Indoor air quality is a phrase that makes most people think about mold. But the truth is, IAQ involves much more than mold. In fact, the U.S. Environmental Protection Agency lists 14 pollutants as sources of IAQ problems. Mold certainly contributes to a home’s IAQ problems, but more important is controlling sources of pollutants in the first place.
Controlling IAQ pollutants at the source is only part of the systems approach to good IAQ, according to the EPA; proper ventilation and air filtration are the other parts. With tighter homes and constantly advancing building product technology, ensuring good IAQ has never been more important.
The American Lung Association cites a roughly 65 percent increase in childhood- and adult-onset asthma in the past decade, and similar increases in allergy development, as cause for concern over IAQ. “It’s a paradox because during that decade, the outdoor air has improved in general, in terms of the ozone and the particulate loads we’re exposed to. So the logical conclusion is that IAQ is worse,” says Steve Klossner, technical director for the ALA Health House.
According to the EPA, less than 20 percent of Americans believe the air inside their homes is more polluted than the air outdoors, even though the EPA states levels of air pollution inside a home can be two to five times higher than outdoor levels, and nearly 75 percent of Americans live with someone who has allergies, asthma, emphysema or another respiratory illness. In addition, asthma annually accounts for an estimated 3 million lost workdays for adults and 10.1 million lost school days for children.
One bit of IAQ misinformation is the belief that a tightly built house cannot have good IAQ. Tight homes can have good IAQ if pollutants are addressed, says John Girman, senior science adviser, indoor environmental division, EPA. “Builders ask, ‘Can a home be too tight?’ So we came up with a list of must-have specs to reduce the risk of poor IAQ. It can be found on the Energy Star website at energystar.gov/homes. In the box on the right, click on Indoor Air Package to see the list of specs.”
When tight construction is done right, it is the backbone of good IAQ, Klossner says. The saying goes: Build it tight; ventilate it right. Proper ventilation and air filtration must work together in any home, especially in tight homes, for good IAQ. The technology of whole-house filtration systems has improved enough to dispel outdated myths builders or architects might believe, he adds.
“The reputation filters have for creating high static pressure problems by prohibiting airflow is for the most part an old problem that has been remedied. I’m not sure if there’s one single fear builders or designers have that stops them from accepting new IAQ products, construction styles and techniques except that, in general, they’re not quick to embrace changes,” he says.
The ALA Health House program, which certifies homes built to specific guidelines, has been around for more than 10 years, and continues to stress efficiency and durability. The root of the Health House program is a systems approach to moisture control and sound VOC practices, including continuous ventilation, CO combustion control and filtration/pressure control.
Builders who join must build homes according to ALA guidelines to earn the Health House label. One Health House must be built each year to maintain qualification as a Health House builder. Completing continuing education courses is an alternative to building one home a year.
Builders benefit by minimizing exposure to risk, by third-party confirmation of how a house performs when turned over to the owners. “At first builders think it’s a marketing program, but it becomes more than that after a few years,” he says. For more information visit healthhouse.org.
The road to better IAQ takes builders through source control, proper ventilation and air filtration. The EPA website (epa.gov/iaq) includes a wealth of information on the sources of, and solutions to, IAQ problems, and outlines steps to take to arrive at good IAQ.
Step one is source control. “To control mold, for example, you must eliminate moisture. If you don’t eliminate mold, you can only treat it after it’s airborne. And mold particles are heavy, so they’re not always in the air long enough for air cleaners to catch them,” EPA’s Girman says.
Step two is proper ventilation by increasing the amount of outdoor air coming indoors. Most home heating and cooling systems, including forced-air heating systems, do not mechanically bring fresh air into the house. Opening windows and doors, operating window or attic fans when the weather permits, or running a window air conditioner with the vent control open increases the outdoor ventilation rate.
The third step is air filtration, which can be accomplished with different products. One product is a whole-house air cleaner, several of which are highlighted below:
Electronic air cleaners
Electronic air cleaning systems are similar in their use of electricity to charge particles in the air and then catch those particles on oppositely charged surfaces. They differ in how they apply the initial charge, and the surface on which the particles are trapped. But they all produce small levels of ozone, a recognized pollutant. They use a combination of electrically charged wires, plates, grids and deep-pleated filter media to clean the air. They are installed next to the air handler, requiring in general an extra foot of space for installation.
