Updated on Jul. 21, 2025
An evaporative cooler can be a more cost-effective and eco-friendly option to beat the heat. It is better than central air conditioning
Our editors and experts handpick every product we feature. We may earn a commission from your purchases.Learn more.
Evaporative coolers—commonly known as “swamp coolers” but also called evaporative air conditioners, desert coolers, wet air coolers and even swamp boxes—have been around in their modern form since the 1930s. But the basic concept can be traced to the ancient Egyptians, who discovered that hot, dry breezes could be made pleasantly cool and moist when blown through damp reed mats or past porous clay pots filled with water.
“Installing an evaporative cooler is a great way to keep indoor air fresh and cool, especially with the windows open,” says Scott Jenschke, an air circulation and accessories merchant for The Home Depot.
Here’s what you need to know if you are considering this type of cooler for your home.
On This Page
An evaporative cooler uses an electric-powered fan to draw hot, dry air through a dampened pad and blow the cooled air out into the room. This relatively simple process consumes much less energy than a standard air conditioner and doesn’t require ozone-damaging refrigerants to work.
It is also less expensive to install and maintain than central air conditioning.
Jenschke explains that evaporative coolers, or swamp coolers, utilize evaporation to cool the air temperature. “The liquid turns into gas when water evaporates, releasing the highest energy particles and causing the temperature to drop,” he says. “This is why your forehead feels cooler after you put a moist cloth on it on a hot day.” This same scientific principle can be applied to the evaporative cooling process for the air inside your home.
Evaporative coolers consist of four essential parts: a fan, a water tank, filter pads (sometimes called media) and an internal motor. The motor pulls warm air through a wet internal filter pad, where the evaporation process quickly lowers its temperature before it is circulated back into the room. The internal pads also act as a filter, removing dust and allergens from the air.
“Evaporative coolers work best in arid climates, where you can see as much as a 30-degree reduction in temperature,” says Jenschke. “In less arid climates, they’re not as effective, but can still cool the surrounding air by five to 15 degrees.”
Jenschke also recommends opening nearby windows to help renew the air and keep the breeze fresh.
There are four main types:
Evaporative coolers and A/C units work with different technologies.
“Air conditioners use chemical refrigerants in tubes and coils to remove hot air from your home and leave behind drier, cooler air,” Jenschke says. “In many situations, an air conditioner is connected to the outdoors because the tubes and coils absorb heat from indoors and release it outdoors. You can feel warm air coming from an air conditioner outside for this reason.”
Evaporative coolers, on the other hand, harness the power of evaporation to cool the air naturally.
“The evaporative cooler is a more sustainable option as it uses one-fourth of the energy and costs about half as much to install as an air conditioner,” says Jenschke. “It also doesn’t require ductwork to move the cooler air throughout the house like a central air conditioning unit does.”
You can use these evaporative cooler maintenance tips to make it last longer and save money:
1. Evaporative coolers are most efficient in drier climates where the humidity levels stay under 60% most of the time. However, they can still be somewhat useful in the more humid climates of the South and Midwest, working effectively in fan mode to circulate air throughout a building. And, of course, you could always use them on days when the humidity levels are low.
2. According to ScienceDirect (2023), there are various types of natural fibers for cooling effects. “The aspen cooling pads look like grass and are made up of wood shavings and synthetic fibre. This type of natural fiber is cheap and, hence, economical, and reduces the cost of the ECS. This type of fiber needs higher maintenance and is less durable.”
Evaporative coolers can cost less than $100 for small portable models to around $1,500 for down or side discharge models powerful enough to cool an entire home.
“Some municipalities offer rebates of up to $250 for the purchase of a whole-house unit through your utility provider,” Jenschke says.
To figure out the best evaporative cooler for your home, you need to check the cubic feet per minute (CFM) rating. This is the cubic feet per minute the unit can cool. Calculate the minimum CFM you need by determining the cubic feet of space you want to cool (length in feet x width in feet x height in feet = cubic feet) and multiplying that total by the number of times you want the air to turn over in an hour.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) suggests five to nine air changes an hour for residential rooms. Then divide that total by 60 (minutes). The result tells you the CFM rating you need. Some models also list a square foot rating, which is less precise but still helpful when choosing the right cooler for your space.
Here is the table comparing various types of evaporative coolers with their costs, capacities and functionalities
| Evaporative Cooler Types | Approx Cost (USD) | Cooling Capacity (Sq. Ft.) | Water Tank Capacity (Liters) | Best Suited For | Key Features & Functionality |
|
$50 – $150 | Up to 150 | 5 – 10 liters | Small rooms, personal use |
|
|
$100 – $300 | 200 – 600 | 30 – 60 liters | Hot, dry climates, large rooms |
|
|
$80 – $200 | 150 – 400 | 10 – 25 liters | Medium-sized rooms |
|
|
$150 – $400 | 300 – 700 | 30 – 50 liters | Rooms with accessible windows |
|
|
$500 – $3000+ | 1000 – 5000+ | 100 – 200+ liters | Warehouses, workshops, outdoor use |
|
|
$200 – $800 | 500 – 1200 | 40 – 100 liters | Patios, gardens, events |
|
|
$1000 – $3000+ | Entire house (1500–2500 sq ft) | Connected to plumbing | Homes in dry climates |
|
Evaporative coolers generally come with all their necessary parts except possibly the motor (see below), but you’ll need to purchase replacement pads over time. You can buy these and other accessories from the same supplier from whom you purchased your cooler, home centers or even Amazon. Good accessories will give you the perfect eco-friendly cooling solutions.
Evaporative coolers are very efficient in dry weather. If humidity levels are below 60%, you will get the maximum performance from these coolers. However, they are not very effective in humid areas. But you can use them in fan mode in high humidity. It will improve air circulation, making these coolers ideal for dry days or in airy rooms.
Frequent maintenance and check-ups are crucial for optimal performance. You should change cooling pads annually and regularly clean the water tank and fan blades. It will prevent mold and mineral buildup. Always check for leaks and ensure proper airflow. If your unit has replaceable components, check the motor and pump at regular intervals.
Evaporative coolers consume less energy than traditional air conditioners. These swamp coolers use up to 75% less energy than traditional ones. Also, the installation cost is much lower. These are a smart and sustainable alternative. These will reduce electricity bills and carbon footprint, giving you one of the eco-friendly cooling solutions.
