Foundation System

Basements are notorious for problems with water intrusion, cold temperatures, humidity, mold, and uncomfortable, if not unhealthy, living conditions. The Westbrook Solar EarthCraft House demonstrates how a properly sealed, insulated, and moisture-protected basement increases comfort, saves on energy costs, improves durability, and reduces the entry of moisture, soil gases, and other potential irritants or pollutants into the home.

A drainage matt was installed along the exterior of the below grade foundation walls to assist in the movement of excess water to the foundation drain located around (not on top) of the footer. This technique has proven to be very effective in diverting water away from below grade walls and keeping the interior of the home dry.

To prevent condensation from occurring on the foundation walls and to maintain a more constant temperature throughout the basement, the interior side of the foundation walls were covered with a layer of R-8 foam board followed by a 2x4 framed wall filled with R-13 spray applied cellulose insulation. The framed wall was then sheathed with a layer of drywall.

The top of the foundation was sealed to the bottom plates of the framing structure through the use of sill seal and spray applied foam. The sill seal also provided a capillary break between the top of the foundation walls and the bottom plate of framed walls to stop any water from wicking into the framed structure by the wood.

Exterior Claddings and Drainage Plane

The exterior walls of the home are what separate the occupant(s) from ambient weather conditions. The walls need to be able to handle heavy rain and high humidity levels preventing damage to the wood-frame structure. The walls also need to be able to dry once they get wet. The Westbrook Solar EarthCraft House shows how cost-effective preventive measures can be taken to ensure this is possible.

The exterior cladding of the home on the terrace level is brick, while the first and second levels are covered with fiber cement siding. Behind the brick and siding, a drainage plane was installed to encourage the fast exit of any water that penetrates the exterior claddings and prevent water from being absorbed by the framing structure of the home.

Around window and door openings flashing was installed to protect the wood framing members against moisture penetration, and to provide proper exiting of any water that flows along the drainage plane.

Inside the home measures were taken to prevent interior moisture problems from arising. For example, where the master shower pan liner intersects with the curb, the pan liner is often cut back on the sides so it can continue over the curb creating a vulnerable area for water intrusion into the framing of the shower. In the Westbrook Solar EarthCraft House, flashing was applied where the liner was cut to provide extra protection against water being absorbed by the wood framing.

Insulation System

Insulation in a home works to prevent heat transfer through a wall, ceiling, or floor. The higher the R-value of an insulation, the more effective it is at stopping heat transfer. Properly sealed and insulated walls help increase comfort, reduce noise, and save on energy costs.

Approximately 50% of the exterior sheathing on the Westbrook Solar EarthCraft house is R-3 rigid foam board. The exterior framed walls were sprayed with R-13 insulation. Special attention was paid to ensure insulation was installed behind showers and bathtubs, areas often missed in conventional construction.

As noted before, the foundation walls have a total insulation value of R-21. (R-8 rigid foam board and R-13 spray applied cellulose insulation.) The ceilings of the home were insulated with R-38 loose fill cellulose insulation.

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 was 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 in the home is the foam board/OSB sheathing on the exterior walls of the house, and the drywall ceiling separating the conditioned space from the attic space. All plumbing, electrical, gas, and other miscellaneous penetrations in these sheathings, as well as ones that enter into the band areas of the house, were sealed by caulk or spray applied foam sealant. All recessed can lights used in the home were airtight and sealed to the drywall.

All the exterior door and window rough openings, including the attic access door, were sprayed with non-expanding foam sealant to insure a tight connection between the exterior sheathing and window/door frame. Weather stripping was applied to all exterior doors.

As noted earlier, all bottom plates between the top of the concrete foundation and bottom of the wood-framing members were sealed. Airsealing and draftstopping materials were applied behind all bathtubs and showers located along exterior walls.

The exterior walls of the fireplace chase, as well as the cantilevered floor created by the fireplace chase, were insulated to R-13, and then draftstopped with fire rated sheetrock that was sealed at all intersections. In traditionally constructed homes, this fireplace draftstopping detail is often missed. Usually the builder insulates along the face wall of the fireplace and does not provide an air barrier between the insulation and open chase cavity or beneath the cantilevered floor. Due to this, fireplace chases are often attributed to major air leakage and homeowner discomfort.

Ductwork chases pose similar types of problems as fireplaces do in conventional homes. In the Solar EarthCraft House, all duct chases were insulated and draftstopped along the exterior walls, with blocking and airsealing where they enter into the attic space.

Framing System

Advanced framing techniques were implemented in the home to allow the use of less lumber and to provide room for the complete coverage of insulation in exterior walls. Some of these techniques include ladder t-walls, two stud corners, and insulated headers. Engineered wood products were used throughout the home allowing the builder to use less lumber by placing floor joists 19.2” on center as compared to the conventionally required 16” on center, and allowing the wood that was used to be new growth wood as opposed to old growth making the materials more sustainable in the eyes of the lumber industry.

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.

One way of complying with the new law is by installing windows that have a low-e coating. Low-emittance coatings are metal or metallic oxide coatings that are not visible to the naked eye. They are applied to reduce the amount of radiant heat transfer through the window. This is important because most of the air conditioning load in the summer is due to radiant heat gain from windows.

All glazing installed in the Westbrook Solar EarthCraft House is low-e, double paned and wood framed, with a U factor of 0.35 and a SHGC of 0.34.

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. On average 41% of a home’s energy usage goes to conditioning (heating and cooling) the house. With this in mind, the Westbrook Solar EarthCraft House displays the most efficient space conditioning systems suitable for the home.

