Posts Tagged ‘ventilation’

Cutting edge science! Circa 1891

January 23, 2014

Dr smithThis time of year our homes are often closed up tight and we can get a little stir crazy by it.

Dr. Smith, pictured in the print, subjected himself to this voluntarily, we find out in a text book on ventilation printed in 1891.  His little home was made of lead and the window was there so he could break out if no one would let him out. A more trustworthy assistant would have been nice.

The door was weather stripped with an India rubber tube.  Funny how over 100 years later we still could use doors on our homes that work as well as his did!

Well Dr. Smith discovered that fairly quickly the room got unpleasant and moist.   He lasted for 100 minutes and then “three persons then went in and at once, pronounced the air to be very bad.”  Not sure this counts as science, but it works for me.  If it smells bad it is bad.  Good enough.

Ironically even today there are ongoing arguments about how much ventilation is needed but we need it.  I’ve written about controlling the airways and it’s a good idea to have your ventilation strategies worked out too.  Expert advice is only a call away.  Don’t worry at GreenHomes America, we don’t use lead rooms and emergency glass.



image comes from a google book in the public domain

Worse than Burning the Bird

November 20, 2013

There are plenty of things to consider for Thanksgiving, like making sure you  thaw out the bird properly, and cook it at the right temperatures.  And some guests may have food allergies as well so it’s always good to ask.


Food aside, there are other concerns, and ventilation is an important one. People need it and so do homes.  Over the holidays it can get stuffy with so many people visiting, but if your home is that way without guests, you suffer from high humidity or poor air quality, maybe it’s time to do something about it.   An assessment is a good place to start.  It’s nice to have ventilation systems in place all the time not just for the holidays.

One specific kind of ventilation, exhaust fans in kitchens, help us by removing smoke and odors, and especially if you’re cooking with gas, carbon monoxide.  While it’s not smart to use a grill inside, most people forget that their gas stove is a source for Carbon Monoxide; cooking a turkey in a hot stove for hours without exhausting the kitchen could put your family at risk for CO poisoning, and that is worse than burning the bird!





Where do you grow your mold, the bathroom or the attic?

February 11, 2013

Sometimes it’s the simple things that can be done to make your home a healthier and safer one.   Bath fans help move a great deal of moisture out of the room and are a really good idea.  But where the moisture goes next is just as important.


Not quite far enough


A ten minute shower can use 16 gallons of water or more, and generate a great deal of steam.    It’s not good to leave all that moisture to accumulate on the walls and ceiling in a small room since it can lead to odors as well as mold growth.

So we fire up the fan and it hums away pulling moisture out of the room to…..the attic?  It seems pretty simple, but  it needs to go to the outside.  Often vents end up in the attic or even worse, buried in insulation or a wall and stop there.   Every exhaust fan in a home needs to vent to the outside.

Maybe your mirror won’t fog up if it vents to the attic, but moisture will build up elsewhere.  Rotting out the roof or growing mold in the attic isn’t any better!    Ice dams and roof damage should not be part of your ventilation strategy!

Bath fans can help the whole house too, and I’ve written about it in the past in taking control of the airways.  Ventilation is important in our homes, make sure excess moisture gets outside!



Taking Control of the “Airways”

July 11, 2011

If you have been following along recently you know the benefit of bath fans in doing more than clearing the mirror when it gets steamy,  or other mundane but useful tasks.  They can be a good way to move a little air, in our homes something we can really use. 

We need fresh air and a fan pushing out helps to draw some in from some of the leaks in the building.  But we want some control and that’s why we always stress air sealing in conjunction with proper ventilation.  When we rely on “natural ventilation” in a home we are really relying on random, often inadequate or excessive leaks to provide us with fresh air, sometimes not from fresh places, good air-sealing and a bath fan is a great start at taking control.

There are better options still.  Heat Recovery Ventilators (HRV’s) and Energy Recovery Ventilators (ERV’s) are both devices that supply fresh filtered air to your home and exhaust the stale air which can contain pollutants.  Bath fans don’t quite do that.  

