Foundation System

In most areas of the United States where crawlspaces are constructed, the standard building practice is to insulate underneath floors over unheated areas. However, studies have proven that insulating the walls in well-sealed crawlspaces can be an effective alternative to the often unreliable under-floor insulation. For the Solar Energy Cottage, we implemented the technique to provide an example for others to see how well-sealed and insulated crawlspaces can perform in swampy areas.

The construction of the crawlspace consists of a poured footer with, CMU blocks stacked on top, reinforced, and filled with more concrete. Damp-proofing was applied to the exterior sides of the crawlspace walls. To the interior sides, a layer of 6 mil polyethylene was laid out with sealant applied to all seams and the edges turned up and sealed to the walls. A 1 inch extruded polystyrene board with an R-value of 7.5, was then applied to the walls beginning four inches above grade (to allow for termite inspection) and continuing to the bottom of the floor joists. The band area was then sprayed with expanding polystyrene to further insulate and seal cracks and penetrations.

Framing and Insulation Systems

Structural insulated panels (SIPs) were used in place of conventional framing for the administration building. SIPs are constructed of insulation sandwiched between two pieces of structurally sound material such as orated strand board (OSB) or plywood. Building with SIPs eliminates the need for exterior sheathing materials and insulation. SIPs also allow for short construction time since the panels are normally cut to size while in the factory with window and door openings pre-cut. The prepared panels are then delivered to the site and erected, taking approximately 3-4 days for a standard size home.

The administration building utilized SIPs for the walls and ceiling while the floor was framed. The SIPs used for the ceilings, dormers, and gable ends are made of R-38 polyisocyanurate foamboard sandwiched between two sheets of OSB. For the walls, the SIPs used are R-22.6 expanded polystyrene sandwiched between OSB.

Exterior Cladding and Drainage Plane

A drainage plane was installed directly to the exterior side of the SIPs to encourage the fast exit of any water that penetrates the exterior fiber cement cladding and prevent it from being absorbed by the OSB.

Around window and door openings, flashing was installed to protect the OSB against moisture penetration. Overhangs were also installed above most windows to serve the dual purpose of protecting the window from water damage and provide shade.

Air Leakage System

Air infiltration causes high-energy costs and can be a source of excess moisture and contaminants. The recommended strategy in both new and old homes is to reduce air leakage as much as possible and to provide controlled ventilation as needed to supply fresh outdoor air.

The key to a tight home is a good air barrier. The primary air barrier layer in the Solar Energy Cottage is the SIP and crawl space walls/ceiling separating the interior of the home from the exterior, and the layer of poly along the crawlspace floor. All plumbing, electrical, and other miscellaneous penetrations in these panels/walls were sealed with caulk or foam sealant. Window and door rough openings were also sealed with a low expansion spray foam. All doors leading outside were weather-stripped for added draftstopping.

Glazing System

Starting January 1, 2004, all homes permitted in Georgia must have windows and glass doors with a Solar Heat Gain Coefficient (SHGC) less than 0.4 and a U-factor of 0.65 or less. The SHGC is a measure of the amount of solar heat (heat radiating from the sun) that an object blocks. The lower the SHGC the more heat gets blocked. The U-factor is a measure of a material’s ability to conduct heat, or the inverse of the R-value – a material’s resistance to heat flow. The lower the U-factor, the more heat the window will block from the interior of the home.

All windows in the Solar Energy Cottage are Low E II with argon fill gas, and have a U-factor of 0.31 and a SHGC of 0.30. The windows have a fiberglass frame with wood interior façade. They are also all shaded by the porches and overhangs to help prevent direct solar heat gain.

Space Conditioning Systems

Determining the correct size of heating and cooling equipment is key for achieving comfortable interior conditions. Size of cooling systems is particularly critical for optimal energy efficiency and comfort. Over-sized equipment has a higher initial cost, costs more to operate, and can lead to discomfort because humidity removal is compromised. The space-conditioning system for the Solar Energy Cottage was sized using Manual J calculation methods and detailed thermal performance information.

The 14 SEER heat pump chosen for the Solar Energy Cottage has a HSPF of 8.95 and is used in conjunction with a 2.5-ton indoor coil that has a variable speed blower. A programmable thermostat that allows different temperature settings on various days controls the heat pump.

Ventilation System

All homes need ventilation – the exchange of indoor air with outdoor air – to reduce indoor moisture, odors, and other pollutants. Ventilation can occur four ways 1) natural ventilation – opening windows, 2) air infiltration - uncontrolled air movement into a home through cracks, small holes, doors, and windows, 3) spot ventilation – the use of localized exhaust fans (e.g., kitchen range and bath fans), and 4) whole house ventilation – the use of one or more fans and duct systems to exhaust stale air and supply fresh air to the house. The goal is to minimize air infiltration and use other ventilation methods.

