ASHRAE 62.1-2022 sets the minimum ventilation rates for acceptable indoor air quality, and its requirements directly drive how much outdoor air — and therefore how much recoverable energy — a system must handle. Energy recovery is the bridge between good ventilation and reasonable energy bills.
The Ventilation Rate Procedure
Section 6.2 uses the Ventilation Rate Procedure. The outdoor air requirement for a space is:
Vbz = Rp × P + Ra × A
where Rp is the outdoor airflow per person, Ra is per unit area, P is the number of people, and A is the floor area. Table 6.2.2.1 lists Rp and Ra for every occupancy. High Rp spaces (classrooms, gyms, labs) push outdoor-air fractions above the 70% threshold that triggers ASHRAE 90.1 recovery mandates.
Why Recovery Pairs with 62.1
- More outdoor air means more heating and cooling load. A membrane energy recovery ventilator or wheel returns most of that energy to the incoming stream.
- 62.1 requires that ventilation not create pressurization problems. Balanced supply and exhaust with a recovery core keeps the building near neutral pressure.
- In critical spaces, separation matters: labs and cleanrooms favor non-cross-contaminating membrane cores over rotating wheels.
Local Exhaust and Makeup Air
When a space has local exhaust (fume hoods, kitchens), 62.1 requires matching makeup air. That makeup air is a prime recovery candidate — but check the 90.1 exceptions for hazardous and grease exhaust before specifying a wheel.
Practical Sizing
Start from the 62.1 rate, then run the AHU selection calculation and the AHU component layout with the recovery core in the airstream. Sizing the recovery device first lets you right-size the cooling coil and heating coil on the recovered load, often saving one equipment size.
Frequently Asked Questions
How does ASHRAE 62.1 drive energy recovery?
Its ventilation rates set how much outdoor air a system must condition, and that outdoor air is the recoverable energy a wheel or membrane can reclaim.
What is the Ventilation Rate Procedure?
A method using per-person and per-area outdoor-air rates multiplied by occupants and floor area to set the space requirement.
How does 62.1 relate to 90.1 recovery mandates?
High outdoor-air fractions from 62.1 can push a system above the 70% threshold that triggers 90.1's recovery requirement.
Why size recovery before the coil?
Sizing the core first lets the cooling and heating coils be right-sized on the recovered load, often saving an equipment size.
Frequently Asked Questions
How does ASHRAE 62.1 drive energy recovery?
Its ventilation rates set how much outdoor air a system must condition, and that outdoor air is the recoverable energy a wheel or membrane can reclaim.
What is the Ventilation Rate Procedure?
A method using per-person and per-area outdoor-air rates multiplied by occupants and floor area to set the space requirement.
How does 62.1 relate to 90.1 recovery mandates?
High outdoor-air fractions from 62.1 can push a system above the 70% threshold that triggers 90.1's recovery requirement.
Why size recovery before the coil?
Sizing the core first lets the cooling and heating coils be right-sized on the recovered load, often saving an equipment size.
Specify the right heat exchanger
Our engineers size the core to your airflow, temperature and pressure-drop budget, and select plate, rotary or heat-pipe recovery by application. Read the heat exchanger guide or contact us for a specification.
Related products
Plate, wheel or pipe recovery for HVAC and ventilation.
Stationary, high-surface-area cores for air and liquid.
High-effectiveness energy recovery for large airflows.
Passive, fully separated streams for clean applications.