Just A Little Ventilation

With our Wagner Solar hot water system installation complete, none too soon, at home I move onto the next project.  Preparing for the insulation in the attic, which in fact will need very little preparation.  However, as I mentioned in previous posts, our house, built-in 1998 is just a little too tight to go without supplemental ventilation.  AHRAE recommends  a whole house air change rate of .35 per hour.  Currently, due to the conventional construction of my home, we have an air change rate of .30 – slightly too little.

For new homes, generally built much tighter, the ambient air change rate is much lower, thus demanding a mechanical ventilation system such as an HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator.)  These systems suck out stale air through a hose that is intertwined around another hose that is pumping in fresh air at a slow controlled rate.  The warm stale air preheats the cold fresh air as it enters.  In new construction, the installation of an HRV is simple and cost-effective, but in an existing home it is not.  The quotes I have received ranged from $2000 to $2500, plus the cost of the HRV.  Piping hoses through finished walls and joists is just plain time-consuming and expensive.  In order to pump out a mere 90 cubic feet of air per minute, the amount my house requires, the cost is two high.  (Note: older, conventionally built homes generally leak 2 to 3 times this amount without a ventilation system.)

The solution for this problem in my home is simple:  today I installed two Panasonic Whisper Green whole house  / bathroom ventilation fans.  I chose the Panasonic Whisper Green for a number of reasons, but the most important being its energy efficiency.  While other ventilation fans such as Broan and NuTone consume 40 watts of energy at the same exhaust rate, the Whisper Green uses a maximum of 11.1 watts.  On top of that, the entire Whisper series of fans are the quietest on the market at .3 sones or less, and the DC motor is sure to double the life of the system, paying back yet another way.

So, for our house we placed one 80 CFM Whisper Green in the bathroom in the center of the second floor and one in the utility room / bathroom just off the kitchen.  When we are sleeping we will run the upstairs system continuously, while during the daytime hours of occupancy and cooking we will run the downstairs system.  Controls will be installed next week that will allow us to preset the hours of operation while also permitting the switch to override the settings when the bathrooms are used for showering and other needs.  The only drawback to this plan is that these systems will only draw unhealthy air out; they won’t draw fresh air in.  We’ll just have to use that “old-time” technique of cracking a window now and then to completely change the air.  It’s not the perfect answer, but there is no other affordable answer to this imperfectly built house.

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