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Forum Index : Other Stuff : habitable temperature / humidity

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isochronic
Guru

Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 04:28pm 11 Feb 2017
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Eastern Aus is in heatwave, more than usual.

I measured the temperature on the window ledge here (indoors)
at 50.3 degrees C the other day. A while later it cooled down
but the humidity shot up and was cited at 86%..

Granted the ledge was in sunlight but, this is residential living space...

So I wondered, what is the habitation limit wrt temperature etc, using simple electric fans and sweat to cool down ?

At a guess, I think, the max limit would be very close to the "dew point", ie , the point at which a wet surface (lungs/skin) is in equilibrium with the humid air. IE when hot humid air enters your nose/lungs, it cools to your body heat, and subsequently if it is too humid, water will condense and dump heat..cheerful isn't it.

So I found the dew point calculator on the net ... for a dew point of 38 deg C,
ie lungs. [any better figures, anyone, please speak up]

Temp @ Humidity
C %
...
40 90
42 81
44 72
46 65
48 60
50 54
...

In other words, any zones beyond that are not viable. It might seem
unlikely, but it is easy to get a combination of humid air (raining)
and a local environment that has yet to cool down. It would be interesting to see maps
of where those conditions are going to occur often and which cities.

 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 4723
Posted: 05:22pm 11 Feb 2017
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Its 41c here at the moment inside the house. In the shed ( open roller doors ) its 48c. Both thermometers are in the shade, ventilated area, thats important to get a accurate measurement. Yesterday we broke several heat records, and they expect more records to be broken today.

I believe humans can tolerate over 50c, provided we drink lots of water, dont exert ourselves and our sweat can evaporate. Thats where humidity comes into it, our sweat needs to evaporate. It also helps if we can cool down at night. Other animals can struggle with the heat, depending on where they evolved. Cats are from Africa desert regions, and can handle a bit of heat, but dogs are from northern Europe and can get into trouble during heat waves.

Comfort is another thing. I'm sitting in my little office with its little air conditioner running flat out. I'm catching up on work, and my dog is asleep on the floor. Its about 28c in here, which is OK for me. I check the power inverter ever hour or so, all up I'm pulling 1100 watts from my system, and its fan is going flat out!

Nasty weather.


"Treat the earth well, it was not given to you by your parents, it was lent to you by your children"

JAQ Software
 
TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 3127
Posted: 07:30pm 11 Feb 2017
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You should move to Tassie.
15.1 maximum today and currently 12.6 63% humidity

Apparent temperature was 0.9 a short time ago.

Jim


It all started with the ZX81....
VK7JH
http://www.c-com.com.au/MMedit.htm
 
gpalterpower

Senior Member

Joined: 19/07/2009
Location: Australia
Posts: 175
Posted: 02:09am 12 Feb 2017
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Yep. we copped it today too. Man it was hot.

I found myself in town today at Harvey Norman looking for a small window air conditioner. They quickly advised me that they just sold the last one that morning.

Not to be deterred I asked about portable ones.The choice of 3 were 2.5 to 3.5 kw. These were not inverter type and I knew that my off grid system probably wouldn't handle that kind of power demand so I looked at split systems. A 2.5 kw with power usage of 0.49kw. How is this possible? I understand with inverter technology the fan/compressor is not cutting in and out, but constantly changing speed, but still dosent add up.
A trip to Bunnings later in the day showed some better priced air con units. $399 for a 2.6kw unit. Usage 0.68kw. Still within my system capabilities. Is this the maximum power requirements to run this unit? I'll be back there first thing tomorrow morning if it is! Marcus

Ps. Definitely cooled down now but nowhere like Tassies temp! That sounds nice!
if it aint broke dont fix it!!
 
isochronic
Guru

Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 03:30am 12 Feb 2017
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Dry heat is fine. I enjoy it ! The marathon runners are the best example I guess,
as long as there is water to drink and evaporation, there is cooling.
But it is not dry heat so much.

The temperatures/humiditiy pairs above are a little optimistic, in that resting metabolism adds
80 - 100 watts to be dissipated as well. It cannot be dissipated outside the curve above.

