What is an Air Exchange Rate and Why is it Important?

What is an Air Exchange Rate and Why is it Important?

One of the unfamiliar terms you may encounter as a homeowner is “air exchange rate.” Understanding what the term means is vital, because it's a key factor in how well your HVAC system heats and cools, and whether you and your family enjoy a comfortable, healthy living environment.

Air Exchange Rate Basics

Air exchange rates, or “air changes per hour,” simply refer to the number of times that air gets replaced in each room every hour. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides guidelines for air changes per hour, and they vary depending on the room: bedrooms should have five–six, kitchens 7–8, and laundry rooms require 8–9 changes.HVAC contractors use these “changes per hour” recommended ranges to calculate the amount of airflow that's needed in different rooms to ensure adequate house-wide air exchange. Each room's volume (height × width × length) is multiplied by the recommended number of hourly changes, then divided by 60.

Why Air Exchange Rates Are Important

Homes today are built and weatherized to minimize energy losses and maximize efficiency. Here in Oklahoma, homes also tend to be closed up to keep conditioned air indoors during our lengthy cooling seasons. If air exchange isn't sufficient, trapped allergens, pollutants and irritants can degrade the indoor air quality and affect the well-being of a home's occupants.If your home is older and not as tightly-built or weatherized, air exchange can occur through leaks in the exterior envelope. If that's not enough, or you have a well-sealed home, your HVAC pro may advise you that extra measures are needed to ensure good air quality, such as:

  • Installing a ventilation system to remove stale air and pull in fresher air from outdoors.

  • Adding an air cleaner to the HVAC system to help reduce airborne allergens and pollutants.

  • Consistently maintaining your HVAC, ventilation and air cleaning equipment, and making filter changes as recommended to keep everything operating at an optimal level.

If you're wondering whether the air exchange rate in your Broken Arrow home is adequate, contact us at Air Assurance to schedule an HVAC system assessment.

Our goal is to help educate our customers in the Tulsa and Broken Arrow, Oklahoma area about energy and home comfort issues (specific to HVAC systems). For more information about other HVAC topics, call us at 918-217-8273.