A/C EFFICIENCY

[Anonymous]

We live in Southern Arizona. The A/C unit is on the south side of the house. and gets direct sun most of the day. In the summer time, you could fry eggs on the A/C housing.

Is there any advantage to erecting some sort of shade over the A/C unit ?

Enough to where the ( energy ) savings would be significant ?

( planning my summer projects.... )

[trader4]

Yes, anything you can do to shade it without cutting down on air flow immediately around it will help significantly. Usually some type of bushes, plants, tree, etc is a good choice.

[DK]

I've never heard of a single scientific study that showed that shading would reduce energy usage significantly.

The ambient conditions are essentially overwhelmed by the energy required to run the compressor.

If you live in a cave and use solar powered electric compressor to drive a 1 ton ac, then maybe it would make a slight difference.

[CJT]

Have you heard of a single scientific study that showed it won't?

Have you heard of a single scientific study that addressed the issue?

[NotX]

Have you heard of a single scientific study that showed that eating pork pies will NOT protect you from rabid skunks?

Have you heard of a single scientific study that addressed the issue or the effect of pork pies on rabid skunks?

[Stormin Mormon]

Common sense says shading is a big help.

Someone on alt.hvac posted a study awhile back. Someone set up two identical houses, and found the shade versus sun made no difference.

I'd plant some trees, or rig a shade if possible. Remember, AC units can produce a LOT of air flow.

Having the outdoor unit professionally cleaned every couple years will do more good than shade. The tech should take the outer housing off, use spray on liquid chemicals, and rinse the fins thoroughly with a water hose.

One I did a couple years ago, the unit was drawing about 9.5 amps,a nd hardly cooling. I cleaned it, and the current draw went down to about 8.5. The fellow said it was the first time in years the unit shut off cause the house reached temp. I'm sure I saved him a lot of money.

[trader4]

This is beyond stupid. The lower the outside temp, the less energy it takes for any air conditioning unit to lower the temp. That is simple physics. It;s also simple physics that on a hot day, it;s cooler in the shade than it is to stand out in the direct sun.

I'm sure you can find a "scientific study", but do you need one? Do you need a scientific study to tell you it's not good to cross a street full of moving traffic?

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[CJT]

No, I don't. But the other guy seemed to think one was needed.

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[Mark Lloyd]

YOU will be cooler in the shade. That doesn't mean the air is cooler.

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[Mark Lloyd]

Common sense is often wrong.

Once it was common sense that the Earth couldn't be moving. You don't feel motion. Now we know the Earth is moving, and very fast. Also that we never feel movement. Just acceleration.

I needed mine cleaned a couple of years ago. It had quit cooling at all.

[Ermalina]

I was surprised to find this:

Excerpt:

"Air Conditioner Shading Shows Minimal Savings

"A study by the Florida Solar Energy Center (FSEC) on the effects of shading outdoor air conditioner condensers indicates that energy savings benefits are modest at best--less than 5%. Although the study involved just three sample cases, and researchers describe the experiments as somewhat inconclusive, the results suggest that if shading is not done properly, the risk of interrupting air flow to the condenser could more than offset any benefits."

and a follow-up by the researchers:

"Our report, "Measured Impacts of Air Conditioning Condenser Shading" (FSEC-CR-827-95), does not show that shading A/C condensers cannot save energy (see "Air Conditioner Shading Shows Minimal Savings," Sept/Oct '95, p. 7). It does indicate that the potential savings are small. The report shows that if done properly, as at Site 1, an improvement in A/C efficiency of about 1% can be realized. On the other hand, the data show that when shading is done improperly, A/C efficiency can be lowered. Proper and improper shading strategies appear to be delineated by the proximity of the landscape shading to the condensing unit and its air flow pattern. A proper attempt at A/C shading would use landscape that is sited so that the unit is shaded in the late afternoon hours, but air flow is not impeded--particularly the hot exhaust air plume. This usually means using larger specimens (or waiting for smaller ones to grow), so that the shade trees are at least 6 ft away from the unit. We do indicate that such shading is not cost-effective when done solely for the purpose of shading an air conditioner. However, often landscaping is placed around homes for other purposes (beautification), and allocating one or two medium shade trees to this duty might be considered a no-cost option."

[Amanda]

[..]

How difficult it it to take the outer housing off?

[scott21230]

There are available sprayer things that mist the compressor with water that supposedly work much better than any shading could.

[trader4]

I saw that report too. I found it interesting that when the first study showed some savings, they almost dismissed it because it was less than 5%. I don't know about you, but I would think saving say

4% on an cooling bill in say AZ or FL is not insignificant. If you spend $1000 a year on cooling, that's $40 every year. And if you can work some attractive landscaping into it that brings other benefits as well, it seems well worth it to me.

If it really is

trees or shrubs to shade air conditioning units but not to block the airflow. Place your room air conditioner on the north side of the house. A unit operating in the shade uses as much as 10% less electricity than the same one operating in the sun.

But, unfortunately, they don't cite what this is based on.

[udarrell]

Stormin is correct, it will make a considerable difference. The hotter the air entering the condenser the more energy it will take because of numerous factors. Shade it but do not block entering or discharge airflow!

- udarrell

[LayPerson Tom]

imho:

Sounds like a good idea. If you can keep your AC condenser cooler, it should have to work less transfering indoor heat to outdoor air.

Just a guess....

tom @

[Mark Lloyd]

I saw the technician take mine off. It didn't look very hard. Turn off the electricity first (mine had a disconnect right there) and remove a few hex-head screws.

[CJT]

But I don't think it's wrong in this case.

[CJT]

Even 1% is not insignificant. How many barrels of oil would be saved by a 1% improvement nation-wide?

On the other hand, the data show

[CJT]

I'd be concerned about corrosion.