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Exploring the ratios and losses between building elements

SteamyTea

Entry posted by SteamyTea in Compare U-Values and ACH

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Been a bit bored as I have not been able to concentrate on anything much recently, but life is getting back to normal.

 

I read on here a lot about the advantages of insulation, airtightness, MVHR etc, but this misses a few points.

Form is one of them, a simple cube is a pretty good shape for thermal efficiency, and the bigger it is, the better it looks.

So I thought I would knock up a very basic spreadsheet that can be used to explore the differences between size, form, thermal properties (just U-Value), air changes an hour for a cuboid.

This is basically to just show the ratios and theoretical power transfers.

Cells B3 to B11 can be changed with the snapshot results shown in cells B13 to B17.

Below that are some data arrays that show ventilation and fabric losses, and ratios for surface area to volume and fabric to ventillation for different form factors for the cuboids.

Not sure how useful this will be to anyone, but it does put numbers to changes i.e. you can change the ACH and U-Value and see which will have the greater effect.

 

This is a very limited scope spreadsheet, so a lot of interpretation is needed.

It does produce some charts though.

 

 

Compare U-Values and ACH.ods

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-rick-

-rick- 257

Posted

2 minutes ago, sgt_woulds said:

Talking of screwpiles reminds of another GSHP project in London; They were using a machine to fit a vertical deep-bore heat pipe.

 

TFL arrived and asked them to stop - less than politely but for very obvious reasons -when it was pointed out that their back garden was directly above part of the Norhern line...

 

A developer actually drilled through into the Northern City line near me (site is close to Old Street). They were piling foundations. Could have been very nasty.

 

Rail staff avert tunnel disaster | BelfastTelegraph.co.uk

saveasteading

saveasteading 3141

Posted

1 hour ago, sgt_woulds said:

screwpiles

I mean the ones they say you can turn in manually yet will support an extension. There were two such at Buildit Live.  1m long costing £35 each.  

I'm happy they can support decking or fence posts but they say 'extensions' too. That is naughty and scary.

There were substantial screw piles there too, from Canada.

 

1 hour ago, sgt_woulds said:

above part of the Norhern line...

Hardly an unmapped feature.  Plenty of surplus heat in there.

I wonder what opportunity these useless contractors are currently messing with. Probably solar or superfoil.

SteamyTea

SteamyTea 5681

Posted

6 hours ago, sgt_woulds said:

Could it include occupancy levels and biogenic heat sources?  

Not really as it is not about houses per sec, it is about form factor ratios, fabric thermal properties and ventilation losses, for a simple cuboid.

The real world is very different.

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saveasteading

saveasteading 3141

Posted

22 minutes ago, SteamyTea said:

The real world is very different.

That needs to be in the small print of... everything really.

SteamyTea

SteamyTea 5681

Posted

7 minutes ago, saveasteading said:

That needs to be in the small print of... everything really.

Needs to be highlighted I think.

It is why 'scientists, get a bit despondent when talking to lay people.  No matter how often limitations are stated, these will be ignored and the 'in the real world' 'facts', based on a sample of 1, for a very different scenario, will be quoted as the truth, loudly.

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