What is the best way to cool an atrium in the summer?
I conducted an energy audit on a 1600 sq ft earth contact home with an atrium. The room is 6×14 with a brick thermal-mass floor, south facing glazing and about 9 sq ft of skylights. Four grilles along the bottom interior wall and 4 registers at the top circulate air in the winter to the home. Conducting a blower door test I found out this small room leaks air at the rate of 1000 cfm. The pine board ceiling is connected to the attic. The AC runs continuously during the summer. Will adding a screen door to the entrance for ventilation allow enough cooling to occur through the ceiling to the attic, reducing the heat load on the home during the day?
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I think you need to focus on minimizing heat gain as well as review the ventilation.
We've used an exterior shade screen material on atrium skylights to minimize on solar gain in the summer while still allowing for the view of the sky from below.
We've also had great success on exterior shading of south windows using a trick learned from Peter Peiffer of making shade trellises from "McGirt" Galvanized hat channel sold for use in industrial metal buildings and manufactured by McElroy Metals.
If the pine board ceiling is dumping heat and humidity into the attic between the planks then it seems that it is missing on optimizing heat collection in the winter and likely creating a flow of air from the house through to the attic contributing to depressurization of the house.
One way to take control of that air flow is by containing the air above the leaky wood ceiling and providing controlled ventilation to the exterior. You could frame a styrofoam wall separating the attic over the atrium from the attic over the conditioned space and provide controlled ventilation from this space to the exterior that could be opened in the summer and closed in the winter. Be careful you don't inadvertently create a sealed attic that would have condensation problems in the winter when you do this though. Provide a ceiling on the underside of the rafters to allow the area under the roof to be ventilated.
At the same time you may want to review the ability to isolate the atrium from the house below when the registers are closed to confirm that they really make an air tight closure. I'm assuming that the south glazing and skylights are all fixed glass which is leading you to look at a screen door. Would it be possible to hinge the skylights?
Thanks for the analysis Micheal..I like the trellis idea very much. The registers do not make a tight seal between rooms. All grass is fixed but making a skylight operable was one suggestion to the home owner. I'll offer some of these suggestions back to him and see where we go from here. Thanks again!