A set is how many times you are going to lift and then take a break. So if you lift the weight five times, take a break, and lift again you will have done two sets. The five times would be your reps. My coaches like to write the workout like so: Squat 3x2, Bench 2x5, and so on.
Evaporative coolers use both electricity and water. How much water is used depends on the humidity of the day and the fan speed that the unit is set to operate on. A portable unit might use up to 4 litres per hour while a central system could use as much as 25 litres per hour. Ducted evaporative coolers must refresh their water supply otherwise it can become too salty, and a range of water management systems are used by different brands/models.
It varies from model to model, but by comparison with similar capacity refrigerated systems, evaporative air coolers use about 20% of the electrical energy. In comparative terms, if a refrigerated cooler costs $400 to run for a season, an evaporative cooler will cost around $80..