kWh per m2 per annum

[Declan52]

43 minutes ago, Oz07 said:

c'mon @joe90 make the effort just look at a couple of bills! mind I suppose you'd have to estimate heating/other split usage 

 

@Declan52 you and @ProDave have the best performing up to now. Yours is pretty traditional construction isn't it declan? What width cavity do you have and what's in floor and roof?

 

@tonyshouse post your numbers here

@PeterW cmon I bet you know your figure?

Block build with a 100mm cavity full fill graphite insulation boards. Inside skin is lightweight blocks. Lots of tape and membrane.

150mm pir in the floor.

Mine is a room in the roof house so on the most part it's 140 high density rock wool with 50 PIR underneath. On the flat roof section 400mm Rockwool. 

[joe90]

Not sure how to measure this input ?

[Oz07]

Lol I bet steamy tea does though. Declan do you have a fire apart from wood pellet burner? Dave how often do you light yours?

[Oz07]

Wicked performance for that size cavity declan do you have any special upstand at floor perimeter or just 25mm? What u value is that wall with those graphite boards?

[SteamyTea]

I have done a quick power frequency analysis, my water heating and space heating accounts for around 9% of my total load, just water heartng is 6%, so that leaves 3% for space heating.

87% of my total usage is 600W or under.

 

So if I divide my 4.122 MWh/Year by 48m², my heating load is will be 3% of that, or 2.6 kWh.m^-2.y^-1

 

Suck on that.

 

(actually I live in a very mild part of the UK, some years I have never put the heating on, and there are incidental gains to be had, which are amplified by having a small volume, I probably heat the place up a degree or two)

Edited December 7, 2020 by SteamyTea

[joe90]

3 minutes ago, Oz07 said:

Lol I bet steamy tea does though

yes, @SteamyTea will have me measuring the size of the logs, petrol consumed by the tractor fir cutting it up, calories I burn splitting the logs, energy used bringing it into the house.      Nah, can’t be bothered thank you, all I can say is just watching it is worth the effort ?

[SteamyTea]

11 minutes ago, joe90 said:

Not sure how to measure this input

 

7 minutes ago, Oz07 said:

I bet steamy tea does though

I do.

Weigh the amount of timber you put in, and every 15 minutes, note the rise in air temperature.

Work out the mass of air in the room, then calculate.

 

And while you are at it, count the number of 'rings' on each log, work out the mean, and compare the number of years it takes to grow, compared to the number of minutes it takes to burn.

[Oz07]

Mic drop we have a winner @SteamyTea the steam off his sh!t is all that is needed!

[tonyshouse]

42kWh/m2/y.  Overall, can’t separate heating and HW  but think 7kWh/m2/y 

[joe90]

11 minutes ago, SteamyTea said:

Weigh the amount of timber you put in, and every 15 minutes, note the rise in air temperature.

Work out the mass of air in the room, then calculate.

 

And while you are at it, count the number of 'rings' on each log, work out the mean, and compare the number of years it takes to grow, compared to the number of minutes it takes to burn.

I did not instal a woodburner to be efficient, it’s the asthetics.  

[Oz07]

Don't know why but that's just reminded me of this scene 

 

[Declan52]

33 minutes ago, Oz07 said:

Lol I bet steamy tea does though. Declan do you have a fire apart from wood pellet burner? Dave how often do you light yours?

I have a wbs that gets lit maybe 6 times a year. You can't have it roaring or the living room and kitchen gets to 28 degrees+ very quick.

[jack]

56 minutes ago, Oz07 said:

That's lock stock though isn't it @jack like steamy tea includes even appliances etc etc. Heating alone is the most accurate measure as Dave says

 

For sure, but I don't have any way of measuring that!

[Declan52]

33 minutes ago, Oz07 said:

Wicked performance for that size cavity declan do you have any special upstand at floor perimeter or just 25mm? What u value is that wall with those graphite boards?

Just 25mm pir. Been a long time since I worked it out. 