The space-conditioning system for the home was sized using Manual J calculation methods and detailed thermal performance information. Based on these calculations, it was decided that one 5-ton air-handling unit, located within conditioned space, would be sufficient to serve the entire house. Built conventionally, this house would have two separate units (totaling 8 tons) that would serve each floor. The total cooling loads were less for the one unit system because of its location in conditioned space and the factoring in of all thermal performance attributes in the house. Temperature control for each floor is maintained in the design with a mechanical zoning system. Advantages include having one piece of easily accessible equipment instead of two units, being easier for homeowners to maintain with fewer filters to change/clean, and cost savings.

Heating is provided by a variable speed, direct vent natural gas furnace with a heating efficiency of 94% AFUE. The cooling system is rated at 14.25 SEER. Having a variable speed system is important because it allows the system to run at a lower speed when demands are less, insuring proper dehumidification. Being directly vented is equally important since it ensures that no combustion air will be taken from, or is backdrafted into, the home.

For air filtering, an upgraded electronic filter and UV light were installed. Electronic filters never need changing and therefore cause less trash for our landfills, however they must be washed every 1-2 months.

Programmable thermostats on each level control the space conditioning system, automatically allowing different temperature settings during the day and week to save energy.

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 three ways 1) natural ventilation – uncontrolled air movement into a home through cracks, small holes, doors, and windows, 2) spot ventilation – the use of localized exhaust fans (e.g., kitchen range and bath fans), and 3) whole house ventilation – the use of one or more fans and duct systems to exhaust stale air and/or supply fresh air to the house.

Spot ventilation is located in the kitchen as well as all of the bathrooms. All bath fans are vented to the exterior and were wired to the light switches so that whenever someone is in the bathroom, the fan runs removing any excess moisture being produced.

Whole house ventilation for the Westbrook Solar EarthCraft House is met and controlled by a ventilation dehumidifier. Due to the tightness of the house, a fresh air intake duct draws outdoor air in and conditions it before it is introduced into the air distribution system. The unit also dehumidifies existing indoor air in order to insure the relative humidity stays at a comfortable level.

Duct System

Typical duct leakage in new homes can exceed 20%. Under the EarthCraft House and Building America guidelines, a home’s ductwork must have less than 5% leakage to the outside. The Westbrook Solar EarthCraft House has ****% duct leakage. The following steps were taken to ensure the home performed this well.

All the ductwork consists of sheet metal or flex duct; no panned ductwork was allowed. All connections and seams in the ductwork were sealed with mastic and mechanically fastened. (On larger gaps and connections, foil tape was applied to serve as a solid surface over which the mastic could then be spread on top and at least 2” in all directions past the edges of the tape.) Ductwork was wrapped in R-6 insulation to prevent heat loss in the winter, and heat gain and condensation in the summer.

A detailed duct design was drawn up for the home to insure 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 sheetrock or sub floor.

Even with today’s advanced software packages being used to size the heating and cooling equipment as well as the duct diameters and layout, some adjusting was still needed after installation to insure proper airflows in every room. In preparation of this, balancing dampers were installed at all take offs from the main trunk line and at all y-splitters. Once the home was complete, diagnostic tests were run and the dampers were manually adjusted to insure each room was receiving adequate airflow.

Domestic Hot Water System

Water heating is the third highest energy cost in a home - 16% of total energy cost on average. 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 model home, we decided the best type of water heating system was a gas tankless water heater. Tankless water heaters heat water directly, more efficiently, and without the use of a storage tank, thereby leaving more space for the homeowner. The gas powered model we chose can produce a 50? F water temperature rise at a flow rate of 5.2 gallons per minute which allows for two showers to occur simultaneously.

Renewable Energy System

One of the main goals of this project was to show people how they can feasibly create some or all of the energy required to run their home. Some of the electrical energy required to run the model home will be provided by a 2kW photovoltaic (PV) array. Like all other Zero Energy Homes, the PV system will be connected with the utility grid so that when the panels are producing more power than the home was 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 consumes unreasonable amounts of energy 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 Westbrook Solar EarthCraft House displays a variety of compact fluorescent light fixtures along side traditional light fixtures housing compatible compact fluorescent light bulbs. As a result the amount of energy due to lighting is reduced by approximately 40%.

Appliances

Where ENERGY STAR® standards exist, appliances installed in the home meet or exceed ENERGY STAR standards. 35% in energy savings (for this end-use) are expected due to the high efficiency appliances.

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.

The average U.S. household uses 146,000 gallons of water per year with up to 20% of that water going towards toilets. The Westbrook Solar EarthCraft House displays dual flushing toilets that will give the user the option of using a 0.8 gallon flush or a 1.6 gallon flush depending upon the amount needed. By using the dual flush toilets, we estimate the household will use 7,300 gallons of water per year less than a comparable home built today.

All shower and sink fixtures in the home are low flow, meeting or exceeding the National Energy Policy Act (NEPA) standards. (NEPA requires a flow of 2.5 gal/minute or less.)

Sponsors Many organizations and companies made this project a success including:
	Big Frog Mountain Corporation
	Bosch
	Building America
	EarthCraft House
	Georgia Environmental Facilities Authority
	Georgia Pacific
	Hedgewood Properties
	Honeywell
	Hughes Supply
	IBACOS
	Lithonia
	Reliance Heating and Air
	Rheem
	Southface Energy Institute
	U.S. Department of Energy