Edited by chronic 2017-02-13
 
gpalterpower

Senior Member

Joined: 19/07/2009
Location: Australia
Posts: 175
Posted: 01:25pm 12 Feb 2017
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Hi Gizmo,
Just wondering if your batteries lasted thru the night, powering your Air, or did you get that cool change in the early hours of this morn and turned it off. Was such a relief! Dragging that sort of power from them is demanding, unless you had some wind blowing up Toowoomba way. Apparently some records broken there yesterday too!

Marcus
if it aint broke dont fix it!!
 
joebog1
Senior Member

Joined: 07/11/2015
Location: Australia
Posts: 114
Posted: 02:50pm 12 Feb 2017
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I started life as an Eng Elec.
My technology is so old that I began a new career 15 year ago as a heavy lift crane operator.
I was at Phosphate Hill ( near Mt Isa ) a few years ago and it was 44C. A crane has 4 glass sides, AND a glass roof!! ( watch that boom!!!! ) I didnt use the air con!!
( HORRIBLE things POOHH!!! ) I did drink LOTS of water! How much can a Koala bear??
I dunno, but I did move from the snowy mountains to get away from the cold, and I was born there.
Soory mods, somewhat off topic.
Joe
 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 4723
Posted: 03:07pm 12 Feb 2017
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  gpalterpower said   Hi Gizmo,
Just wondering if your batteries lasted thru the night, powering your Air, or did you get that cool change in the early hours of this morn and turned it off. Was such a relief! Dragging that sort of power from them is demanding, unless you had some wind blowing up Toowoomba way. Apparently some records broken there yesterday too!

Marcus


I've only got the air-con in the office, and its too small to cool the whole house. At night the temp drops down very quickly ( usually ), so never saw the need of installing air-con in the bedroom. Last night was a bit nasty though, was still 30c at midnight. I spent the evening in the shed working, was a bit cooler in there, and went to bed about 12:30 after a cold shower. Crap nights sleep, up at 5, bit tired.

But your right, the batteries would struggle running the air-con all night, I dont have the capacity.

Yes Toowoomba broke a record yesterday, first time over 40c.

Glenn
"Treat the earth well, it was not given to you by your parents, it was lent to you by your children"

JAQ Software
 
Boppa
Guru

Joined: 08/11/2016
Location: Australia
Posts: 787
Posted: 05:00pm 12 Feb 2017
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Waves hi @ Gizmo from Tara

Its definitely waaay too hot here, no aircon and only 2 fans in a caravan, all running from solar atm

Hit nearly 45 at one point yesterday, must admit I did a couple of `cool down' cold showers at the hottest part of the arvo, today's been better with a nice cooling breeze
 
isochronic
Guru

Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 12:15pm 07 Jan 2018
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Well a year later ...last year it hit 45...today it is 47 in an outer Sydney suburb. 53 on my window sill (inside, behind part shade.) Hope it is not a trend. Later january often is hotter
 
Boppa
Guru

Joined: 08/11/2016
Location: Australia
Posts: 787
Posted: 05:15am 08 Jan 2018
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I am back in Brisbakers atm, although it isnt as hot as Tara, man with the humidity, it feels 100 times worse

Definitely a dry heat is much easier to handle than this humid coastal heat
 
lastchord
Newbie

Joined: 29/10/2019
Location: Australia
Posts: 1
Posted: 07:44am 01 Nov 2019
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I would recommend installing proper pvc windows, I can recommend this company https://www.blueskywindows.com.au/windows/. It helps a bit to sustain optimal air moisture and temperature level.
 
Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 2875
Posted: 07:25am 11 Nov 2019
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  Quote  So I wondered, what is the habitation limit wrt temperature etc


I was telling a mate that lives in northern Scotland that it was too bloody cold to work out in the garage, as it was only twelve degrees Celsius.

He laughed and said if it ever gets up to twelve degrees here, we are all running around in shorts and sun hats. True !
Cheers, Tony.
 


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