Technology Fact Sheet SPOT VENTILATION DESIGN SPECIFICATIONS N OISE For more information, contact: SPOT VENTILATION C APACITY REQUIREMENTS Noise is a major reason people avoid using Energy Efficiency and Bath fans should be sized to provide the larger of ventilation fans. Small bathroom fans (less than Source control to improve indoor air quality Renewable Energy 50 cfm or 8 ACH in the bathroom. The required 76 cfm) must have sound levels of no more than Clearinghouse (EREC) cfm capacity to provide 8 ACH can be calculated 2.0 sones to be labeled as Energy Star compliant; PURPOSE OF VENTILATION 1-800-DOE-3732 www.eren.doe.gov by multiplying the volume of the bathroom in large bathroom fans must have sound levels of no All homes need ventilation—the exchange of INDOOR AIR POLLUTION SOURCES cubic feet by 8 and dividing by 60. more than 1.5 sones. Bath fans with noise levels indoor air with outdoor air—to reduce indoor Or visit the Building of 1 sone or less are also available and should be moisture, odors, and other pollutants. Technologies Program Kitchen range hood fans should have a capacity Web site at of at least 100 cfm or 40 cfm per linear foot of considered to eliminate noise problems. Contaminants such as formaldehyde, volatile www.buildings.gov hood, whichever is larger. For peninsula or island To receive the Energy Star label, range fans must organic compounds (VOCs), and radon that may cause health problems can accumulate in poorly Or refer to Understanding ranges, the fan capacity should be based on the have sound levels of no more than 4.0 sones. The Buildings for Ventilation: How to Design, combined length of the exposed three or four sides quietest kitchen range hoods are rated at less than the 21st Century ventilated homes. Inadequate ventilation prevents Select, and Install Residential of the hood. If the hood is more than 27" above the 2 sones. If multi-speed fans are used, be sure that unpleasant odors from being removed. Excess Radon Outdoor Ventilation Systems Buildings that are more moisture generated within the home needs to be People contaminants The Healthy House Institute range surface, the capacity should be increased. the sound level at the high speed is 4 sones or less. energy efficient, comfortable, Furnishings 812-332-5073 removed before high humidity levels lead to The capacity of both bath and range hood fans is Remotely mounted fans are not typically sound- and affordable…that’s the Cleaning products www.hhinst.com physical damage to the home or mold growth. typically provided at 0.1" and 0.25" of static rated because various factors affect the perceived goal of DOE’s Building Building materials Written and prepared for pressure to account for different duct types, duct interior sound levels. Technologies Program. VENTILATION STRATEGIES the U.S. Department of length, duct configuration (number of turns and To accelerate the development Ventilation techniques and strategies have such as a garage or crawlspace, or may not Energy by: INSTALLATION elbows), and exhaust termination. See the fan and wide application of energy become more sophisticated as homes have ventilate the house uniformly. MOUNTING NAHB Research Center manufacturer’s recommendations to determine efficiency measures, the become more complex. The American Society of 800-898-2842 Seal gaskets and fan housings mounted on Whole-house ventilation—use of one or more the fan’s capacity based on these duct Building Technologies Program: Heating, Refrigerating and Air-Conditioning www.nahbrc.org ceilings or walls. In insulated assemblies, do not use fans and duct systems to exhaust stale air and/or characteristics. Generally, the capacity at 0.25" • Conducts R&D on technologies Engineers, Inc. (ASHRAE) requires that natural, or supply fresh air to the house—can better control Southface Energy Institute fans that are not rated for insulation contact. should be used. The capacity at 0.1" is usually and concepts for energy effi- natural plus mechanical, ventilation provide a 404-872-3549 the exchange of indoor air with outdoor air. appropriate only if the duct is smooth, straight D UCTS ciency, working closely with www.southface.org whole-house ventilation rate of 0.35 air changes Whole-house ventilation may be exhaust-only (one elbow or less), and less than 15' in length. If The most efficient fan ducts are smooth, short, the building industry and with per hour (ACH), but not less than 15 cubic feet (relying on leakage into the building for fresh U.S. Department of Energy’s manufacturers of materials, the duct is longer than 15', has a diameter of less straight, and properly sized. Smooth sheet metal per minute (cfm) per person. Oak Ridge National make-up air), supply-only (relying on air leakage than 4", requires the use of multiple elbows, and/ ducts offer low airflow resistance. Because equipment, and appliances Laboratory Natural ventilation—uncontrolled air