A while back we installed radiant heat barrier in our attic. After the first test month, it was positive that it was making a significant impact on our electricity usage, but, with differences in the average daily temperature (it was hotter and summer was longer this year than last) it’s tough to make a definitive assessment.
The company that sold us the barrier guaranteed a 30% reduction in energy used for heating/cooling. Like all such guarantees, that’s a really tough on to prove, and it’s based on a rather imprecise measure. “Energy used for heating/cooling†is based on a federal government estimate of the total percentage of household energy usage. In other words, the 30% is really 30% of something like 70% of my electricity bill. (I don’t have the exact number at my fingertips.)
Even though we had to install a second air conditioner because the heating/cooling characteristics of the rooms changed, we’ve still be showing noticeably significant drops in electricity use, month after month, and now the real savings begin.
Here in Phoenix, we generally have mild winters and brutal summers. This, at least for my house, leads to significant swings in my summer/winter energy use. Arizona Public Service (APS) offers an equalizer plan: The energy usage for the previous 12 months is totaled and averaged and your bill for the next 12 months is set at fixed payment. At the end of the next year they “settle up†and outstanding credit or debit, and the payment is adjusted for the next year.
Our barrier was installed at the first of June. Our Equalizer plan year ends mid-November. The numbers are in. The barrier has been in for 5.5 months, including the worst months of the year, and our bill is being adjusted downwards from $363.00 to $277.00 per month, or a real reduction of 24% of the total energy bill. This doesn’t take into account the rises in cost per kilowatt hour, either. That’s a savings of $1032 in the coming year.
It’s unclear how the winter months will play out. Winter has been late coming and it’s only begun to be cold outside in the last two weeks or so. (Right now it’s a mind-numbingly cold 45º outside at 5:30AM.)
Using last month as an example, though, the average daily temperature was 65º. Last year, same period, it was 63º. This year kilowatt hour usage is down 13% over last, but how much of that is just the 2º temperature difference?
Only time will tell, but right now, I’m pretty happy with the radiant heat barrier.
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