Night sky cooling.
Last Post 25 Jul 2010 03:33 PM by jonr. 8 Replies.
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ls7corveteUser is Offline
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20 Jun 2010 06:00 PM
I have not seen much talk about night sky cooling. This paper has been the best reference I have found so far.
here

Anyone have any experience or some more information?

I hope we can keep a discussion going about this, it seems like a great addition especially with more people going to PV.
cmkavalaUser is Offline
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21 Jun 2010 06:01 AM
Is7corvette;

I have been to the test buildings and the design does work, but you would need to analyze the cost difference to see if it is worth the extra money. I don't know of any "real life" applications that have done this. FSEC could advise if someone has put it to the test

I hope the test data is accurate, I thought I saw a SIP ceiling on their prototype? but regardles the prototype design was not built to meet any hurrcane code so one would need to factor those costs in for the final analysis
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
Dana1User is Offline
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21 Jun 2010 12:07 PM
Variations of passive-cooling have been used commercially (notably by Steve Baer/Zomeworks, who has also done radaint-cooling using swimming pool solar collectors as radiators), but since it's sensible-cooling-only it's only a partial solution at best (mostly for climates where the dew points rarely break 60F.)

Glorified swamp coolers like the Coolerado ventilation system would probably have broader utility. By exhausting all of the humidity-laden air that's doing the cooling to the outside, and using only the cooled dry-air fraction of the air stream for ventilation it's a significant improvement over older swamp-cooler technology, but still of limited use when outdoor dew points are over 65F, since it can only cool to about the wet-bulb temp. On a 90-95F day with a dew point of 65F the Coolerado would deliver ventilation air in the mid 70s, no lower. But with dew points of 50-55F the ventilation air would be in the high-60s. By not adding to the latent load the way traditional swamp-coolers do it isn't relegated to desert-use only. In moderately dry climates the power use is a small fraction of that used by compressor technology- even less power consumption per BTU of the fans used in the FSEC radiant-cooled attic experiments.
ls7corveteUser is Offline
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21 Jun 2010 05:58 PM
Yes it was SIP in that building.I am surprised that you are against the cost, the building is a metal rool over partial sip construction. That is right up your alley.

It would be hard to justify the costs with a grid tied system. Though the costs do seem minimal, Sip with metal roof is already done affordably.

Certainly only a partial solution but together with other ideas I think it is a good one. Seems like there is not much info on this and I hope some innovation develops.
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21 Jun 2010 06:10 PM
Posted By ls7corvete on 21 Jun 2010 05:58 PM
Yes it was SIP in that building.I am surprised that you are against the cost, the building is a metal rool over partial sip construction. That is right up your alley.

It would be hard to justify the costs with a grid tied system. Though the costs do seem minimal, Sip with metal roof is already done affordably.

Certainly only a partial solution but together with other ideas I think it is a good one. Seems like there is not much info on this and I hope some innovation develops.
What I was eluding to was if it was a SIP that is not what their study shows therefore it is not a fair comparison to a fiberglass insulated ceiling in the other building

I am not against using SIPs at all, but it is a waste of money to lay SIPs in the flat and then build a secondary roof over the top, the metal roof that was built was not built to hurricane code requirements either so how can one identify what the true costs are?
I don't think the study has accomplished what it could have if the construction methods were kept similar , we really don't know if the night cooling is beneficial or not
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
ls7corveteUser is Offline
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21 Jun 2010 07:40 PM
I missed that, good point. I did see where they re-tested because of the different roof material used.

More reason to keep our eyes out for other tests/info.
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22 Jul 2010 02:45 AM
Hi..
This night sky cooling system enables downsizing of conventional cooling equipment and reduces annual energy cost by cooling water in a radiative and evaporative fashion.Water is sprayed over a flat or low slope roofed surface at night, filtered,stored and delivered the following day for cooling.The system is comprised of a room-spray assembly, a thermal-storage component, and a microprocessor control unit.The process is most applicable to arid climates where hot days are followed by the cooling night with minimum temperatures below 18C.

http://www.solarlightsmart.com/
cmkavalaUser is Offline
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22 Jul 2010 03:28 AM
Posted By rahinajoseph on 22 Jul 2010 02:45 AM
Hi..
This night sky cooling system enables downsizing of conventional cooling equipment and reduces annual energy cost by cooling water in a radiative and evaporative fashion.Water is sprayed over a flat or low slope roofed surface at night, filtered,stored and delivered the following day for cooling.The system is comprised of a room-spray assembly, a thermal-storage component, and a microprocessor control unit.The process is most applicable to arid climates where hot days are followed by the cooling night with minimum temperatures below 18C.

http://www.solarlightsmart.com/
rj;

I am sure it works well , just wish testing was done with same system constrution so one could draw an accurate conclusion to the test data and how much ROI would be

Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
jonrUser is Offline
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25 Jul 2010 03:33 PM
I'd try to use rain water for any evaporative system - otherwise you get all the dissolved matter coming out of the water.
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