Honeywell offers its F300 air cleaner, which includes a feature that adjusts the power supply as the filter gets dirty to minimize strain on the HVAC equipment. “We increase the voltage through the collector grid to make sure we attract a high percentage of dirt. Based on conditions, the filter can last up to a year, but with so many variables like pets, or living in an area like Phoenix with dust storms, it can be down to a six-month range,” says Jeremy Peterson, senior marketing manager, Honeywell Homes.
The majority of sales for this unit is in the retrofit market, not new construction, because the HVAC contractor speaks directly to the homeowner, Peterson says. “Builders can be nervous about the price-point of these products so homeowners might not get the chance to learn about the available solutions. Whole-home solutions enhance the value of a home, and make builders look more professional while allowing them to distinguish themselves by offering such a comfort and benefit to their customer.”
Carrier’s take on the electronic air cleaner is the Infinity Air Purifier, whose collection media includes a permanent electronic field that not only traps, but also kills, what it catches. The media filter needs to be changed, not cleaned. “This is patented technology no one else has. It kills the things that are captured, including airborne bacteria, mold and fungi, pollen, allergens, and also weapons-grade anthrax. The particles are electrocuted,” says Mike Branson, manager, systems products, Carrier Corp.
“This product is more likely to be in a remodel application than new construction. We’re finding the challenge is getting builders to offer whole-house air cleaners, not getting the homeowners to want them. Consumers are unaware that their builder can be a source of information. These products are out of many builders’ comfort zone, but it’s a new market opportunity,” Branson says.
Outdated concerns might contribute to builders’ resistance to electronic air cleaners. “We’ve overcome installation restrictions, and nuisances like popping and the excessive amounts of ozone they produce,” Branson adds.
The Aprilaire 5000 electronic air cleaner includes a filter with 6-in. pleats, which translates to effectiveness at trapping particles, and a need to change the filter only once a year. The air cleaner has low airflow resistance to minimize static pressure drop and strain on HVAC equipment. “If you unfold our filter material, you’d find it’s 40 ft. long. With that much surface area, you get low air resistance,” says Tom Rodgers, marketing director, Aprilaire.
Rodgers’ take on consumers’ slow acceptance of whole-house air cleaning technology is a lack of awareness. “We conducted a national consumer study in 2004 that found less than 5 percent of consumers realized whole-house air cleaners existed. The most effective way to sell these products is for the homeowner to talk to the heating and cooling contractor directly. Even in custom home building, the homeowner might not be allowed to talk to the trades. But it would be beneficial to the homeowner, and could result in profit for the builder,” he says.
In simple terms, filter media whole-house air-cleaning products are similar to the 1-in. furnace filters most homeowners use; only theses are much more advanced, and effective, in many ways. Without using electricity or producing ozone, these filters contribute to whole-home energy savings by removing the contaminants that collect on an HVAC system’s coil.
IQAir’s Perfect 16 air cleaner uses micro-particle filtration. “We use an extremely tight filter, and provide a large surface area for air to flow through, so pressure drop is not affected. It’s built with two V shapes that provide a high surface area. The result is a unit that is maintenance-free for three years,” says Frank Hammes, president, IQAir North America. This unit is independently certified at MERV 16, he says. MERV is a rating system based on worst-case product performance in which higher numbers are better.
The builder market for IQAir’s filter can be divided into custom and production homes. “There’s a need for differentiation. In the custom home market, and customers drive demand. People are building dream homes, and they want everything in them to be the absolute best,” Hammes says.
Air cleaning products like the Perfect 16, which was featured on the TV show “Extreme Home Makeover,” are not sexy, he adds, “But being featured on that show made people realize you can actually get emotional about these products, especially when lives are at stake.”
The Lennox Healthy Climate 16 media filter is different on a molecular structure level than any on the market, says Jennifer Shelby, CIE, IAQ product manager, Lennox Industries. One challenge with designing these products is stabilizing static pressure. “But because of the different molecular structure of our filter, we maintain static pressure well within industry tolerances and deliver industry leading performance,” Shelby says.
Historical interest in whole-house IAQ solutions is similar to the water purification/filtration market 20 years ago, Shelby says. “Consumers were hit by messages from the Culligan man as a solutions provider, and not from the plumbing industry which could have provided more effective solutions, as it does now. It’s the same with this market. The HVAC industry is now expected to provide the best solution, as it always should have been.”
