Greenhouse Cooling Basics: Keeping a greenhouse, or sunroom, cool is a balance between ventilation, misting and shade cloth, in the hotter months. Ventilation via operable vents may “sometimes” provide proper ventilation in a “pre-engineered and manufactured greenhouse”, but seldom will one achieve success in a site built structure. Add an exhaust fan and inlet shutters/dampers to effectively move air. Select a 2 speed fan so it starts slow, eliminating strong blasts of cold air. Place fan high and shutters low. For sunrooms a 110 Volt Fan-Tastic Vent Fan can be installed on the wall or on a roof. Simply cut a 14″x14″ hole in the polycarbonate, place a 2×2 wood frame on the inside and install the fan.
Natural Ventilation: Some greenhouses can be ventilated using side and ridge vents, which run the full length of the house and can be opened as needed to provide the desired temperature. This method uses thermal gradients, creating circulation due to warm air rising.
Greenhouse or sunrooms with only side vents depend upon wind pressure for ventilation and are usually not satisfactory. The warm air must be allowed to rise through the ridge vent while cooler air enters along the sides. The vent size is important. Ridge vents should be about one-fourth the floor area and the side vents about the same size. The roof vents should open above the horizontal position to provide about a 60-degree angle to the roof.
Also add a misting system. The mist is good for your plants and will dramatically assist in the cooling process. Jaybird Mfg Misting Equipment makes simple to install and high quality units. Do this and you should only need to add shade cloth when it starts to get hot. Keep it simple and effective.
Search Google for Greenhouse Exhaust Fans Many sites offer education, tech support and equipment.
• Roof vents for pool enclosures? We recommend sliding glass doors on the walls and a large exhaust fan.
Heating Questions & Options:
• Do you sell heaters? No, visit Southern Burner Company for small greenhouse heaters or search the web.