movement from the building to exhaust stale air), or or uses corrugated duct material, the capacity corrugated ducts have greater flow resistance, it is • Promotes energy/money Buildings Technology Center into a building through cracks and small holes balanced systems that include both exhaust and 865-574-5206 achieved in the actual installation may be less important to keep them as short as possible— saving opportunities to both (infiltration) and through vents such as windows fresh air intake components. www.ornl.gov/btc than even the 0.25" capacity rating. stretch the corrugated material to its full length and builders and buyers of homes and commercial buildings and doors—is the traditional method of allowing Spot ventilation—the use of localized exhaust U.S. Department of Energy’s cut off excess. Minimize the number of elbows. Seal E FFICACY fresh outdoor air to replace indoor air. Nowadays, National Renewable Energy joints with duct mastic. To inhibit condensation • Works with state and local fans (e.g., kitchen and bath fans) to quickly Fan efficacy refers to the energy needed to move because of central heating and cooling, as well as Laboratory problems in unheated spaces, insulate the ducts regulatory groups to improve remove pollutants at their source as they are a specified amount of air. To calculate fan the desire for privacy, people tend to make little 303-275-3000 building codes, appliance generated—is an important tool to improve air www.nrel.gov/buildings efficacy, divide fan capacity (in cfm) by power and slope the ducts away from the fan. Ducts standards, and guidelines for use of windows for ventilation, so infiltration has quality and ventilation effectiveness whether consumption (in watts)—the larger the ratio the should match or exceed the fan duct fitting size. efficient energy use become the principal mode of natural ventilation natural or whole-house ventilation strategies are NOTICE: Neither the United States better. Both capacity and power consumption D UCT TERMINATION in homes. Unfortunately, a home’s natural used. Spot ventilation strategies are often government nor any agency values are available from the manufacturer’s Ducts expelling water vapor or other pollutants infiltration rate is unpredictable and uncontrollable thereof, nor any of their employees, integrated with whole-house ventilation designs. literature or the product container. Consider the must exhaust directly to the exterior—never into makes any warranty, express or because it depends on the home’s airtightness, In addition to its whole-house ventilation implied, or assumes any legal use of Energy Star® rated fans to reduce operation attics or crawl spaces prone to moisture problems. outdoor temperatures, wind, and other factors. requirement, ASHRAE recommends intermittent liability or responsibility for the costs. To receive the Energy Star label, small bath Use wall caps or roof jacks with flap dampers, Homes with low infiltration rates may lack accuracy, completeness, or or continuous ventilation rates for bathrooms fans (up to 75 cfm) must achieve 1.4 cfm/W or screens, or both to deter access. Unless they are usefulness of any information, sufficient ventilation for pollutant removal. Homes and kitchens as alternatives to operable apparatus, product, or process higher and larger bath fans and range hoods up already integrated into the system (e.g., wall cap with high infiltration rates may experience high windows: 50 or 20 cfm for bathrooms and 100 disclosed. The views and opinions to 500 cfm must achieve at least 2.8 cfm/W. with flapper), equip ventilation ducts with backdraft of authors expressed herein do not energy costs. Also, infiltration may allow or 25 cfm for kitchens, respectively. necessarily state or reflect those of dampers at or near the insulated building boundary contaminated air to enter from a polluted area the United States government or Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste. to reduce infiltration. any agency thereof. BUILDING TECHNOLOGIES PROGRAM December 2002 DOE/GO-102002-0786 OFFICE OF ENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY SPOT VENTILATION SPOT VENTILATION DESIGN SPOT VENTILATION ISSUES Building codes may provide specific requirements concerning Spot ventilation may contribute to unacceptable radon levels BATH AND KITCHEN FAN CONTROL SWITCHES spot ventilation. Generally, the guidelines in this fact sheet meet or inside the house if fan operation draws in radon-contaminated air VENT FANS Fan controls can be simple Spot ventilation fans in exceed code requirements; however, it is important to consult via leaks in the floor, although this is less an issue for intermittent switches activated the bathroom and local codes and code officials before sizing and installing spot fan operation. Local codes or building officials should be able to manually. For bathroom kitchen are critical ventilation systems.