She continues; “It intrigues me that most people will spend $30,000 on a car they’re in for only two or three hours a day, yet spend only $300 on a mattress and box spring they’re on for seven or eight hours a day. Only with air cleaners they are hesitant to invest a fraction of that in a system that will make their home a better place to breathe.”
To address the need for proper ventilation, Broan-Nutone offers its Fresh Air Systems which include HEPA filtration. These products exchange a home’s incoming and outgoing air to dilute VOCs and improve IAQ.
Two models are based on different operating principles: heat recovery ventilation and energy recovery ventilation. HRV passes incoming and outgoing air across a membrane, where the heating or cooling energy in the air leaving the home is transferred to the incoming air; so heat is recovered.
“The membrane has a series of about 50 layers the air passes through that diverts the air through different paths. The ERV product operates on a larger scope by introducing humidity control,” says Tom Heidel, indoor air quality product manager, Broan-Nutone. “The same energy transfer takes place as in HRV, but a different membrane covered in desiccant absorbs the humidity in the incoming air and transfers it to the outgoing air. No ozone is emitted in the process.”
The market for these units is split 50/50 between retrofit and new construction. “Builders at the beginning were offering it as an option. Now that they have learned that providing good IAQ is valuable, builders are looking to distinguish themselves by offering this as standard, not as an option,” Heidel adds.
Another air-cleaning option is an ultraviolet lamp. These lamps use the UV-C portion of the light spectrum, also known as germicidal UV in the medical industry, to kill bacteria and other contributors to poor IAQ. Steril-Aire’s UVC Emitters are installed on an HVAC system’s coil because coils are the largest single source of IAQ problems in buildings, says Bob Scheir, president, Steril-Aire. “Mold and mold byproducts come off the coil, including irritating allergens and odors. Our lamp eliminates the coil as a source of IAQ contaminants,” Scheir adds. The UV light penetrates the coil via reflection.
UV lamps are not as effective at killing bacteria in a moving air stream because moving air cools the surface of the lamp, reducing its output, Scheir says. “Cleaning the coil allows the HVAC system to work more efficiently because coil buildup reduces the heat exchange efficiency.” UV lights do not produce ozone.
UV can be effective at killing bacteria in a moving air stream, as long as the device used provides adequate output, Scheir adds. Two types of UVC lamps are commonly used in HVAC applications. “With older-style lamps, output is reduced when moving air cools the surface; performance is compromised. However, a new generation of UVC lamps is designed specifically to operate in the cold/moving air environments of HVAC systems, overcoming the limitations of older-style lamps. So be sure to select UVC devices that are engineered for HVAC use,” he adds.
Reducing Heat Inside a Home
An indirect contributor to IAQ problems is heat. Heat accelerates the off-gassing of such substances as furniture glue and even mold. Therefore, while lowering the temperature inside a home will not solve IAQ problems, it can improve it. Two ways to reduce heat are window film and radiant barrier panels.
Ainsworth offers its Thermastrand radiant barrier panel, designed to reduce the buildup of heat in a home. It is an OSB with foil overlay on one face, and perforations to allow the wood to breathe. The foil has low emissivity and high reflectivity to transfer less heat into an attic space.
“The unique one-step in-line application of foil to Thermastrand panels occurs during the manufacture of the OSB so it doesn’t delaminate,” says John Murray, manager, marketing communications. “Our product helps reduce heat in the attic, and reducing heat in the attic reduces the overall heat in the home which also saves on the energy consumption of an air conditioning system. An architect or builder would simply spec our radiant barrier sheathing for a roof. It’s that simple.”
V-Kool window film reduces interior temperatures by blocking the sun’s energy from entering the home. “Film like ours blocks the sun’s heat but also transmits visible light,” says John Miller, spokesman for V-Kool. The film is almost colorless and virtually clear, but is not obvious to the eye. “The generic name is spectrally selective film. It’s an evolution of the low-emissivity coatings, referred to as Low-E, which reflect heat generated by your furnace back into your home.
“You must be certain what coating is on your existing window, because while this is rare, there are certain types of glass you should not put film on. It can cause the glass to crack from thermal stress.”