A whole house dehumidifier provides supplemental dehumidification to the Solar Energy Cottage. Whole house ventilation is provided by a central fan-integrated ventilation system with a motorized damper, using the controller built into the whole house dehumidifier.

Duct System

Typical duct leakage in new homes can exceed 20%. Under the EarthCraft House and Building America guidelines, the Solar Energy Cottage ductwork could have no leakage to the outside (all ducts are located in the conditioned crawlspace and interior walls), and less than 5% leakage to the inside. Testing results show that the building had no recordable duct leakage. To ensure the building performed this well, all seams and penetrations in the duct system were sealed with mastic.

A detailed duct design was drawn up for the home to ensure proper placement of supply and return boots, and adequate air distribution for each individual room. To prevent extensive duct runs, trunk lines were used with short take-offs to individual boots. All boots were caulked to the interior finish wall or sub floor.

Even with today’s advanced software packages to size heating and cooling equipment and the duct system, some adjusting was still needed after installation to ensure proper airflows in the separate rooms. Balancing dampers were installed at all take offs from the main trunk line and at all y-splitters. Once the building was complete, diagnostic tests were run and the dampers were manually adjusted to ensure each room was receiving adequate airflow.

Hot Water System

Selecting the appropriate fuel and water heater type, using efficient system deign, and reducing hot water consumption can manage water-heating energy costs. Water heating options include solar water heating, storage water heaters, combination space and water heating systems, tankless coil water heaters, and tankless water heaters.

For the administration building a 50-gallon storage electric Marathon hot water heater with an energy factor (EF) of 0.94 was used.

Renewable Energy System

One of the main goals of this project was to show people how they can generate some or all of the electricity required to run their home. We estimate 67% of the electrical energy required to run the Solar Energy Cottage (heating, cooling, hot water, and electrical appliances such as computers) will be provided by the 4.1kW photovoltaic (PV) array. The PV system is connected with the utility grid so that when the panels are producing more power than the home is using, the extra power will be fed into the grid for others to use. Likewise, when the panels are producing less power than the home requires, the missing power will be provided to the home by the grid.

Lighting System

Traditional (incandescent) lighting is not efficient when compared to compact fluorescents. With an incandescent bulb, for every $1 spent on electricity, about 10¢ goes to light and 90¢ goes to heat. The wasted energy increases lighting and air conditioning costs and is responsible for over 500 pounds of atmospheric pollution. The Solar Energy Cottage will displays a variety of compact fluorescent light fixtures along side traditional light fixtures housing compatible compact fluorescent light bulbs.

Indoor Water Conservation

By the year 2050, the worldwide availability of freshwater will have decreased by a third as a result of global warming, population growth and wasteful habits. The natural underground aquifers will be at all-time low levels. Scarcity of fresh water will become the limiting factor for healthy, livable communities. Using water conservation techniques helps reduce negative impacts on our water supply, keeping our cities vibrant and healthy.

All faucets in the Solar Energy Cottage meet or exceed the National Energy Policy ACT (NEPA) standards. (NEPA requires a flow of 2.5 gal/minute or less.)

Recycled Material Use

Sustainable buildings strive not only to reduce the amount of energy required to run them, but also the amount of energy needed for construction. One way of reducing the environmental impact of a building is by using recycled materials in the construction process. The administration building displays recycled porch decking made out of post consumer plastic bottles. The carpet in the building was made from recycled materials and used a low volatile organic compound (VOC) adhesive for a healthier indoor environment.

Sponsors Many organizations and companies made this project a success including:
	Advanced Energy Inc.
	Building America
	Building Science Corporation
	Carpet and Rug Institute
	Classic Products
	Copper Development Association
	EarthCraft House
	Eaton Cutler Hammer
	Evergreen Solar
	EXPO Design Center
	Fantech
	Future Smart Networks
	Georgia Environmental Facilities Authority
	Georgia Pacific
	Heat-N-Glo
	Husky Hardwoods
	Ingersold Rand Schlage
	Insulspan
	LP
	Marvin Windows
	OneWorld Renewable Technologies
	Panasonic
	Phillips
	Pure A Tech
	R-Controlled Allied Foam
	S-5
	Sherwin Williams
	Southface energy Institute
	Spalding Truss
	Sun Systems, Inc.
	TOTO
	U.S. Department of Energy
	Unirac
	Whirlpool
	Winterpanel