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Traditional air conditioners—window type air conditioners, central air conditioners, and even those bulky portable air conditioners with ugly large hoses—are good tools for dissipating heat in a room. Although using air conditioning does make you feel cooler than before, it is also an energy-intensive process. Air conditioning costs money, and it also leads to a self-fulfilling prophecy: all energy use will lead to global warming, which means we need to use more air conditioning, which consumes more energy, which costs more Money, wait forever. That was before we even got into the complex contribution of chemical refrigerants.

Evaporative cooling (PDF) is a refrigerant-free alternative that uses less energy. There are many different ways to take advantage of the natural evaporation process, but a common solution is to build or purchase an evaporative cooler. Also known as a swamp cooler, this device uses a fan to recirculate the air in the room through a cool wet pad (aka wick), and then exhaust fresh and humid air into the room. Do you know those little spray bottles with fans on top that people use to spray water on their faces when they wait in line for the roller coaster in the summer? That's basically it, on a larger scale.

But are these swamp coolers really useful? If so, why doesn't everyone use them?

Evaporative cooling is roughly based on an ancient and time-honored process called sweating. You may have heard of it. Our body automatically cools by releasing moisture from the skin; the moisture is taken away by the pleasant breeze, returning us to a more comfortable temperature. Quickly passing through the sprinkler has the same effect. This is basically the effect of the swamp cooler on the room air. However, as we discovered in our tests, your initial environmental conditions largely affect how it makes you feel cool.

We tested two portable commercial swamp coolers, Frigidaire EC200WF and Frigidaire EC300W-FA, and compared them with our portable air conditioning picks to see how they stack. Slowly but surely, the swamp does cool the room, although not as good as the (notoriously inefficient) portable air conditioner. However, every 1 degree reduction in the indoor temperature by the swamp cooler will also increase the humidity by about 2% to 3%. On a technical level, this makes sense; after all, this is their purpose. In contrast, portable air conditioners and window air conditioners actually dehumidify the space during the cooling process, and we have also seen this in our tests (this is why the window air conditioner on the second floor always drips on you ). Both of these methods can help you stay cool; they just use different methods to achieve this goal.

But in the test environment we used—in the northeast coastal area, on the day when the outdoor humidity exceeded 50%—we basically set these swamp coolers to malfunction. Because the air is so saturated, there is nothing the machine can do except over humidify the room to make it humid without any significant cooling or comfort. When your sweat cannot evaporate on a sultry day, you will have the same unpleasant feeling. However, in a drier environment, humidifying the air as it passes through the fan may have a serious impact. According to the US Department of Energy (DOE), evaporative coolers can successfully reduce the ambient temperature by 5 to 15 degrees-but even the US Department of Energy quickly clarified that this process is only suitable for low humidity areas.

In other words, the swamp cooler is not a good choice for places like Boston (where we conducted preliminary tests). However, if you live in a warm, arid climate, especially in the western United States, then it may be a reliable and cost-effective way to cool your summers. An Amazon reviewer in Arizona gave the Frigidaire EC300W-FA we tested five stars. He said, "For me, the added benefit is that I can take it to my workshop or put it next to me. On the porch-there is no air conditioning.” Another reviewer said that although Frigidaire EC300W-FA lowered the temperature by a few degrees, “it also increased the relative humidity in the room from 13% to 40%.” In places like Las Vegas and Boise, Idaho, there are many other commenters who also talked about the coolness they get from the swamp cooler, while acknowledging that the coolness is not always the same as the actual air conditioner. .

If you want to save more money-and you think you are cunning-you can also use a 5-gallon bucket (video), a styrofoam cooler (video), or even an empty old computer fan. Make your own swamp cooler milk carton (video). These DIY evaporative cooler projects all rely on the same basic components: an electric fan, a container or pump that supplies water, and a wick or aquarium tube that delivers water to the fan. You may need some basic cutting tools, some of which MacGyvered swamp coolers recommend additional ducting to keep the airflow strong. But in the right climate, one hour's work and one hundred dollars can make you a good choice for buying a new air conditioner. A DIYer even said that his homemade swamp cooler "it takes a while to cool the entire room, but it can reduce the average temperature of my room from 25 °C [77 °F] to 16 °C [60.8 °F]."

For places like Boston (where we conducted preliminary tests), swamp coolers are not a good choice. However, if you live in a warm, arid climate, especially in the western United States, then it may be a reliable and cost-effective way to cool your summers.

But, of course, time is money, and it may be easier to buy a prefabricated swamp cooler. The Frigidaire EC200WF we tested cost only $80 more than the homemade model. Adding about $70, the larger Frigidaire EC300W-FA will provide you with nearly three times the size of the water tank and nearly twice the fan power. EC300W-FA can also be used outdoors, adding a gentle breeze to your terrace. Even in the worst case, you can still use any swamp cooler as a giant fan. On a hot summer day, this is better than nothing.

This is Wirecutter's chill week! Read more about how to cool down and make the most of summer.

Author: Tom Dunn and Liam McCabe

After 130 hours of research and more than 90 hours of testing, we believe that Midea U MAW08V1QWT is the quietest and most efficient AC.

If window air conditioners or central air conditioners are not suitable for you, we have the best choice for portable air conditioners.

Teach your window air conditioner to become smarter and more like a family air conditioning system.

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