Fans can be an economical and ecological alternative to supplement, or even replace, air conditioning. Window fans are particularly suitable for areas and seasons with very hot weather during the day and cool, dry weather at night. The goal is to cool a building during the night by using the outside air, and by reducing or even eliminating air conditioning during the day. In addition, the fans consume electricity at night, and therefore, are advantageous both in the case of dual day-night tariffs, and in the case of areas subject to blackouts due to overload. To use window fans to cool your home, follow the criteria outlined in the article.
Steps
Step 1. Assess if your situation is appropriate for this solution
- If the temperature is unbearably hot and humid both day and night, this solution is not appropriate. On the other hand, if the temperature were hot and humid only during the day, a window fan could be successfully used to lower it during the night.
- If you live in a very polluted area, a window fan will bring pollution into the house.
- The window fan is not recommended if the necessary protection is not present, because insects and other animals can enter through the open windows. Mosquitoes and other types of tiny insects can still enter through such covers, so don't use this solution if you can't stand them.
- In the most disreputable areas, windows accessible from the outside are a godsend for thieves.
- Also, outside noises will be more annoying with open windows, although fan noise masks some.
Step 2. Choose the fan
The ideal model is the widest that can fit into the window body. Avoid fans that are too large for the size of the window, because by placing them outside the window structure they often end up falling. The building should have a balanced air exchange capacity (bearing in mind that it is necessary to consider adding smaller fans when designing the system). If there is an imbalance that cannot be easily balanced, it is better to introduce more air, in order to create a greater internal pressure; this prevents the entry of dust and insects when the doors are open, and stops the "bad air" coming from the chimneys.
Step 3. Decide where to place the window fans
This also means deciding which fan will convey the outside air and which one will suck the air from inside. There are several considerations to make in this regard:
- Directs the air from the side where the air is cooler. Generally, this will be the shadow side.
- It accompanies the direction of the wind, orienting the fans in the same direction rather than against the wind. When the wind is strong enough, the use of fans may not be necessary.
- In a single-storey apartment, arrange the fans to channel the air on one side and expel it on the opposite side, keeping the internal doors open to promote maximum air circulation.
- For houses with more than one storey, it can be exploited the fact that hot air tends to rise, so the circulation system should provide for the intake of air from the ground floor and the escape from the upper floors, including the attic. (with the attic door open if possible).
- Avoid introducing air from areas with accumulated waste, or from parking areas. The air taken near trees and plants is often more fragrant and pleasant, unless you have the problem of pollen.
- Directing the incoming air directly to a refrigerator or freezer facilitates the escape of air to the outside (especially when these appliances are open), thus increasing the workload of the fan; therefore, it should be avoided.
- Remember that the air conveyed inside by the fan can scatter or damage loose sheets of paper, so avoid using fans in office areas, or secure the paper first.
- Avoid placing fans that convey air over valuables, such as an antique desk or an expensive oriental rug, especially to avoid damaging them with drops of water or humidity.
- The rooms with fans that convey air will cool off earlier (due to the increase in air circulation) than those that have fans to expel it.
Step 4. Place the fans in the windows
Tighten the windows as tightly as possible around the fan to keep it blocked and to avoid a vicious circle of air. The vicious circle occurs when the air introduced by the fan is sucked around the fan to the outside, in a circle that repeats itself indefinitely. The consequent effect is that the air is heated by the fan motor.
Step 5. Cover the window slots adjacent to the fan
If the fan conveys air inside, the air tends to return due to the increase in pressure in the room. Generally, placing some fabric (or even paper) on the sides of the fan is sufficient, as they will be pushed towards the window pane. For fans that expel the air, covering the slits is more complicated, because the air around them tends to flow back. Consequently, cardboard or paper must be placed on the outside of the window, if this is accessible, or taped the slots from the inside. For fans that push the air out, you can also avoid covering the slots, but in this case, you must accept that they operate with reduced efficiency.
Step 6. Turn on the fans whenever it is cooler outside than inside
Turn them off, remove them from the window and close it when the building is cool enough to compensate for the temperature expected for the next day. A general rule based on common sense is that the indoor temperature during the day will be equal to the average between the outdoor temperature during the day and the indoor temperature at night. So, if you want to keep the internal temperature at 21 ° C, and expect an outside temperature of around 27 ° C during the day, you need to lower the internal temperature at night to 15 ° C. This will vary by building, but you can use this rule until you have determined more accurate values for your area. In the previous example, the fan can be turned off once the internal temperature has dropped to 15 ° C.
Advice
- Place the fans that expel air as high as possible; for example, in a second floor window. Since the hot air tends to rise, the fans positioned at the top will tend to expel the warmer air first.
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The fans cool in 3 ways:
- Bringing fresh air from the outside and eliminating the hottest one from the building. This is the main solution considered by this article.
- By pushing away the warmer and humid air close to people, and replacing it with cooler and drier air. Ceiling fans, for example, cool in this way.
