David Miller, a lecturer and research affiliate at MIT’s Sloan School of Management, recently had his zero-net-energy home featured on the 40th season premiere of “This Old House,” which aired Oct. 1.
In the episode, Miller, who also serves as the managing director of the Clean Energy Venture Fund, gave a tour of his Newton residence to host Kevin O’Connor and Richard Trethewey, an expert on plumbing and heating. Crew members of the PBS show were tasked with transforming a Jamestown, R.I., bungalow into a larger net-zero house, and viewed the lecturer’s property for examples of the energy-efficient changes they could make during the project.
Miller, in an interview with Boston.com, explained that a “zero-net-energy” home produces as much energy as it uses over a given time period.
“In general, the home would be producing energy using solar photovoltaic panels,” he said. “And if you add up the total amount of energy produced by those solar PV panels over the course of the year — or any other forms of local energy generations — and then compared that to the amount of energy the home uses over the course of a year, if the two are equal to each other, the home is exactly net zero.”
And if a home produces more energy than it uses, it’s net positive, Miller said.
Miller said his family was motivated to do their part to produce renewable energy and use energy efficiently, especially because of “how much of a challenge climate change is to our civilization,” he said.
“That’s what I do for [my] career: help support clean energies and new technologies,” he said. “And so it only made sense to kind of walk the talk and live in a way where we’re minimizing emissions and trying to do our part as a family.”
The most energy used by houses is often from heating and cooling, but making energy-efficient changes, such as installing cellulose insulation and air sealing, can enable to a property to “retain the heat it has in the winter and be cool in the summer,” he said.
For those interested in reducing the amount of energy their home uses, Miller said the next step is to evaluate the systems and appliances they have, including the type of heating, refrigerator, washer, and dryer, all of which can consume a lot of energy.
“If you have kind of an inefficient oil heating or even gas heating, that could be, again, wasting a lot of energy,” he said. “Whereas in our house, we’re using an electric basis; what’s known as an air source heat pump.”
Miller said an air source heat pump functions by taking energy from out of the air and using it to help heat or cool the home as needed. And it’s easier to use than a geothermal, which is a ground source heat pump that leverages energy in a similar fashion, because homeowners only have to place it beside the home, rather than underground, he said.
“It’s powered by electricity from the grid. And for every unit of energy that it uses, it actually puts out something like three or more units of energy,” he said. “You don’t have to worry about any kind of fuel delivery, and you don’t have to worry about any kind of emissions.”
For appliances, Miller said while more energy-efficient models may cost more up front, “over the lifetime you save so much energy that they more than pay for themselves.”
One of the major advantages Miller said he had in electing to make his home zero-net-energy was that the family was designing it from scratch as opposed to making renovations.
“We could pay attention to something like how the house is oriented. And so we oriented the house so that most of the house faces towards the sun,” he said. “It makes the solar panels work better and generate more energy. But also, the windows that face the sun in the winter, the sun comes in through those windows and helps to heat the house.”
As a result, Miller said his house does not have to run any kind of heating system because the sun is doing the job instead.
“It’s great because it could be zero degrees outside and as long as it’s a sunny day in the winter, the sun is low and it’s just coming in right through the windows and heating the house,” he said. “The house is also well-insulated so it’s keeping the heat in.”
Another advantage is cost savings, Miller said.
“By being zero-net-energy, on a net basis, the utility bill is zero essentially over the course of the year,” he said. “And the solar panels have other benefits because there’s solar renewable-energy credits. There were some tax benefits, so we’re actually getting paid by generating the solar energy.”
The family is also adding a battery storage system from a company called Pika Energy as another modification to the home, which essentially makes it a self-sufficient “energy island,” even during a blackout, Miller said.
“We really have to kind of move into a future where we’re using renewable energy and we’re not destroying the climate,” he said. “It’s not just saving the world [but] saving the ability for people to live in the world, which is kind of an important thing.”
Watch the full episode and check out Miller’s appearance between 12:30 and 16:40.