The debate heats up among builders and engineers over the need for new ventilation standards

Fanning the flames: the debate heats up among builders and engineers over the need for new ventilation standards

Sharon O’Malley

In a move that has the National Association of Home Builders fighting mad, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has adopted a standard that could spur code officials to require builders to install mechanical ventilation in new homes,

Calling it a “one-size-fits-all approach,” Jeff Inks, assistant staff vice president for construction codes and standards at the NAHB, criticizes ASHRAE standard 62.2 for its “subjective assumptions” about the way homeowners use bathroom fans and windows.

The standard, which was published in December after appeals by the NAHB, two gas associations, and the Association of Home Appliance Manufacturers failed, could raise the builder’s cost per home by up to $1,000, pricing 337,000 potential home buyers out of the market, contends Inks.


In the works for more than six years, 62.2, ASHRAE’s first residential indoor air quality standard, recommends that every new home come with some form of continuous mechanical ventilation–such as a super-quiet, continually running bathroom fan vented to the outdoors; a heat- or energy-recovery ventilator; or a controlled air inlet into the return side of the air conditioning system’s air handler. It also says each bathroom and kitchen should have an exhaust fan vented to the outside for spot ventilation.

In addition, the guidance, which is expected to be incorporated into some local building codes by around 2008, calls for ventilation in garages and unconditioned attics and crawlspaces that are adjacent to living areas, and for builders to do a backdraft test on some water heaters located within a home’s living area.

The standard, which is voluntary until code officials opt to incorporate it into local laws, is “good, basic common sense,” notes Max Sherman, a Lawrence Berkeley National Laboratories engineer who chaired the ASHRAE committee that wrote it. “People need fresh air. The standard tells how to provide it.”

Sherman says the envelope of the modern, energy-efficient home is so airtight that fresh air can’t penetrate it in the quantities needed for healthy indoor living. Occupants of homes with stale, dirty air, he notes, suffer from maladies ranging from asthma to allergies, and their homes are at risk for damage from mold.

And Sherman says the cost to comply with the standard is between $100 and $200, as most builders already install bathroom and kitchen fans and could meet the requirement for continual ventilation by upgrading just one of them to an ultra-quiet model that residents would be willing to run all the time.

“You certainly could spend thousands to meet the standard if you want to, but that’s a question of design,” the engineer says. “If you set out to meet the standard in a cost-effective manner, it doesn’t cost that much. Some builders are already doing it and don’t even know it.”


Indeed, estimates Patrick Nielsen, product manager for bath fans at Broan-NuTone, 90 percent of builders already install bathroom fans that meet ASHRAE’s minimum requirement for airflow of 50 cubic feet per minute (cfm), a measure of how much air the fan moves. But because noisy fans are less expensive than quiet ones, most builders choose fans with a sound–or sone–rating of 4 or higher, which is about as loud as a normal conversation of the comfortable volume on a television or radio.

ASHRAE says bathroom fans that provide intermittent ventilation should have a sone rating of no higher than 3, and those intended for non-stop operation–only one such double-duty fan is needed per house–should carry a sone rating of 1 or less, the equivalent to the unobtrusive sounds of a quiet night in the suburbs. Sherman says homeowners are more likely to let a fan run around the clock if it’s so quiet they can’t hear it.

Builders pay about $10 for a Broan-NuTone fan with a sone rating of 4; $25 to $30 for a fan with a sone rating of 3; and $70 to $80 for a fan with a sone rating of 1, Nielsen estimates.

“It’s not going co break the bank at all,” notes Juneau, Alaska, custom builder Marquam George, a member of the ASHRAE committee that wrote the standard.

But Custom builder Dwight “Sonny” Richardson Jr., NAHB’s representative from Alabama, disagrees. He says he will have to increase the size of the air conditioning units he installs by a half ton per floor if he is forced to vent bathrooms and kitchens co the outside.

Richardson says the five homes he builds every year in Tuscaloosa feature premium insulation, double-glazed windows, and foam-filled doors to keep the summer humidity and 100-degree-plus heat out of the house.

“If we have to design for the extremely hot and the extremely wet, it’s more front-end costs for the equipment and also higher operational costs,” the builder says, explaining that a larger air conditioning system installed to accommodate summer humidity will sit dormant for much of the year.

Besides, Richardson notes, the Tuscaloosa lifestyle involves often-open windows and doors, so plenty of fresh air finds its way into even the tightest homes.

“We’re caught in a catch-22,” he says. “If we get the reputation of building houses that are expensive to heat and cool, then we’re shot.”


Yet some–even manufacturers who stand to benefit from increased sales of ventilating equipment should the standard find its way into local building codes–say the document doesn’t go far enough.

The guidance says the mechanical ventilation system should draw outdoor air inside at a rate of 7.5 cfm per person plus 1 cfm per 100 square feet, an amount Dennis Dietz, vice president of engineering for American Aldes Ventilation, says is half of what people need for healthy living.

“This is going in the wrong direction,” he says, adding, “The standard does a disservice.”

Nielsen agrees that “it’s definitely a very minimal standard.” But he adds, “we’re definitely at least making ground. There are still too many basic 50-cfm bath fans going in very large bathrooms. I’d like to think that [the standard] is slowly making progress on that.”

George, who admits that the standard “most certainly was a consensus” that “didn’t get out what the committee wanted out there”–partly because of NAHB’s opposition–adds, “It’s a great step in the right direction … for both the consumers and the builders out there.”

