Methods of cooling a room

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Andy Hall wrote:
<snip heat calculation>
Andy, your patience is truly infinite...
--
Grunff


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You mean his foolishness is infinite. There was no calculations from a reputable source, just Andy and his scattered uncoordinated thoughts.
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The sources were quite clearly stated as the Approved Document to Part L1 of the Building Regulations.
I took a simple example of a 4 bedroomed detached house of typical dimensions.
U values for materials and surfaces, where they were not listed in the above publication were taken from BS5449 : 1990.
The remainder is perfectly co-ordinated multiplication, subtraction, division and addition.

.andy
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Please put me on your killfile.
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wrote:

difference
It is:
On a 3 year spread the initial cost of loft insulation to the money saved in heating using gas, levels out at 400mm. It starts to rise at around 500mm. The bottom line: 400mm is the optimum thickness over 3 years. In the longer term, over 3 years, the thickness level rises. Source: The Whole House Book, by The Centre of Alternative Technology. http://www.cat.org.uk
The thicker the better.
Note: A reputable source is given.
And again...
In the book EcoHouse - A Design Guide, they gave a study that calculated in 1987 200mm was the optimum in walls at the then current fuel prices.
As fuel prices rise and the insulation manufacturing costs too, the whole payback calcs were skewed somewhat. So they calculated insulation levels on energy to make insulation. They came to the thickness of 650mm. The conclusion was that what constrains you is the detailing of the structure to hold as much insulation as possible.
Note: A reputable source is given.
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That all assumes a house constructed on some sort of "eco-principle" from scratch. You don't say who "they" are, so it is not possible to determine the reputation of the material.
I did not base my illustration on that, and did not say that I was doing so.
I clearly stated that the illustration was on the basis of today's requirements from the Building Regulations and used figures to illustrate the point that in the overall context of a house built to those standards, the effect of the amount of insulation in the roof beyond 100mm becomes negligible.
I then illustrated what the case would be for less well insulated walls, and that is even less.
These are real-world examples from the typical housing stock of today.
Your material from CAT and elsewhere is interesting I'm sure, but I don't really think that the average person is going to insulate their walls with 650mm of material or even their loft with 500mm, so it's academic.
.andy
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wrote:

block
wasting
walls
Please
in
500mm.
longer
in
on
to
No. Any house.

You obviously can't read. The sources were given.

500mm for a loft? 300-400mm CAT say, as the payback falls right off after that. If fuel rises dramatically in the next 3,4,5 years then 500mm is feasible.
Let me see. In winter the bedrooms 20c and the loft 1C. Hot goes to cold so a difference of 19C. the larger the difference the greater the heat flow. In summer, a loft at 48c and the bedrooms below at 25C, a difference of 23C. Appears better pack the loft with insulation in order to cool the house.
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With 650mm wall insulation? Sure...

The authors?

What kind of calculation is that? All you have mentioned is the temperature difference. THe heat flow depends on the U value of the material and the thickness as well. That's the whole point......
Good grief!
I really don't believe you can be any kind of HVAC professional (or any kind of professional for that matter) when you seem incapable of understanding two of the most fundamental formulae:
Heat loss = Area x dT x U
and the basic principle of transfer of
mass x specific heat x temperature rise or fall
.andy
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wrote:

calculated
whole
levels
structure
Sue Roaf, and the rest can be seen on Amazon.

after
cold
difference
the
The pint was that insulation may be more beneficial in summer than winter. That was obvious.
< snip drivel >
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Hall wrote:

I'm not 100% convinced: at the weekend I pointed my laser thermometer up into my loft and it was 52C - there's a long south facing slope acting like a giant solar panel. But of course at night the reverse happens and the roof acts like a big cooling radiator.
--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
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wrote:

OK.
If I use my example of the 8m x 8m house and the current Building Regs U value of 0.16, and let's say the room temperature of the upstairs rooms is 25 degrees.
Through the upstairs ceiling, the major heat gain would be transmission through the insulation (and I suppose bridging through the ceiling joists if they weren't covered.
Heat gain would then be
64 x 27 x 0.16 = 276W.
Also, due to convection, that heat would remain near the ceiling. This doesn't suggest a major heating effect to the rooms and I can't see any other mechanism for heat transmission through the ceiling.
I suppose one could do the solar gain calculations, but it would seem to me that this and air changes are the major reasons for the house growing warmer....
I found that by ventilating the loft with a fairly chunky fan using air from outside, the temperature drops fairly quickly after late afternoon. When it becomes less than the first floor average air temperature, it's worth opening the loft hatch. In that scenario the loft insulation doesn't help
.andy
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Andy

Wrong!
A pool of heat (hot air) is trapped against the ceiling. This pool of heat heats the thermal mass ceiling plaster and joists and in turn this acts as large radiator radiating down haeting the people and room below. That is why with windows not up to ceiling level it is best have a small ventilator at ceiling height, or on the ceiling. The vent extracts this pool of trapped hot air making the room far cooler and actually cooling the ceiling plaster. This means not requiring an expensive needless a/c.
Victorian houses had high ceilings to take the fumes of gas lights. With Georgian windows up to ceiling level you can pull down the top sash for effective cooling.
Most people don't understand any of and go out and buy expensive a/c equipment. Understand nature and go with it.
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heat
ventilator
ceiling
Guys, enough already!!! Everything that can be said has been. IMM - it's apparent you're not any sort of technical professional as all the engineering stuff just goes way over your head, so stop replying with such silly postings. If you don't like a/c's, then fine - don't bloody use any! For the rest of us, the temperatures recently have been way above what any natural cooling will make comfortable. That's not to say some of what you've been saying isn't correct - it is, just your arguments for how much they are correct compared to Andy and other's calculations are pure bullshit!
Suggestions:
Trust Andy, he knows of what he speaks Don't go buy an a/c and be a proud wee martyr Use your good suggestions for ventilation to make you house vaguely bearable in this heat (not the foil under roof one though, that was utter bo**ox!) Get yourself a spell and grammar checker for when you post to NG's
Sigh .....
a
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Verandahs that's what you need in a hot climate. Ask the Australians. Build them to the right depth and the low sun will still come in the windows in the winter.
Peter
--
Peter Ashby
School of Life Sciences, University of Dundee, Scotland
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wrote:

cool a

You are right, but the Aussies only have single floor houses.
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wrote:

What a sweeping generalisation. I currently live in Sydney and there are more double (or more) floored houses than not.
However, I will grant that verandas are only effective for the ground floor. We do have a two to three foot overhang on the first floor which is not as effective as the larger one downstairs, and it would get very hot without effective cooling (we tried it last summer and it was unbearable).
Good to hear about the weather in the UK at the moment - it's cold here.
Rob
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? Must have been hallucinating whenever I've been there then. Same with the two storey verandahed builidings In New Zealand where I grew up. Sure, many houses are single storied but by no means all. House I spent most of my teenage years in you entered at first floor level from the road and descended to the recreation room, laundry and two bedrooms. On the back of the house there were decks on both levels with cover on the upper deck, guess that makes it a verandah. You could get under the lower deck on one end as the slope was compound. So is this a single story house, a two storey house or a one and a half storey house?
Peter
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Peter Ashby
School of Life Sciences, University of Dundee, Scotland
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The numbers are quite clear and the sources official....
.andy
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wrote:
<snip>

... but where's the website reference to support such an outlandish idea?
;-)
Julian (currently wondering whether some solar panels on the south-facing roof of our house would provide enough power to drive some form of a/c).
--
Julian Fowler
julian (at) bellevue-barn (dot) org (dot) uk
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On Fri, 08 Aug 2003 11:46:30 +0100, Julian Fowler

The clipboard wasn't large enough to support the cut and paste. It was only 2GB in size.,........
.andy
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