Victoria and Greg Pryor met on the beach in Montauk, New York, when they were both just 13 years old. The Hamptons hamlet, the setting of so many idyllic childhood summers, continued to exert a strong pull on the couple into adulthood. So when they decided to build a retreat for escaping Manhattan’s bustle with their boys, Dylan and Lucas, it didn’t make sense to do it anywhere else.

Nor did it make sense to work with anyone other than Victoria’s younger brother, Paul Masi of Bates Masi + Architects. For his sister and brother-in-law, Masi designed a house whose defining feature is a double-height living-dining-kitchen space that opens to the outdoors when large glass pocket doors slide out of sight. “We wanted to bring the outdoors in and make it a seamless transition,” Victoria says. After two years of construction, the house was completed in 2008.

Green features such as a prefabricated foundation and a geothermal heating and cooling system are buried below ground. Nontoxic finishes and passive systems inside the home add to its sustainable cred and helped keep the project on budget. The result is an elegant beach house that is perfectly in tune with its environment.

Passive Heating and Cooling

The living-dining-kitchen space opens completely on two sides, allowing for natural ventilation in spring and fall. An overhang blocks direct sunlight in summer, but in winter, when the sun sits low in the sky, light and warmth flood the space.

Two layers of aluminum woven-coil drapes hang outside the large, south-facing windows above the living area. The drapes keep the house from overheating in August and can be pulled aside to help the sun warm the space during chillier seasons. Similar in texture and appearance to fireplace netting, the drapes are made of recycled scrap metal by an Oregon company, Cascade Coil Drapery, that also supplies the hearth market.

Geothermal Heating and Cooling

The open-loop geothermal system uses the constant 55-degree temperature of the site’s groundwater to heat and cool the house. The requisite equipment fits in a basement utility room, so there was no need for an exterior condenser. “Out here, the salt air just corrodes them,” Masi says. “So to be able to do geothermal and get rid of [the condenser] was huge.”

Your Turn: Geothermal Heating and Cooling

There are several types of geothermal systems, though all use the Earth’s constant temperature—warmer than the open air in winter and cooler in summer—to heat and cool buildings. Which kind to use, and whether it makes sense to install one, depends on several factors.

Open versus closed loop.

In an open-loop system like the Pryors’, pipes draw well water into the house, where a pump extracts heat from—or transfers excess heat to—the water before it is returned to the ground. In a closed-loop system, the pipes are buried under-ground and filled with a solution that acts as a heat exchanger. If a well can supply enough clean water to the heat pump, an open-loop system is often more economical as it requires less excavation.

Types of closed loops.

A pond-loop system sub-merges pipes in a body of water. If one isn’t handy, a horizontal-loop system buries them six feet under-ground. For small lots, vertical-loop systems may be best, though burying pipes up to 400 feet down can be cost-prohibitive.

Affordability.

Geothermal systems are more expensive to install but over the long run are more economical to operate and maintain than gas furnaces and air-conditioning systems. Annual energy savings can reach up to 60 percent, and tax incentives often help offset the upfront cost.

Prefab Design and Construction

Insulated concrete panels by Superior Walls of the Hudson Valley were delivered to the site, craned into place, and bolted together to form the structure’s foundation. The panels, made of a dense, water-resistant concrete mix, did not require waterproofing and eliminated the need for coatings that can leach into the soil.

An early plan to prefabricate the exterior walls was scrapped when it proved more expensive than building on site. However, factory-made panels from Cement Board Fabricators were used for the rain screen. The panels help the house stay cool by absorbing heat and transferring it up through ventilation gaps between the panels and siding.

Nontoxic Finishes

Throughout the house, Masi specified finishes low in volatile organic compounds (VOCs), toxic chemicals such as benzene and formaldehyde. Interior walls were painted with Benjamin Moore Aura matte paint. The American walnut floors were sealed with Osmo Polyx-Oil, a finish made with sunflower, soybean, and thistle oils.

Your Turn: Nontoxic Finishes

Limit your exposure to off-gassing, the emission of VOCs into the air, by using nontoxic paints and finishes from these manufacturers.

AFM Safecoat: afmsafecoat.com

Benjamin Moore : benjaminmoore.com

BioShield: bioshieldpaint.com

Bona: bona.com

Citron Paint: citronpaint.com

Mythic: mythicpaint.com

Osmo: osmona.com

Sydney Harbour Paint Company: sydneyharbourpaints.com

Unearthed Paints: unearthedpaints.com

Yolo Colorhouse: yolocolorhouse.com