“Fact” number one: Evaporative coolers can cool by no more than 8 to 10 deg C. The figure of 8 to 10 deg C is based on a 30 deg C, 50% RH day (typical air conditioning industry design conditions). It is not true that only 8 to 10 deg C is available at other conditions. For example, at 36 deg C and 25% RH, you’d get 14 deg C of cooling.
“Fact” number two: The fact that it’s hotter inside than outside without cooling is a bad thing for evaporative coolers. If the warehouse is 5 deg C warmer than outside, it follows that simply replacing the indoor air with outdoor air (without cooling it) will reduce the inside temperature by 5 deg C. If that air is allowed to stay in the room it will of course increase in temperature over time, but with evaporative cooling we don’t allow that to happen. Add cooling into the equation, and the result is compliant temperatures even in extreme conditions.
“Fact” number three: On hot days you’ll get no cooling because it’ll be too humid but the truth is that high humidity and high temperatures do not coincide in the UK.
“Fact” number four: Evaporative cooling systems use single units delivering air in one spot and so can’t achieve good air distribution. This is a little like saying a poorly designed evaporative cooling system won’t work as well as a well designed air conditioning system, which is obviously true! The principles of good air distribution are as crucial and as easy to apply for both systems, though evaporative cooling starts with an advantage as it circulates far more air and mixes things up better.
“Fact” number five (contradicts fact number four!): Evaporative cooling systems use multiple units on the roof, risking leaks from roof penetrations and from water distribution systems. We can issue weatherproofing guarantees of up to 10 years if required, water pipes are never run through the warehouse and roof mounting is far from the only option anyway. Using multiple units means that if one fails, the vast majority of the system is still working and very little cooling is lost.
“Fact” number six: Evaporative cooling systems are difficult and expensive to maintain. Annual maintenance costs are very similar to those for air conditioning and the work doesn’t have to be carried out by specialist refrigeration engineers.
“Fact” number seven: Evaporative coolers can give you legionnaires disease.
“Fact” number eight: There’s only one example of evaporative cooling being used for pharmaceutical storage, which is in the South of France where conditions are very different. The French example is far from the only one available, but is a good one because it demonstrates what happens not only under “normal” UK conditions, but also at the exceptional conditions we might experience as global warming takes hold. |