Thursday, June 4, 2009

The furnace man come'th

My family had a guy come by yesterday to evaluate our house's heat retainment. He examined the exterior and measured windows. Then he set up a fan in the front door to create a bit of a vacuum inside the house and went around with a smoke stick to show us where air was getting into our house. Where air was getting into our house would also be where hot air was escaping reducing the efficiency of our heating system.

The worst leakages were through the cracks around the window framings and through the sliding door. The sliding door in particular was very bad, the evaluator said that all sliding doors had poor seals and that there wasn't much to do except replace them with french doors. The leakages around windows weren't so much through cracks between window and frame as between frame and the rest of the wall. This was independent of how new the windows were, we had a new window put in upstairs recently and the sealing around the frame just wasn't done as we hadn't specifically asked the construction people to put it in. Of course, we also have some very old windows that had a lot of leakage as well.

There were also some interesting leaks that I hadn't thought of before, such as through the light fixtures recessed into the ceiling and around the fireplace.

The evaluator is going to write up a formal report, but the reason we had him come in was so we could consider doing some renovations to the house that could earn us some ecogrants from the government. If replace the furnace with a high efficiency one: we'll get money. If we seal up a percentage of the leaks to the outside: we'll get money. If we replace certain windows and doors: we'll get money.

So after the evaluation, I sat down with my parents to work out the financial side of making some of these changes.
The high-efficiency furnace was quoted at $5700 by my dad, though I haven't confirmed this. 'High-Efficiency' seems to be about 95% of heat created from burning the gas goes into heating the house; as opposed to the 60% estimate for our current furnace. This is a difference of 30-40%, so in theory a new furnace would reduce gas consumption by the furnace by that amount.
Our gas usage per month fluctuates between ~$70 and ~$220 from summer to winter, and gas prices have fluctuated from $4 to $13 [1] per *** over the last couple years. For our calculations we decided to assume our gas bill was $160/month, of which $60 was fixed as taxes and fees (and so wouldn't change with improved heating efficiency).
This gives a nice round $100 per month that we pay to fuel the furnace, the stove, and the hot-water heater. Assuming that all of our gas is used for the furnace (not true, but only slightly optimistic), we'd save 30-40% of $100, or $30-40.

$5700 for a new furnace
$4000 for a new furnace, after government grants[2]
$4000/$40 is 100, which is the number of months it would take to pay it off.
Or 10 years.
(Yes, these are just quick numbers, I didn't think too hard about them. I'm assuming that improvements in house insulation will be balanced by the fact that we have other items like the stove that use gas and won't have their consumption reduced by fixing heating systems.)

10 years to pay off the furnace. My parents have no idea currently how long they will stay here. At least 3 or 4 years until my youngest brother graduates, and they certainly won't demolish the house in their lifetime, but if the house is sold it will almost certainly be torn down and redeveloped, negating any future benefit of the furnace.

I'll update when the family comes to a decision.

[1] This isn't a steady increase over the years from cheap to expensive. My dad tied the $13 gas to hurricane Katrina damaging gas production, and points out that the price has gone back down again. He is a exploration geologist who helps locate natural gas and oil in Alberta. He says that gas prices fluctuate fairly independantly from oil prices (though the fact that they have overlapping uses does tie them together somewhat), and that there doesn't seem to be a peak gas happening as there is with peak oil.

[2] We'll get $790 from the Feds, and $700 from the Province, plus $199 if we improve house insulation by 10% as measured by another visit from the examination guy.


  1. It's good to see the numbers on something like this. I wonder if it's comparably lucrative to build green originally rather than retrofitting.

  2. We'd have to look for different grants.
    There's a pile of pamphlets here on my desk that might contain something though...