Affect of unvented attic during lengthy power outage following a hurricane
Hello! I have lived in Central Florida four years and have already “stared down” three major hurricanes and survived being in the path of Irma’s eye.
With Irma we lost power for three very hot and humid days, and some of our friends were without power for three weeks.
We know the chance of having an extended power outage during hurricane season is possible, and my husband and I are trying to address two concerns, one is a longterm priority of energy savings as our average monthly electricity cost is $321. The other concern in the short term is hurricane season is approaching and we hope to update and improve the overall feel of our home when we are without power should we ever have another Hurricane Irma type of scenario happen again.
We have a 17 year-old house with cellulose insulation, and we plan to grow old in this house. My husband got a nice bonus at the beginning of the year that we have been saving and we’re thinking about having a contractor vaccuum up the cellulose and insulating our 2300 sq. foot one-story home with open cell foam.
Our A/C unit is also 17 years old and we will eventually replace it with a 2-speed heat pump which we already have current bids on.
Not being building science experts but having read many white papers on the topic over the years, we think this is the way to go.
However, the concern of possibly not having power to run our A/C after a hurricane due to a power outage has us concerned about that overall feel of the home when we are unable to run our A/C and the air is very hot and humid with no breeze for several days after a hurricane.
Irma was just awful and we hope to have a little more comfort by addressing our current 140 degree temperature in our attic.
Does anyone have any experience with living in an unconditioned house with an open cell foam attic during a power outage?
Which situation would give the best comfort during an extended power outage when the attic space is unconditioned, a vented attic with a solar fan and radiant barrier which would be also insulated with new cellulose or with rockwool, or the unconditioned house with an unvented cell foam and unconditioned attic?
Thank you in advance for your opinions and expertise.
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Replies
I think you want to pick door number 3: get a backup generator so that you can run your AC during a power outage. If you have natural gas available, and if it’s been reliable in past hurricanes and utility outages, then use that to fuel your generator. If you don’t have natural gas available, or if your natural gas service isn’t reliable after hurricanes, then use a diesel generator. Don’t use gasoline, it can’t be stored for long periods and it’s much less safe to deal with than diesel fuel. With a properly sized, permanently installed backup generator with an automatic transfer switch, you won’t have to worry about power outages anymore. Note that I’m not a fan of the generac units, especially if you need to run them for long periods, or with heavy load (like an AC unit), or in very hot conditions. There are much better backup generator options out there, and a big part of my work is consulting on these commercially (usually much larger units than you’d use at home though :-)
Your electric bill seems high to me. I suspect you’re running your AC a lot in Florida, so the more efficient higher SEER units will be worth it. I would prioritize this upgrade.
Do you have any ductwork in your attic? If you do, then converting the attic to conditioned space would probably be beneficial. If you don’t have any ductwork in your attic, then I’d continue to insulate with cellulose, but I’d consider vacuuming the old stuff out, doing a thorough job of air sealing, and then putting in new blown cellulose to higher than code minimum levels. Radiant barriers can be helpful IFF they are installed correctly. Don’t expect magical energy savings or spectacular insulating performance though. Radiant barriers are just another tool in the insulation toolbox, despite the amazing claims you sometimes hear about them.
To answer your original question, I don’t think there would be a significant difference between the two attic insulation types in a power outage situation, all other things being equal.
Bill
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