Tuesday, May 20, 2008

Oil bill

The heating oil truck pulled up early this morning, for the last time until September or October. I looked at our oil tanks the other day, and both were below half. So this will be at least $1000. We have radiant heat in the first and second floors of our house, on two separate zones, and we keep those thermostats at about 64 F all winter. On another zone, we have two spaces, a basement studio with a Thermolier blower and an uninsulated addition with baseboard heat around the outside walls. The thermostat for that zone is in the basement, near the thermostat. There is a staircase going down to the basement from the addition, with a door at the bottom of the stairs. We use the studio during the day, and keep that thermostat at64 during the day and 59 or 60 at night, and we keep the door closed, with the blower enabled. This combination makes it very cold in the uninsulated addition, which is the entry way and kids' playroom. Keeping the blower enabled keeps the thermostat warm enough so that we lose the minimum heat with this awful configuration.

This was our first winter in this house, and the users of the studio and playroom were cold and miserable, to the point where we bought a space heater for the studio to help my wife warm up when she's working. Even then, on the colder days, she would have to retreat to the main part of the house with her laptop. Here's our first step in improving our situation. A friend from work installed homemade thermal drapes last year, and forwarded us the link for the supplier. We have huge floor to ceiling plate glass windows and sliders in the studio and playroom and three rooms on the main floor. We will start with the studio as our test area, building insulated drapes for approximately 25 by 8 feet of glass. The frame on the studio slider is aluminum, with no thermal break, so heat just gets sucked out through the frame, in addition to the massive loss through the glass itself.

My wife says that it will cost us around $500 per room to make the drapes ourselves. For the studio, a rough calculation gives us an improvement from about 6000 BTUs per hour lost through the glass wall to 1000 BTUs per hour, given an external temperature of 20 F, and an internal temperature of 60 F. A gallon of diesel is about 140,000 BTUs, so the drape will save us one gallon of diesel for every 28 hours in those conditions. That's payback in just a couple of years. If we can do 1000 square feet of glass before next winter, we will be looking at over $10/day in savings for the entire winter. I'll tot up our actual gallons and dollars for this past winter, and post a more accurate estimate as we work through the project.

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