[Greenbuilding] [BULK] Re: Passive cooling design question

[Keith Winston]

In my neck of the woods, with a little aclimatization you can easily 
last into late July or August. Still, there's a month or so that I'm 
willing to agree is pretty rough, I think of that as our cooling season. 
That's the period when it's so hot and humid at 5am, that night flushing 
is a completely useless strategy (that's what gets you up to that point, 
BTW). And, since I do more rehabs than new construction, we end up with 
AC. Hence my love of the 21 SEER Fujitsus.

Of course, as plainly readable between the lines, the biggest share of 
energy reduction is attained by occupant choices, not hardware...

Keith


Lawrence Lile wrote:
> I'am able to cool my house with the following strategy:
>
> R60 roof, tight walls, shaded windows and overhangs keep the heat out
>
> Turn on the air conditioner at night for an hour - AC is a lot more efficient at night when it is cooler outside. 
>
> If I didn't hafve allergy problems, I'd open the windows at night or even use a whole house fan, but that isn't an option in pollen season.  I'm a lot healthier with a house shut tight. 
>
> The house will fluctuate between 76F and 80F most days
>
> Humidity control is definitely an issue.  Having a small AC, or a stage in the main AC unit, would help.  It is difficult to control humidity without mechanical refrigeration.  
>
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org on behalf of Robert Waldrop
> Sent: Mon 1/14/2008 10:54 AM
> To: Nick Pine; greenbuilding at listserv.repp.org
> Subject: [BULK]  Re: [Greenbuilding] Passive cooling design question
>  
> ----- Original Message ----- 
> From: "Nick Pine" <nick at early.com>
>   
>> I don't think that will help much on an average 
>> July day, with a 70 F
>> wet bulb temp. The main problem would be 
>> dehumidification. Cooling the
>> outdoor air to 70 F would raise the RH to about 
>> 95%--uncomfortable.
>> ASHRAE says humidity ratios over wi = 0.0120 are 
>> uncomfortable... 0.0120
>> is OK at 80 F. You might cool the house with the 
>> earth or wellwater and
>> run a small window AC with reduced airflow for 
>> dehumidification, if the
>> house is very airtight.
>>     
>
> This has been our experience in central Oklahoma 
> (five years without AC).  We have done a lot in 
> terms of shade (trees, insulation, windows, and 
> vegetation), ventilation (windows and Tamarack 
> whole house fan), and avoiding interior heat build 
> up (we cook all meals outside all summer, attic is 
> passively ventilated), but we were never able to 
> do anything about the humidity.  Nick's post has 
> some interesting ideas though to pursue further.
>
> This past summer, with the high rainfall all year, 
> the humidity was really bad and so we bought 3 
> window unit air conditioners.  As it turns out, 
> however, we bought way too much AC, as only one of 
> them was used regularly.  So we managed to keep 
> our 1548 sq ft house very comfortable with one 
> 5,000 BTU window unit AC, that we operated only 
> when we were in the house during July, August, and 
> the early part of September.  One of the other 
> window units, an 8K BTU, was operated for maybe 20 
> hours total until we figured out it was overkill. 
> The third unit, a 5K btu, was only turned on a 
> couple of times.
>
> If we were able to stay out of AC buildings all 
> the time, we think we would have done pretty well 
> without the AC.  We were most uncomfortable just 
> after getting home from the perfectly air 
> conditioned work space.  If we could stay out of 
> AC buildings for 2 or 3 days, we noticed that we 
> would acclimate pretty well.  But in Oklahoma, 
> unless you stay home all the time, it is 
> impossible to avoid air conditioning in the 
> summer.
>
> Bob Waldrop, Oklahoma City
> www.energyconservationinfo.org 
>
>
> _______________________________________________
> Greenbuilding email list
>      Environmentally-preferable design, construction, building elements
> List info: http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
> List email: Greenbuilding at listserv.repp.org
> Managed by BuildingGreen, Inc. http://www.buildinggreen.com
>       publisher of Environmental Building News and GreenSpec
> Hosted and archived by REPP / CREST http://www.crest.org
> To get on the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
> To get off the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
>
> _______________________________________________
> Greenbuilding email list
>      Environmentally-preferable design, construction, building elements
> List info: http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
> List email: Greenbuilding at listserv.repp.org
> Managed by BuildingGreen, Inc. http://www.buildinggreen.com
>       publisher of Environmental Building News and GreenSpec
> Hosted and archived by REPP / CREST http://www.crest.org
> To get on the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
> To get off the list:
>   http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
>   or mailto:greenbuilding-request at listserv.repp.org?subject=unsubscribe
>
>