These units exchange air while recovering some of the energy from the exhaust air on its way out.   In the winter that saves some of the heat from exiting the building and they can cool the air coming in warmer weather.  ERV’s have the added benefit of transferring moisture and so they can reduce the excessive dryness that can occur in winter and reduce the demands on your AC system in the hotter months, because of this ERV’s are often recommended when humidity extremes are a year round problem.

When drafts in a home are really reduced, these ventilation systems start making a lot of sense.   With the types of controls available, they can be calibrated to help your home run like a fine tuned machine, making it a much more comfortable and healthier place to be.  Not everyone wants to micro-manage the airways though rest assured that the controls that run them are easily set up to handle it all for you.

HRV’s and ERV’s aren’t for everyone and for many the superhero bath fan is enough (and lest I confuse you, we’ve had some applications for Pansonic’s FV-04VE1, a spot ERV bath fan).  Retrofitting these systems may not be the easiest thing to do but it’s worth investigating.

You ought to have a well insulated and air sealed home to start with, a real high performer if you will.  This is one reason it is still good to have an energy assessment even with what seems to be a well put together home.  Discovering what kind of ventilation you need with an energy advisor can get you started down the road to commanding the air (at least at home).

Image from

The Secret lives of bath fans: part II

July 6, 2011

Many of us think of our homes as a safe haven where we can breathe easy, but that is not always the case.  Sometimes it is stuff outside our homes we want to keep out and sometimes its inside with us and we need to get it out!  That’s why it’s always good to tighten up a home and ventilate it right. 

In last week’s post I wrote about the importance of bath fans for moisture and spot ventilation, and touched on a larger task that they can accomplish.  This is the secret life they can lead; it is subtle but a super hero task none the less and really shouldn’t be a secret at all.  All homes should have ventilation and for many a bath fan is a good place to start, particularly in cold climates.   

Attached garages, spaces where we store the car and lawn mower, paints and chemicals and basements and crawlspaces the all too often damp musty underbelly of the home can be a problem.   Keep chemicals under the sink? How about in the bathroom?    Just because they are “household” cleaners doesn’t mean they are good to breathe in.  In cold and mixed climates, an exhaust fan such as one in a bath room calibrated to provide the right amount of ventilation for a home can help to reduce our exposure to these contaminants.   Even if you’re in a hot-humid climate like Houston, bath fans make sense.  In this case, you don’t want to use the fan as a whole-house ventilation aid, but as mentioned in my last post, removing that hot and humid air from the shower, keeps your house more comfortable when you’re trying to keep cool.  I will get into energy-recovery ventilators in a future post!

But the point is this:  Builders start sounding like old wives with tales to tell when they talk of homes being too tight. There is no such thing as too tight. Having the right amount of air exchange for a home is a really good thing and there is a balance point between energy efficiency, and indoor health.  A very leaky home is a very inefficient home—and do you really want your supply of “fresh” outdoor air to be coming through leaks in your attic or crawlspace?   Relying on leaks means you’ll often have too much air-exchange when you don’t want it (e.g., when it’s cold), and not enough exchange when do (e.g., a nice Spring evening or Fall afternoon).   That said an unventilated home may also be an unhealthy one.  The mantra really should be “build it tight, ventilate right”.  Consider an energy assessment from a BPI accredited company, one that looks at the whole house.  The secret’s out, the first step to a healthy home may be a bath fan away. 


The secret lives of bath fans

June 28, 2011

90% of your time may be spent indoors.  Not in a bathroom I hope, but indoors for sure.    

Most of us understand some of the benefits of having a good fan in the bathroom.   I’ll just say it, odor is one.  So is moisture, but it goes beyond avoiding foggy mirrors after a shower.  That much moisture in a home shouldn’t stick around for a number of reasons.  Mold is a big one.   (The kitchen is another place where moisture adds up and should be exhausted.)  The moisture needs to be pushed outside of building , there’s no sense of just moving it to the attic to cause problems there.