[joe90]

7 minutes ago, Declan52 said:

I have a wbs that gets lit maybe 6 times a year. You can't have it roaring or the living room and kitchen gets to 28 degrees+ very quick.

mine gets lit more than that but only fir about an hour, maybe two, it’s currently 25’ in here (the lounge, in my tee shirt) but I have been Outside working and got thoroughly cold so enjoying the warmth. The house will be still be warm in the morning so saving me lecky fir the ASHP. ?

Edited December 7, 2020 by joe90

[JamesP]

1 hour ago, Oz07 said:

Similar in roof too then? Do you have an insulated foundation?

Same in the roof. Foundation is 100mm concrete, 150mm Celotex, 40mm screed.

Figures below are for just over 10  months.

 

 

Edited December 7, 2020 by JamesP

[AliG]

I just realised looking at the above, if you have an ASHP then the electricity usage is correct in carbon terms, but as electricity is currently around 6x the price of gas then a very low kWh number for an ASHP heated house won't necessarily give that large a saving. In fact it might cost more before the RHI is taken into consideration.

 

 

 

[Thedreamer]

This has been a useful thread. 

 

Honestly I'm surprised by the amount of energy being used by others.

 

Many of the builds seem to have more insulation than me but the energy use seems to be higher.

 

If we light the stove it raises the temperature by 4 degree but it would still be comfortable at 19 degree without it and since moving in it's not gone below 18.

 

The last few nights have been minus temperatures but still little difference.

 

[Thedreamer]

5 hours ago, AliG said:

I just meant I am not sure it is worth dividing these costs by the area of the house as they are fixed and unrelated to the size of the house.

 

The heating cost for the pool is actually quite low (Around 2200kWh/yr or £500), however the dehumidifier and pump use a lot of electricity. Between them and the Tesla my electricity bill is larger than my gas bill.

 

Do you recycle the heat leaving the pool? I would imagine you would recover a fair amount using an exhaust air source heat pump.

[AliG]

1 minute ago, Thedreamer said:

Do you recycle the heat leaving the pool? I would imagine you would recover a fair amount using an exhaust air source heat pump.

 

Yes, the pool is covered as the first thing to do is try to limit the evaporation.

 

Then there is a massive Heatstar machine which sucks humid warm air out of the room above the pool. It feeds the heat back into the pool and cool air out into the room across the windows. It also kicks in to heat the room up very quickly with hot air when you open the pool cover.

 

So this keeps the heating costs low but at the cost of £20k of machine and ductwork. It also uses a lot of electricity, but it is hard to isolate exactly how much.

 

 

[MikeGrahamT21]

@Oz07 Its a 1960's bungalow, part way through renovation. Recently come under the 100kwh/m2/a, im hoping this comes down quite a bit more over the course of the winter, as this is the first winter with a big chunk of the house renovation complete, and the MVHR in place.

[SteamyTea]

3 minutes ago, MikeGrahamT21 said:

100kwh/m2/a

100 kWh.m^-2.a^-1

[MikeGrahamT21]

8 minutes ago, SteamyTea said:

100 kWh.m^-2.a^-1

 

Would you like me to change my signature? ? ?

 

Please don't make me do the water... 104L.Person^-1.day^-1

Edited December 8, 2020 by MikeGrahamT21

[SteamyTea]

1 minute ago, MikeGrahamT21 said:

Would you like me to change my signature

I can't see it, so you are safe there.

[Gone West]

Do these calculations actually mean much when interior and exterior temperatures aren't known nor is exposure of the building known. Wouldn't the number of occupants affect the energy use. I would have thought the number of variables is too high to make these figures useful. I would use a lot more energy heating my house if I lived up near @ProDave for example. When I ran PHPP, designing my house, I found heating it to 20 degrees would use 12kWh/m2/a and heating it to 23 degrees would use 20kWh/m2/a. There's also no mention of whether all a house is heated to the same temperature all the time, or whether when at work the heating is off. Not really knocking it but take it all with a pinch of salt.