Bathroom Fans: A Complete Guide
Last Updated: Mar 19, 2025After an exasperating day at work or school, a long, hot shower is often a preferred method for relaxing and letting go of some of that excess stress. Low-flow showerheads can help cut back on the water and energy used by the occasional steamy shower. However, if your bathroom does not have an exhaust fan or an operable window, those long showers might be leading to long-term problems for your home. In this complete guide, Rise takes an in-depth look at the role and importance of bathroom fans in protecting your indoor air quality and maintaining optimum humidity levels in your home. These relatively inexpensive additions to the bathrooms in your home consume limited amounts of electricity while adding several tangible benefits.
Table of Contents
- What Does a Bathroom Fan Do?
- What is an HVI Certified Bathroom Fan?
- Do Bathroom Fans Use a Lot of Electricity?
- What Are the Different Types of Bathroom Fans?
- What Type of Bathroom Fan Do I Need?
- What Is a Ceiling-Mounted Exhaust Fan?
- What Is a Wall-Mounted Exhaust Fan?
- What Is a Exterior Exhaust Fan?
- Do Exhaust Fans Have Lights?
- How Do You Know If a Bathroom Fan Is Efficient?
- How Do You Calculate the CFM Required for a Bathroom Fan?
- How Long Do Bathroom Exhaust Fans Last?
- Why Does a Bathroom Fan Make Noise?
- How Long Should You Run the Bathroom Fan After a Shower?
- Optional Add-Ons for Bathroom Fans
- How Do You Maintain a Bathroom Fan?
What is an HVI Certified Bathroom Fan?
HVI Certification for bathroom fans ensures that the product has undergone rigorous performance testing by a third-party organization. The testing required for HVI Certification provides:
- Assurance that independent testing has been completed.
- Confirmation the product will perform as advertised.
- The security that a properly sized and installed model will give the user the right amount of ventilation for the best indoor air quality.
Fans without HVI Certification can inflate their performance ratings and may not always meet building code requirements. HVI Certified bathroom fans are widely available from most major brands, and you can even filter for this attribute when shopping online.
It is worth mentioning that many bathroom fans often come with automatic timers. These allow the bathroom fan to run for 20-25 minutes after someone has taken a hot shower. This timer reduces the energy waste that can occur when the bathroom fan is accidentally left on for extended periods.
What Type of Bathroom Fan Do I Need?
The best type of bathroom fan for your home will depend on the location of your bathroom, the structure and design of your home, and other particular features. Below, we briefly recommend the optimum type of exhaust fan for different kinds of bathrooms.
What Is a Ceiling-Mounted Exhaust Fan?
This type of fan is best for bathrooms located on the upper stories of a home. The exhaust pipe will move up through the attic and vent to the outside through the roof. For this type of fan, it is vital to make sure that the ductwork is vented to the outside. In addition, assure that it is insulated to avoid condensation buildup that could negatively affect the insulation in your attic.
What Is a Wall-Mounted Exhaust Fan?
A wall-mounted exhaust fan is for bathrooms located next to an exterior wall. In this type of installation, the fan is set up on the outside of the outer wall. Wall-mounted exhaust fans offer power ventilation coupled with quiet operation.
What Is a Exterior Exhaust Fan?
An exterior exhaust fan is mounted on the exterior of the home. These are great for reducing noise levels inside the house while regulating moisture to prevent mold and mildew
Do Exhaust Fans Have Lights?
For homeowners who want to improve the aesthetics of their bathroom, exhaust fans that include lighting fixtures are often less of an eyesore and achieve multiple purposes in one unit.
How Do You Calculate the CFM Required for a Bathroom Fan?
Bathroom fans are rated by their cubic foot per minute (CFM) rating. This doesn't necessarily determine the product's energy efficiency as it doesn't look at per-watt usage. However, it can be helpful to size the best fan for your bathroom properly. Most fans come with a CFM rating anywhere between 50 and 110. Homeowners can adequately size the best bathroom fan for their homes by using the following formula:
Minimum CFM rating required = Length x Width x Height (of your bathroom) x 0.13
How Long Do Bathroom Exhaust Fans Last?
Bathroom fans, when properly maintained, will last for an average of ten years. Dusting and cleaning around the fan intake will help avoid the accumulation of dust and debris, which will put more stress on the fan's small motor. If your bathroom fan is noisier than usual, it might be a sign that it is wearing down and needing replacement.
Why Does a Bathroom Fan Make Noise?
Bathroom fans make minor amounts of noise due to the small motors, fans, and blower wheels that help expel the moisture-ridden air. Most new models of bathroom fans will make minimal amounts of noise. However, homeowners who want the most silent fans should opt for exterior exhaust fans mounted on the home's exterior.
How Long Should You Run the Bathroom Fan After a Shower?
The optimum amount of time homeowners should run the bathroom fan after a shower largely depends on the shower's length, the size of the bathroom, and whether or not the bathroom has an operable window. However, the Home Ventilation Institute recommends leaving the bathroom fan running for at least 20 minutes. This time will lower humidity levels and get rid of excessive moisture and condensation levels in the bathroom and in the ductwork that takes the moisture outside the home.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
