In humid environments or very cold dry areas (climate zones with an “A” or 6B), there may be an opportunity to eliminate exhaust air energy recovery equipment on some HVAC designs as defined in
ASHRAE Standard 90.1. See 90.1 Section 6.5.6 Energy Recovery for details.
As an example, using the IAQP from Standard 62.1, the outdoor airflow on many schools and offices will be less than 20% of the total HVAC system airflow rate. Following table 6.5.6.1.2-1 from 90.1, designers can eliminate energy recovery where systems supply less than 26,000 cfm. This is also true if the system is smaller at 16,000 cfm when outdoor airflow is between 20% and 30% of total system air. This avoids equipment, complexity, service, and energy use to support an energy recovery system. Note that local codes may provide alternative direction to standard 90.1-2022.
