Green Spaces keep your city cooler.

the light works
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Green Spaces keep your city cooler. Jul 22, 2016 14:27:27 GMT

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Post by the light works on Jul 22, 2016 14:27:27 GMT

the morning news featured a talk with someone in Chicago talking about how they were adding green spaces to keep the city cooler.

while i agree with the premise, I'm interested in the other technology our forefathers figured out that we forgot in our eagerness to extract the most commerce from every square inch of city.

I believe public fountains not only provided drinking water, but also evaporative cooling. how else would our urban design affect the microclimate?

GTCGreg
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Green Spaces keep your city cooler. Jul 22, 2016 16:53:24 GMT

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Post by GTCGreg on Jul 22, 2016 16:53:24 GMT

Jul 22, 2016 14:27:27 GMT the light works said:

the morning news featured a talk with someone in Chicago talking about how they were adding green spaces to keep the city cooler.

while i agree with the premise, I'm interested in the other technology our forefathers figured out that we forgot in our eagerness to extract the most commerce from every square inch of city.

I believe public fountains not only provided drinking water, but also evaporative cooling. how else would our urban design affect the microclimate?

Keep things light. Black surfaces convert sunlight to heat. Light colored surfaces reflect the light (and heat) back up into space. Of course, this can be a disadvantage in winter. Especially in Chicago.

And your right about fountains. In downtown Chicago, we have a beautiful large fountain. (Buckingham Fountain) I was in Chicago one very hot summer day a few years ago and was really amazed how much cooler it was standing down wind from it.

Chicago really is a beautiful city at night.

mrfatso Evil Senior Member Posts: 3,856	Green Spaces keep your city cooler. Jul 23, 2016 1:35:16 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by mrfatso on Jul 23, 2016 1:35:16 GMT Having been in a few Mediterranean countries on holiday when it has been very hot, I would add plant trees to provide shade, and wide boulevards that allow the air to flow without obstruction.

the light works Demi-God Posts: 38,311	Green Spaces keep your city cooler. Jul 23, 2016 2:06:39 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by the light works on Jul 23, 2016 2:06:39 GMT you never truly realize how effective evaporative cooling can be until you've been downstream of a dam with a weephole spillway. and yes, deciduous trees for shade in the summer and full sun in the winter.

silverdragon Demi-God Busters Stunt Double, .. because "Life" is something that happens when your planning something else. Posts: 19,452	Green Spaces keep your city cooler. Jul 23, 2016 8:53:13 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by silverdragon on Jul 23, 2016 8:53:13 GMT This is partly why I have a pond. I also have a part of the filter that allows a waterfall effect. This works two ways, one it puts oxygen in, two it lets heat out.
	-x-clacks-GNU Terry Pratchett----Release the Clan Mac Feegle, awae hame ye scunners.[p]Most of my Job is avoiding Stupid. ...You cant Fix Stupid. Especially when you turn Left at Hammerhead.

the light works Demi-God Posts: 38,311	Green Spaces keep your city cooler. Jul 23, 2016 13:18:42 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by the light works on Jul 23, 2016 13:18:42 GMT I wonder how much plant transpiration contributes to the cooling, and how one would measure it without affecting the results.

GTCGreg
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Green Spaces keep your city cooler. Jul 23, 2016 13:31:39 GMT via mobile

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Post by GTCGreg on Jul 23, 2016 13:31:39 GMT

Jul 23, 2016 13:18:42 GMT the light works said:

I wonder how much plant transpiration contributes to the cooling, and how one would measure it without affecting the results.

I'll bet it definitely has a measurable effect. I wouldn't think measuring it would be too difficult. Just take the temperature in a forested area and then again just outside that area but in the shade. I think that may give you a pretty good idea.

Last Edit: Jul 23, 2016 13:32:23 GMT by GTCGreg

the light works
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Green Spaces keep your city cooler. Jul 23, 2016 13:53:40 GMT

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Post by the light works on Jul 23, 2016 13:53:40 GMT

Jul 23, 2016 13:31:39 GMT GTCGreg said:

Jul 23, 2016 13:18:42 GMT the light works said:

I wonder how much plant transpiration contributes to the cooling, and how one would measure it without affecting the results.

I'll bet it definitely has a measurable effect. I wouldn't think measuring it would be too difficult. Just take the temperature in a forested area and then again just outside that area but in the shade. I think that may give you a pretty good idea.

but would that also change other factors?

GTCGreg
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Green Spaces keep your city cooler. Jul 23, 2016 13:59:57 GMT via mobile

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Post by GTCGreg on Jul 23, 2016 13:59:57 GMT

Jul 23, 2016 13:53:40 GMT the light works said:

Jul 23, 2016 13:31:39 GMT GTCGreg said:

I'll bet it definitely has a measurable effect. I wouldn't think measuring it would be too difficult. Just take the temperature in a forested area and then again just outside that area but in the shade. I think that may give you a pretty good idea.

but would that also change other factors?

