Loft Insulation

[Andy Hall]

Do I need to do the sums again for you to demonstrate the point?

I suppose logic must seem strange to you.......

.andy

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[Andy Hall]

Read the post again. I don't believe there is a mistake in the arithmetic. If you believe there is then please correct the numbers and provide the figures.

.andy

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[IMM]

Then you must agree with me then.

[IMM]

Well do them by having a before and after of the ground floor and the 1st floor. Then see how much fuel is saved in each. I bet the 1st floor saves more fuel. Then there is superior cooling of the 1st floor and higher comfort conditions.

You have strange logic.

[IMM]

Read my posts again, about how you approach it.

[Andy Hall]

With two affirmative words:

Yeah. Right.

.andy

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[Andy Hall]

It doesn't use it in the first place if the temperature is lower.

For the ground floor, the heat calculation is generally what passes to the first floor and may be taken off of the local heating requirement of the first floor.

.andy

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[Andy Hall]

I prefer to stick to using information with demonstrable and known figures.

What-if scenarios are a separate topic.

.andy

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[IMM]

That's better.

[IMM]

Then you agree with me then.

[Andy Hall]

No.

.andy

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[Dean Richard Benson]

Funny thing is tho, I can see your point too, I just don't know who is right.

What I do know, is that while I have the opportunity, I will spend as much as I feel comfortable and/or can afford at the moment on sticking in loft insulation into the loft.

Although I realise there is also heat being lost through the walls and windows in each room, I dont have the time or finances to spend at this moment in increasing the insulation for that.

However when I replace the windows, and/or decide to add insulation into/to the walls, I will adopt the same route as I have done for the loft, ie, insulate as much as I can afford at the time.

My goal throughout this insulation in my house is to increase comfort, not so much to save cost. Therefore return on investment for the insulation isn't as important to me as having a comfortable house. This is within reason of course, I do have a limited budget :)

I hope the above explains my angle.

Thanks to both IMM and Andy Hall for their points too.

Dean

[IMM]

You have just contradicted yourself.

[Andy Hall]

Nope.

.andy

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[David Moodie]

I was going to suggest the Knauf U value calculator normally available as a trial version from

but it is unavailable at the moment as it is apparently being updated.

It may be worthwhile checking the site in a week or so if you \re still interpreted.

cheers

David

[IMM]

The point is that the house has to be viewed as upper and lower floors. the difference in the upper floors is marked in most houses.

[Andy Hall]

Heatloss through walls of the same construction, accounting for temperature variation, varies depending on whether you are upstairs or downstairs?

.andy

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[Andy Hall]

THe heatloss calculator programs from the radiator manufacturers have this data as well....

.andy

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[Neil Jones]

Here's my house as an exercise:-

Foot print ~ 70m2 Downstairs wall height ~ 2.1m Upstairs wall height ~ 2.2m Wall construction:- downstairs 27 m solid wall construction U-val ~ 2.0 + 8 m timber clad cavity wall construction U-val ~ 0.6 upstairs 27 m tile hung lath/plaster construction U-val ~ 2.0 + 8 m timber clad cavity wall construction U-val ~ 0.6 Ground floor :- thick concrete + screed + covering U-val ~ 0.3 Ceiling Floorbaord/Joist/Plaster U-val ~ 1.6 Loft currently insulated with ~ 100mm mineral wool U-val ~ 0.5

Windows:- Downstairs

2.2 m2 single glazed timber frames U-val ~ 4.8 5.9 m2 sealed double glazed units in plastic and metal U-val ~ 3.8 Upstairs 2.2 m2 single glazed timber frames U-val ~ 4.8 5.9 m2 sealed double glazed units in plastic and metal U-val ~ 3.8

Doors:-

6 m2 mixed construction U-val ~ 3.0

Air changes :- 1.5 per hour

Design parameters ================= Outside temp -3 C

Downstairs temp 21 C (delta-T = 24) Upstairs temp 18 C (delta-T = 21)

Heat loss - downstairs ====================== Floor = 70 x 0.3 x 24 = 504 W Walls = (27*2.1 - 5.9 - 3) * 2.0 * 24 ~ 2295 W +( 8*2.1 - 2.2 - 3) * 0.6 * 24 = 167 W Walls Total = 2462 W

Windows = 2.2 * 4.8 * 24 = 254 W +5.9 * 3.8 * 24 = 538 W Windows Total = 792 W

Doors = 6 * 3 * 24 = 432 W Ceiling = 70 * 1.6 * 3 = 336 W Air changes = 70 * 2.1 * 0.36 * 1.5 * 24 = 1896 W

Downstairs losses = 6422 W

Heat loss - upstairs ==================== Floor = 70 x 1.6 x -3 = 336 W Walls = (27*2.2 - 5.9) * 2.0 * 21 ~ 2247 W +( 8*2.2 - 2.2) * 0.6 * 21 = 194 W Walls Total = 2441 W

Windows = 2.2 * 4.8 * 21 = 222 W +5.9 * 3.8 * 21 = 471 W Windows Total = 693 W

Ceiling = 70 * 0.5 * 21 = 735 W Air changes = 70 * 2.2 * 0.36 * 1.5 * 21 = 1746 W

Upstairs losses = 5951 W

Total losses for house = 12.3kW

Downstairs losses are 51.9% of total losses from house.

Losses through:-

Ground floor 4% Downstairs solid wall 19% Downstairs cavity wall 1% Downstairs windows 6% Ceiling to upstairs 3%

Roof 6% Upstairs solid wall 18% Upstairs cavity wall 2% Upstairs windows 6%

Then see how much fuel is saved in each. I bet the 1st floor saves

[IMM]

Grow up! The rooms in the upper floors have a large area that is the ceiling with a cold loft over in winter and hot loft over in summer. Insulate the loft heavily and heat loss in these rooms reduces considerably, giving superior comfort conditions in winter and summer, moreso than the ground floors.

You didn't know that did you?