Build Tight, Ventilate Right
New home builders are concerned with air sealing to create a “tight” building and they want to maximize both energy efficiency and indoor air quality. The accepted findings of the building science community are that is not possible to build a home too airtight for energy efficiency but that ventilation options must be considered.
A home insulated with Icynene spray foam insulation will typically experience an exchange of air every 5 to 10 hours which can be contrasted to an existing home’s (over 20 years old) exchange every 90 minutes. The reduction in energy load requirement and the increase in comfort and indoor air quality, with the improvement in air tightness are significant.
The option of leaving the house leaky is not viable, as the primary ingress points are the attic and basement or crawlspace – not very conducive to indoor air quality.
The right way to proceed is to ensure that your ventilation options of high energy exhaust fans in the bathrooms or supply ventilation using a duct from the from the return plenum of the air conditioner to a gable end of the house or the recommended method of balanced ventilation using either an ERV or HRV unit.
More information on all of these options can be found in the white paper “ Proper Design of HVAC Systems for Spray Foam Homes” Huntsman – a report written by Doug Garrett, CEM ACCA Certified instructor.