Production builder Max Wade, vice president of Artistic Homes in Albuquerque, N.M., goes further: “It’s absolutely necessary. Yes, those things add to the price of the home, but the potential liability and actual liability are far greater than how realistic it is just to put in the fans.”

In Minneapolis and Washington, every builder already installs mechanical ventilation because building codes require it, as do local codes in various cities around the country.

“It’s working out fine,” says Ed VonThoma, product development manager for Centex Minnesota, who says the builder has had fewer callbacks and “comfort complaints” since it started installing in-line fans in mid-range homes and heat-recovery ventilators in upper-end models.

“In Minnesota, where you’ve got an extreme climate, you can’t rely on the homeowner to operate the windows for the air changes, so you’ve got to rely on mechanical means to do that from controlled sources,” VonThoma says.


But what’s necessary up North may not be a best building practice nationwide, says NAHB’s Inks. “There’s no dispute that whole-house ventilation is a viable means for controlling ventilation and indoor air quality, but in terms of establishing a one-size-fits-all approach, it’s not the way to go,” he says.

Inks objects to a standard that he says is based on a subjective definition of “acceptable indoor air quality”–ASHRAE calls it air that satisfies “a substantial majority of occupants”–and a lack of data to substantiate the need for mechanical ventilation. In addition, he says a good test for backdrafting is not available.

“This is not to say that this kind of guidance is not needed,” he concedes. “But why don’t we take a different tack and develop a guidance document that would allow us to be much more flexible?”

In fact, Inks notes, the NAHB is creating such a guidance for its members. “You’re better off to provide guidance [rather than a standard that could become law] because home construction varies so greatly from area to area,” he says.

Richardson agrees. “We always prefer a market-driven approach and we always prefer an education approach to mandatory things,” he says. “We think a consumer is fully capable of understanding and telling a builder what he wants.”

The NAHB has appealed to the American Standards Institute to reject the ASHRAE standard. In the meantime, many builders are adding mechanical ventilation, either in response to local codes of customer demand.

“It’s all in how it’s marketed,” notes Randy Folts, national vice president of construction for Pulte’s Arizona, Nevada, and New Mexico operations. “This is a price-per-square-foot industry. You still have to have the right product at the right location for the right value. If you have that and [mechanical ventilation] as a feature, it gives you something strong against your competition. It helps you differentiate yourself.”

NuTech Solutions. The Lifebreath heat recovery ventilator eliminates the need for separate exhaust fans in kitchens and bathrooms. The unit features aluminum heat exchange cores, a built-in dehumidistat, and a five-speed control. 514-457-1904. www.lifebreath. com. Circle 310.



A sone measures sound output. Sones translate decibel readings into numbers that correspond to the way people sense volume, and follow a linear scale, like inches (see chart below). Sone readings offer quick sound comparisons for laymen and engineers.


Sound Level Situation Sone Level How We Feel

Traffic Noise 8.0 Conversation with

7.0 Added Noise



TV/Radio 4.0 Normal

3.0 Conversation

Calm Office 2.0


Night in Suburbs 1.0 Comfortable Zone

Free from Noise

Rustling Shrubs 0.5

Panasonic. The WhisperLite ventilation fan features sone ratings from 0.3 to 1.2, and is rated for continuous operation. The fan, which is Energy Star-rated, mores as much as 110 cubic feet of air per minute. Installation is via a double-hanger bar system. 866-292-7292. Circle 311.


American Aldes Ventilation. The SV160 multi-port bathroom exhaust system can be installed between floors and in drop ceilings. The unit allows the builder to vent two areas with lower-flow ports (40-50 cfm each) and one area with a more powerful port (80-100 cfm). The fan’s acoustically insulated motor uses 80 watts of energy. 800-255-7749. Circle 312.


Research Products. This Aprilaire energy recovery ventilator is an efficient, effective way to exchange scale inside air for fresh outside air. In winter months, the exclusive EnergyMax Transfer Core uses the heat of indoor air to warm up the incoming cold fresh air, recovering about percent of the energy, the firm says. In summer, warm fresh air passes near outgoing conditioned air, cooling it down. 888-257-8801. Circle 313.


Broan-NuTone. Featuring a curvy design, K3500 series range hoods sit a minimum of 24 inches above the cooking surface. An optional flue extension for a 10-foot ceiling is available, as is an exterior blower version. The hoods feature multi-speed, electronic push-button controls with individual speed indicators and halogen lighting that can be set bright for cooktop illumination or low for nighttime. 800-558-1711. Circle 314.


Fantech. The company sells its dual-point in-line bathroom fan as part of a ventilation kit that includes one 243-cfm bath fan with mounting bracket, one Y-adapter, and two 6-inch decorator grilles with clamps. The fan may be mounted remotely–in an attic, for instance–to keep the sound away from the living space, or placed directly over a toilet or tub. 800-747-1762. Circle 315.


York. The Maxa-Miser energy recovery ventilator absorbs heat in the home’s exhaust air and transfers that energy into the intake air, warming the air in the winter and cooling it in summer. This process reduces heating and cooling loads and the associated energy costs, the firm says. By tempering intake air temperature and humidity to match the temperature and humidity level of indoor air, the unit also helps to provide more consistent indoor air quality. 877-874-7378. Circle 316.


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