I feel that every year, I’m surprised by how hot the weather gets during the summer and I’m left trying to concoct quick schemes 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 draw out odors and moisture from the bathroom by exhausting the air containing these. The air has to be replaced and, depending on the source of the “new” air, the exhaust system can help to cool down the house. But there are also other, potentially more reliable alternative solutions.
Bathroom exhaust fans can help to 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 for this purpose during the night when the temperature drops.
Outdoor Temperature Must Be Lower Than Indoor
The whole notion of cooling a house using a bathroom exhaust fan to cool the house relies on the fact that the air moving into the house is cooler than the air in the house. In summer, when you are attempting this technique, the odds of that being the case are slim, although not impossible.
Rooms that are in full, midday sun are often much hotter than the air outside. Airtight houses are also susceptible to building up heat that exceeds the temperatures outside as a result of all the passive and active heat created in a house (breathing, exercising, cooking, boiling the kettle, etc.).
In addition, the outdoor air temperature can also fall below the indoor temperature at night, in which case, running the fan at night will help to cool the house. But you will need to turn it off in the morning before the outside temperature starts to rise again.
If you are wondering why you can’t just open a window and achieve the same effect, then you need to take into consideration the fact that the fan actively removes the warmer indoor air, forcing cold air to enter the house.
An open window alone relies entirely on passive movement of air, and the cooler air entering your home or the hotter air leaving it depends on too many factors to be as reliable as the exhaust fan.
The larger the temperature difference, the more effective the fan will be, and high CFM fans will be more effective simply because they exhaust more air, thereby increasing the amount of cooler air enter the home.
However, sizing up your fan for this purpose is inadvisable. Fans must match the size of the bathroom or there will be unintended and negative side-effects.
For example, yes, air can be pulled in from outside, but it can also be pulled from your toilet and drains if there aren’t enough other openings around the house.
Another limitation of this method is that it only really works for rooms near to the bathroom. A room on the floor above or on the other side of the house on the same floor will not be likely to experience any effects from the air that is pulled in.
Don’t Use With the AC
If you have an air conditioning unit and you are looking to boost its effects, the bathroom extractor fan is not an option. All you are doing is taking the air that you have paid to cool and exhausting it outdoors only to bring in air that your AC has to cool again.
Bathroom Fan Cannot Run Overnight
Out of all the situations in which the outdoor temperature will be cooler than indoor temperature in the summer months, the temperature dropping at night is the most likely. This makes leaving it running over night seem like the best approach.
However, the most common bathroom fans are designed for short-term use. Running two, maybe three hours at a time is all it’s really supposed to handle on a regular basis.
In addition to consuming power, leaving the fan on all night reduces its lifespan and increases the risk of overheating, which can be dangerous.
Like any other machine, continuous operation increases the wear and tear, making the fan deteriorate faster.
In terms of the increased risk, a motor that is working harder than it is designed to do will experience a lot more resistance and friction, which is released as thermal energy.
Motors that are overheating can short-circuit and pose a fire risk, although admittedly it is a low risk in most circumstances.
You do get fans that are rated for continuous operation, but these are drawbacks to using these for bathroom ventilation, which you have to remember is the main purpose of the exhaust fan.
Alternative Solutions
A Portable AC Won’t Break the Bank
When a recent heatwave hit us, at first I tried everything under the sun to cool my house using things that I had laying around the house.
I made a makeshift evaporative cooler. All that did was make the house humid and even more uncomfortable.
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 and the moment air was not blowing directly on me, it was really 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 only lasts for a couple of weeks a year, so I can’t justify a built-in air conditioner, or even a split AC.
However, a portable AC (amazon link), 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!
Create a Cross Breeze
While one open window is not as effective as the bathroom fan, opening a window can optimize the technique.
Opening a window and having the fan on will ensure that replacement air easily enters the house.
You should open a window that is as close to opposite the fan as possible.
Not only will cooler air have an easy pathway into the house, but any rooms along the path between the window and the bathroom will also get the effects of the breeze created.
The one-window cross breeze effect can also be achieved by running the range hood.
A range hood works better than a bathroom fan since it has a higher CFM, creating more airflow. In addition, it is usually more centrally located, allowing major living areas to benefit.
You can also always just use two windows to create the cross breeze.
Use Fans
Despite my previous harsh judgement against fans, they do work when they are blowing over you.
You can also pat water onto your skin or wet your clothing a bit. When the fan blows over you, the cooling effects of fans are multiplied.
Reduce Humidity
Maybe what is really getting to you is the humidity and not the heat.
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.
Reducing the humidity can reduce the perceived indoor temperature even if it doesn’t reduce the actual temperature.
A dehumidifier can be used to remove the moisture from the air.
Ideas to Prevent Indoor Temperatures Rising
Instead of trying to cool down the indoor temperature, you can try to prevent the heat from building in the first place, or add these methods to your attempts to lower the temperature.
Block the Sunlight
Direct sunlight adds a lot of heat to the air inside the house. It can heat up the walls in a brick house, but the most common culprits are the windows, particularly if they are not double- or triple-paned.
Normal curtains don’t make much of a difference to this, 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.
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.
Limit Appliance Usage
Almost all electrical appliances emit heat to some degree. Your lights, your TV, your laptop, etc.
It is definitely worthwhile limiting the use of these, but the biggest difference is going to come from the actual heat-producing appliances, like dryers, irons, stoves, ovens, electric kettles, hair dryers, etc.
Doing your laundry first thing in the morning can limit the heat released into the house from the iron or dryer.
Try to also 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.
The dishwasher is another appliance that leaves the house hotter. The build-up of heat is what makes most manufacturers recommend a gap between the dishwasher and countertop. Consider washing the dishes 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 a more permanent solution in place for those typical sweltering summer days.