BSC Building America Performance Criteria

Requirements: Design

• Residences must reduce whole house energy use (HVAC, hot water, lighting, and all appliances/plug loads) as stipulated in the table below:

• Whole-house dilution ventilation: a mechanical ventilation system must be installed to be capable of meeting ASHRAE Standard 62.2 which stipfulates a ventilation rate of 7.5 CFM per person (counted as the number of bedrooms plus one) plus 0.01 CFM per square foot of floor area. While 62.2 stipulates that operation of the ventilation system is at the occupant's discretion and the Standard is silent regarding whole-house distribution of ventilation air, this Performance Criteria stipulates that the 62.2 ventilation flow rate be delivered at least one-third of the time and that whole-house distribution is required.
• Local exhaust ventilation: Intermittent spot exhaust of 100 CFM must be provided for each kitchen (no recirculating cooktop hoods). Intermittent spot exhaust of 50 CFM or continuous exhaust of 20 CFM when the building is occupied must be provided for each room having a toilet, bath, or shower.
• Ventilation intake locations: When a supply-only or balanced ventilation system is used, the intake must go through an outside wall and not the roof (due to proximity to exhaust/vent pollutants, and heated air/VOC's/odors from the roof). Wall intakes should be located at least 10 feet from, and not directly above, any wall exhaust or vent.
• All combustion appliances (except a gas stove or cooktop) in the conditioned space must be sealed combustion. Specifically, any furnace inside conditioned space must be a sealed-combustion 90%+ unit. Any water heater inside conditioned space must be direct- power-vented. Any boiler inside a conditioned space must be sealed combustion.
• Windows with the following climate-specific performance values must be used:
   

  Climate Zone3	Maximum U-Value	Maximum SHGC
  Zones 1-3	0.40	0.35
  Zones 4-8	0.35	0.40

• All ducts and air handling equipment must be in the conditioned space.
• Major appliances (refrigerator, clothes washer, and dishwasher) must achieve Energy Star performance in the top one-third of the DOE Energy Guide rating scale.
• All lighting must be Energy Star qualified with the following exceptions: motion-sensitive outdoor spotlights and solar-powered accent and pathway lighting. LED technology is currently not certified by Energy Star, however LEDs are acceptable.
• Carbon monoxide detectors (hard-wired units) must be installed (at one per every approximate 1000 square feet) in any house containing combustion appliances, and/or an attached garage.

Requirements: Testing

• Building America testing of the house must be completed as part of the commissioning process.  The SNAPSHOT form is a testing template and is available for download to record the testing information (Snapshot Form).  Instructions for completing the form are also available (Snapshot Instructions).
• In a production setting, each model type (i.e., floor plan) must be tested until two consecutive houses of this model type meet testing requirements. Additional, testing on this model type can be reduced to a sampling rate of 1 in 7 (i.e., 1 test, with 6 "referenced" houses). Small additions to a floor plan (e.g., bay window, conversion of den to bedroom) are considered to be the same model type; major changes (e.g., bonus room over the garage, conversion of garage into a hobby room, etc) must be considered a separate model type. Unique or custom house plans must each be individually tested.
• Air leakage (determined by pressurization testing) must be less than 2.5 square inches/100 square feet surface area leakage ratio (CGSB, calculated at a 10 Pa pressure differential); or 1.25 square inches/100 square feet leakage ratio (ASTM, calculated at a 4 Pa pressure differential); or 0.25 CFM/square foot of building enclosure surface area at a 50 Pascal air pressure differential. The calculation of the building enclosure area includes the foundation or below-grade surface areas.  If the house is divided into multiple conditioned zones, such as conditioned attics or conditioned crawl space, the blower door requirement must be met with the access to the space open, connecting the zones.
• Total space conditioning system duct leakage must be less than five percent of the total air handling system rated air flow at high speed (nominal 400 CFM per ton) determined by pressurization testing at 25 Pa. Two compliance mechanisms are acceptable: (1) test total duct leakage at finish stage, or (2) test total duct leakage at duct rough-in stage. When more than one air handler exists, each air handling system must individually meet the requirement. If zoning is used, all zone dampers must be open. Manual or motorized outside air ventilation dampers must be closed.
• Local and whole-house mechanical ventilation system airflows must be tested during commissioning of the building.
• Forced air systems that distribute air for heating must be designed to provide balanced airflow to all conditioned spaces and zones (bedrooms, hallways, basements). Inter-zonal air pressure differences, when doors are closed, must be less than 3 Pa using passive transfer grilles or jump ducts, or active return ducts (see Transfer Grille Detail and Transfer Grille Sizing Chart).

Recommendations: Mechanical Equipment

• System external static pressure must be within manufacturer specifications (0.5 WIC/125 Pa maximum typical).

Recommendations: Energy Conservation, Occupant Comfort

• Information relating to the safe, healthy, comfortable operation and maintenance of the building and systems that provide control over space conditioning, hot water or lighting energy use should be provided to occupants.
• The building enclosure and mechanical systems design should be capable of maintaining comfortable conditions throughout the conditioned space as defined by ASHRAE Standard 55-2004 (Thermal Environmental Conditions for Human Occupancy).
• Indoor humidity should be maintained in the range of 25 to 60 percent by controlled mechanical ventilation, mechanical cooling, or supplemental dehumidification. In very cold, cold, and mixed climates (Zones 4 through 8) during the winter, indoor relative humidity should be kept on the lower end of that range (see article "Relative Humidity" for guidelines). 

Recommendations: General Construction

• The building enclosure and sitework design and construction should provide effective drainage measures to prevent moisture intrusion, conveying water off of and away from the building.
• Design and construct the building foundation to prevent the entry of moisture and other soil gases.
• Building assemblies should be designed and constructed to permit drying of interstitial spaces.
• Design and construct building assemblies to prevent or control airflow into insulation systems from both the interior and exterior.
• Use radon resistant construction practices as referenced in the ASTM Standard "Radon Resistant Design and Construction of New Low Rise Residential Buildings.
• Provide filtration systems for forced air systems that provide a minimum MERV of 11 or higher.

Recommendations: Green Building

• Material use for the building enclosure should be reduced by 25% using advanced framing or systems engineering of other enclosure systems (concrete, masonry, earth-based or agricultural waste-based systems). Reference: "The Future of Framing is Here"
• Recycled/salvaged materials and new materials with a high recycled content should be used where cost effective and practical.
• Substantial substitution (30% or more) of waste materials (fly ash or blast furnace slag) for the Portland cement component of concrete and other cementitious building materials should occur. Reference: "Some Basics About Substituting Pozzolans for Portland Cement in Concrete".
• FSC (Forest Stewardship Council) certified wood products should be used whenever they are competitively available. 
• Construction waste generation should be reduced by 15% or more. Reference: "Setting Up Performance and Prescriptive Criteria for Domestic Water Use and Construction Waste Generation"
• Domestic water consumption should be reduced by 25% or more. Reference: "Setting Up Performance and Prescriptive Criteria for Domestic Water Use and Construction Waste Generation"
• A Risk Assessment Protocol should be developed to promote durability.  Reference: "Increasing the Durability of Building Constructions"