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Heat watch
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emordnilap



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PostPosted: Tue Jul 18, 2017 12:16 pm    Post subject: Reply with quote

Could this work? If it does, where does the heat go? If it doesn't, why do they claim a temperature drop?
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adam2
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PostPosted: Tue Jul 18, 2017 1:38 pm    Post subject: Reply with quote

I do not believe that it removes heat from indoors as does an electric air conditioner.
It would in some conditions reduce temperatures by reducing solar gain whilst still permitting ventilation. An open window with an external awning or sunshade would permit of maximum airflow whilst almost eliminating solar gain.

A more significant improvement would be a sunshade and an electric fan. Fans use very little electricity and are affordable to use from grid power, or DC fans are easily powered from small and cheap PV systems.
A fan does not normally reduce the actual temperature, but does greatly improve comfort by promoting evaporation of perspiration.
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cubes



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PostPosted: Tue Jul 18, 2017 10:59 pm    Post subject: Reply with quote

adam2 wrote:
I do not believe that it removes heat from indoors as does an electric air conditioner.
It would in some conditions reduce temperatures by reducing solar gain whilst still permitting ventilation. An open window with an external awning or sunshade would permit of maximum airflow whilst almost eliminating solar gain.

A more significant improvement would be a sunshade and an electric fan. Fans use very little electricity and are affordable to use from grid power, or DC fans are easily powered from small and cheap PV systems.
A fan does not normally reduce the actual temperature, but does greatly improve comfort by promoting evaporation of perspiration.


It's just a way of speeding up the air and making it feel a little cooler from what I can see. Might help a little I suppose.
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johnhemming2



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PostPosted: Wed Jul 19, 2017 9:01 am    Post subject: Reply with quote

If on the windy side of a property it could slightly compress air which cools a bit on expansion. The waste heat would go into the air and bottles on the outside. It would be interesting to see test results.
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kenneal - lagger
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PostPosted: Wed Jul 19, 2017 12:16 pm    Post subject: Reply with quote

I think it works in the same way that mountains cool air and cause rain. The wind blows from the sea / a plain over mountains and the air flow is compressed and speeds up. This cools the air which then condenses any moisture which then falls as rain. As the air then expand again and slows it warms but with a lower moisture content. This drier air would then help keep people cool as it would evaporate sweat more effectively.

If you stood next to the window you might get some cooled air but further into the room you should get drier air. Not sure how much cooling that you would actually get; it would depend on the relative air speeds, I suppose.
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woodburner



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PostPosted: Thu Jul 20, 2017 1:56 am    Post subject: Reply with quote

Mountains cool air because the air is forced to rise, and the cooling occurs adiabatically at a rate of between 1.5ºC and 3ºC per 1000ft as the air expands. As it is carrying moisture the point is reached where the air can no longer hold the moisture so it drops out as rain, or maybe snow, or fog.

The bottle coolers only provide cooling in buildings which have poor insulation, little thermal mass and so have tremendous heat gain. In well insulated building with large thermal mass it is better to keep ventilation to a minimum so the mass absorbs the heat and reduces the temperature increase.
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kenneal - lagger
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PostPosted: Thu Jul 20, 2017 3:09 pm    Post subject: Reply with quote

Thanks for that correction.

Now one of my own. Thermal mass will only cool a building if there is a source of cool air, e.g. cooler night temperatures, which can be used to cool the structure. Where you have hot temperatures for 24 hours thermal mass is a distinct disadvantage. In such circumstances you usually find that light weight structures are normally used.

Heavy weight structures are common in hot desert climes where the nights tend to be much cooler than the day. These structures often incorporate wind towers to force ventilation combined with an airflow into cooler cellar areas below ground. They also are often built around a closed, outside windowless, courtyard with a fountain in the middle to assist cooling.
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woodburner



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PostPosted: Thu Jul 20, 2017 8:25 pm    Post subject: Reply with quote

What I wrote about the buildings was not contradictory to your reply, I just didn't explain as fully as you did.
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johnhemming2



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PostPosted: Thu Jul 20, 2017 9:25 pm    Post subject: Reply with quote

kenneal - lagger wrote:
Thanks for that correction.

Thank you for being someone who wishes to work towards identifying what the truth actually is. (unlike quite a few who post in this forum).
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kenneal - lagger
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PostPosted: Fri Jul 21, 2017 12:23 pm    Post subject: Reply with quote

Having just reread that last few posts, it has reminded me that this window fitting would seem to work in the same way that the wind tower does. The new ecotown, who's name escapes me at the moment, built in the desert of the UAE has wind towers which cool the streets by moving the air.
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adam2
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PostPosted: Fri Aug 04, 2017 2:54 pm    Post subject: Reply with quote

Extreme heat in various parts of Europe, said to be directly dangerous to human health in the worst affected areas.
http://www.bbc.co.uk/news/world-europe-40825668
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emordnilap



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PostPosted: Fri Aug 04, 2017 3:58 pm    Post subject: Reply with quote

adam2 wrote:
Extreme heat in various parts of Europe, said to be directly dangerous to human health in the worst affected areas.
http://www.bbc.co.uk/news/world-europe-40825668


I saw a forecast on a pub tv recently which showed 39ºC in Rome which is desperate enough.

But 43ºC, crikey. That's 109/110ºF for those in the dark ages Laughing .

Still, a good bit to go before anyone decides "something must be done."

Bruce wrote:
'Hot enough to boil a monkey's bum, your majesty,' and she smiled politely. She's a good sheila.

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raspberry-blower



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PostPosted: Sat May 05, 2018 6:23 pm    Post subject: Reply with quote

emordnilap wrote:
But 43ºC, crikey. That's 109/110ºF for those in the dark ages Laughing .

Still, a good bit to go before anyone decides "something must be done."



Just how hot does it have to get? It is certainly heating up in the Asian subcontinent

Quote:
Even in Pakistan, no stranger to blistering heat, the temperature on Monday stood out: 122.4 degrees Fahrenheit.

The reading came from Nawabshah, a city of 1.1 million people in southern Pakistan, and meteorologists say it is the highest temperature ever reliably recorded, anywhere in the world, in the month of April.

The World Meteorological Organization keeps global temperature records, but not by month, which means Monday in Nawabshah cannot be officially confirmed as the hottest April day. But experts on extreme temperatures say it probably is.


NYT: Hottest day in April was probably Monday in Pakistan
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adam2
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PostPosted: Sat May 05, 2018 8:22 pm    Post subject: Reply with quote

Some parts of the world that were already uncomfortably hot are rapidly becoming dangerously hot.
In places with significantly lower nigh time temperatures, then thermal mass and night time cooling helps a lot. Forced air circulation at night uses very little electricity and can give a greater effect.

In some of the hottest places, especially if also humid, electric air conditioning is rapidly becoming a necessity.
At least PV is getting cheaper and cheaper, and PV production roughly matches air conditioning demand.

And the coming bank holiday Monday is predicted to the hottest ever in parts of the UK.

http://www.bbc.co.uk/news/uk-44015562
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PostPosted: Mon May 07, 2018 1:17 pm    Post subject: Reply with quote

As was forecast, today is the hottest early May bank holiday on record, and I consider it likely that still higher temperatures will be recorded later in the day.
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