Does a Bathroom Exhaust Fan Help Cool the House?


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Every year it’s the same thing once the heat comes. Everybody starts looking for ingenious ways to cool the house. Once I tried to build a DIY air conditioner out of frozen water bottles and fans. It goes without saying that my experiment was not very successful 🙂

Bathroom exhaust fans help cool living spaces when the outdoor temperature is lower than the indoor temperature. The greater the temperature difference, the more effective it will be. This is why exhaust fans are best used during the night when the temperature drops.

A bathroom exhaust fan draws out odors and moisture from the bathroom, leaving behind dry, clean air. The accumulation of warm, moist air leads to mold growth which affects the fixtures in the bathroom and even the other areas of the house. Under some conditions, the bathroom exhaust fan can also help cool the house.

Later I will discuss some alternative ways on how to cool your house during a hot spell.

Exhaust Fan Only Cools the Room if the Outdoor Temperature Is Lower Than Indoor Temp

As the bathroom fan draws out air, a similar amount of air is drawn into the house to fill in the vacuum. Does this air make the house cooler? Well, only if the external temperature is lower than the internal one, which is mostly the case at night. When the AC is running, making the indoors cooler than the outdoors, the fan will bring in hot outdoor air.

The larger the temperature difference, the more effective the fan will be. High CFM fans will be more effective. The more air is moved, the more cooling effect is achieved.

In most cases, the only time it makes sense to turn on an exhaust fan to cool the house is during late evenings and nights.

Tips to keep in mind when cooling the house using exhaust fans

  • Make sure the outdoor temperature is lower than the indoor temperature
  • Don’t use an AC together with an exhaust fan
  • Turn on the exhaust fan for the night and turn it off before it gets warm
  • Use a fan that is rated for continuous operation (most modern fans are)
  • A quiet fan won’t disturb your sleep

Is It Safe to Leave a Bathroom Fan on All Night?

Normally fans ought to be left on only for a short period of time, mostly after running a shower or a steam bath. Only a fan that has been rated for continuous operation can be left on all night.

When running constantly, a fan is bound to clog up pretty fast and must be cleaned regularly. Without constant cleaning, the fan will be less efficient and you’ll notice the bathroom getting foggy after a shower. Fortunately, cleaning the fan is pretty easy.

To begin with, the fan’s cover is vacuumed in place, to keep the dirt from littering the floor when removed. The cover is then removed by tugging it from the surface; most are held into place with a spring. At most, the cover is secured with screws.

Once removed, the cover is scrubbed under the sink with a brush and soapy water. The motor housing is also vacuumed (with power turned off) before the now dry cover is replaced.

If you have an air compressor then you could use this to blow any remaining dust out of the motor housing. (make sure you turn on the fan for this. the fan will exhaust most of the dust that is kicked up by the air compressor)

In addition to consuming power, leaving the fan on all night reduces its lifespan. Like any other machine, continuous operation increases the wear and tear making the fan deteriorate faster. Even if they are rated for continuous operation, the service life will be greatly reduced if they are turned on 24/7 instead of a couple of hours per day.

Portable AC is a Great Way to Cool Your House On A Budget

BLACK+DECKER BPACT10WT Portable Air Conditioner with Remote Control, 5,500 BTU DOE (10,000 BTU ASHRAE), Cools Up to 150 Square Feet, White

When a recent heatwave hit us, at first I tried everything under the sun to cool my house using things I had laying around the house.

I made a makeshift evaporative cooler. All that did was make the house humid and even more uncomfortable. (It only works in very very dry climates)

Then I bought a bunch more fans to place all over the house. Nothing really made a difference because the fans don’t cool down the air. To me, it seemed that a dozen fans I placed throughout the house made the indoor temperature higher.

The moment air was not blowing directly on you, it was HOT again.

If the outdoor temperatures climb past 95°F/35°C it is very difficult to keep cool without a real air conditioner.

Where we live, this kind of heat lasts for a couple of weeks a year. So I can’t justify buying a built-in air conditioner, or even a split AC.

However, a portable AC(amazon), that can be had for less than the price of a couple of concert tickets is worth the price for a cool sweat-free house.

The nice thing about the portable AC, compared to a window AC is that you can move it to the bedroom for the night. That’s what we do. During the day it is in the living room, and about an hour before bedtime I roll it to the bedroom. I think it is a very cost-effective way to stay cool during the hottest days of the year.

The best part is, my house isn’t filled with fans anymore 🙂

How to Create a Cross Breeze with One Window

A cross breeze is created when you have an air inlet and outlet. Air comes in through one space and goes out through the other. If you have only one window, you can create a cross breeze by using the window as an inlet and either a bathroom fan or a range hood as the outlet.

