Outdoor Air Conditioning?
It’s summer. It’s hot and humid and we’ll do anything to ease the heat off, even a little bit. Or in some cases, we’ll do anything to ensure our guests, customers, and clients don’t melt just for coming to a major public event. The problem is, how do we cool people down outside? It can’t be that hard, right?
Mother Nature’s Onslaught
We first need to understand what we can’t do. On a hot sunny day, there’s effectively hundreds of thousands of BTUs of heat in the air. If we attempt to use a standard air conditioner outside, it’d be every bit as effective as blowing in the wind or using a match to solder 6″ piping. We’re fighting an uphill battle.
Modern air conditioning works because we can keep it inside. Air naturally wants to mix and achieve a temperature equilibrium. By putting cool air into buildings, we contain it and prevent any significant dispersal from occurring. Our 40,000 or 400,000 BTU of cooling is able to actually get something done in this way.
We could put these massive machines outside and try, but chances are they would have to remain constantly on. Even if a target temperature could be reached, the movement of the air would soon blow our nice, coolness away. It quickly becomes a matter of impracticality. The size, cost, and logistics of the cooling equipment to cool your company picnic or cool an entire amusement park isn’t viable. There is however, one thing that will work.
At a major event or location, it’s not necessarily the temperature, but rather the temperature difference that matters. All winter long, we get used to cold temperatures. By the time spring comes, 60 or even 50 degrees can feel like shorts weather. We’re not perturbed the coolness because we’ve become acclimated to it. If you spend an entire working day in a freezer such as a meat packing plant, the cool temperatures aren’t anywhere near as bothersome to you as others.
For major outdoor events, we can exploit this by providing cooler areas. We employ shaded areas where our customers will stand in lines, put up massive fans near food areas, and encourage people to spread out as much as possible to help keep them cool. When done correctly, the ambient temperature may be 95 degrees, but the 10 degree decreases in the shade and perhaps even 15-20 degree perceived changes in areas with shade and fans can have the same net-effect as an air conditioner: your guests feel cooler.
These strategies ironically, only work outdoors. Indoor environments are the exact opposite. Heat collects inside enclosed spaces and nothing except the direct removal of that heat is really effective at creating customer comfort. However, the physics of air conditioning do still work outdoors, just with some minor adjustments.
We said air conditioning won’t work outside, so what gives? The problem with air conditioning is the delivery system and the costs involved. The idea however, remains sound if we change how it works. It costs significant amounts of power to cool the air down and at the end of the day air is a really awful thermal conductor.
Consider that 65 degree air feels pretty comfortable, but 65 degree water can make your entire body freeze up in shock. There is an identical amount of energy present, but one of them slams into you like a freight train and one doesn’t.
The water is conducting heat out of your body. While you’re in a pool, your body is just like a pool heater, in an impossible battle. You’re pumping body heat into an immense amount of water and it’s going nowhere. Your physical presence would need hundreds of thousands of calories to actually heat that pool on your own.
Water does not need to be as cool to effect the same cooling as air. A ten or twenty degree water-air difference can have a significant impact. As the water is in contact with the air, it causes the air to cool by draining it of energy in the same manner as a pool. When it comes in contact with a person, it has an even more rapid effect.
This approach is actually used in industrial settings in what is called a ‘spray pond’. Hot water is sprayed into the air as a mist in order for it to cool and be re-used. We’ll essentially do the same but instead of the water being cooled, it’s people.
Misting Fans and Attractions
This is where fans re-enter the picture. By misting cool water on visitors, we can create a significant temperature change and improve their experience. For temporary attractions, this gets the job done well enough. You roll out a few fans and put them where they’re easily accessible to your guests.
One fan alone will cool a few individuals in a small area. Additional fans can cool the entire temperature of a slightly larger area, with the water absorbing heat from the air. There is however, one further step, one more way to take this to extremes.
Theme parks and other permanant facilities have water rides and ponds with some spraying attractions. Used strategically, these can offer a few guests an immediate and significant cool down and spray water into the air to cool down a larger area. We create small temperature changes, but in extreme heat, these small differences are enough to soothe your clients, customers, and guests immediate discomfort and prolong their stay or increase their willingness to return.
Cool by Design
Remember, it’s not the environment’s real temperature, only the perception of that environment. When having guests in outdoor environments, design your layout to maximize opportunities to cool down. Your guests will thank you for it.