Since 1991 in Washington State, some means of bringing fresh air into the home has been required by the Washington State Energy Code. This requirement is for new construction as well as significant remodels. So, as an inspector, I am always looking for these systems.
On remodels it is common to find these systems missing. When they are missing it is one of the indications that work was done without proper permits.
When they are missing in new construction it is usually because someone forgot to install the timer and simply installed a regular toggle switch to operate the fan. Obviously if this is the case it is not a difficult repair.
There are several means of meeting the requirements of the code and the simplest of these is accomplished by installing a timer-control on a Bathroom exhaust fan or the Laundry exhaust fan. Other approaches involve being integrated with the heating system ductwork. Sometimes it is done by means of a Heat Recovery Ventilator (HRV).
These systems don’t just exhaust the air, they also require locations for bringing fresh air into the home when the fan is operated. With no means of providing air to the home, the home would be placed under negative pressure and air would or could then be pulled into the space from less than desirable locations. Sometimes this means down chimneys and the vents of other fuel burning appliances. Some jurisdictions used to allow for leakage around doors and windows to be the source of this make-up air. Obviously not the best solution to the problem.
The other thing to keep in mind is that when any exhaust fan is operating (kitchen, bathroom, dryer etc) make-up air must be provided. The lack of adequate air intake when exhaust fans are running is often evidenced by dark “ghosting” at carpeting around exterior walls of the home or by “ghosting” at poorly fitted exterior doors and windows. It can cause smoke to be drawn into the home from fireplaces and it can be related to back-drafting of gas appliances like water heaters.
Fresh air intakes are a REALLY good idea–and will help your home have balanced air pressure–neither negative pressure or positive pressure. Balanced air pressure within the home is good for avoiding moist air from either being drawn into walls from the exterior or driven into walls from the interior. In energy efficient homes these considerations become more critical. In old drafty homes it is done more or less automatically–along with emptying your wallet and supporting the oil barons.
Some windows (like the one in the picture at the beginning of this post) come with little vents in the windows that can be opened to allow air to enter the home–or even leave the home if for some reason a positive pressure was created. Most home buyers have no clue what these things are–if they noticed them at all. During the inspection they are almost always closed–consistent with the homeowner not knowing what they are or what they are for .
On a recent inspection I found another common type of air intake.
When this type is installed the inspector will usually find one in each room of the home. This ensures that fresh air will be drawn into all areas of the home when the exhaust fans in the home are operated. These are mounted on the wall and have a screened cap at the exterior. These screens must be maintained free of debris and easily clog with lint because they will act as a filter for the air moving through them.
Sometimes they suffer from house painters that also have no clue what they are for.
This one, in brand new construction, will need to be replaced due to being heavily painted.
By Charles Buell, Real Estate Inspections in Seattle
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Hi I just read this article. We are in DFW area in Texas. This summer we had Lifebreath ERVs put into our home with hopes of exchanging the air and make are indoor air quality better. Our concern was increasing humidity levels in our home and had conversations with contractor prior to agreeing to do this. We spent over $5000 for this system (we have 3 a/c) and our humidity levels have increased to the point we have problems sleeping its stagnant and humid air. Any suggestions?
I have never seen the window air inlet. In our harsh Minnesota climate air exchange systems have been mandatory since we started building tighter, more efficient homes. We struggled with water intrusion around the windows, especially in our stucco homes.
Older homes naturally leaked and never had the problems that were discovered in our better built homes.
Your discussion points out the importance of understanding regional impact of different climates.