Comments on: Power Attic Ventilators Banned by New Georgia Energy Code

By: Jeremy Begley

Jeremy Begley — Sun, 08 Jul 2012 18:14:15 +0000

Id just like to chime in here
Id just like to chime in here by quoting someone I consider a far greater expert on the subject than myself, Paul H. Raymer,from his book "VENTILATION HANDBOOK- Ventilation to Improve Indoor Air Quality”,
“As with many technologies, layered in tradition, eventually these original purposes were forgotten, particularly in cooling climates where ice dams are not an issue. The thought was that attic venting could lower the attic temperature, which would reduce the cost of cooling and prolong shingle life even though there was no research to support those concepts. Adding an active cooling system or fan was assumed to amplify the effect, but field testing has shown that the temperature of roof sheathing of a [sic] unvented roof will rise by a few to no more than 10°F more than a well ventilated attic. Despite this, shingle manufacturers generally insist on the vented deck design and most codes require it” Chapter 16, pg 199
“In terms of the effect of the cost of cooling the air in the house, reducing the attic air temperature has only a small effect. Warm air flows upward. The hot air in the attic will not flow down into the house. In terms of conduction, if the floor of the attic is poorly insulated, the ceiling of the house will reach the same temperature as the attic, and that heat will be conducted and radiated into the house. You can feel it if you stand under a poorly insulated attic hatch. If the floor of the attic is well sealed and insulated, then the attic temperatures will be isolated from the house, and the large temperature swings up there are less important” Chpt 16, pg 201

By: Allison Bailes

Allison Bailes — Sun, 01 Apr 2012 17:03:41 +0000

Samuel H.:
Samuel H.: Ah, I see. Because the finance industry is corrupt, no one should trust anyone talking about building science. That's quite an extrapolation.

You also said:

Why shouldnt a property owner be allowed to do whatever he/she wants on their own property if it does not harm others.

Gosh. Where do I start? If you read this article and the one I linked to in the first sentence, you'll see that power attic ventilators can harm people. More generally, we do give government the power to regulate so that people don't do stupid things. Yes, we can discuss bad examples of how they apply this power, but keeping people safe in homes is well within government's purview.

Finally, you said:

If you think a certain appliance will be a positive factor in your environment or provide a savings, invest in the product and try it.

The Georgia energy code doesn't stop people from doing stupid things with their own houses. It stops builders from doing stupid things to houses they sell to unsuspecting homebuyers.

By: Samuel Hay

Samuel Hay — Sun, 01 Apr 2012 11:57:45 +0000

Much ado about nothing. Why
Much ado about nothing. Why shouldnt a property owner be allowed to do whatever he/she wants on their own property if it does not harm others.
There is never a one size fits all for these types of debates. There are dozens of factors involved in calculating theoretical performance, many of them are not at all accurate. My studies and research on these subjects, including development of solar equipment since 1967 gives me a great deal of experience to fall back on. If you think a certain appliance will be a positive factor in your environment or provide a savings, invest in the product and try it. You have the option to remove it and sell it on ebay.
We have so many experts getting paid a lot of money to tell us what we need to do when in fact we are our own best friends when our lives or pocketbooks are are at stake.
I refer to the banking and investment industry. Listening to those idiots has cost us more than any collective errors in judgment in whether to install a power vent in our attic.

By: Bob

Bob — Wed, 14 Sep 2011 16:14:07 +0000

The problem is solar power
The problem is solar power attic fans are basically worthless as far as real CFM ratings go. Does anybody actually believe that a 20 watt motor can move 800CFM of air blowing into a solid dome? They seem to be about the only people that are getting 40CFM per watt. A standard A/C powered fan using 400W to get 1200CFM is only 3CFM per watt. Somebody is exaggerating ratings...

If new construction I'd just seal at the roof-line, make the attic conditioned space. For retrofit on current homes I can see doing an A/C power roof fan if you get one with a PSC motor (uses 1/2 the power of shaded pole motors) AND you have plenty of intake ventilation. In breezy parts of the country the "whirlybirds" are just as effective as power fans and don't require any power to operate.

