IanR

Heat in Buildings Strategy Statement

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Its not just that assessors won't fill in the correct data... In some cases they simply can't. My assessor did update the assumed values when i showed him the insulation, but the possible values only go up to a certain level. He had no way to enter Uw values for my 3G - he just had to check the 'double glazing' box.

Edited by gravelld

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I had a look at my EPC report after reading the above posts and it mentioned we were 79. This report is said that we would have used 3,124 Kwh of electricity for space heating, but I only had the one electric heater on for maybe five or six hours over the course of the year.  

 

Just noticed that it states this document should be fixed to the dwelling, who does that?

 

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3 minutes ago, Thedreamer said:

Just noticed that it states this document should be fixed to the dwelling, who does that?

 

I used to in rental properties as that is apparently a requirement.

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On 12/10/2021 at 17:41, saveasteading said:

Many houses have hardly any insulation, I believe, or 50mm from when it was a new idea and 2". They would benefit from another 150.

After that there is diminishing return (in my opinion but never proven) and I am surprised that 500mm is mentioned as a possibility.

 

What would be your choice for 1. cynical improvement of epc at least cost?

2. Best value for actual improvement?

I am surprised that you have never modelled it.

Plotting thermal conductivity against thickness produces an exponential decay, similar to Newtons Law of Cooling i.e. rapid decline at first, followed by slow decline as the thickness increases.

The line stays the same shape, regardless of temperature differences, just that the power losses change in proportion.

So taking the two extremes of Styrofoam (0.033 W.m-1.K-1) and concrete (0.92 W.m-1.K-1), you can see on the chart that even adding 0.01m (10mm) of styrofoam, will always outperform concrete.

So the best value, for poorly insulated buildings is to add insulation.

It is only when losses though air leakages are greater than conduction losses that the algorithm has to be changed.

The trouble with solving air leakage is that many 'holes' will be in places that are hard to get at i.e. under floors, and if airtightness is significantly improved, then mechanical ventilation must be used to control humidity.

 

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5 hours ago, SteamyTea said:

I am surprised that you have never modelled it.

I don't have the programme any more. We did play around with different thicknesses but in the regions of up to 250mm, at which all tests were being passed and costs were unjustifiable.

 

As you say,  other priorities come into play.

Intuitively there is little sense in having 500mm in the roof and 50 in the walls.

 

The blue line on the graph surprises me, and perhaps I am not understanding it properly. 

Is it implying that after, say, 60mm the benefit is minor?

 

It is surprising what an immediate benefit (real life, not perhaps in theory) there is from an underlay of 10mm on cold concrete.

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On 13/10/2021 at 22:42, Thedreamer said:

I had a look at my EPC report after reading the above posts and it mentioned we were 79. This report is said that we would have used 3,124 Kwh of electricity for space heating, but I only had the one electric heater on for maybe five or six hours over the course of the year.  

 

Just noticed that it states this document should be fixed to the dwelling, who does that?

 

 

I normally serve it on tenants in the house file.

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2 hours ago, Ferdinand said:

this document should be fixed to the dwelling,

Well, you can't do that can you? However the epc could be encapsulated and fixed in the plant room/next to the fuse box, and it could also say that Ferdinand built this lovely house in 2021 and gave a full maintenance manual to the owner.

 

I tried this for a while, by summarising on an encapsulated A4, the building construction, eg the bricks are marley sussex, the tiles are redland xyz, and the insulation is 200 thick abc. the metal cladding came from..etc. and the epc is B+ .

The client was not interested but did not object either. You can also direct the owner to the safety and maintenance  manual which is both helpful to them, and there as a protection against future claims. Should have done it more often.

Then maintenance manuals became compulsory and no need for the little notice.

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