Work is underway on a 3400-sq.-ft. house and adjoining carriage house at the University of Georgia’s Tifton campus. The project combines a variety of energy-efficient features with advanced building materials and internet-based monitoring and control systems.
The Future Farmstead has brought together student and faculty designers and builders, building professionals, and a number of corporate donors to create a living laboratory and demonstration project. Its creators hope the project will attract as many as 15,000 visitors a year. When completed sometime later this year, the four-bedroom house will become home for graduate students connected to the project.
The project is the brainchild of Craig Kvien, a professor of crop and soil sciences who has taught at the school since 1979. Kvien said the idea for the project grew out of university programs on energy efficiency in agriculture, plus a need for more space for graduate students.
The Tifton satellite campus, which is in a town of 15,000, is home to the Colleges of Agricultural and Environmental Sciences and Family and Consumer Sciences. It’s located some 50 miles north of the Georgia-Florida state line and about 200 miles south of the university’s main campus in Athens. Kvien says the Tifton campus is well-known for its turfgrass breeding program.
The exterior of the two-story house is finished, with work continuing inside. Future Farmstead has been aided by a number of government agencies as well as dozens of companies that contributed money, building products, or “intellectual help,” Kvien says.
The project’s website has this description: “The home/lab is a learning center to be explored by the thousands of people we expect to visit each year to learn more about living smart, net-zero homes, gardening, agriculture, food preservation, and about using communications tools to make life at home and business better.”
Energy system combines solar hot water and thin-film photovoltaics
The roof of the main house is both a solar hot-water collector and a source of electricity, similar in design to the Englert Solar Sandwich. Beneath the standing-seam metal roof is a network of 1/2-in.-dia. PEX tubing held in place by galvanized-steel purlins. A mixture of water and propylene glycol circulates through the tubing, carrying heat to two 80-gal. tanks where it heats the domestic hot-water supply while simultaneously cooling the bottom of the Unisolar peel-and-stick photovoltaic film.
In all, there are four circuits of 280 lin. ft. of PEX tubing, each arranged in 9-ft.-long rows and covering a roof area of 216 sq. ft.
The thin-film PV was applied to the roofing before roofing panels were installed, and they cover a total of 864 sq. ft. The system’s total nominal capacity is 5kw. Researchers plan to study the effect of the PEX loops on the output of the solar array (higher rooftop temperatures erode PV output).
Below the loops of PEX and their supporting purlins is a reflective radiant barrier and Huber’s Zip System sheathing.
“Given that the whole house is an experiment,” the website says, “we plan on gathering data on how the system functions over time–monitoring flow, electrical use and temperature. This information will feed into our whole house system that is able to monitor and control most of house functions.”
Heat is provided by a ground-source heat pump with heat-exchange tubing in horizontal loops 6 ft. underground as well as in a nearby pond.
Buildings showcase a variety of materials
Both the main house and the carriage house are constructed from precast concrete walls, insulating concrete forms (ICFs), and conventional stick-framing.
First-floor walls in the main house are precast concrete panels manufactured by Superior Walls set on a footing of crushed stone and insulated to R-20 with closed-cell polyurethane foam and UltraTouch denim batts. Second-floor walls are conventionally framed with 2x6s and sheathed with Huber Zip R3 panels that combine a layer of continuous insulation with structural sheathing. As on the first floor, cavity insulation is a combination of spray-foam and denim-batt insulation.
At the main house, a 4-in.-thick slab was poured inside the precast walls after the panels were set in place, with Delta-MS used as a vapor barrier beneath the concrete. The truss roof is insulated to R-40 with a combination of 3 in. of spray foam plus denim batts.
The one-story, 600-sq.-ft. carriage house is made with ICFs on a poured-concrete footing and slab. Exterior walls have an R-value of 28.
The slabs for both the main house and the carriage house are made with concrete in which fly ash, an industrial byproduct of coal-fired generating stations, and additives made by BASF take the place of 50% of the cement. “That’s well above the norm,” Kvien wrote in an email. “It took a while for the concrete to set up.”
As of late May, the buildings had not been tested for air leakage with a blower door. Kvien said that would take place after all the insulation had been installed and both before and after drywall is hung.
Other features:
- An energy-recovery ventilator for whole-house ventilation, plus an experimental liquid desiccant system designed to cope with Tifton’s warm and humid climate. Kvien said desiccant systems are used in many commercial buildings and that the one in the Tifton house was in the very early stages of testing.
- Double-glazed low-e casement windows with a solar heat-gain coefficient of 0.18.
- LED lighting, energy-efficient appliances, water-saving fixtures, and a gray-water irrigation system.
- Features to make the house accessible, including wide doors, a wheelchair lift, and zero-threshold shower stalls.
Kvien estimates basic construction costs at between $130 to $150 per sq. ft. Features such as the wheelchair lift, wider stairs, a sprinkler system, and data-collection sensors added another $35 to $45 per sq. ft.
Planting edibles in addition to flowers
The main house and the carriage house are key parts of the Future Farmstead, but they’re not the only ones. The project also includes an “edible landscape,” with blueberry bushes, frost-tolerant lemon and tangerine trees, and a variety of disease-resistant fruits and vegetables. Edible plantings are interspersed with flowers in raised beds around the house in the hope of having something blooming every day of the year.
In addition, there’s an adjacent 2-acre pond for a variety of fish species and water birds. A 1300-sq.-ft. deck built in the shape of a leaf will serve classes in water quality, aquaculture, and ecology.
The campus also has an extensive communication and control system, another of Kvien’s interests. Sensors monitor temperature, moisture, sound, and a number of other variables, and they can be used to control functions such as irrigation. The system can be monitored through a smartphone, tablet, or computer via the local wireless network.
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This 3400-sq.-ft. net-zero-energy house on the Tifton campus of the University of Georgia is part of a project called Future Farmstead.
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I'd be interested in hearing about the true cash cost to build this...
Also, I am reasonably sure Huber specs preclude using spray foam inside the I insulated panels ( wouldn't that create a double vapor barrier at the OSB?)
Pbr