A range hood works best since it has a higher CFM, which means it allows more airflow. Cool air comes in through the door and out through the range hood, creating a cool space. Remember such a cross breeze should only be created when the AC is off.

Ideas to Cool the House without an AC

Air conditioning makes the house habitable during summer. On the other hand, you have energy bills to worry about. Or your AC has a malfunction and repairing it will take some time. Here are some ideas to help you keep your house cool without running the AC.

Block the Sunlight

H.VERSAILTEX 100% Blackout Curtains 96 Inches Long Full Light Blocking Curtain Draperies for Bedroom Living Room Thermal Insulated Functional Soft Thick Window Treatment Set of 2 Panels, Natural
Blackout curtains

Sunlight is great on most days, but during summer they add a lot of heat into the house. Normal curtains don’t make much of a difference even when drawn.

Block the sun’s rays using blackout curtains (amazon link) or shades, whose fabric is infused with room-darkening features. Such curtains are thicker than normal curtains as they accommodate an extra layer of blackout fabric.

This does not mean that you’ll be confined to dull curtains throughout the summer. Blackout fabrics are now available in a wide array of brighter colors, including white. You can get one that blends into your interior decor and still keeps out the sunlight.

If the house gets too dark, you can open the curtains on the windows that don’t face the sun directly.

Reduce Humidity

TaoTronics Dehumidifier with Pump 50 Pint for 4500 Sq. Ft, Energy Star Dehumidifier for Basement with 6L Water Tank, Intelligent Humidity Control, Continuous Drainage for Living Room/Closet

The heat is one thing, and humidity is a different factor all together. When it’s hot you sweat, and the sweat absorbs heat from the skin as it evaporates, leaving the body cooler. When the air is moist, sweat does not evaporate, and you’re left with that hot sticky feel which is miserably uncomfortable. A dehumidifier sucks the moisture leaving the air dry and more bearable.

Use Fans

Amazon Basics Oscillating Dual Blade Standing Pedestal Fan with Remote - 16-Inch

Fans don’t reduce the temperature of the air but only set sin in motion. Sometimes it feels as if the fans are merely circulating hot air around the house. The placement of your fans is of the essence here. If you have multiple fans, place them near doors and windows, with some facing inwards and others outwards.

A cross breeze is created where cool air is blown in and hot air is sucked out. If you’re in a storied house, remember warm air rises. Place the outfacing fans on the upper floor to suck out hot air.

Did you know that the direction that the fan blades are running affects the airflow? When running clockwise, they push the air away while when running anticlockwise, the air is pulled towards them. During summer, ceiling fans should be running anticlockwise so they can pull up the warm air.

Limit Appliances

Heating appliances will only make the house hotter than it already is. The stove and oven, for instance, raise the temperatures significantly. You can use alternative appliances such as the microwave and pressure cooker. Try to cook during the morning hours when the temperatures are not high yet. For the rest of the day, you can do with short-term heating or even eat the food at room temperature. When running clockwise,

The dishwasher also leaves the house hotter. Consider washing the utensils by hand on those blazing days. If you must blow dry your hair, use the lowest setting. In addition to keeping the heat down, limiting the appliances also reduces your power bill.

The above ideas are mostly temporary. They’re used when the AC is out of service for some time, or on days that are not too hot. Ultimately, you need an AC in place for those typical sweltering summer days.

Luckily you don’t have to install an expensive whole-house AC system to keep you cool. A simple window AC in the bedroom will be more than enough. What’s more, you don’t need to worry about heavy rainstorms damaging it, since the window AC units are waterproof and don’t need any special care during inclement weather conditions.

Exhaust Fans Draw Out Warm Air During The Winter

As we discussed earlier, exhaust fans are not very effective at cooling the house during summer since the temperature difference is not very big.

During wintertime when the difference between indoor and outdoor temp is huge. Exhaust fans actually cool the house very effectively. However, this is not something that we want since most likely the house is being heated.

Whenever the house is being heated or cooled. Energy is wasted when the bathroom fan runs longer than it takes for the humidity to clear. This takes normally between 20 and 60 minutes. Depending on the bathroom fan capacity and climate.

To prevent wasting money on your energy bills it’s wise to use a bathroom fan with a humidity sensor. This way it will only run when necessary and forgetting it running will be impossible.

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Joonas

I like it when I'm able to fix everything that needs fixing around the house. In order to do that, I have to do a lot of research. This site will cover everything I learn and maybe help others do the same.

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