Z Hot Summer Night

Two things come to mind (actually more but would only create arguments):

1. The true measure of energy usage is the number of kilowatt hours used and the cost per kilowatt hour.

2. I would bet the reason for the high cost when using the A/C is the low R factor associated with masonary construction. The R factor ( a measure of insualtion value) is R30 in our ceiling and R19 in our walls and triple pane windows. Masonary construction with no insulation might be and R3????

Discussion: I looked up rate plans for my power company. Even in English it takes a bit (maybe a lot) of study to get to the bottom line for the rate plans. KW/hr costs range from .09 off peak winter to .17 peak summer. The statement about getting cheaper the more you use was confusion on my part. This only applies when usage for high energy consumption items, i.e., A/C and dryers, are used off peak.

Actually very little of the above applies to our home. We went solar. It takes 6.5 years to get our investment back and then the KW hours are no cost for 13.5 years. Our total bill is $17 a month to cover administrative costs, not the cost of producing and delivering the A/C. If our system has a surplus of KW (on a yearly basis) then we are paid 0.45 per KW. We used Solar City for our solar installation. Well designed and the processs was easy and transparent.

When we built our place in Zihua, I suggested to the architect/contractor to put some insulation between the masonry and the stucco on the south and west sides. He had never heard of such a thing, so it didn't happen. We generally make do with the ceiling fan in the bedrooms.

When planning our new house in Montana, I decided to make the place highly energy efficient: R 80 walls, R 100 ceiling, very well sealed (we have a heat recovery ventilator), triple pane windows, 4 solar water heating panels and 30 P/V panels, which generate up to 7000 watts. Our hope is to sell back to Northwestern Energy as much as we consume. The last 2 bills were for $2.50 each month; their delivery charge. Last winter - the crappiest in 20 years here - the thermostat was set at 64 F, but the house stayed at 68; presumably from body heat and appliances.

Needless to say, this project will not pay off in my lifetime, but it seemed like the right thing to do.