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Message: [QUOTE="DirtMechanic, post: 224970, member: 5568"] Regarding your solar loading, two things might be controllable and suit you. The solar spectrum heat comes from roughly 49%Visible, 49%IR, 1UV. To cool while maintaining visible light you can increase glare of angled light with frosted film. Glass absorbs a surprising amount of IR, but further reduction can be made preferably externally with solar films. Plastics can pass most IR or be treated to stop most IR. We put 80 % vlt solar films on car windshields because they absorb 90% of any IR that makes it through. Car glass is usually 75%VLT and at least 60%IR filter if not 80%IR on solar ray types. The films handle the difference coming through onto you and add interior absorption where the shiny glass was acting as a retentive mirror for heat. This helps heat leave for passive cooling. It never equals ambient temps but is much better. There are also uv sensitive films of PET and Urethane that self darken in sunlight to a specified range of VLT. There are also electrically switchable frosted films that can be controlled via thermostat if you have power or batteries out there in the greenhouse. They are clear or frosted based on the switch on or off. They need a glass substrate for mounting. Anyway, IR control can be a challenge because it is invisible. Heat flows from the high to the low so interrupting that flow is to control emissions from one source to another, radiantly, convectively or via contact. Heat rejective surfaces are used for retention in cold climates by facing them inwards so usage depends on orientation. In warm climates they are faced or layered on the outer skin of a structure. LOW-E glass for you would have 2 layers of glass where the outer layer has the IR mirror coating. This would produce a 40f degree difference between the outer and inner layers of glass here at 33° latitude. A space separated outer layer of frosted translucent plastic can act similarly in your environment. Its best to have some electrical, even battery fans, to mechanically balance heat but controlling the radiant barrier helps also. [/QUOTE]

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