This past weekend the winners of 2011 Solar Decathlon were officially announced in Washington DC and Team Maryland took first place, however we'd also like to shine a light one of our favorite sun-powered prefabs: Team Massachusetts' 4D Home. Designed for the harsh climate of coastal New England, this elegant prefab draws from traditional gable house vernacular while incorporating a 21st century set of passive and active building strategies to produce more energy than it consumes. The home features a beautiful trellis topped with 28 high-efficinency SunPower photovoltaic panels, a solar thermal system that provides 90% of the home's domestic hot water load, and a flexible floor plan that can easily adapt to changing family needs. Read on for an exclusive look inside!
The 4D Home beautifully blends traditional architecture with modern building techniques to create an exceptionally efficient off-grid home that can produce more energy than it consumes. The heart of the home’s active energy generation system is a 6.4 kW array of 28 “E19 238” SunPower photovoltaic panels rated at 19.1% efficiency – that means’ they’re able to convert a fifth of the sun’s energy in to clean electricity. The panels are perched atop a south-facing trellis which also serves to shade the home from the brunt of the sun’s heat. A set of hybrid solar thermal panels mounted immediately behind photovoltaic modules serves as a heat sink that reduces the temperature of the photovoltaics while providing 90% of the home’s hot water needs.
An ultra-efficient 16 SEER heat pump and a heat recovery ventilator round out the project’s active strategies, providing ventilation while capturing 85% of the thermal energy from the home’s air before it is circulated outside. The 4D Home is designed to have a net negative energy balance during the cold winter months, and it is expected to produce an abundance of electricity during the summer, generating a surplus of energy each year.
The two bedroom prefab’s smart Passive House design aids the active systems by greatly reducing the need to heat and cool the interior. The home’s structural system is designed to minimize thermal bridging, and the gable layout creates space for massive insulation cavities that are filled with blown-in fiberglass and closed-cell polyurethane spray foam. As a result the home’s insulation r-values are exceptional: the walls are R-56, the floor is R-57, and the roof is R-64. Meanwhile, a set of triple-pane Makrowin windows allow daylight to flood the interior while boasting a solid rating of R-7.5.
The 4D Home’s interior elements were carefully considered as well – all of the furniture, decor, and housewares were designed and built by the student team. A moving wall system allows the interior to be easily reconfigured – for instance, the living and dining rooms can be expanded to host larger gatherings. The floor plan central work space that serves as a buffer between the living and dining room and the more private rooms in the back. All of the home’s appliances are ultra-efficient and energy-star certified, including a stand-by heat pump water heater and a Whirlpool refrigerator that uses less electricity each year than a 60-W lightbulb.