How many BTU should a camping air conditioner be?
Using a camping air conditioner can vastly improve your camping experience by allowing for a more comfortable night’s sleep. However, tent air conditioners come in a variety of styles and styles. To know how much cooling capacity you need, there are a few questions you’ll need to answer about your intended camping experience.
Different kinds of air conditioners
The most common type of tent air conditioner is the portable, compressor-driven style. It works by compressing a refrigerant, which causes it to become a cold liquid, and then it passes air over the cooling coils containing that refrigerant.
The cooling capacity of the air conditioner is measured in British Thermal Units (BTUs), which refers to the heat required to raise the temperature of one pound of water one degree. It’s commonly used to measure the capacity of electric and gas heaters, but it can be reversed to give a measure of cooling too.
Evaporative coolers (sometimes called swamp coolers) work by blowing air over water, which causes it to evaporate and absorb heat from the air. Since the water does the cooling, they aren’t rated in BTUs like a compressor-driven air conditioner. Their cooling power is determined by how much air their fan can move, measured in cubic feet per minute (CFM).
How big is your tent?
Compared to houses, the square footage of tents doesn’t vary all that much; a two-person backpacking tent might have 30 square feet of living space while an eight-person multi-room car camper might have 120 square feet. The average bedroom in a home is between 120 and 200 square feet, which just about any window-mounted air conditioner is capable of cooling.
That being said, bedrooms have insulation and tents do not; it takes more BTUs to cool off a tent compared to a similarly sized room in a house. However, many tents have a low ceiling, less than six feet, while most houses have at least eight feet of headspace.
Where are you camping?
Perhaps more important than the size of your tent are the conditions you’ll be camping in and the time of day you’ll be using it. If you’re only sleeping in the tent, the daytime temperatures aren’t so important. Camping in the deserts of Nevada or Arizona, the midday temps might be above 100 degrees, but it cools down to 75 in the evening - the magic of a low-humidity climate.
The same can’t be said for humid regions like Louisiana or Alabama, where the differences between day and night temperatures are much less significant; these are the places where a tent air conditioner will be most useful. Additionally, a compressor-driven unit can suck the humidity out of the air so you don’t wake up feeling sticky.
What's your power source?
It doesn’t matter how much cooling capacity your air conditioner has if you don’t have the means to power it. Are you planning on plugging your air conditioner into mains electricity at a developed campsite? Then you really don’t need to worry about power; those outlets are designed to power RVs with all their accessories running.
If you're camping off the grid though, power consumption is more of an issue. Higher BTU units require more fuel from a generator and batteries will only last a short period of time. This is especially true if you’re using a power inverter to run the unit off your vehicle’s battery, which is not recommended as their starter batteries aren’t designed for continuous usage (even with the engine running).So how many BTUs do I need?
Let’s get down to the numbers; how many BTUs do you actually need to cool your tent?
Start with tent size: is your tent more or less than 100 square feet? We’ll err on the side of caution by assuming you have six feet of headspace, but if it’s less than 100 square feet, a 5000 BTU system should be more than enough.
With 100 square feet or more, you’re likely sleeping in a 4+ person tent and those extra warm bodies require a bit more cooling capacity. In that case, 7,000 or 8,000 BTUs should be more than enough.
But what if you’re using an evaporative cooler instead of a compressor-driven air conditioner? A good estimation involves taking the square footage of the tent, multiplying it by height, and dividing by two to get the necessary airflow. For a 100 square foot tent with a six foot ceiling, that’s 300 cubic feet per minute. For anything larger, go with a cooler that can do 450 cfm.
Neither of those calculations takes into consideration the environment you’re camping in thought. For compressor-drive units, you should go one step up if you’re camping in a humid environment. So if your 80 square foot tent requires a 5,000 BTU while camping in Nevada, choose a 7,000 BTU unit when overnighting in Louisiana.
However, for an evaporative cooler to function, you need low humidity. The U.S. is divided into three zones: Zone 1 is where these coolers work well, primarily west of the Rocky Mountains. Zone 2 is immediately east of the Rockies, while Zone 3 covers just about everything else.
The previous calculation for evaporative coolers is for Zone 1; if you’re camping in Zone 2, choose a cooler with about 50% more airflow. It’s still limited in functionality as higher humidity air can only cool so well, but it will help.
Choosing the right air conditioner
BTUs are important when picking a tent air conditioner, but they’re not the only factor. Once you find a unit that’s in the right range for your camping setup, you’ll need to examine other factors like portability, ease of maintenance, running costs etc - all of which can be just as important as cooling capacity.