Nathan Scandella (personal)

Results of Home Insulation Project

Last winter, I conducted a major upgrade of my home's insulation. I made use of the federal stimulus energy tax credits, to get a 30% rebate on my qualified purchases of insulation. I added fiberglass batt insulation to attic walls, and blown-in cellulose (primarily recycled newspaper) insulation for the attic. Thanks go to my dad, who helped me with the blown-in insulation (definitely a two-man job!).

After one winter, I have preliminary results of the job. At the end of April 2010, I replaced a gas water heater with an electric one, so after that point, I can no longer make an apples-to-apples comparison between my home before and after the insulation job, with respect to natural gas usage.

As a result of the attic insulation (batts and loose fill), this year I experienced a daily natural gas usage of approximately one half therm less, per day. The total natural gas usage, of course, is comprised not only of furnace heating, but of hot water heating. The attic insulation has no effect on water heating, so relative (i.e. percentage) changes in total energy usage cannot be directly assessed, since the natural gas bill includes both furnace, and hot water heater consumption. I make no other use of natural gas in my home (not for clothes drying, or for cooking).

At Seattle's rate of approximately one dollar per therm (that's a marginal cost, not average ... since natural gas bills include a baseline overhead fee that is independent of energy usage), this equates to a savings of approximately 50 cents per day during heating months. Note: national prices are a little higher. I heat my home to approximately 60 degrees Fahrenheit, which makes about 7 months of the year heating months for me. Of course, there are still more benefits of the insulation, that aren't measurable in my heating bill. Even though I don't normally heat my house during May and September, having the insulation does keep my home a little warmer (than 60 degrees), which adds to my comfort level. Also, during July and August, the attic insulation will keep the upstairs bedrooms cooler, during our infrequent heat waves. But, solely taking into account the direct savings on natural gas, this insulation upgrades saves more than $100 per year. The basic material cost for this upgrade was $TBD, not including the tax credits, or $TBD with the tax credits. No installation cost is included, because I did the work myself (adding insulation is a messy, but fairly easy job for a DIYer).

Prior to the insulation upgrade, my attic had old rock wool insulation with an estimated R-value of about R8, on ceilings and walls. After the upgrade, I had between R30 and R38 on the ceilings, and between R18 and R21 on the walls. My house has 2260 square feet of finished space (I do not heat the unfinished basement). However, during the winter, I do not heat the upstairs (approximately 900 sq. ft.) to more than 52 degrees Fahrenheit. This usage pattern was consistent, between the periods before and after the insulation upgrade.

Posted at 02:01PM Jul 16, 2010 by Nathan in Environment  |  Comments[0]