By: Allison Bailes

Allison Bailes — Mon, 12 Sep 2011 14:44:56 +0000

Whole House Attic<
Whole House Attic: Solar powered attic ventilators have many of the same problems that grid-tied PAVs do. In addition, they're almost never cost-effective to install because the actual savings are so small. As I've said before, improving the building envelope is the way to go, not power attic ventilators, even if they're solar.

By: Whole House Attic Fan

Whole House Attic Fan — Mon, 12 Sep 2011 10:15:43 +0000
Well, I agree with you about
Well, I agree with you about the GA is America's leading state in the field of building science in home builders. It is good to follow the law and nowadays there are some good solar attic fans in the market. It is keeps the house cool and they are good as well.

By: Allison Bailes

Allison Bailes — Wed, 31 Aug 2011 19:05:36 +0000
Craig: <
Craig: Caveat emptor (Let the buyer beware) should be everyone's motto. The government, the Better Business Bureau, and the Chamber of Commerce aren't going to protect you. There are plenty of perfectly legal products installed or used improperly. One of the reasons I write this blog is to warn people about the bad stuff people are trying to sell them.

Mike M.: Since you sell power attic ventilators, I'm not surprised you think this new part of the energy code is a mistake. Building science is not on your side, however. PAVs are bad for homes. (Since your main product seems to be fans to ventilate crawl spaces, I guess you probably don't want to hear what I have to say about that.)

By: Mike Martin

Mike Martin — Wed, 31 Aug 2011 18:17:19 +0000

&

Attic venting Blog, 30 August, 2011

An associate suggested I respond to this discussion. I believe that the Georgia State Amendment to the Energy Conservation Code 2009 in regard to attic ventilation is a mistake and will be repealed on down the road. Relying on convection and solar powered vents will not serve the public good. Anyone that believes that heat gain and moisture retention in the attic is useful is mis-informed. My own attic is a case in point.

I built my house fourteen years ago. My house has a large attic with two gable end vents on either end. The first two summers I ignored the heat to the detriment of my shingles and items stored in attic. I installed static vents fifteen feet apart. While up on the roof, noticed the heat damage to my new shingles. The added static vents lowered the attic temperature and my cooling bills dropped nicely, I ignored it.

Ten years of consistent summer power bills incurred until I installed two power vents that I designed to stop ember entry for the West Coast market. I set them in my attic to test my design before sales to the public. My power bills have dropped an average of ten dollars per month. I am thinking of setting a third unit at the other gable end. These units run well into the evening removing unwanted heat, which a solar powered unit would not. My ceiling penetrations are sealed off from the attic, so I do not worry about extracting my conditioned air.

Centrally heated and cooled homes, with properly installed HVAC systems, should create a slight positive pressure in the conditioned space. So if the augment against a slight negative pressure in attic or crawlspace is that it will suck the conditioned air out, I would have to say, the positive pressure from within would have caused the very same problem anyway. It would seem that this problem with negative air pressure is more about poor construction techniques than heat and moisture removal.

The one saving grace to the new code for power attic vents is that it only applies only to new construction, as I read it. There will not be to many new homes built in the next ten years, so the damage will be limited and revisable. The best building science is one that works and does the least harm.

Sincerely,

Mike Martin

Licensed: Electrician, Plumber, and Real Estate Broker

Owner of: Vent the Crawl

Ventthecrawl.com

By: Craig

Craig — Sun, 28 Aug 2011 18:51:28 +0000
In Alabama and Florida we
In Alabama and Florida we have many companies that sell radiant barrier rolled on attic floors, solar attic fans, remote controlled supply register restrictors to reduce HVAC air in some rooms.... and the chamber of commerce, BBB, ...do nothing. There needs to be national consumer protection on energy, and building inspections done correctly for new and retrofit improvement or consumers will waste their money and it will take longer to get what works done. There is SRCC for solar thermal because of the huge number of bogus products and bad installs of solar water heaters in the 1980s before the SRCC. Please learn from the past.

By: Allison Bailes

Allison Bailes — Thu, 18 Aug 2011 23:42:02 +0000
Steve: I'd
Steve: I'd love to hear what they have to say, too. If you know any, send 'em over here to have their say.