Posts Tagged ‘ERV’

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

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

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