- By increasing the evaporation index of a liquid to produce fresh by evaporation. To cool a room this solution can only work well in areas with very low humidity, such as desert areas. To cool people, this solution is good if people are wet or sweaty, for example after a shower, a bath, a swim in the pool, or after strenuous exercise.
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Fan maintenance:
- Leaving the fans running for a significant fraction of the day reduces their duration, especially if they remain in the window during a downpour. However, doing some maintenance increases its duration.
- Do not turn on a fan that is not working well, especially if the fans are not moving at all and / or there is a burning smell. A fan in these conditions can cause a fire to break out.
- The most common problem is a lack of lubrication. A signal is given by the slowing down of the fans, especially at startup, compared to when they were new, or even by their blocking, and by the increase in noise. In this case, unplug the fan from the electrical outlet, and move it to the garage or to an area where vapors are not a problem, then lubricate the fan shaft and the parts around it. It may be necessary to remove the guard grilles and the fan block to do a job well done, although a can of WD40 lubricant (or equivalent) with a spray nozzle can reach the lubrication points more easily. Rotate the fans during and after lubrication to distribute the lubricant evenly. Be careful not to spread drops of oil in the electrical parts, especially in those near the switch. Do not operate the fan for a few days, until the excess lubricant vapors evaporate. Use this fan initially to expel the air so that the residual vapors are blown outside.
- Another common problem is an electrical fault - usually a cable that has come loose from a solder point or connection. If you know how to weld, you can repair it yourself. The switch is the one most affected by this type of fault. If necessary, you can also bypass the switch, and turn on the fan directly, by plugging in the power socket. However, this may mean that you lose the ability to vary the fan speed.
- Removing the fan from the window when not in use helps maintain the right temperature, but can be tricky for older people and the weak. In these cases the fans can be left in the windows. However, during thunderstorms, fans should be removed to prevent water damage in the building.
- If the ventilation with the fan is not appropriate for the building, the fans can still be directed towards people, with the windows closed, to cool them directly. In this case, be sure to turn off the fans when people are no longer in the room, as they will produce heat without any cooling effect.
- If the building cannot withstand the electrical load of a centralized air conditioning system, the fans do not normally cause overloads; since they absorb less electrical power, use them during off-peak hours, and distribute them throughout the building.
- This cooling solution can make the temperature excessively cold at night. Wear warm clothing and use a blanket to sleep if this happens.
- For a short time (about an hour) you can greatly increase the cooling effect by covering the back of the fan that conveys the air with ice towels. This, pushed by the fan, will pass through the towel with the ice. The towel should be the size of the fan (a beach towel would probably be too large). In addition, it assesses the potential water damage and electrical risk; do not use this method if the water produced by the ice tends to drip onto the electrical outlet or electrical connections.
- A bathroom fan can be used to expel the air. These are often positioned on the ceiling and maximize the rising effect of the hot air.
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Cleaning the fan:
- The fans tend to get very dirty, collecting dirt and dust from the air they circulate. Even if they use filters to clean the air, the problem of cleaning remains. In fact, they will collect grease if used near a kitchen, and tars if used near smoke sources.
- Unplug the fan to clean it, then use water, window cleaner, or diluted dish detergent with a paper towel. If you use a detergent then remove it with a damp paper towel. Again, you may need to remove the protective grilles to access the fans and clean them. Turn on the fan before repositioning it so that the fumes of detergents and solvents are blown out of the building.
- Another possibility is to simply use the dirtiest fans in the windows of the less used rooms and use new fans in the busiest rooms.
- Some doors used in unsavory areas use protective screens and may have bars, allowing protected access to convey the air inside. In this case, if there is a fan throughout the building used for the dispersion of the chimney fumes, the air can be circulated, keeping the doors open, without compromising the safety of the building.
Warnings
- Avoid having the fans too close to the ground. At night, this could increase the humidity in the building and form mold.
- Do not leave the fans in the windows with rain showers, because water could enter through the window and damage the building. This is particularly a problem for fans that convey the air inside. Roofs with wide pitches can help reduce the problem, especially on the top floor, except when the winds are strong.
- Be prepared to accept a difference in indoor temperature of 3 to 7 degrees between day and night, because fans do not allow you to control the temperature with the precision of an air conditioner.
- Do not use a fan that does not work well. If the fans are not spinning at the right speed, or if you smell burning, unplug the fan immediately. Otherwise you risk a short circuit and set fire to fabrics and curtains.
- Avoid using fans when there are children around who might stick their fingers in the fans. The protective grids on the front and back are often spaced far enough apart for a child's fingers to insert a pen or other objects.
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Be careful with electrical cables:
- Don't squeeze them with the window and don't leave them along the floor where they could trip. If necessary, use an extension cable so that they do not get off the ground and are pushed against a wall to avoid the danger of tripping.
- Do not put cables under carpets, as they could generate heat and, therefore, ignite.
- Make sure the fan doesn't fall out of the window.
- The window fan solution can create problems for wooden furniture, because variations in temperature and humidity can cause cracks and warping.