It could, but I'm sure someone with enough time on their hands could find out how much water a tree evaporates and how much cooling is produced by that evaporation.

Last Edit: Jul 23, 2016 14:14:40 GMT by GTCGreg

GTCGreg
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Green Spaces keep your city cooler. Jul 23, 2016 14:29:46 GMT

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Post by GTCGreg on Jul 23, 2016 14:29:46 GMT

Jul 23, 2016 13:59:57 GMT GTCGreg said:

Jul 23, 2016 13:53:40 GMT the light works said:

but would that also change other factors?

It could, but I'm sure someone with enough time on their hands could find out how much water a tree evaporates and how much cooling is produced by that evaporation.

Wow! Did a little digging, (rather googling) and found that a large oak tree transpires, (that's the fancy name they give water evaporation from plants), about 40 gallons of water in the 10 hour daylight period of a 70º summer day. Recalling from my thermodynamics classes in college, it takes about 8000 BTU of heat to evaporate 1 gallon of water. So if an oak tree is evaporating 4 gallons of water per hour, that's the equivalent of a 32,000 BTU air conditioning system. So one oak tree has almost the same cooling capacity as a typical home central air conditioning system (36,000 BTU).

I'd say that a forest of oak trees would definitely be the place to hang out on a hot summer day.

the light works
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Green Spaces keep your city cooler. Jul 23, 2016 15:51:25 GMT

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Post by the light works on Jul 23, 2016 15:51:25 GMT

Jul 23, 2016 14:29:46 GMT GTCGreg said:

Jul 23, 2016 13:59:57 GMT GTCGreg said:

It could, but I'm sure someone with enough time on their hands could find out how much water a tree evaporates and how much cooling is produced by that evaporation.

Wow! Did a little digging, (rather googling) and found that a large oak tree transpires, (that's the fancy name they give water evaporation from plants), about 40 gallons of water in the 10 hour daylight period of a 70º summer day. Recalling from my thermodynamics classes in college, it takes about 8000 BTU of heat to evaporate 1 gallon of water. So if an oak tree is evaporating 4 gallons of water per hour, that's the equivalent of a 32,000 BTU air conditioning system. So one oak tree has almost the same cooling capacity as a typical home central air conditioning system (36,000 BTU).

I'd say that a forest of oak trees would definitely be the place to hang out on a hot summer day.

definitely better than downwind of a house running a 32KBTU A/C system.

the light works
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Green Spaces keep your city cooler. Jul 23, 2016 15:55:52 GMT

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Post by the light works on Jul 23, 2016 15:55:52 GMT

here's a theoretical question.
could you design a shade structure that would effectively let sunlight heat an outdoor space in the winter, but block the summer sun?

I'm thinking of a structure based on the same principle of horizontal blinds - but could such a structure be oriented in such a way as to be seasonally effective without having to be adjusted?

silverdragon
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Green Spaces keep your city cooler. Jul 24, 2016 8:58:49 GMT

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Post by silverdragon on Jul 24, 2016 8:58:49 GMT

Jul 23, 2016 15:55:52 GMT the light works said:

here's a theoretical question.
could you design a shade structure that would effectively let sunlight heat an outdoor space in the winter, but block the summer sun?

I'm thinking of a structure based on the same principle of horizontal blinds - but could such a structure be oriented in such a way as to be seasonally effective without having to be adjusted?

Yes, if you have a "low sun" during winter.
Theoretically.
If the struts on the blinds were aligned in a "U" formation, black on the outside, and a mirror on the inside, where the mirror effect was aligned to reflect a high sun in the sky on an east-west trajectory, but absorb the sun on a low trajectory, the inside of the "U" being pointed at the sun at its zenith kind of thing
Those blinds would have to be on the outside of the window, or course, to dissipate the heat during the summer, but on the inside, during winter, to dissipate the heat as needed...
So between a series of double glazing panels that are ventilated as required would probably work.

-x-clacks-GNU Terry Pratchett----Release the Clan Mac Feegle, awae hame ye scunners.[p]Most of my Job is avoiding Stupid. ...You cant Fix Stupid. Especially when you turn Left at Hammerhead.

the light works
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Green Spaces keep your city cooler. Jul 24, 2016 14:30:47 GMT

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Post by the light works on Jul 24, 2016 14:30:47 GMT

Jul 24, 2016 8:58:49 GMT silverdragon said:

Jul 23, 2016 15:55:52 GMT the light works said:

here's a theoretical question.
could you design a shade structure that would effectively let sunlight heat an outdoor space in the winter, but block the summer sun?

I'm thinking of a structure based on the same principle of horizontal blinds - but could such a structure be oriented in such a way as to be seasonally effective without having to be adjusted?

