Building Air Quality
DHHS (NIOSH) Publication Number 98-123
Step 5: Develop and Implement a Plan for Facility Operations and Maintenance
Reference: Building Air Quality – Action Plan: Section 5, “Managing Buildings for Good IAQ: Facility Operation and Maintenance,” Pages 34-36; also, “Appendix B: HVAC Systems and Indoor Air Quality” Pages 123-137.
Purpose: To maintain and operate your building to prevent IAQ problems.
IAQ can be affected both by the quality of maintenance and by the materials and procedures used in operating and maintaining the building’s components. Keeping IAQ in mind when you plan for operations and maintenance is a good way to prevent IAQ problems.
HVAC Operations: A building operations schedule is basically a daily/weekly/monthly schedule of each individual HVAC component compiled together in a comprehensive whole. This allows for cross comparison of different components schedules and synchronization. It is imperative that your operations schedule reflect actual use of your building, ensuring that the HVAC system is providing ventilation during all periods of significant occupancy. It is important that this schedule be written and comprehensive, so that there is a “one-stop” reference that is complete, easily updated and accessible to all who need it.
HVAC Operations Specific Steps:
- Operate the HVAC system during periods of significant activity and confirm that written operating schedules reflect this.
- Economizers and energy recovery systems, when properly used, can reduce energy costs while increasing outdoor air supply.
- Operate the HVAC system with as much outside air as practical prior to occupants’ arrival.
In general, ventilate your building with the maximum volume of outside air that is practical, taking into account your HVAC system capacity and current climatic conditions–refer to the latest publication of ASHRAEexternal icon Standard 62 for the current ‘best practice’ in HVAC system design (see Appendix 3 for ASHRAE contact information).
Economizer operations can reduce cooling costs while increasing outdoor air ventilation. However, malfunctioning economizer controls have been known to cause IAQ problems, such as dampers stuck in the closed position. Make sure economizer controls are frequently maintained and recalibrated, especially if you use enthalpy controls (ones that take into account both temperature and relative humidity). Exercise care to ensure that on/off set points are adjusted to avoid indoor relative humidity problems. Enthalpy controls can give the highest energy savings as well as help prevent the potential for excess moisture to be delivered into the building, which is especially important in areas of the U.S. where humid conditions are prevalent. However, the ASHRAE Standard 90.1 User’s Manual recommends that drybulb (temperature only) controllers be used in dry and mild climates (e.g., southwestern U.S.) because they are less expensive, require less maintenance and are more reliable than enthalpy sensors (ASHRAE/IES 90.1-1989, User’s Manual; see Appendix 3 for ASHRAEexternal icon contact information).
Energy recovery systems may make it feasible to increase outdoor air ventilation rates during temperature extremes. The hotter the outside air, the more energy heat recovery saves. The same is true on the heating side, but only to a point – make sure not to freeze the moisture in the outgoing air stream. Any time you would normally use 100% outside air, turn the heat recovery off.
Finally, before building occupants arrive for the day, schedule the introduction of as much outside air as practical to dilute pollutants that may have accumulated over night. Flushing can also provide pre-cooling, or night cooling – another way to contain energy costs. However, make sure that the amount of outside air used is consistent with the proper function of the HVAC equipment (e.g., coil freezing during extreme cold) and maintaining recommended relative humidity levels (30-60%, ASHRAE 55-1992 or latest publication; see Appendix 3 for ASHRAEexternal icon contact information).
2) Housekeeping: Inadequate housekeeping can cause IAQ problems — keep your building clean. Also, cleaning materials themselves may be pollutant sources that produce odors and emit a variety of chemicals. Select cleaning methods that are effective for the given need. Read product labels and Material Safety Data Sheets (MSDS) on all cleaning products in use in your building. Remember, your housekeeping staff will be the most highly exposed to the chemicals in your cleaning products. Buy products with the least adverse impact on human health.
Housekeeping Specific Steps
- Prepare and follow written housekeeping procedures that detail the proper use, storage and purchase of cleaning materials.
- Be aware of the housekeeping products and equipment used in your building, particularly those that are potential irritants or have other IAQ impacts.
- Purchase the safest available housekeeping products that meet your cleaning needs.
- Educate housekeeping staff or contractors about proper use of cleaning materials, cleaning schedules, purchasing, materials storage and trash disposal.
It is important that the housekeeping staff, whether they are in-house staff or contractors, be trained on how your housekeeping procedures and products may affect IAQ. In fact, OSHA’s Hazard Communication Standard (29 CFR 1910.1200)external icon requires employers to explain the labels and MSDSs of all hazardous chemicals used, even infrequently, by an employee, and to train those employees in how to protect themselves from emergencies.
Other issues regarding housekeeping that are important to maintaining and improving your building’s IAQ include: having written procedures; knowing what equipment and products are used in your building; and purchasing safer products.
Preventive Maintenance: A written preventive maintenance program is an effective tool for improving IAQ. The plan should include monitoring, inspecting and cleaning HVAC components such as outside air intakes, outside air dampers, air filters, drain pans, heating and cooling coils, the interior of air handling units, fan motors and belts, air humidification, controls and cooling towers. Pages 34–36 of the Building Air Quality guide contain general information on maintenance activities while pages 123–137 detail specific HVAC components, their role in IAQ, and instructions for preventive maintenance.
Preventive Maintenance Specific Steps:
- Develop and follow a preventive maintenance plan that includes maintenance schedules. Activities in the plan should include:
- Inspect outside air dampers for nearby sources of contamination,
- Ensure that air dampers are clear of obstruction and operating properly,
- Regularly replace or clean air filters,
- Clean and inspect drain pans,
- Inspect and clean heating and cooling coils,
- Inspect and clean as warranted interior of air handling units,
- Inspect fan motors and belts,
- Regularly inspect and clean air humidification equipment and controls,
- Inspect, clean and treat cooling towers, and
- Inspect and clean as needed air distribution pathways and variable air volume (VAV) boxes.
- Update your maintenance plan when equipment is added, removed or replaced.
The frequency of maintenance activities may vary from building to building. It is important that you develop a maintenance schedule based on the needs of your equipment and building. However, your schedule should ensure that all equipment is in good, sanitary condition and is operating as close to design set points as possible.
Unscheduled Maintenance: When unscheduled maintenance events (e.g., equipment failures) require the prolonged deactivation or modification of building HVAC equipment, maintenance personnel should be instructed to immediately notify the IAQ Manager. The IAQ Manager should review the situation carefully and provide recommendations to maintenance and administrative personnel on how to proceed without compromising the building’s IAQ. The IAQ Manager should also communicate with building occupants and tenants to inform them how their air quality is being protected.
Unscheduled Maintenance Specific Steps:
- Immediately notify the IAQ Manager.
- Ensure the building’s IAQ is not compromised.
- Notify tenants and/or occupants how their air quality is being protected.
Building Air Quality – Action Planpdf icon [PDF – 905 KB]
Building Air Qualitypdf icon [PDF – 2,851 KB]