August 23, 2018

This account was originally posted on the Rocky Mountain Institute website and has been lightly edited.

I have a confession. I've been an energy and sustainability architect for many years, I work at one of the most innovative non-profit energy think tanks in the world, and my 100-year-old house consumes 1.5x the energy of an average house of similar size… or rather, it used to. In 2012, I participated in the Denver Energy Challenge and weatherized my little 1,800 sq. ft. house, hoping to reduce my energy costs from $2,100 per year to $1,500.

It starts with a home energy audit

I had a home energy audit, blower door test, and infrared thermography done on my home by my local utility. Okay, I actually did this two years ago. So why did it take me so long to act on it? I have the same issue that most people have—money. My planet-saving job comes with a non-profit salary, and that was a real hurdle for me when I wanted to walk my talk. The most common reason homeowners give for delaying energy efficiency projects is expense. My energy audit was heavily subsidized and offered at very low cost. That helped get me started, but it took the Denver Energy Challenge for me to finally take action.

Making the energy upgrades

Because of costs, I had to keep this simple and hit the big problems first. My house was extremely leaky. A blower door test indicated that 90% of the air in the house was exchanged every hour, and I don't even have central air. (A good tight home should come in at about 35%.) This was coming in through basement penetrations, deteriorated weatherstripping, new yet poorly installed windows, and construction joints that had never seen a bead of caulk or foam. (I could have told the inspector I had leaky doors without the test, since my urban chickens congregated by my back door, where a constant flow of warm air kept my hens comfortable on cold winter days.) I gave Precision the go-ahead to seal up everything they could reach. It cost me $1,850.

The ancient boiler for the warm, wonderful hydronic heating system is likely 100 years old, though I don't know for sure. It has never let me down but is terribly inefficient and clearly on its last legs. It failed the CAZ test for carbon monoxide, and although venting is adequate and I have a CO detector, this still freaks me out. Replacing it and bringing the system up to code will cost $10,000–$16,000. Despite a "generous" $160 rebate from Xcel for a new energy efficient boiler, that's something I just cannot do right now.

Another issue is insulation. My house has uninsulated brick walls on the first floor over uninsulated crawl space, and wood frame construction upstairs. The upstairs was first finished in 1971 as a groovy waterbed loft, with minimum insulation, if any. I remodeled parts of it eight years ago and added R-30 to the attic, which when audited came closer to R-24. The solid brick actually works as a nice thermal mass on the south end, and I do feel the benefit of that. I can insulate the inside of the crawl space easily, but as a long-time historic preservation architect, I did not want to add insulation to the outside wall of my lovely brick home. I settled for adding cellulose insulation to the accessible attic spaces (only about one third of the attic area) to reach R-50, and it would cost me $700.

My old house still has original windows on the first floor and in the front dormer upstairs. They are beautiful, with lead weight counter-balances that allow one-handed operation and oak frames that you would pay dearly to replace in kind. I have wood storm windows on the outside that were added in the mid-20th century. Upstairs, I have eight-year-old, double-glazed, low-e, insulated Kolbe & Kolbe windows. During our energy audit, infrared photography showed the new windows far more leaky than the old ones. I can hear outside conversations through one of the upstairs windows and see a thin strip of daylight along the frame, so I called Kolbe & Kolbe to fulfill the promise of their warrantee.

While I waited on Kolbe & Kolbe’s warrantee, I called my local window-tinting guys, Scottish Window Tinting, to explore options for window film on historic units. Window film has come a long way, and it's a great retrofit product. It can be clear (very important to me) and reduce heat gain dramatically better than a plain low-e film. I installed window film on the east and west windows only, as Colorado summers are becoming more intense, and my house cooks during those hot mornings and evenings. The south-facing windows are an important part of my winter solar heat gain strategy and do not suffer direct sun in the summer. The film cost $605 installed.

Final thoughts

If you're doing the math, I've now committed to a $3,155 investment in home energy efficiency; however, Home Performance with Energy Star rebates will provide $550, making the total investment $2,605. Remember that energy efficiency financing I mentioned earlier? Elevations Credit Union gave me a 3.125% interest rate for my loan, with monthly payments just a bit more than my anticipated energy savings, and a four-year simple payback.

The work was completed three weeks ago, and I am already enjoying a more comfortable home. It is noticeably warmer, the drafts are less obvious, and I can’t wait for summer to test our window heat gain. There's still more progress to make; in the meantime, I've taken my house from "absolutely awful" to "better than many its age." I'll know in a year if I hit the performance goals I'm aiming for, but right now, everyone except the chickens is very pleased with the improvements.

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