COVID-19 Update:

To protect the health of our staff and our customers, Efficiency Vermont offices are closed to the public. We have cautiously begun scheduling project related site visits when required. You can find more information on our safety protocols here.

We know that you need support in reducing energy costs now more than ever, and we will continue to launch new offers and programs over the course of the summer. In the mean time, our customer support team is available to help you remotely. Contact us at (888) 921-5990 or

How one Vermonter found herself on the path to net zero

Five years ago, Karen Correll and her husband David were already on the path to make their Rutland home net zero, but they didn’t know it at the time. Net zero is the balance between the power a home needs and the renewable energy you can generate to match the need. With new heating technology and lower-cost renewable energy systems, any home can get to net zero. Karen and David’s starting point was an offer from Green Mountain Power to complete an energy audit and a blower door test to see how they could save energy in their home.

They weren’t sure what they would find, but they were hopeful. Their home was using around 800 gallons of fuel oil a year at the time – Karen recalls it costing over $3000 per year to heat the home.  “I hate having the furnace on,” Karen mused this fall.

Green Mountain Power recommended two solutions to the Corrells: 1) install a cold climate heat pump to reduce their reliance on the furnace; and 2) complete a comprehensive weatherization project to keep more of the heat they were using inside the home and make it more comfortable.

These weren’t the first steps they’d taken on the Path to Net Zero. They’d started replacing their incandescent lightbulbs with LEDs several years before. When they’d made those changes, and when they decided to move forward on the heat pump installation and the weatherization project, it wasn’t with a goal of going net zero. It was about knowing they’d pay less and be more comfortable.

We weren’t on a mission to go green, necessarily. But that has been an added bonus of the work we did,” shared Karen. “We just wanted a more comfortable home that we could enjoy while lowering the cost of living in Vermont.”

Karen connected with Efficiency Vermont to identify a contractor in our Efficiency Excellence Network who could complete the weatherization project. Karen worked with Vermont Energy Works and HEAT Squad to insulate the basement and attic, and air seal the entire building. Vermont Energy Works also recommended installing a programmable thermostat to help manage the two heat sources and keep the home at a comfortable temperature. They also recommended replacing an older, less efficient bathroom fan with a newer model. The more efficient ventilation would help keep the air fresh once the home was tighter.

Karen never looked back. The year after the projects were completed, the home used just 150 gallons of fuel oil. That’s a lot of savings, but the big takeaway? “We’re comfortable in our home. We feel the difference every day – it’s the best thing we did.” Because heat pumps work most efficiently when you don’t adjust the temperature too often (the “set it and forget it” model), their house is warmer than it was with the furnace alone. And the weatherization keeps that heat inside, so even though it’s warmer in the house, they’re still burning less fossil fuel.

Comfort throughout summer and winter

The biggest surprise for them was the next summer. Karen and David had gotten used to carting in a window air conditioner every summer to keep their home livable in the hottest months of the year. That year, they left the heat pump on.

The humidity dropped immediately – it was so comfortable! And the cool air from the heat pump makes the house a great reprieve from the heat.”

They were convinced. Karen and David decided to reduce their fuel bill as much as they could by replacing their water heater with a heat pump water heater. In addition to saving on fuel, the heat pump water heater allowed them to get rid of the dehumidifier they’d had to keep in the basement previously. Now they’re unexpectedly able to dry clothes on a rack in the basement using the dehumidifying effect of the heat pump water heater. And it’s not just heating – the couple looks for energy saving opportunities by seeking out ENERGY STAR® appliances whenever they need a replacement.

What’s next for Karen and David? “We really want to eliminate the furnace entirely. We hope to add a second heat pump that expands the heat to the upstairs. It’ll be a great day when we can eventually remove both the furnace and the fuel tank from the house altogether.”

While it’s still recommended to keep a back-up heating system when you have heat pumps, by taking advantage of Green Mountain Power’s renewable grid (already 60% renewable and 90% carbon free), the Corrells are well on their way down the path to net zero.



  • APRIL HENDERSON said Reply

    How do you deal with the below zero bouts of weather with the heat pump. Ours is inefficient at very cold temps or with wind chills. Thanks.

    • Efficiency Vermont said Reply

      Thanks you for your comment! We do recommend having a back up heating system for when temps are very low. We have a guide that has some tips for operating a heat pump: You can also call our customer support team and they can help you optimize the use of your heat pump system in colder temperatures. Call 1-888-921-5990. AE

  • Steve Simpson said Reply

    It is interesting that their oil consumption dropped by such a drastic amount. I would like to know how much their electric bill increased? What was their overall energy bill prior to the heat pumps? After the heat pumps. I am considering doing heat pumps and would like to know if it will be worth it

    • Efficiency Vermont said Reply

      Thank you for your questions and suggestions. We are always curious to learn more about the barriers folks have to deciding if a heat pump is right for their home. We'll consider adding that information to the story. If you'd like a one-on-one consultation (it's free!) to talk about your home and heat pumps, please give us a call at 1-888-921-5990. AE

    • Reed Sims said Reply

      When we too, wanted to stop using our fuel oil furnace, we went with geothermal - before air source heat pumps were available. I might still have made that decision, because it works fine no matter what the weather is outside. The fuel oil cost went to zero, and indeed the electric bill climbed greatly, but the net savings for energy to heat the home and water system was about 400 dollars anyway. Geothermal also has a way to heat our hot water (called a de-superheater), so in winter when geo is running, very often the breaker for the hot water heater is off.

      So, yes, electric costs go up, but the cost of PV is descending and our 7 kw system supplies all the electricity the geo needs, plus everything else we use, including charging a plug-in car. Last year we had a 34 dollar bill; this year it has been 0.00 even in January due to summer production credit GMP accounts for.

  • ANDREA MCMAHAN said Reply

    We are on the same road and have been pretty much net zero for a few years, even running a home business that has high electrical use. Our trip started 40 yrs ago when I sited our house due south! After working with Building Energy and Efficiency Vermont and testing our log home, we added PV and hot water panels 7 yrs ago after sprayfoaming our roof. Next came having the whole basement sprayfoamed and adding a heat pump. After that, we were making so much electricity, we were able to remove our propane boiler and hot water tank, add an electric tank as our back up hot water. Next came our Tesla Powerwalls, some of the first in Vermont! Two yrs ago we had our log home refinished and all the seams and corners were re-chinked which really helped also. I can relate how wonderful the heat pump is in the us that is the best! Cool and dry! Now we are working on upgrading our boarding kennel which already is powered by solar by adding spray foam and new siding. None of this is cheap, but we are thinking efficiency as necessary maintenance comes up every year and bit by bit, it is getting done! We have slashed our propane usage (which right now only is used for the radiant heat in the kennel), cut our firewood use from 12 cord/winter to about 4, and our annual electric bill runs about $0-300.00/yr. For us, it has been a win/win!!

Add a Comment

Read our commenting guidelines