Yes, if you have a "low sun" during winter.
Theoretically.
If the struts on the blinds were aligned in a "U" formation, black on the outside, and a mirror on the inside, where the mirror effect was aligned to reflect a high sun in the sky on an east-west trajectory, but absorb the sun on a low trajectory, the inside of the "U" being pointed at the sun at its zenith kind of thing
Those blinds would have to be on the outside of the window, or course, to dissipate the heat during the summer, but on the inside, during winter, to dissipate the heat as needed...
So between a series of double glazing panels that are ventilated as required would probably work.

I was thinking more in the direction of roof than window - but I agree, surface treatments on the slats would help make them more universal. I suppose a person could even make them with a bimetal structure so they would "fatten" in hot weather. it kind of gets away from being a low-tech solution, though.

mrfatso
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Green Spaces keep your city cooler. Jul 24, 2016 20:29:28 GMT

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Post by mrfatso on Jul 24, 2016 20:29:28 GMT

Another technology just occurred to me, it's has been used elsewhere I know, but my local National Trust Visitor centres on Dunstable Downs uses a system known as a windcatcher to cool it.
A vent is placed on the hill side with a 90 m long tunnel to the building, the wind pushes air down the tunnel,which is cooled in summer and heate din winter by the earth around it, and into the building.
www.architype.co.uk/project/chiltern-hills-gateway-centre/
This could not be used anywhere, the Chilterns hills are pretty windy used a lot by Gliders, Kites flyers etc, but anywhere similar could use it, it has no on going costs after construction and no moving parts.

Last Edit: Jul 24, 2016 20:32:27 GMT by mrfatso

the light works
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Green Spaces keep your city cooler. Jul 24, 2016 21:15:11 GMT

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Post by the light works on Jul 24, 2016 21:15:11 GMT

Jul 24, 2016 20:29:28 GMT mrfatso said:

Another technology just occurred to me, it's has been used elsewhere I know, but my local National Trust Visitor centres on Dunstable Downs uses a system known as a windcatcher to cool it.
A vent is placed on the hill side with a 90 m long tunnel to the building, the wind pushes air down the tunnel,which is cooled in summer and heate din winter by the earth around it, and into the building.
www.architype.co.uk/project/chiltern-hills-gateway-centre/
This could not be used anywhere, the Chilterns hills are pretty windy used a lot by Gliders, Kites flyers etc, but anywhere similar could use it, it has no on going costs after construction and no moving parts.

If you were to shape the tunnel properly, it would compress the air as it comes in, giving it more heat to be dissipated by the earth - and then it would cool as it decompressed at the other end.

silverdragon
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Green Spaces keep your city cooler. Jul 25, 2016 6:31:11 GMT

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Post by silverdragon on Jul 25, 2016 6:31:11 GMT

If your using tunnels, geo-thermal power!....
You can get systems that go down a few feet under the garden and use a heat pump to use sun power and ground heat to exchange heat from the ground to heat during winter.
You would need a heat exchange unit, and the ability to "swap" from extracting to pushing heat into the pipes under the ground.
If you have solar panels, it could use sunlight to power the pumps.

I also know of someone lucky enough to have natural cave tunnels on their property that say at a constant 12degC all year round, he pushes air through those, and uses a heat exchange to warm the house/cool the house by Solar powered pump.
The air leaving the house goes over exchange plates of the air entering the house to swap out heat to keep the house at the same temp, then the water from the cave pump system uses a heat exchange to either warm or cool the very last few feet of the air duct.
He has got a good thermal seal on the house though, so its minimal needs.

-x-clacks-GNU Terry Pratchett----Release the Clan Mac Feegle, awae hame ye scunners.[p]Most of my Job is avoiding Stupid. ...You cant Fix Stupid. Especially when you turn Left at Hammerhead.

Green Spaces keep your city cooler.

Post by the light works on Jul 22, 2016 14:27:27 GMT

Post by GTCGreg on Jul 22, 2016 16:53:24 GMT

Post by mrfatso on Jul 23, 2016 1:35:16 GMT

Post by the light works on Jul 23, 2016 2:06:39 GMT

Post by silverdragon on Jul 23, 2016 8:53:13 GMT

Post by the light works on Jul 23, 2016 13:18:42 GMT

Post by GTCGreg on Jul 23, 2016 13:31:39 GMT

Post by the light works on Jul 23, 2016 13:53:40 GMT

Post by GTCGreg on Jul 23, 2016 13:59:57 GMT

Post by GTCGreg on Jul 23, 2016 14:29:46 GMT

Post by the light works on Jul 23, 2016 15:51:25 GMT

Post by the light works on Jul 23, 2016 15:55:52 GMT

Post by silverdragon on Jul 24, 2016 8:58:49 GMT

Post by the light works on Jul 24, 2016 14:30:47 GMT

Post by mrfatso on Jul 24, 2016 20:29:28 GMT

Post by the light works on Jul 24, 2016 21:15:11 GMT

Post by silverdragon on Jul 25, 2016 6:31:11 GMT