As a licensed Florida Home Inspector, and one who has inspected more then a few homes in The Villages, I will tell you that everything I have read and studied state that Solar powered vents are a bad idea. I know there are companies out there that will tell you different, but one must ask if their info is designed more to make a sale, or is it based on current industry studies.

A typical Attic is designed to pull cooler air passively from the soffits up through either a ridge vent or non-powered roof vents placed close to the ridge. This natural convection works well as long as you have the proper amount of ventilation.

When you install a powered vent, it will take air from the least resistance. This usually is from the already installed ridge vent....thus "short circuiting" the natural convection from the soffits and leaving much of the attic with less air movement.

Worse, sometimes they can produce negative pressure from openings in the living space ceiling and draw CONDITIONED air from the interior of the house into the attic....costing you money. Now this would not happen if you had a completely sealed ceiling, but I have YET to see one. If your ceiling was totally sealed and well insulated, you would then not care about attic temps.

This negative pressure could also cause backdrafting from a water heater and put carbon monoxide into the house.

Studies have shown that powered ventilation may lower the temps up by the ridge by about 10 degrees, but the temps right above the insulation show a drop of less then 5 degrees.

David Butler, author of Optimal Building Systems states that putting the pressure imbalance issue aside, there is simply not a good payback. Let's say one spends around $400/year on A/C. (I know that is low for around here, but bear with me). Ceiling loads typically represent 10 to 25 percent of your cooling costs....which would then be between $25-$100 dollars. It's a well known fact that radiant gain from the roof makes up well over half of the ceiling load, (that is why many folks feel radiant barriers are a good idea in our climate). If you assume a 50% figure, and the difference between your interior temp (let's say 77 degrees) and your lower attic temp drops from let's say 120 degrees to 115 degrees, giving you a delta t of 38 degrees instead of 43 degrees, or about 12%, (given on a 100 degree outdoor temp), cooler days it would be even less. Even if you make the most optimistic assumptions, your savings would come out to be between about $3.00 to $12.00 a year.

When factoring in the short cycling of the air, potential of backdraft, the possibility of drawing in CONDITIONED air into the attic, making another opening in your roof that might leak someday, very low if any payback, my suggestion is to invest your money elsewhere.

This is not just my opinion. Many agencies, like the Florida Solar Energy Center, as well as the American Society of Home Inspectors, etc say basically the same thing.

I apologize for the long post. My only intent is to help by giving some industry info on the subject.

Respectfully, Frank

FRANK............where the heck have ya been, man?

Bill :)

Solar Tubes
 

I think many of us look at homes and for some reason they seem lighter and brighter? Maybe its out positive energy and enthusiasm to move to TV.

Our house once we were in it for a day or so the wife looked at me and said, Were living in a cave! It is to dark in here.

Were thinking up to 3 -4 Solar tubes.

No tax credit for them but a tax credit on the radiant barrier and solar fans.

In Attics! LOL

Agree

Not saying you're wrong just want to understand, there is more sq" of ventilation area in the soffits than the ridge vents, I think you agree.
Therefore, the least resistance in not the ridge but the soffit, does that make sense?

But those openings would have to have less resistance than then the ridge or soffit I would think.

That's a stretch, how about using the right size not oversized fan in the first place. Moreover, with that theory those same fumes would exhaust out thu the attic.

Can you please point me to those?

Frank, understand I think the radiant barriers are my first choice, my second choice is to seal all the duct work in the attic, than a fan if that doesn't cut it.

Great to have a professional contribute but some of us like to dig deep into silly things like this :highfive:

Dear Jimbo,
I understand what you are saying.....I do not disagree, but I think that even though there is more sq ft of sofitt perhaps, there may still be less resistance from the closer ridge vents is some cases.

As to the backdraft situation, it has actually happened and is not too much of a stretch. I've inspected many homes where just having the bath vents and exterior exhausting range hood going caused a backdraft situation on a gas water heater or furnace. You could actually see it fogging a mirror when held next to the draft vent of the heater. With homes being tighter now it happens easier then when homes were more drafty.

As you asked, here are some interesting articles on the subject of not using powered attic ventilators.....

Home Energy Magazine :: Drawbacks Of Powered Attic Ventilators
Advanced Energy
http://tinyurl.com/66qq8jv

Hope you enjoy them, they are interesting.

BTW, I think the solar tubes are great in some homes, as long as they are quality ones and installed properly so as to not cause a roof leak.

Respectfully, Frank

Installation
 

Frank- I love you man! :D

D0 you think the Solar Guys are a quality product and just to summarize as I do not understand all teh psts, is a solar fan a goo or bad idea? Just basic language for me please.

Frank says no Carguys says yes, I think yes, but the first thing to install is a radiant barrier in the attic, if not satisfied then the fan.

