Why Fall Is Whole House Fan Season in Las Vegas
Fall is the best time of year to have a whole house fan in Las Vegas. The days are still warm enough that you’re running the A/C, but the evenings cool off fast, and that’s when a whole house fan does its best work. Open a few windows after sunset, turn the fan on, and within minutes it pulls fresh, cool outside air through your home and pushes the hot, stale air out through the attic. Many homeowners find they can turn off their air conditioner for the night.
What Is a Whole House Fan and How Does It Work?
A whole house fan is a powerful exhaust fan mounted in the ceiling, usually in a central hallway, that vents into the attic. When it runs, it draws fresh outdoor air in through open windows, moves that air through your living spaces, and pushes the warm indoor air up into the attic, where it leaves through the roof vents, resulting in an actual exchange of air.
An air conditioner cools and recirculates the same indoor air, while a whole house fan replaces it. That exchange also flushes heat out of the attic, which matters in Las Vegas, where attics bake all day under tile and shingle roofs and keep radiating heat into the rooms below well after dark. Solatube rates its Engineered Performance Series fans as capable of lowering indoor and attic temperatures by as much as 30 degrees when outdoor conditions cooperate.
How Does a Whole House Fan Improve Indoor Air Quality?
Cooling gets most of the attention, but for many families the bigger benefit of a whole house fan is the air itself. Every time the fan runs, it replaces the air inside your home with fresh outdoor air, carrying out the pollutants, odors, moisture, and airborne particles that build up indoors. The EPA has long reported that indoor levels of many common pollutants can run two to five times higher than outdoor levels, and ventilation is one of the three core strategies it recommends for lowering them (along with controlling the sources and filtering the air).
Why Indoor Air in Las Vegas Homes Gets Stale
From late spring through September, most Las Vegas homes are closed up around the clock while the air conditioner runs. Many people are surprised to learn that a central A/C system only cools the air already inside your home. It brings in very little fresh outdoor air, so pollutants, odors, allergens, and bacteria circulate through the house for months. Carbon dioxide from everyone breathing, along with cooking byproducts, pet dander, household dust, and chemical vapors all have nowhere to go. When the evenings cool off in the fall, running a whole house fan pulls fresh air in through your open windows and pushes the old air out through the attic, so the air in your home actually gets replaced.
Venting Fumes From Cleaning Products, Paint, Cooking, and Furnishings
Many everyday household products release volatile organic compounds, or VOCs, into the air, and cooking adds its own smoke, grease particles, and odors. Gas ranges also release combustion byproducts that can linger well after dinner. Kitchen and bathroom exhaust fans help at the source, but they only clear one small area, and some don’t vent air outside at all.
A whole house fan moves air through the entire home at once. That makes it especially useful after a deep clean, after painting a room or refinishing furniture, during the first few weeks after new flooring or furniture arrives, or after a cooking mishap that fills the house with smoke. Pair the fan with simple habits like choosing low VOC products and storing chemicals in the garage, and the air in your home stays noticeably fresher and safer.
Can a Whole House Fan Help Reduce Germs in the Air?
Cold and flu germs spread through tiny particles in the air, and those particles build up in homes that stay closed up. The CDC recommends bringing fresh outdoor air into your home and using exhaust fans to encourage a healthy air exchange. A whole house fan does exactly that for your entire home at once.
The timing works out well in Las Vegas, too. Cold and flu season lines up with the months when the evenings are cool enough to run the fan. When someone in your house is sick, or you’ve just had a house full of guests for the holidays, running the whole house fan clears out the air everyone has been breathing and brings fresh air in. It works best alongside the usual habits like handwashing, getting vaccinated, and staying home when you’re sick to help prevent the spread of germs.
Is a Whole House Fan Good for Allergies?
A whole house fan helps clear indoor allergens that build up in a closed house, including pet dander, dust, and the musty odors that can come from damp bathrooms and laundry rooms. For people whose symptoms flare indoors, regular air exchange can make a real difference.
However, it’s important to note that outdoor pollen could be a tradeoff. The fan pulls outdoor air inside, and if pollen counts are high, pollen will come in with it. If seasonal allergies are a concern in your household, check the daily pollen forecast before running the fan, keep window screens clean and in good repair, and favor evening and overnight use, since pollen counts for many plants tend to be lower later in the day. Running the fan with care during the right hours lets allergy sufferers get the benefits of fresh air while limiting exposure to possible irritants.
Fresher Air for Children, Older Adults, and Immunocompromised Family Members
Some people are more sensitive to indoor air quality than others. The EPA notes that children breathe more air relative to their body weight than adults do, which makes them more susceptible to pollutants in the air around them, and young children spend most of their day indoors. Older adults, people with asthma or other lung conditions, and people with weakened immune systems can also be more vulnerable to indoor pollutants and airborne germs.
For these households, regularly replacing indoor air with fresh outdoor air is one of the simplest ways to keep the home environment cleaner. The EPS Focus can be especially useful here, since it has the ability to ventilate a single room (like a nursery or a bedroom where someone is recovering) and it works with the door closed. Outdoor conditions matter even more for sensitive family members, so skip the fan on days with wildfire smoke, blowing dust, or poor air quality alerts, and talk with your doctor about the right approach for a specific medical condition.
