Decarbonizing A 100-Year-Old Home (Part 1)

Extensive Home Energy Work Often Starts With Other Goals In Mind

My friends’ Mark and Rhona have a 100-year-old home they retrofitted to be within striking distance of net zero, and it was only the solar panel that caused them to fall short. (The size of the solar panel was limited by the utility’s net metering program requirements.)

In Mark and Rhona’s case, their project began as a way to make room for their family, especially their in-laws visiting from England and Ohio. In renovating their basement, which is what they initially wanted to do, they decided to remove the furnace and use a high-efficiency heat pump that would sit outside to create more space in their basement. Next, enlarging the basement’s permitter led them to think of ways to remove all the old boiler’s pipes that were in the walls and while they were add it, add foam insulation. Soon each decision in their project included the goal to save the planet for future generations, a sentiment many share.

The Reality of Old Homes and Energy Efficiency

Old homes require a lot of work to be energy efficient, a fact I am already familiar with. In 2009, I launched an energy efficiency website for the state of Pennsylvania and later engaged with the Department of Energy's Home Energy Score program. The program, widely adopted in certain parts of the country, labels homes with an energy score, similar to MPG ratings for cars.

Recently, I assessed our 115-year-old home in Minnesota using the Home Energy Score tool. I found the software much improved. It impressively estimated our home's annual energy use within 5%, based solely on the home’s characteristics.

Our score? A dismal 2 out of 10. Most homes the age of ours score a 1, which seems about right, since half of all homes in America would score a 1 or 2, according to a presentation I heard on the Home Energy Score. The good news is is that means there’s a lot of potential to remove carbon emissions. How?

Any home scoring 4 or less, in my opinion, is a candidate for a deep, whole-home retrofit - that’s the only way to achieve energy savings of 50% or more and decarbonize the home in the process.

First I Need To Overcome Limited Advice

The second part of the Home Energy Score report—the recommended energy-saving measures—lacked ambition. The advice felt like choosing the path of least resistance rather than undertaking the deep changes needed to bring a 100-year-old old home up to modern standards in energy use, comfort, and air quality. The measures it suggested would only bring our home to a 5 on the 10 point scale, about 20% energy savings. For our home, that leaves a lot of meat on the bone. I also have this concern with our utility-backed energy audit program in Minnesota. They gave us a free energy audit, but their suggestions were also limited to "cost-effective" changes suggested incrementally over time.

For several reasons, I want to do more. I want to save 50% in energy use and kick fossil fuels at the same time!

My own state, Minnesota, has set a goal of carbon free emissions by 2040. It’s the law for utilities and homeowners, of course, are urged to participate as well and the state energy office is lining up its own array of incentives.

In Part 2, I’ll dive deeper into the details, costs, and strategies to achieve 50% energy savings and decarbonization of a 100-year-old home using my home as an example.

Probably in the 1930s, some brave soul took it upon themselves to stop using coal and convert the boiler in in our home to natural gas. Now, I feel like now it’s my turn to make big changes.

If you want to see where your home currently stands, you can create an unofficial report using the DOE’s Home Energy Score or other measuring tool. See you on the next page…