EPC Ratings

[Marvin]

8 minutes ago, Mr Punter said:

For clarity please confirm that was the external temperature!

Yes. Out side air tempreture. Bit damp, cloudy, fairly light wind.

Not bad for the Isle of Wight, in December.

 

Oh and internal temperature about 22C. 

Edited December 21, 2021 by Marvin

[epsilonGreedy]

9 hours ago, Marvin said:

The assessment score was discussed at great length. As soon as you mention LPG 47kg bottled gas you've had it. Worse than electric heaters as far as EPC concerned.

As for the thermal efficency, I think I wrote it up in my blog, but basically anything higher than about 8C and no heating required. Today no heating from 8am until 7pm and temp today about 8C.

 

 

Your feedback on heating demand and the insulation thicknesses you provided earlier indicate a high spec build thermally speaking. If powered by mains gas you would get a B EPC rating I assume.

 

I pay £64 per 47kg LPG bottle = £0.098 per kWh  (92 litres x 7.08 kWh per litre).

 

EPC is a cost per sqm rating.

The cost per sqm difference between B and F is 100% or a doubling in heating cost.

Bulk LPG is about 30% cheaper than bottled.

I know new builds on bulk LPG with slightly better insulation than building regs can get a C EPC rating.

 

Based on actual heating costs you should get a C or D EPC on bottles and a B EPC bulk lpg.

 

The EPC rating formula must use a daft kWh unit price for bottled LPG.

Edited December 21, 2021 by epsilonGreedy

[Marvin]

5 minutes ago, epsilonGreedy said:

 

Your feedback on heating demand and the insulation thicknesses you provided earlier indicate a high spec build thermally speaking. If powered by mains gas you would get a B EPC rating I assume.

 

I pay £64 per 47kg LPG bottle = £0.098 per kWh  (92 litres x 7.08 kWh per litre).

 

EPC is a cost per sqm rating.

The cost per sqm difference between B and F is 100% or a doubling in heating cost.

Bulk LPG is about 30% cheaper than bottled.

I know new builds on bulk LPG with slightly better insulation than building regs can get a C EPC rating.

 

Based on actual heating costs you should get a C or D EPC on bottles and a B EPC bulk lpg.

It was a while ago, but it did include the heating of the 200 litre tank of hot water..

 

Our LPG was £85 a bottle...

Edited December 21, 2021 by Marvin

[epsilonGreedy]

1 minute ago, Marvin said:

It was a while ago, but it did include the heating of the 200 litre tank of hot water..

 

 

If you are still on bottled LPG I guess your actual annual heating cost is acceptable regardless of the EPC rating.

[Marvin]

7 minutes ago, epsilonGreedy said:

 

If you are still on bottled LPG I guess your actual annual heating cost is acceptable regardless of the EPC rating.

We spent £500ish a (6 bottles) year for heating and hot water, easily measured each year for 3 years. But now we have an ASHP, and I would not change back. The PV, ASHP, MVHR and electric vehicle combo works for us.

 

Its especially good on the heating because the ASHP runs at a low level in the background. The boiler needed 60C ish to run at best efficiency and so when the heating came on we got over heating as the TRV take about 20 mins to respond and the rads were full of 60C water which is an overkill in our home

Edited December 21, 2021 by Marvin

[epsilonGreedy]

7 minutes ago, Marvin said:

We spent £500ish a (6 bottles) year for heating and hot water, easily measured each year for 3 years. But now we have an ASHP, and I would not change back. The PV, ASHP, MVHR and electric vehicle combo works for us.

 

 

6 lpg bottles = about 4000 kWh annually which is excellent even for a mid sized 120 sqm house. Many here build much larger.

 

I wonder if you would get an A EPC rating now with your improved PV, ASHP, MVHR setup?

[SteamyTea]

Gasoline from my local Tesco is £1.42, so 15p/kWh.

Cheaper than mains electricity.

[Marvin]

11 hours ago, Marvin said:

Today no heating from 8am until 7pm and temp today about 8C.

 

This is a bit misleading. We heated the 200 litre hot water tank and the heat from that leaks into the building, as do many other devices in the bungalow. But the point I was trying to make was that as a result of the work to improve the thermal efficiency and air tightness we now need a lot less additional heat; we used about 7kw for the 24 hour period (I have a meter on the power for the ASHP), and that an EPC doesn't necessary reflect the real picture on heating a home.  

[epsilonGreedy]

5 minutes ago, Marvin said:

This is a bit misleading. We heated the 200 litre hot water tank and the heat from that leaks into the building, as do many other devices in the bungalow.

 

 

The House Builders Bible calls these incidental heat source gains. The book's model 1600 sq ft house requires 5 or 6 kWh of energy to maintain a 20 degree delta but in practice incidentals brings down the theoretical energy demand by 30% (humans are a useful heating energy source apparently).

 

The @Jeremy Harrisheat modelling spreadsheet does not account for incidental gains or heat loss via air leakage. People say the spreadsheet is accurate so I assume for many air leakage heat loss and incidental gains tend to cancel out.

[SteamyTea]

2 hours ago, Marvin said:

7kw for the 24 hour period

You don't mean that.

It could be 7 kWh, or 168 kWh.

(not kw, or kwh)

[Marvin]

1 hour ago, SteamyTea said:

You don't mean that.

It could be 7 kWh, or 168 kWh.

(not kw, or kwh)

Your right. 7kwh. I'll try to be more of a pedant in the future....

Edited December 21, 2021 by Marvin

[SteamyTea]

1 hour ago, Marvin said:

Your right. 7kwh. I'll try to be more of a pedant in the future....

Or not.

kWh.

W for watt, named after Watt. Only use Watt if refering to the man, or at the begining of a sentence.

[Marvin]

1 hour ago, SteamyTea said:

Or not.

kWh.

W for watt, named after Watt. Only use Watt if refering to the man, or at the begining of a sentence.

Watt?

 

Oh! Jimmy Whatt. Got you.

Edited December 21, 2021 by Marvin

[SteamyTea]

14 minutes ago, Marvin said:

Watt?

Killer wot our

[Andehh]

Thanks very much all!

 

Turns out SAP calculator chap used the wrong figure for the floor.... it should be 0.11, not 0.17, as designed. Jetfloor likely to be replaced as insufficient height for it, alternatives tbc to achieve this. 

 

Seems the walls are a tiny bit over as well but not massively. Roof is at 0.18 correctly. 

 

All others are assumed values for boiler (or ASHP more likely), MVHR, windows, hw tank, etc so might squeeze some extra there. We're expecting named units/known specifications in January, so will review it again then.

 

Builder suggesting around £4k for roof top up and another £4k to beef up wall insulation to meaningful differences (ie extra 50mm+) which makes a very unappealing deal with everything else going on. We're being hammered on the price increases anyway, so one to accept as is & move on sadly. 

 

Thank you again for the feedback everyone... The joy of wanting uber grand designs on an insufficient budget!!