But if I install a fan it will be ducted down near the attic floor to mitigate any short cycling.

My understanding is a cooler attic is a cooler house? No one is hanging out in their attics so I am just trying to ascertain the exact reason to put anything in the attic to keep it cool, aside from obvious reasons to keep air circulating to maintain the things you keep up there? I am getting a little lost on this discussion and I scored 15/100 on mechanical reason so I am struggling with all this.

Jane,
Mine is only one opinion, and I certainly do not intend to criticize any other business here. To answer your question, yes, I do think their solar tubes are a quality product. If I were having one installed by someone, I think I would strongly consider them, as they do a lot of work here, and I would assume they would stand by their work.

I have seen too many times when someone hires a fly by night, unlicensed, uninsured contractor who does substandard work and by the time problems show, they are long gone. Doing business with a company that has strong roots in the area is almost always a good idea.

My personal home faces 115 degrees southeast and has a floorplan that seems to lend itself to having bright, open rooms. I have neighbors whose homes seem to just be dark......then they have solar tubes installed and they look great and change the whole look of the house. I like solar tubes MUCH better then regular skylights, which can be prone to their own set of problems.

So to answer your question, my personal opinion is Solar Tubes can be a nice addition to homes that have dark rooms. They should be installed properly by trained people to minimize the chance of a roof leak.

I personally would NOT buy solar powered vent fans for my home for the reasons stated in my earlier posts.

I hope that helps.

Respectfully, Frank

The attic can get very hot, 120-maybe 160 degrees.

That heat is what you want to lower with the items already mentioned.

If you don't you will use more energy $$$ cooling

So yes "your understanding is a cooler attic is a cooler house"

Thank you. We face SW, we get nice light in our home but there are certain spots like bathrooms and a hallway with no windows that only have electric lights. I also things a few other places could use some mroe natural light. I like a happy environment and sunshine to me and natural light is happy. Thank you all for your explanations.

Sorry to throw a monkey wrench into this topic but no one mentioned roof color.

If you have white or a lite color you beat out fans and radiant barriers

read more from Fl solar energy.

Yes, a cooler attic is a cooler house. Even with all the insulation mentioned in previous posts, the attic heat (as much as 150 degrees or so) will transfer down the studs into the walls, so less heat is less transfer. The answers can be simple but a lot depends on the type roof you have (hip or gable). I have on my house and believe in the powered attic fan (or gable fan as appropriate) and think the solar fan does not have enough power to pull enough air out, especially if you have ridge vents. My fan is both manual and automatic so I can control it. I have also sealed my roof with white elastomeric sealant and that alone has reduced the temps by at least 20 degrees on the hottest of days. The roof fans, solar or powered, will not work as well if you have the ridge vents for the reasons posted. Absent the roof ridge vent, they will pull from just the soffits and produce better air flow if the proper cfm (cubic feet of air movement) is obtained. Back in the 50's or so, most Florida houses had white roofs when there was no air conditioning. I know as I grew up in Florida then. It was the standard. Apologies if this has added to the confusion!

Well I gambled and went with the 22 inch solar attic fan and put in five solar tubes, two in the Master bath, one in the guest bath, one in the laundry and one in the kitchen. One day I will let you know how it all works. We have a red roof. i appreciate all the input, it is all so interesting, the diversity of opinion. I like the idea of solar and was at a house party for Canada Day in Seattle that was solar powered. It swayed me to try it. If it does not work I will re-read all these posts and try another idea!

So with a light colored roof, you benefit more than the barriers and fans can provide with a darker roof? What about a light roof AND the barrier/fan combo? Sure seems like that would be the best of all.
Don

garage solar fan???
 

I'll start off by saying this is our first summer in The Villages, and to thank every one for the info here, and that we are loving it!
My problem is the hot garage, I like spending time out there, my man cave and all.
I have talked to two contractors and got two choices.
One, vent the bottem of the garage doors, and install a power vent in the garage ceiling, pulling the warm air from the garage into the attic. Cost about $525. This work would be covered under the permit we have in effect from the solar light they just installed. By the way the solar light is great!
The other option is a solar powered vent with a duct pulling the warm air from the garage to the atmosphere. Cost about $900 plus another $65 for another permit.
Any opinions??
Frank, I would realy like your input.

I believe the air in the attic is hotter than in the garage. Why not just open the garage door and install a ceiling fan?

Maybe against the building code to exhaust ait into attic, but you can use a small duct thru roof, then cut vents into bottom of door for intake or just open it.

The air near the bottom of the door should be cooler than the top.

installed garage vent
 

Well, they convinced me to go with the door vents and power vent in garage ceiling. Installed today. They claim this unit will actually keep the attic cooler as well as the garage. I can stand in front of the door vents and feel a good bit of draft. I will post my opinion of the results.

