Last fall, I completed a series of energy efficiency upgrades to my home – most significantly I added insulation to the attic. I’ve been curious to see if the touted claims of energy savings were reflective of my actual experience. It may be too soon to tell, but my initial results are quite promising.
My first step was to calculate how much colder this winter was compared to last winter. I found a website that could help me calculate Heating Degree Days. It’s the difference between the cold outside temperature and the desired indoor temperature. The chart below shows the cumulative heating degrees needed to reach my desired indoor temperature. In total, this past winter was about 12% colder than the winter before based on these calculations.
If I were to have done nothing to the house, I would expect my energy usage to have increased by 12% or more since more heat loss occurs the colder it is outside.
After comparing the fuel purchased during the winter and adjusted for what was in the tank at the start and end of the season, I discovered that I used exactly the same amount of oil per month as I did the year before, not 12% more.
If my assumptions are correct and the insulation reduced my heating expenses by 12%, then I would recoup my investment in less than 2 years. That beats the rules of thumb I’ve seen of 5 years.
This gives me a warm feeling.