We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Industry

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Are Air Changes per Hour?

Mary McMahon
By
Updated: May 17, 2024
Views: 7,783
Share

Air changes per hour reflect the number of times air in a room is replaced per hour through normal circulation. Fresh air is critical for health and comfort in addition to structural integrity; stale, humid air can contribute to the growth of microorganisms that may damage structural components like beams and flooring. Many building codes set out recommendations for air changes per hour, and in some cases, a specific number is required by law for safety.

Improvement of building techniques makes air changes per hour especially important. In older structures, a certain amount of porosity is present, and air moves through cracks and chinks, creating some circulation even without fans, windows, and other ventilation options. Newer structures are more tightly sealed, especially in cases where they are designed to be clean and sterile. Laboratories and operating rooms, for example, rely heavily on mechanical ventilation for safety.

In a space where activities are minimal, air changes per hour can be low. Somewhere like a warehouse only needs two to four changes to maintain appropriate circulation. Workers will be able to breathe comfortably, carbon dioxide is eliminated, and the supplies in storage will be safe from mold and mildew. In environments where hazards are present, more circulation is necessary. Gases and particulates need venting, both through specific hoods and ventilation systems, and some environments can feel closed and uncomfortable with poor ventilation.

Laboratories and other facilities where workers handle potentially hazardous substances may need 15 to 20 air changes per hour for safety. In a place like a commercial kitchen, as many as 60 may be necessary. This environment can feel hot, closed, and hard to work in as a result of fumes from food, consumption of oxygen by flames on the stoves, and heat vented from freezers and fridges used to keep food at safe temperatures.

Contractors and engineers will consider air changes per hour in the design of a space. They can install ventilation systems to meet the need and may build in flexibility so the system can increase ventilation easily when it becomes necessary. If the code requires a set number of air changes per hour, this must also be integrated into the design, with evidence to show building inspectors that the space will be safe for use. Personnel are also responsible for maintaining ventilation systems while a structure is in use, including changing filters and keeping vents clean so air can flow freely. Obstructions may limit air exchange and could lead to hazards like buildups of dangerous gases.

Share
WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WiseGeek researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Editors' Picks

Discussion Comments
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
Share
https://www.wisegeek.net/what-are-air-changes-per-hour.htm
Copy this link
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.