Too often, the cheapo fan, a.k.a. rattle boxes or noise makers, can certainly be heard but don’t really move much air.  And some older fans draw a lot of electricity even while they’re not helping much.  Every home assessment we do includes health and safety testing for carbon monoxide, for example.  We also determine if there is adequate ventilation for the home.  I’m often asked why after tightening up a home we would recommend running a fan, essentially make it leakier—it has to do with indoor air quality something I’ve talked about lately.  I’ll touch on that next week. 

Exhaust fans like those from Panasonic  or Renewaire can take care of more than spot ventilation.  In cold or dry climates, they can help make the whole house better.  If you don’t have a bath fan yet maybe it is time make it part of your healthier home.  Consider having your house assessed by a BPI accredited company.  Our certified advisors can help determine how safe your home is and what kind of ventilation you need.  You never can tell what secrets may hide right under your nose.

 photo from


Vent those bath fans to the outside–NOT into the attic

July 25, 2010

One of the things we look at in homes is the ventilation.  I’ll write more about that in the coming months.  The short version is that good ventilation is necessary to protect your health and your home.

Wait! You say.  Aren’t you making my home tighter with all that air-sealing?  But I need ventilation to bring air in? 

Yes, that’s exactly what we’re trying to do.  In my view, the perfect home would be perfectly tight, with no “natural” exchange of air—but allow you to determine both the rate of air-exchange, and where an how it comes from.  But we’ll save that for another day.  Right now, I’m going to focus on the bathroom—in part because GreenHomes Advisor John Scipione just found another doozy, this one in Fresno, CA.

Bathroom ventilation is particularly important to remove excess moisture (and heat in the summer).  Pulling out this moisture at its source helps prevent the mold and mildew from growing, and that a good thing.

Most of the bathrooms we see have poor ventilation, either no fans or cheap rattle traps which make a lot of noise but don’t move much air.  Adding a well-functioning exhaust is something I highly recommend.

I’ve talked before (maybe putting the cart before the horse?) about the Panasonic and Renewaire bath fans that I like.  Excellent choices.   And keep making good choices by exhausting the air directly to the outside via ducts, and not just into an attic or some other space in the house.  If your contractor says it’s OK to vent into the attic, the best solution may be to find a new contractor.   Dumping moist bathroom air into the attic can help rot your roof.  And remember those ice dams we’ve talked about?  In snow country, exhausting your bath fan into the attic—with all that warm air—is a recipe for ice dams (and more on ice dams).  Don’t do it!

Three bathroom fans exhausting into an attic

Please don't exhaust your bathroom fans into the attic!

Which brings me back to what John found in Fresno.  Exhausting one bath fan into the attic is bad enough.  How about three?  And if you’re going to do three, why not tie them together to concentrate the problem?  At least the installed helped with a well-organized bad practice.  Don’t do it!  Vent to the outside.


Renewaire’s new bath fan is a winner!

September 11, 2009

As mentioned previously, Renewaire has a new line of bath fans.  As promised, I’ve installed one in my own home, and the preliminary results are in.  The fan is a winner.  Solid performer.  While I obviously don’t have longevity data on it yet, this is a fan I wouldn’t hesitate to recommend or install for our clients.  The one is definitely worth checking out.


Renewaire’s new bathroom fan line

September 2, 2009
Renewarie's New Bath Fan Line

Renewarie's New Bath Fan Line

Back in July, I mentioned my preference for the Panasonic bath fans.  Well, Renewaire, a company out of Madison, Wisconsin, has introduced a very promising line.  I just got a demonstration model.  The specs are every bit as good as the Panasonic, with  lower (better!) sone and watt ratings.  At first glance, it appears well built and good attention to detail.  I’ll install it by this weekend, and we’ll see how she blows.  Based on initial impressions, though, this looks like a worthy alternative to the Panasonic.


%d bloggers like this: