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Concentration of CO2 in the Atmosphere

Passive House at Maple Corner: Part 3

Barbara and Greg Whitchurch

In the previous issue of G.E.T., we wrote two articles about the Dawkins Passive House in Maple Corner, Vermont (bit.do/get-mcph1 and bit.do/get-mcph2). Here in Part 3, we explore some of the issues that Meg and John Dawkins considered as they focused on their personal environmental impact, and on how and where they live.

Their house is the first of six in a private residential development of 28.75 acres with shared infrastructure (three septic systems, one water well and one driveway), which reduces the members’ environmental impacts. Three other homes are under construction now. The homeowner’s association, “Perennial Field,” is preserving the land around the houses in accordance with the previous owner’s wishes. Meg Dawkins, who is the driving force behind this project, said, “It fits the Smart Growth Model that the town of Calais has adopted, due to clustering the homes within 3.65 acres and never developing the remaining 25 acres but managing it using regenerative practices, for example, rotational grazing.”

As mentioned in the previous articles, Matt Lutz, their architect, was brought in very early and helped them to select a high-end envelope, a sustainable design, and to limit the need for mechanical equipment, thereby reducing their carbon footprint and operating costs. They chose to use the Passive House standard (PHIUS.org) to guarantee their outcomes, guide the details of their choices, and provide them with a certification of the value of their home when finished. Chris Miksic was chosen to be their Certified Passive House Consultant (CPHC, Montpelier Construction), helped Meg and John choose environmentally conscious methods, materials and appliances to build their fossil fuel-free home.

Like practically everyone who builds a home, the Dawkins had to make some hard choices. (As their architect said, “Cost still makes the big decisions at the end of the day.”) But by building to a high-energy standard, they cut their built-in energy costs severely. By choosing to put money into the design and structure, they claimed long-term energy savings that will help them afford to make smaller improvements later. For example, the high-quality building envelope was something that they chose to do up front, knowing that their energy and maintenance savings would allow them to add such things as screened-in porches later on. Efficiency Vermont helped with incentives and free professional advice along the way (bit.do/evt-hphp).

The house features R-52 double stud wall construction containing 9.25 inches of dense-packed cellulose and then a continuous layer of 4.75 inches Gutex wood fiber insulation board over the outside wall, which makes it safer than traditional construction (which often uses plywood). The R-113 roof is insulated with 30 inches of loose-fill cellulose. Under the slab is 10 inches of EPS foam (recyclable and clean), surrounded by a R-40, two-foot-wide anti-frost apron extending four feet around the corners, all of it sloped to carry water away from the house. The windows are triple-pane Klearwall and are taped to the moisture-controlling membranes surrounding the structure.

This initial investment in a high-performance envelope reduces monthly energy costs. And hitting the sweet spot of Passive House means that the sun, heat from appliances (computers, fridge, cooking, etc.) and, amazingly, body heat are major factors in the heating. (One of our favorite ‘PH’ stories tells of an elderly woman in Europe who invited friends over on cold days, which warmed up her house.)

The total annual electrical load (plug loads, hot water, ventilation, cooking, lighting, heating and cooling) for the Dawkins house is about $800 a year compared to an average of $4,500 for a traditional home. (Ka-ching! There’s their screened-in porch.) Energy Star appliances, an induction cooktop, and LED lighting provide additional savings. They’ve decided not to have a clothes dryer or dishwasher. And they’ve used low-maintenance materials, such as a polished concrete kitchen floor. (There is no need for a heated floor in a Passive House, another energy and maintenance savings.) They finished the exterior siding through a process called Shou sugi ban (bit.do/mcph-ssb), which requires very little maintenance.

When Meg and John install their small 5.5kW solar electric system, their energy expenditure will be reduced to net zero. That is, they’re investing some “extra” money in their home and in their future at the beginning instead of spending more money on fuel, with no return, for the life of the home. (Also, the maintenance and replacement costs of fuel-burning appliances are far greater than those of solar and electric appliances, not to mention the dangers of having volatile fuels stored in and around the house.)

According to the Dawkins, “Our major accomplishment is that of having a highly energy-efficient and naturally-lit house. Due to the contributions of our architect, Matt Lutz, and our builder, Montpelier Construction, we now inhabit a home that is visually stunning and inspires people to explore it and ask questions.”

Barbara and Greg Whitchurch are Board members of Vermont Passive House (VTPH.org) and have their own Passive House in Middlesex, VT (bit.do/phc-vtbiz & bit.do/mdx-mec-bldg).

 

Captions (Photos coming)

The porch awaits some screens. Three more homes are under construction in the background. Credit: Whitchurch.

Meg, Barbara (article co-author) and the Shou sugi ban siding. Credit: Whitchurch.

The light and airy kitchen. Credit: Whitchurch.

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