Issue link: https://hi.iaq.net/i/655416
52 Energy Savings Plus Health | INDOOR AIR QUALITY GUIDELINES FOR MULTIFAMILY BUILDING UPGRADES PRIORITY ISSUE 19.0 MECHANICAL VENTILATION FOR MULTIPLE DWELLING UNITS USING CENTRAL EXHAUST ASSESSMENT PROTOCOLS (AP) MINIMUM ACTIONS (MA) EXPANDED ACTIONS (EA) AP 19.1 Determine Whether Dwelling Units Are Served by Central Mechanical Exhaust Ventilation Systems Central exhaust ventilation systems serving multiple dwelling units is a configuration where the building has one or more central exhaust fans, each of which serves multiple dwelling units. Ventilation is provided to dwelling units via outdoor make-up air induced by the central exhaust fans. Note: A central HVAC air handler supplying outdoor air directly to multiple dwelling units is uncommon in existing multifamily residential buildings. This document does not include guidance for this configuration. For other dwelling unit ventilation configurations, refer to Priority Issue 18.0 Mechanical Ventilation for Individual Dwelling Units or 20.0 Natural (Not Fan-Powered) Ventilation. AP 19.2 Determine Whether Central Mechanical Exhaust Ventilation Systems Meet ASHRAE Standard 62.2-2013 Requirements Determine whether the ventilation in each dwelling unit meets ASHRAE Standard 62.2-2013 requirements (including Appendix A for existing buildings and Section 8 for multifamily buildings). This includes: • Dwelling unit ventilation rate. • Bath and kitchen exhaust fan airflow rates. • Proper location of exhaust discharges. Conduct the assessment in as many dwelling units as possible. If a sample of dwelling units is assessed, be sure to include any units for which there are indoor air quality complaints. AP 19.3 Determine Whether Common Corridors and Nonresidential Spaces Meet Ventilation Requirements Determine the amount of outdoor air ventilation provided to common corridors and whether this meets the ASHRAE Standard 62.1-2013 minimum MA 19.1 Repair and Upgrade Central Mechanical Exhaust Ventilation Systems As Needed If dwelling units are served by central mechanical exhaust systems: • Adjust, repair, or replace the ventilation systems so each dwelling unit served by the central exhaust system meets the requirements of ASHRAE Standard 62.2-2013 for existing buildings (including Appendix A and Section 8), including: o Adjust, repair or replace the central fans, ductwork and fittings to meet ASHRAE Standard 62.2-2013 requirements for whole-building ventilation for all dwelling units served. o Ensure that each dwelling unit receives the required exhaust airflow by: - Removing blockages in exhaust ductwork. - Air sealing exhaust air ductwork using approved materials. Ensure the roof curb connection, the lateral connections, and the sheetrock/ plaster connections behind the exhaust grilles are sealed. - Installing air-regulating exhaust dampers at each exhaust grille (typically proprietary flow-limiting devices or orifice plates). • If possible, adjust the exhaust system to provide continuous operation, and meet the ASHRAE Standard 62.2-2013 whole-building ventilation rate requirement for each dwelling unit. Intermittent operation should be avoided unless each unit is provided with a backdraft damper or motorized damper at each exhaust point. EA 19.1 Air Seal Exhaust Ventilation Shaft Air seal the central exhaust system's ventilation shaft with a spray seal system (aerosol or fluid applied). This allows sealing of the leakage area associated with non-accessible duct joints to provide pressure control and improve the capability to balance exhaust airflows among dwelling units. Ensure that the ductwork sealing required under Minimum Actions (roof curb connections, lateral connections and connections behind exhaust grilles) has been completed before air sealing the ventilation shaft. EA 19.2 Meet Outdoor Air Filtration and Air-Cleaning Requirements of ASHRAE Standard 189.1, As Applicable to Nonresidential Spaces If nonresidential spaces are included in the scope of service, in geographic locations where the outdoor air exceeds the national standards for particulate matter (PM 2.5 , PM 10 ) or ozone, ensure that the outdoor air filtration and air-cleaning requirements of ASHRAE Standard 189.1-2014, Section 8.3.1.3 are met for mechanical ventilation systems: • Particulate-matter filters or air- cleaning devices with a MERV of at least 8 shall be used in areas where the National Ambient Air Quality Standard for PM 10 is exceeded. • Particulate-matter filters or air- cleaning devices with a MERV of at least 13 shall be used in areas where the National Ambient Air Quality Standard for PM 2.5 is exceeded. • Air-cleaning devices to remove ozone must be provided and used in areas that are in "nonattainment" with the National Ambient Air Quality Standard for ozone. The ozone removal efficiency of the system shall be at least 40%. Appendix B: Property Management and Occupant Education