Is the fan going into the attic or thru the roof

My neighbor had the garage ceiling attic fan installed along with garage door vents, he paid $300 and gave me the guys card and said he has done many. Instead I just had the horizontal screen door sliders installed for $850 on my 12' garage door, I figured that would be even better yet. Also, my wife is out there a lot since the W/D is in the garage.

If you're going to be working in the garage why have the door down, this way it's the same temperature as outside and I don't have to worry about bugs, snakes or gators. I had one neighbor already find a rattlesnake in his garage. I also leave the attic stairs pulled down about a foot and I can feel a good breeze going through. Since this has happened we have raised our inside thermostat a degree.

We had a home energy audit by SECO. The inspector said that attic fans can help lower the attic temperature but from a $ savings perspective, they are not worth the investment. That is, it does not save you much on your electric bill nor does it prolong the life of the roof. His recommendation was to prop the access door to the attic open and leave the garage door open a few inches and let the natural thermal circulation do its job.

I can't give you any facts but we chose not to get the fans.

A 1500 cfm fan cost about $150 a year to run. Based on $0.125 per kWh, forgot what our rate is, so that may be +-

I think the offset in AC costs should offset that, but beyond that the garage is now a improved living/work space.

If the fan was solar the payback is 3-4 years then free.

How does that work for keeping pests out, it don't.

.

Had the roof replaced this week on our 4 year old home (owens corning issue) and the roofers said we had more than enough ventilation with our ridge vents. So since we have nothing in the attic and I was ecstatic with our last electric bill I'm not sure what all that extra stuff would accomplish. I think you need to be careful here that you don't get sucked into the latest and greatest. If you think something might be a good idea give yourself some time to think about it, the cost, and the return on your investment. I am new here (6+ weeks now) but when I walk my neighborhood I am amazed how you will find a group of homes with some "extra stuff" added on. Think it is a situation of "oh my, that looks like a good idea" not so much do I really need that???

Solar Star Solar Attic Fans Work
 

It is a shame you do not believe the solar fans worked on your home. I know for a fact that the Solar Star solar attic fans by Solatube work on my home, as well as on my garage. As for the home inspector, I have talked to numerous inspectors that support the use of attic fans. Solar powered simply make more sense financially than electric ones, not to mention that the Solar Star fans are absolutely whisper quiet. That is a win-win for me and my family.

Just saying from my personal experiences.

Please forgive me for my late response.
The main reason for me not endorsing a powered attic vent fan is the possibility of "short cycling".
The topic of ventilation is as you can read here is complex. Things are not always cut and dry. Sometimes when you do something in your home for one reason, albeit good, it can compromise other systems.

For instance, installing a vent on the bottom of your garage door and opening the attic hatch a bit WILL allow cooler air to be drawn up into the attic, thus having a cooling affect.....but does this have any negative consequences? I would have to say yes, in that it could very well compromise wind mitigation ratings, as this could cause negative pressure during a hurricane, thus compromising the hurricane rating of the garage door. Opening the garage door is an option, but then as stated pests can get in. I"ve noticed some folks in my neighborhood have screened in garages where they keep the screen door closed and keep the garage door up a bit. They may also keep their garage walk in door open allowing airflow in the home...I do not know.

Sometimes things are gray, and not black and white. My own home has vents installed on the plywood part of the attic stairs. If I had a fire in my garage, this would clearly be the first area where the fire could reach the attic. It would clearly negate the fire rating of the drywall ceiling.....but then again, so does the thin 1/4" plywood door of the attic stair. Yes, they do make fire rated attic stairs, but you hardly see them, as they are much more costly.

Opening a garage window a bit and "cracking" the attic hatch would cause more cool air to get to the attic....would it make that much difference? I do not know. I do know that when I open my attic steps and climb up when the garage door is open I DO feel cool air rushing up into the attic, but really, I have to assume that this is constantly happening by the soffits, but I cannot easily stand by them to see.

Folks can and will debate this topic forever....but suffice to say that your roof is designed to continuously have cool air drawn into the attic thru the soffits, and have hot air continually expelled through the ridge vent. It would not keep me up at night.

Now if you really want to confuse the issue, you can throw into the conversation the concept of complete insulated encapsulated foamed attic systems where NO venting is the norm and all of the insulation is foamed onto the bottom of the roof decking.....

(Sorry, I could not resist....)

Respectfully, Frank

I AGREE with tambo 100. We have a 1500 sq. ft. cottage home with a solar attic fan & a dehumidistat (set@60 for humidity & 85 for air). Electric bill was $24.02 last mo. & $21.13 the mo. prior!!!!!! We are snow birds.