 minutes ago, Russdl said:

 

No heat pump either so the cold UFH utilised by many here is not an option

Was the driver for us getting a heat pump - started with gas. Never looked back, bills reduced massively 

[saveasteading]

58 minutes ago, Mr Blobby said:

I'm not sure if SWMBO will accept pretend wood

I'm of the same persuasion but we found some that comes in 20 patterns and I like it.

Otoh a relatively thin skin of timber slows heat more, but doesn't stop it.

[Spinny]

Should we be putting cooling loops into the loft so the cool air descends through the house ?

 

OK, people will tell me this is mad and a very very naughty waste of water. What about passing mains water through cooling loops and then erm purging it back out ? How much water would that use ?

 

And when you say you have no condensation - do you mean onto the floor ?

 

I am finding my now levelled suspended floor is a couple of degrees cooler than my insulated concrete slab. Foil over the bifolds seem to help a bit, but I havn't tried covering the rooflights.

Edited 7 hours ago by Spinny

[Ed_]

Hmmm so back of the envelope water is about 4000J/kg K.

Lets say 100kWh a day in heat energy absorbed (e.g 8kW of cooling on average over 12 hours), thats 360000000 Joules

Water at 15 degrees and say useable up to 25 degrees, so 10 degrees delta.

3.6e8 / 10 / 4000 = 9000 litres.

Basically tap wide open all day. My water is £2.75 / 1000l so £25 on a meter.

 

[saveasteading]

38 minutes ago, Spinny said:

cooling loops into the loft

Lofts get silly hot in summer.

[JohnMo]

2 hours ago, Spinny said:

Should we be putting cooling loops into the loft so the cool air descends through the house ?

If you mean under the insulation, then why not - they do ceiling and wall cooling solutions, your just doing ceiling as a retrofit

[JohnMo]

1 hour ago, Ed_ said:

Basically tap wide open all day. My water is £2.75 / 1000l so £25 on a meter.

not sure you want to do it with tap water - first it could be too cold and then have dew point issues and your bedroom ceiling landing on you during the night was its made lots of water and made the plasterboard weigh a tonne

[RedRhino]

6 hours ago, Russdl said:

@RedRhino do you have external shading for your windows/doors?
 

External shading and a (very manual) ventilation strategy is without a doubt what does the trick for us in keeping the house at a comfortable temperature throughout these little heatwaves that keep turning up.
 

We only have heating downstairs and no cooling of any description.
 

No heat pump either so the cold UFH utilised by many here is not an option for us but, fortunately, that has not been a requirement either.

(So far 🤞🏻)
 

 

Yes we do have external shading and I think it’s an essential part of the mix. 
My German wife has always wanted rolladen (European roller shutters) but no one seems to fit them in the UK. And would a subsequent buyer want that European look?

To improvise we have fixed fabric to the outside of the biggest, hottest windows to reduce the solar gain. 
It makes a massive difference and if temp is 30c+ I would say shading is essential. 

 

[LnP]

50 minutes ago, RedRhino said:

My German wife has always wanted rolladen (European roller shutters) but no one seems to fit them in the UK. And would a subsequent buyer want that European look?

To improvise we have fixed fabric to the outside of the biggest, hottest windows to reduce the solar gain. 

There are a couple of exhibitors at the NSBRC who do external blinds, for example, this one.

[Russdl]

Yep, we went with the similar Phantom Screens, I cant remember where we found them, either the NSBRC or a www search. Wouldn't be without them.