Building Materials and Techniques

The types of building materials used affect a home's longevity. The Westbrook Solar EarthCraft House incorporates the use of sustainable building materials and techniques including:

• Caulk with low volatile organic compound (VOC) content
• Cellulose insulation made from recycled newspaper
• Engineered wood products stretch wood resources, are structurally superior, and can be made from new growth trees
• Advanced framing techniques save lumber while allowing complete coverage of insulation on exterior walls
• Fibrous cement siding made from natural materials is durable and requires little maintenance

A radiant barrier (a reflective foil coating on the underside of the roof decking) helps keep the attic cooler during summer months

• French drain around exterior perimeter of footer
• Drainage matt installed along exterior of all below-grade foundation walls provides air space for proper water drainage
• Foundation walls covered along the interior with rigid foam insulation to prevent condensation
• Overhangs above all doors
• High efficiency bath fans vented to the exterior
• Kitchen range hood vented to the exterior
• Direct vent water heaters, furnace, and fireplace, vented to the exterior
• Capillary break installed between foundation and framed walls to prevent wicking of water

Housewrap properly installed on the exterior of all above grade walls provides a drainage plane for water that gets behind the siding

• Eliminating gaps in exterior sheathing and interior drywall reduces air leakage from:
  - Exterior walls of fireplace chase
  - Exterior sheathing under cantilevered framing
  - Behind tubs on exterior walls
  - Duct chase connections to the attic
  - Recessed ceiling lights
  - Door and window rough openings
  - Penetrations into the band area, interior and exterior sheathings
  - Bottom plates between wood framing and concrete foundation or subfloor

• Weatherstripping applied on all exterior windows and doors
• Blocking and sealing between attic and conditioned space prevents air leakage between the two

Insulation

The Westbrook Solar EarthCraft House features a mix of insulation types to minimize heat transfer through the walls, ceilings and floors. Insulation upgrades to the home cost approximately $1,000 for labor and materials.

• 50% of the exterior sheathing is R-3 rigid foam board
• R-13 cellulose insulation sprayed into exterior framed walls
• R-8 rigid foam board insulation and R-13 sprayed cellulose insulation on foundation walls
• R-38 loose-fill cellulose ceiling insulation
• R-4 exterior doors

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Basement

The Westbrook Solar EarthCraft House demonstrates how to properly seal and insulate a basement to increase comfort, save on energy costs, improve durability, and reduce the entry of moisture, soil gases and other pollutants into the home. The basement features include:

Heating, Cooling and Fresh Air Ventilation

On average 41% of a home's energy usage can go to conditioning (heating and cooling) the house. Determining the correct size of heating and cooling equipment is key to achieving comfortable interior conditions -- temperature and humidity -- and saving on the cost to buy and operate equipment. Estimated cost for all HVAC improvements is $2,500.

Home Appliances and Lighting

Lighting and appliances account for more than 45% of all energy bills in a home. Every $1 spent on electricity for an incandescent bulb, provides 10¢ worth of light and 90¢ worth of heat. The estimated upgrade cost for all lighting improvements in the Westbrook Solar EarthCraft House is $300. No additional costs are added for using energy efficient appliances since they are widely available.

• Most appliances in the home meet or exceed ENERGY STAR® standards reducing the amount of energy used to run the appliances by approximately 35%

Indoor Water Conservation

Atlanta, like many communities, is facing a water crisis. Water efficient fixtures save money, provide high performance and protect the environment.

• Dual flush toilets offer the option of using a 0.8-gallon flush or a 1.6-gallon flush depending on the amount of water needed

Water Heating

Water heating is typically 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 design, and reducing hot water consumption can manage water heating energy costs.

• Two direct vent, tankless natural gas water heaters with a total upgrade cost of $1,100
  

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Windows

The Georgia Energy Code encourages that windows and glass doors used have 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. U-factor measures the amount of heat conducted through a material. U-factor is the inverse of the R-value. The lower the U-factor, or the higher the R-value, the more efficient the window.

• All glazing installed in the home is low-E, double paned, wood framed, with a U-factor of 0.35 and a SHGC of 0.34

Photovoltaic System

Photovoltaic (PV) systems silently generate electricity from free sunlight. The Westbrook Solar EarthCraft House demonstrates how PV systems can offset the amount of electric power needed from conventional power plants to improve air quality and reliability.

• The cost for the installed PV system was approximately $13,000

More Information

To view a technical report of the Westbrook Solar EarthCraft House, click here.

To view the technical report of the Westbrook Solart EarthCraft House by IBACOS, click here.

To learn more about the above categories, please visit Southface's factsheet archive.

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