I should know this, and intuitively it would seem that passive turbine air vents would be effective. However, I’m wondering if there is any hard data as to whether these actually help to lower attic temperatures. I’d also like to hear any anecdotal evidence from those who have them, as I’m thinking of installing them. At present, the house has eave vents and ridge vents.
I’ve seen them on commerical buildings, never on a house. Since they only do anything when the wind blows I can’t see how they’d add any advantage if you have roof and eave vents. Maybe they’ll even interfere with the airflow.
I’ve seen several episodes of Holmes on Homes or his other shows (my main source of building lore) where the turbine vents are mentioned, usually negatively. I assume you are talking about the “globe-on-a-pipe” vents; the globe is a series of vanes and the whole globe spins as air exits.
The problem is usually the installation. He often runs across them added after the fact. If it is installed near an ordinary vent on the roof, the result is it draws its air in from that vent rather than exhausting the hot air down by the ceiling area. The ideal is that there should be a flow from soffit vents to evenly spaced out high-up roof vents (turbine or other) so all the air in the attic circulates and exhausts, cooling and (if necessary) drying the attic.
They are not that uncommon on houses in Virginia at least. My house has two over a sunroom.
i think that soffit vents are needed to match the ridge vent to get adequate ventilation.
I have them on my house–they are very common on houses here (Texas) in my experience.
Not true. They spin from hot air in the attic escaping through them, so they will spin even with no outside wind.
However, I can’t really say how much they help. My attic still gets hot as hell in the summers, but then I have no eave vents.
That’s the point - unless the air can get in down low, you aren’t really venting anything worthwhile - probably going from one upper vent to the next. In cold weather (more of a concern up in Canada) this means that condensation will settle on the ceiling insulation, down into the insulation and pool on the vapour barrier and probably not get dried out.
If hot air is spinning them from the inside I can’t see them being more effective than simple eave vents and ridge or gable vents. Without an eave vent or some other inlet I don’t see them doing much in any circumstance.
Well, it was worth a shot. I thought about having a gable vent exhaust fan installed, but the usual mantra is that you should either have eave vents and ridge vents OR gable vents and ridge vents, but not all three.
I can see a gable vent and ridge vents. Not so much eave vents. And I could see an gable vent with an exhaust fan too.
Eave or soffit vents are common for proper attic ventilation. Only problem with an exhaust fan is that it also draws in more hot air from the ridge vents. I think I’ll just leave things as they are.
eave(soffit) vents are important to get hot air away from your ceiling (summer) and to keep the roof deck cold (winter) and to extract moisture. they can be plugged by debris, insects or insulation. it is important to have enough and that the air passage is open. you should have chutes or some method to not have insulation block the flow.
I miss the days of the attic fan bringing in the summer evening breeze.
that would likely be a whole house fan, which is different from attic ventilation.
you can get much the same action with windows and window fans. in a multistory put the fans in top story windows exhausting air. open lower story windows. if there are strong winds then you might do without the fans and partially close the upper story windows on upwind side.
I’m not sure if rising heat is enough to get the turbines spinning, but any quality turbine vent will spin easily with the slightest breeze. It’s rarely dead calm. OTOH, I have no idea how much hot air is actually removed by them. With all of the emphasis on energy efficiency, there are surely studies out there quantifying what if any good they do.
The proper method of ventilating includes nowadays installing cardboard channels that prevent the blown-in ceiling insulation from blocking air flow from the soffit vents to the attic. Since heat rises, the theory is that higher-up vents - turbine or simple covered vents - allow the hot air to escape, while the cooler air comes in the soffits from below. Excessive heat will bake the shingles from below, degrading them and lowering the lifespan. Poor circulation in cold moist climates will result in condensation, which without ventilation doesn’t evaporate. (Ditto I assume for bad insulation in an air-conditioned house - the warm attic humidity will condense on the uninsulated ceiling areas.) Of course, any holes in the ceiling vapor barrier allow moist warm air to escape, shingle leaks and condensation to drip into the house, etc.
Depends how the house is built. I can show you an older farm house that was designed to pull air up through the floor. As the hot air rose it pulled air through the crawl space. I was amazed at how cool it kept the house. There are modern versions that pull air through pipes imbedded in the ground. Never seen one but the potential is there to pull 56 degree air into the house by way of an attic heat pump.
This is how tunnels were ventilated before electric fans. They put a chimney near the entrance and then ran a pipe to the back of the tunnel. As the heated air went up it drew air from the pipe which in turn drew air from the front of the tunnel.
Remember when your bringing in straight outside air your also bringing in alot of humidity and often little bugs too small for the screen. Modern air conditioning systems do much better.
Some article on architecture I read once said the same about some middle-eastern structures. A tower-like structure sitting in the sun would heat up and created an air flow which drew a breeze through the rest of the building.
One of the most popular solutions now is to use continuous ridge venting. The idea is it allows even venting all along the roof rather than just at a few vents and encourages a direct flow of air from the soffits to the ridge. If the roof was not sheathed for continuous vent, an inch gap has to be cut either side of the ridge blocking. Standard practice is to block off gable vents and make sure soffit venting is sufficient. Modern aluminum vented soffit is good, solid soffit may need additional vents added. We use this on all the re-roofs we do (hail or fire restorations).
Inspectors have told me that the problem with wirlybirds is a strong wind can produce more negative pressure than soffit venting can make up for, resulting in moisture laden air being drawn into the attic from living space.