Evaporative cooling uses a system of air flow called the Fresh Air System.  In this system, fresh outside air is brought in through the cooler, where it is cooled and pushed through the building, then exhausted to the outside through screened windows or doors. This type of air circulation differs from traditional air conditioning, which uses recirculated air, allowing the same inside air to revolve over and over again through the building, and unlike the the Fresh Air System, works best if it is sealed off from all outside air leakages and exchange.  This causes stale and toxic air in your home or office!   These problems are known as "sick building syndrome".

The Fresh Air Cooling System, used by all evaporative coolers, is beneficial as compared to the re-circulation of the AC units, because evaporative coolers are designed to supply an entire exchange of all the buildings air every 2 to 3 minutes. Evaporative cooling greatly reduces environmental air-impurities; while AC units will continue to re-use the same polluted air, often causing problems with indoor air quality. 

Please see the diagram below to discover how the Fresh Air System works. 

For for this system to work well, the windows must be partially opened to allow air to escape, which allows the freshly cooled air to enter. If the windows are closed, the exhaust and intake air will be restricted, and the building will become pressurized and not cool well.  The intake of fresh cooled air will be blocked.

Through the use of the SOLAR CHILL Evaporative Coolers, the diagram below shows how the cooling system works without the use of duct work.   It is preferable to eliminate the ductwork and use the building as the ductwork instead.  This is more energy efficient by reducing the friction to air flow that ductwork causes, and saves you the cost of the ducts!