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Need more NFVA for a whole house fan

GCirelli | Posted in Energy Efficiency and Durability on

Hello, I own a 1939 1.5 storey house in Newport, VT, and my structural engineer told me that the (original) gable vents in my small attic weren’t big enough to support a whole house fan.  I would very much like to add one because it can get very hot in the upstairs .5 storey bedrooms in the afternoons and evenings and I do not want to add central air conditioning.

The attic is insulated with pink sheet insulation both on the underside of the roof and the floor of the attic.  There are currently no moisture problems.

How does one add more vents that will not destroy the current look of the house, and what kind of professional should I approach with this question?

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  1. Expert Member
    Dana Dorsett | | #1

    Making holes in the ceiling into a mini-attic to make use of a whole house fan & nighttime ventilation strategy may not be the best approach in a VT location. Opening up more paths to the conditioned space might create moisture problems where none were apparent previously, and add to stack effect driven infiltration increasing the heat load on the house. (Let's not steal a defeat from the jaws of victory here.)

    Is most of the heat gain through the ceiling, the windows, the gable end walls, or the kneewalls? A pistol grip infra-red thermometer and some temperature readings might provide hints as to ways to mitigate against unwanted heat gain.

    What is the "pink sheet insulation", and R-values?

    A half ton window AC unit is more than enough to keep up with the cooling loads of most bedrooms in VT, but perhaps that has been ruled out too?

  2. GCirelli | | #2

    I'm sorry, words failed me when I wrote the post. It is pink batting insulation in between the rafters. I am unsure of what the R-value is -- it was put in by the PO in 2000.

    I would prefer not to make holes in the roof, so I guess my real question is, can I make more gable vents to look like the ones that are already there? Would that be enough? Would it be problematic in cold weather? On the northern end of my attic, the chimney goes through so it is tight over there.

    The attic runs north-south, house is about 1300 sq ft but also with an east-west section with no accessible attic. The house faces west, so I am doing my best to close up shades/windows as the sun goes over. It's just the upstairs that gets really hot.

    I am currently using a portable AC so I can move it around to whatever room I'm in, and it's ok, but I'd rather not be tied to it so much. I really do not want any window AC units.

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