The US. Environmental Protection Agency (EPA)’s Three Rules for better IAQ are: 1) Eliminate Sources, 2) Ventilate, and 3) Filter the Air. Using the application tips below — and knowing related myths and truths, facility managers can develop an IAQ system that will help ensure indoor environment is better for their staff, building occupants and other customers, and business.
Myth: Eliminating sources of unhealthy IAQ is as simple as finding and removing sources of odors resulting from mold, dirty restrooms, strong solvents, and other obvious sources of “bad air”.
Truth: While a strange smell can flag poor IAQ, it is vital to identify, reduce, or eliminate all major sources of contamination — including those beyond human senses — and use a preventive approach.
Sources that are often not well understood or perceived may include:
Excess Moisture — indoor relative humidity (RH) should be above 30% for respiratory and dermal health but below 50%-60% to prevent mold or bacterial growth. Electronic sensors are available as part of HVAC and other air handling systems, or as standalone hygrometers. Ideal RH reduces microbe and mold growth and related IAQ issues.
Road, heavy metal, and pesticide dust are tracked in from outside, becoming airborne. Proper entry matting and maintenance will help, in effect making the floormat an air cleaner.
Desktop facial tissue boxes release a mini dust cloud with every tissue dispensed. Eliminating these will reduce a major source of office dust.
Employee personal fragrances may release harmful VOCs and trigger sensitivities. Ask employees to be aware of the growing chemical sensitivity issue (12.6% of people are chemically-sensitive to low-levels of common chemicals per the National Institutes of Health, and 15.9% of people are chemically-sensitive per the California Department of Health Services).
Air fresheners and fragranced products pollute the indoor environment. Avoid them.
In short, stop bringing pollutants inside, remove the ones already indoors by eliminating the source, clean better, control humidity, and, then, bring in fresh air or ventilate.
Myth: Ventilation with fresh air will drive up energy costs.
Truth: Heat Recovery Ventilators (HRVs) or Energy Recovery Ventilators (ERVs) enable air exchange without excessive energy consumption. As the names imply, these units provide facility ventilation while recovering the energy from the outgoing air stream. During the winter months, an HRV or ERV will exhaust warm stale indoor air while transferring most of the heat energy from the warmer outgoing air to the cooler incoming air using a heat exchanger (often aluminum) for better IAQ while controlling energy consumption. In summer months, cooling energy is recovered from the outgoing air. ERVs also enable humidity control.
Both types of systems can be used in conjunction with existing HVAC ducting or function as standalone units. HRVs and ERVs provide the modern day equivalent of opening a window without the energy loss associated with airy structures, while providing a controlled rate of air exchange for better climate control.
Filter The Air
Myth: The HVAC system takes care of whole-facility air filtration nicely, and uses efficient filters that capture particles and pollutants of concern while requiring very little care and maintenance.
Truth: The ability of a whole-facility HVAC system to properly protect air quality from a particle perspective depends on the proper balancing of the amount of air being moved or pumped through physical filters combined with the efficiency rating of filters (e.g., high Minimum Efficiency Reporting Value or MERV rating equals finer filtration; with more efficient filters offering more resistance to airflow) and integrated with a regular program of filter cleaning or changing to sustain airflow and proper removal of unwanted particles.
However, since HVAC systems are generally designed for particle — not gas or VOC removal, the HVAC unit will not do much to reduce non-particle pollution which requires a different filter medium such as activated carbon to adsorb (with a “d”) unwanted gases or VOCs. Since gas-type-filter media function differently than particle filters (e.g., MERV rated ones), HVAC units equipped with this form of filtration will have different care and maintenance requirements.
Typical HVAC systems are also somewhat anemic when it comes to providing fresh air ventilation, a trait driven by the energy crisis of the 1970s when buildings were made very tight to save energy.
Remember, air is a complex, dynamic, fluid mixture containing thousands of substances — particles and gases — mixed and in motion together. An HVAC filtration system is more accurately called an air improver rather than a purifier, since just capturing some particles such as certain airborne dust, pollen ,or other particulates from air passing through the unit does not necessarily mean indoor air is purified or healthier, as it may still contain many unwanted elements.
The best advice is to remember Rule #1, and eliminate sources first, followed by Rule #2, use intelligent ventilation (think HRVs/ERVs), and lastly apply Rule #3, filtering the air, as the final?and arguably the least effective?measure.