When Is the Best Time to Use a Whole House Fan in Las Vegas?
The best time to run a whole house fan is any time the air outside is cooler than the air inside your home. In Las Vegas, that’s usually in the fall and spring.
Why Fall Evenings Work So Well
According to NOAA, Las Vegas averages a high of about 81 degrees and a low of about 60 degrees in October, and a high of about 67 degrees with a low of about 47 degrees in November. That’s a gap of roughly 20 degrees between afternoon and night. Your home spends the afternoon absorbing heat into its walls, floors, furniture, and attic. In the evening, a whole house fan replaces that warm indoor air with cooler outdoor air and draws the stored heat out of the structure. Because the house itself cools down overnight, it stays comfortable longer the next day, and the A/C starts later in the afternoon, if it needs to run at all.
Should You Run a Whole House Fan in the Summer?
For cooling, summer is the one season when a whole house fan can’t do much in Las Vegas. Overnight lows in July and August often stay above 80 degrees, so there’s no cooler air outside to bring in, and your A/C has to carry the load.
That said, running the fan briefly once or twice over the summer can still be worth it to exchange the stale air inside your home. Most Las Vegas houses stay closed up from May through September, which means months of cooking smells, pet dander, dust, and household fumes with nowhere to go. The best time is right before sunrise, when it’s coolest outside. Open a few windows, run the fan on high for about 10 to 15 minutes, then close everything up and let the A/C take over. You’ll let in a little warm air, but your home gets a full exchange of fresh air in return.
What Happens to a Whole House Fan in Winter?
When the fan is off, its R6 insulated damper doors close and seal the ceiling opening, which keeps your heated air in the house and the cold attic air out. On mild winter afternoons, many homeowners run the fan briefly on a low setting to bring in fresh air and clear out cooking odors and stale air that build up while the house is closed.
Does a Whole House Fan Replace Air Conditioning?
No, and it is not designed to. In Las Vegas, a whole house fan works alongside your air conditioner during the hours when outdoor air can do the cooling for free, while the A/C handles the hours when it cannot. Most homeowners use the fan to reduce the amount of time their HVAC system runs throughout the day. How much that reduces your energy use depends on your home, your habits, and how often you run the fan, so it will vary from home to home.
How to Use a Whole House Fan for the Best Results
A few habits make a noticeable difference in how well the fan performs.
- Wait until the outdoor temperature drops below your indoor temperature, usually an hour or two after sunset in fall.
- Open windows before you turn the fan on, and keep them open the entire time it runs. Opening windows in rooms you want cooled most, such as bedrooms, pulls the airflow through those rooms.
- Start on a higher speed to flush out the heat quickly, then lower the speed for quieter overnight operation.
- Close the windows and turn the fan off in the morning, before outdoor temperatures climb, to hold the cool air inside for the day.
- Skip the fan on high wind days when dust is blowing, whenever wildfire smoke is drifting into the valley, and on days with an air quality alert. If anyone in the house has seasonal allergies, check the pollen forecast too.
The open window rule is the most important one. Running the fan with the house closed up starves it of air, and in homes with gas appliances, such as a water heater or furnace, it can pull exhaust gases back into the living space. Opening a few windows a few inches each is usually enough.
Which Whole House Fan Is Right for Your Home?
Solatube makes five EPS whole house fan models, and the right one depends on your square footage, your floor plan, and how much ventilation your attic already has.
Whole Home Models
Four of the models are sized to cool your whole home. The EPS Zone covers 500 to 1,200 square feet, the EPS Plus covers 1,000 to 2,200 square feet, and the EPS Ultra covers 2,000 to 3,200 square feet. For homes over 3,000 square feet, there’s the EPS Extreme. Each one runs on a quiet, energy efficient EC motor and comes with a remote that lets you adjust the speed. In larger or two story homes, models can also be combined to cool separate zones. You can compare all five models on our whole house fan page.
Single Room Cooling With the EPS Focus
If one room is the problem, like a hot upstairs bedroom, a nursery, a home office, or a laundry room, the Solatube EPS Focus is designed to ventilate a single space of up to 500 square feet. It works with the door closed for privacy and runs at about 30 decibels.
Does Your Attic Have Enough Ventilation?
A whole house fan can only push air out as fast as your attic can release it, so each model needs a certain amount of attic venting. The EPS Focus needs about 1 square foot, and the requirement goes up with fan size, up to 8 square feet for the EPS Extreme. Many Las Vegas homes already have enough, but some need additional vents, and checking this is part of every consultation we do.
Talk to a Las Vegas Whole House Fan Specialist
Sun Cat Skylights has installed Solatube daylighting and ventilation products in Las Vegas homes for more than 30 years. During a free in home consultation, we will look at your floor plan, check your attic ventilation, and recommend the fan size that fits how your household lives and breathes. Learn more about our work across Las Vegas, or schedule your free consultation today. You can also call us at 702.658.9847.