Detailed Recommendations for Mechanical Equipment & HVAC Systems
If a building has poor indoor air quality, investigate the extent to which outdoor air contaminants are contributing to the problem.
In areas where poor outdoor air is a problem, use the highest efficiency filters compatible with current HVAC system, and if necessary, consider retrofitting system to increase filtration capabilities.
Use demand controlled ventilation (DCV) that utilize sensors in occupied spaces to determine when ventilation should be increased due to increased occupancy or other loads. Be wary of using motion sensors that can create significant electromagnetic fields.
Provide liberal amounts of ventilation. It is better to have more ventilation than necessary rather than too little.
Where there is an adjoining parking garage or busy roadway, or nearby heliport, anticipate the need to decrease air exchange and ventilation in buildings prior to and during "rush hours" or times of usage, respectively. During periods of decreased outdoor air ventilation, increase recirculation and filtration of recirculated air.
Adhere to a strict maintenance plan for all HVAC equipment to make sure it is working properly. This will reduce the chance of air contamination, maintain optimal efficiency, and minimize noise and vibration.
Create door and window-opening protocol to maintain proper pressure relationships and air flow in the building. Educate and provide protocol to staff and other building occupants. Policy should include provision that allows chemically sensitive and other individuals to open windows on a temporary or regular basis, as needed because of a health condition. Windows should also be permitted to be opened by occupants when the HVAC system is not working or shut off, such as may occur during nights and weekends. Policy should address emergency situations in which opening windows could exacerbate the crisis.
Maintain HVAC ducts free of particulate matter, dust, and debris. Use non-chemical methods, such as physical removal or use of vacuums.
Do not use HVAC system to disperse fragrances or other chemicals.
Before a building is re-occupied (e.g., in the mornings or after weekends), flush with at least three complete outdoor air exchanges.
Make maximum use of economizer cycle. Avoid energy conservation practices that reduce intake of outside air below minimum requirements.
Make sure the supply and return air diffusers, grills, and registers are working correctly.
Test for stagnant air areas where furniture, wall partitions, or equipment may be blocking air movement. Use ribbons or dry ice rather than smoke to study air flow patterns.
Maintain relative humidity between 30 and 50%.
Avoid or minimize the use of humidifiers in the buildings HVAC system. Maintain the cleanliness of all humidifier equipment and use the minimum amount of water treatment chemicals necessary to prevent antimicrobial contamination and to control dissolved solids and pH.
Prohibit the use of personal humidifiers except where there is a medical need.
Isolate and contain construction chemicals and particulate matter from HVAC system by covering registers and diffusers and using negative-pressure air systems.
Seal return air openings into HVAC system during remodeling and exhaust directly to the outdoors, by temporarily removing window glazing if necessary.
Quickly evacuate a building if the HVAC system becomes contaminated with a solvent, pesticide, toxic gas, or other harmful chemical at a level that can cause adverse health impacts in occupants, including sensitive and more vulnerable individuals.
Eliminate storage of toxic and/or volatile chemicals near HVAC intakes.
Do not allow the use of portable air "cleaners" that emit ozone.
Repair plumbing with least toxic, low-VOC materials.
To clear clogged drains, use mechanical methods such as snakes, or steam cleaning.
Utilize bacterial enzymes to prevent drain clogs, instead of using acids, solvents and alkalines which deteriorate pipes and necessitate repairs.
Inspect floor and other drains, especially those that are infrequently used, to ensure there is water in the P-traps, thereby avoiding sewer gas backup in the building.
Treat grease traps daily with preventive dose of bacterial enzymes, to avoid the need to use strong chemical cleaners if they become clogged.
In decorative fountains, use the minimum amount of chlorine necessary for disinfection, avoid the use of bromine, use closed ozone water treatment systems to the maximum extent possible, and make use of newer, less-toxic disinfecting technologies as they become available.
EPA, Indoor Air Quality Building Education and Assessment Guidance (I-BEAM) Software package, can be downloaded for free from EPA Web site, or can be obtained on CD from IAQ Clearinghouse at at 1-800-438-4318 or via e-mail at email@example.com (ask for EPA 402-C-01-001).
See references regarding HVAC in Building Design & Construction report