[Greenbuilding] [BULK] Re: [BULK] Re: Air Conditioning for Phoenix

Thu Feb 1 09:08:50 CST 2007

As usual George, you have very excellent and detailed suggestions!

Lawrence Lile, P.E., LEED AP

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of George J.
Nesbitt
Sent: Tuesday, January 30, 2007 11:14 PM
To: Keith Winston
Cc: Greenbuilder list
Subject: [BULK] Re: [Greenbuilding] [BULK] Re: Air Conditioning for
Phoenix
Importance: Low

*GREEN COOLING*
    Fix the *building shell* first as much as possible.
       1. Cool roof would be high on my list, but if you need "approval"

then it might not happen. If you insulated the roof underneath then the 
benefit is too society in reducing the "heat island effect".
       2. Radiant Barrier, if you have to have a darker roof and if you 
don't insulate the roof, than I absolutely recommend a radiant barrier 
(help keep the attic and ducts cooler). Roofing is starting to be made 
in darker coolers that have reasonable cool roof properties.
       3. Insulate the roof, to bring the attic and ducts into 
conditioned space, either by placing rigid (polyisocyanerate) on the 
roof deck, or spraying foam (cellulose would also work in phoenix) on 
the underside of the roof deck.
       4. Windows, add low e film, overhangs, trees, replace, etc. to 
reduce unwanted summer heat gain.
       5. Air leakage reduction never hurts. Build tight, ventilate
right.
       6. Paint the house walls a light color.
       7. Insulate the walls if they aren't already.
Now for the *mechanical.
       1. *Manual J or ASHREA 90 room by room load calculation
(accurate).
       2. Manual S equipment sizing calculation, don't add size, if 
anything the load calculation is as much as 1/3 to large. Don't
oversize.
       3. Manual D duct design.
       4. Manual T grill/register design.
Now for the *equipment.
       *1. Swamp cooler, the oasis is the best, direct, indirect 
evaporative cooling. Developed with funding from the California Energy 
Commission, and Davis Energy Group.
       2. There is another one, but can't think of it's name at the
moment.
       3. Split system refrigerant cooling. Forget SEER, it is tested at

82deg F outside temperature, and 50% RH, you want a high EER, tested at 
95 deg F (still cool for Phoenix). The higher the outdoor temperature 
the lower the EER (or SEER for that matter). Stay away from the 2 stage 
condensers, they aren't as efficient on high. (better to under size and 
let it run longer). Install an air handler (furnace?) with a ECM 
variable speed motor. Install a return duct to the outside for fresh 
air, and run air handeler 24/7 (or a percentage of the time) on low 
speed (60-80 Watts).
       4. Water cooled split system. Consider the Freus, and there is at

least one other, hight EER even at higher outdoor temperatures (although

some loss).
       5. No HFC, HCFC refrigerants, use R-410A (Puron is one trade 
name). The Freus is R-22.
Now for the *Installation*.
       1. R-8 duct insulation, especially if the ducts are in the attic,

R-4 if they are in conditioned space.
       2. Insulate the plenum's, and the air hander too.
       3. Install the ducts and test to less than 6% of design airflow 
(400cfm/Ton cooling, ie 12,000 BTU's).
       4. Test the airflow with a Trueflow to check for 400-450cfm/Ton 
cooling.
       5. Braze the refrigerant lines with an oxy-acetylene torch, using

15% silver solder, and run nitrogen in the lines.
       6. Put the refrigerant lines under a vacuum to 500 microns, and 
not less than 800 after 15 minuets.
       7. Verify the charge using Subcooling (install a TXV).
Now for the *operation.
*       1. Use a programmable thermostat, try to live with not less than

a 78deg F indoor temperature.
       2. Enjoy comfort without breaking the bank, or killing the
planet.

Keith Winston wrote:
> Hi there,
>   
>> I'm going to push the limits of what he can handle as it is.  A metal
>> roof makes a lot of sense in Phoenix, and that is the second part of
>> this project that I didn't mention.  Living roofs are great, but
involve
>> structural mods that I'm not willing to consider on someone else's
>> house.  
>>   
>>     
> What about: put your metal roof on purlins (not all mftrs allow it,
but 
> some do) to create an air channel underneath, vented top and bottom 
> (hopefully it's a simple roof -- include insect barriers in the
vents). 
> Use a radiant barrier under it, pointing up.
>
> Insulate the roof from within the attic with spray foam, in the
meantime 
> sealing up the attic so if there are any ducts in there they are
inside 
> the envelope. Sorry, he has to move the nesting dolls. Check with your

> local foam contractor to see how willing/able he/she is to work around

> crap, but probably it needs to be empty. Hire a few young people to 
> clean it out! Leave the insulation that is probably already on the 
> floor, to make the attic a lightly conditioned space. Then you get the

> reflective metal roof, a radiant barrier properly installed, a 
> convective air space to keep the whole assembly from getting TOO hot,
a 
> tightly insulated roof, interior ductwork... have I missed anything?
>
> Say, did you ever find indirect evaporative coolers? We can't really
use 
> them here in DC, too humid. I see that Mastercool has an indirect 
> modification available http://www.adobeair.com/masterCool.html, I
can't 
> find it on their website but call and ask them. The other one is here:

> http://www.oasysairconditioner.com/, which looks impressive.
>
> Another possibility is a Freus water cooled evaporative air
conditioner, 
> quite different from a direct or indirect/2 stage evaporative cooler.
It 
> is a compression-cycle machine that uses a spray of water on the 
> condenser coils to improve performance.
>
> http://www.freus.com/
>
> They don't have a good website. You'll probably gain more information
here:
>
>
http://www.toolbase.org/TechInventory/TechDetails.aspx?ContentDetailID=7
93&BucketID=6&CategoryID=6
>
http://ezinearticles.com/?Evaporative-Water-Cooler---This-Water-Cooled-C
ondensing-Unit-Is-No-Swamp-Cooler&id=269729
> http://www.ecosmartinc.com/productdocs/1-Freus-Overview.pdf
>
> I'm not sure whether it makes more sense to use less electricity, or 
> spray the Ogalala into the air to be whisked away...
>
> Also, I have used/installed the Fujitsu 12RLQ mini-split heat pumps, 
> which are 21 SEER units. If you have an open floor plan and can get
away 
> with just one or two sources, it's a good prospect. Of course, you may

> need to consider ventilation, though with swamp cooling it's part of
the 
> picture. See if an HRV is justified in there, it might remove a bunch
of 
> the moisture while still cooling makeup air. I like the Venmar units.
>
> Warmly, Keith
>
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