Secrets of an Elderly House
Our house was built early in the 20th century. When we bought it in 2004, the seller said they burned 1250 gallons of heating oil the winter before. I spent a good part of that year fixing some obvious flaws before moving in, like replacing leaky single pane windows, which rattled in the wind, and filling the shafts where the old weights and pulleys had been with expanding foam. I improved both exterior doors, eliminated the leaky bulkhead, insulated the daylight walls of the basement, insulated the rim joist and added more insulation to the attic. The house consumed 950 gallons of heating oil the following winter.
In 2006, my partner and I energy-audited the house. Lots of air sealing followed and the installation of interior storm windows my wife and I built in our basement workshop. We also insulated the basement ceiling. Our 2012 heating oil consumption dropped to 800 gallons, yet, due to rising oil prices, our heating costs rose to $3,136 compared with $2,500 when the house used 1250 gallons of oil.
We purchased a pellet burning fireplace insert, to see if we could heat the house with wood pellets instead of oil. Over the next two winters we indeed did so, spending less than $1,560 per year on heating. However we failed to factor in us getting old. Routinely handling 40 lb. bags of pellets did not seem like a smart plan after all. For the same reason we did not want to rely on firewood either. We investigated replacing the oil-burning boiler with a boiler running on bulk-delivered pellets; a geothermal heating / cooling system; and even a high efficiency gas fired boiler. In the end, our decision hinged on comparative costs, including removing or upgrading old equipment.
We sold the pellet burning insert, recovering much of its original price. Then, on a fine June day last year, we had both our new mini-split heat pump and our solar system installed. The heat pump cooled the house as needed all summer long, then mostly heated it as well all winter long. “Mostly”, because we sized the heat pump using the same thinking we used selecting our pellet burning insert: to fully heat the house not in its existing condition, but rather the still a work in progress, more energy efficient version. For now, we make up any shortfall in heat running the old oil fired boiler as our backup system.
Through the end of March we spent only $874 on heating this rather cold winter. Of that $214 went for oil, 89 gallons of it, burned on a few mornings when outdoor temperatures hovered below minus 10ºF. Thanks to our solar system, which generated 3,303 kWh ($495 worth) of electricity since last June, our electricity came to us at no cost, other than CMP’s delivery charges, through October. At that point the need for heating began to gradually use up our accumulated net metering credits.
Since we purchased this house we tracked gallons of oil burned, average fuel oil price, and our savings compared to what we would have had to pay, had we done nothing to the house. Those savings came to between $600 and $3,344 every single year since move-in day, depending largely on the price of oil each year. Cumulatively our savings, through March 31, add up to $17,176. Deducting the cost of all improvements (excluding self-labor), plus the installed cost of two heat pumps (for heating and water heating) and our 16 panel solar PV system (a sum of $19,178), leaves a negative balance of $2,002. In other words, our savings to date have paid for everything but this negative balance, which we will no doubt recover during this year. Not bad. Still, in retrospect I could have done a lot better by doing more to the house before we moved in.
The last number my house wants to share with you is that it saved $8.02 per-square-foot of heated floor space over the past 10 years. Multiply this number by the heated square footage of your own home to get a taste of what you, too, could save you if you set your mind to it depending, of course, on how close your home happens to be to the energy-inefficiency of ours before we began our improvements.