RMS-LB 2018 with 12/20 Revisions

Identify—The Normal Average Operating Condition for the Building CG AARST Companion Guidance RMS-LB 2018 Informational 9 4) Identify When Outdoor Air Ventilation Systems Activate. HVAC Economizer Systems are often designed to provide outdoor air to a building or airspace for both health benefits and to economize on energy expenses. Economizer systems vary the amounts of cool outdoor air supplied to the building to assist with the cooling load of the room or rooms. Some systems are set to introduce a minimum volume of outdoor air during virtually all occupied periods. Energy Recovery Ventilators (ERV) and Heat Recovery Ventilators (HRV) provide health benefits of introducing outdoor air to a building while saving energy as compared to energy consumption for delivering untempered outside air into a building. Low outdoor temperature limits: 35˚to 42˚ F (1.6 to 5.5 C) Dampers that allow outdoor air to be brought into a building will, depending upon the system’s design, completely close or activate to minimum open damper setting when outdoor temperatures fall below about 35˚-42˚ F (1.6 to 5.5 C). This feature is often required to protect water coils, filters and other components within HVAC units from the cold. High outdoor temperature limits: 65° F (18˚ C) Dampers also often close or return to a minimum open damper setting when outdoor temperatures reach about 65° F (18˚ C) and no longer provide energy savings and comfort benefits. High outdoor humidity limits: Comfort Limits Some systems will also close dampers or return to a minimum open damper setting when outdoor humidity brought into a building causes discomfort. Exhaust Systems are sometimes configured to induce cross ventilation with outside air during warm conditions. These systems can be designed to address a large portion of a building, an attic, or a specific area. Examples of Outdoor Air System Activity 24 Hour Averages Daytime Only Averages