When architect Kirsten Thoft designed her family’s home at 45 Linden Lane in Princeton in 2015, she ensured it met the highest environmental standards, earning it a “platinum” certificate according to Leadership in Energy & Environmental Design standards.
The financial trade-off with building extremely efficient homes is to spend more up front on extra design work and materials in order to save money every year on energy and water, and Thoft’s home is no exception. It has a highly efficient geothermal heating and cooling system along with solar panels, and heavy insulation to ensure that no energy is lost. She said that in her first year, she paid a total of $300 for electricity, $300 for gas, and $300 for water.
“I will benefit on a month-to-month basis of having done all that work,” she says. “The solar panels themselves will pay for themselves in five to seven years.”
Thoft continues to design, build, and renovate “green” homes, mostly in the Princeton area, but lately she has been using a different design standard than LEED for her clients. The Zero Energy Ready Home standard from the U.S. Department of Energy is less costly to meet than LEED but provides many of the same benefits for the homeowner.
Thoft will speak about this and other trends in green building alongside a panel of fellow experts at a Princeton Chamber of Commerce event Wednesday, July 25, from 7:30 to 9:45 a.m. at the Springdale Golf Club. At “Going Green: Uncovering the Value Proposition,” Thoft will be joined by Emily Stoddart, energy manager at PNC Financial Services, Mary Brenner, associate vice president of New Jersey’s clean energy program, and moderator Joshua Zinder of the JZA+D architecture firm. Tickets are $40, $30 for members. For more information, visit www.princetonchamber.org.
Thoft grew up in Marblehead, Massachusetts, and studied design as an undergraduate at the University of Pennsylvania, graduating in 1986. She earned a graduate degree in architecture in 1991 and went on to work for Michael Graves and Associates, the famous Princeton architecture firm. She worked on such projects as the Denver Public Library and the Library of Congress Exhibit Hall. She later worked for Hillier, where she helped design the Hoffman La Roche headquarters in Nutley.
Today she lives in Princeton and has three children with her husband, software developer Ted Nadeau.
Her practice focuses on renovating and building homes for individual clients, most of whom are in Princeton, Lawrence, Hopewell, and Cranbury, though some are as far away as Long Beach Island.
She does not exclusively build green-certified structures, but she says it’s something her clients increasingly demand, especially in the Princeton area. “I’m hearing more and more people interested in it,” she says. “It’s becoming more familiar to people … we’re a well educated population.”
For most of the green homes she builds, Thoft now uses the Zero Energy Ready Home standards rather than LEED.
There is much overlap between the two standards in that both are heavily focused on energy efficiency: both require that homes be able to be heated and cooled for a minimal amount of energy, and also encourage the use of solar panels.
But LEED goes beyond this and takes into account the location of the home, awarding points for being near public transit. Thoft says homeowners usually have no control over this. LEED also gives points for using “green” building materials.
ZERH (despite having a worse acronym) ends up being more relevant to most homeowners, Thoft says, because of its narrow focus on energy efficiency. A ZERH-certified house will have similar low energy bills to a more expensive one that is LEED certified. And as its name suggests, Zero Energy Ready means that when solar panels are added, it will give at least as much energy back to the power grid as it removes.
One of Thoft’s latest projects to meet this standard was at 82 Valley Road, which was the subject of an article in the December, 2017, issue of the Princeton Echo. She completed the new five-bedroom house in April and sold it in June.
Thoft worked with an “energy rater” company that inspected and tested the home before awarding its ZERH rating. In general Thoft uses the same techniques to make homes energy efficient. They look the same on the outside, but their interior construction differs dramatically from traditional building techniques.
Firstly, the walls are thicker, and every part of the house has thicker insulation than a home normally would. The HVAC ducts are sealed tight to prevent any loss of air. When adding insulation to a home, the rule is generally “hat, boots, coat,” meaning the biggest energy gains are to be found by adding it to the attic, then the foundation, and lastly the walls, where the least energy is lost.
The homes are also ventilated differently from traditional houses. In order to minimize heat loss, there is no vent fan in the attic. Instead, a special piece of equipment called an Energy Recovery Ventilator is installed. This piece of high-tech heat-exchanging gear recovers the warmth or coolness from the air, depending on the season, and re-uses that energy instead of just blasting it out into the air like a conventional HVAC system would — it allows for fresh air to circulate without wasting electricity, keeping the air quality high.
Every appliance is of the energy efficient variety. For heaters, this means high-efficiency gas powered units or even electric heat pumps, a technology long popular in Europe that is just catching on in the U.S. (These differ from traditional electric baseboard heating, which Thoft described as functioning like a toaster and are notoriously wasteful of electricity.)
Thoft says that from attending green building conferences every year, she has seen that electric heat pumps have come into vogue in a big way, in an effort to reduce fossil fuels.
All of these systems can be smaller in a normal home if the house is well insulated.
Other energy-hogging devices are minimized. In one recent project, Thoft had to make sure there was only one ceiling fan in the home, as it turns out they are big energy wasters. Electrically heated bathroom floors are never in the “energy budget,” but Thoft says they are not needed in a good green certified house. “If you insulate your house really well it doesn’t matter,” she says. “You won’t have cold floors.”
In recent years LED lighting has come to replace incandescent bulbs as an obvious energy-saving measure.
All of this is expensive up front, Thoft says, but will pay off in the long run. Unfortunately, this means that green building has thus far been restricted to wealthy homeowners. (Thoft says that building a home in Princeton typically costs well over $1 million when all is said and done.) However, she says that the sustainable energy community is now focused on bringing these techniques to the masses.
“There recently is a push to make green building more accessible to a greater number of people,” she says. “The conversation has started to turn to ideas about when is a building good enough, specifically the idea of a ‘pretty good house,’ which means that the construction is similar enough to the norms of the building industry that production builders (large-scale developers) can follow guidelines that dramatically reduce end-user energy consumption but still make sense for mass production.”
Progress has been slow, however. Thoft says that in her own experience, contractors tend to be conservative and skeptical of trying new techniques.
Some of the push for green building has come from state and federal programs that reimburse homeowners for making energy efficient investments, making it an even more attractive option. Thoft wonders how much longer these incentives will last in the current political climate, but hopes that whatever happens, homeowners will see the wisdom of building for the long term.
“I hope that the demand continues and that people realize that low energy bills and comfort are worth pursuing, whether or not there’s a state subsidy there for it.”