The use of landscape elements in passive cooling strategies for buildings

Design for passive cooling in hot climates presents particular design challenges due of the magnitude of the sources of overheating versus the potential of the natural sources of cooling that are usually available. Despite the general recognition that the landscape can have a significant impact in improving comfort and reducing energy use in buildings, there is little quantified research. Much of the previous research on the effects of the landscape on building energy use is on the application of trees or whole landscape strategies to small buildings, such as single family homes (Parker, McPherson). This dissertation presents the results from a series of experiments on the uses of several less well studied elements of the landscape in the cooling of buildings; vines, landscape ponds and vegetated roofs. The experiments include both laboratory and field studies. Tests were conducted on: the effects of vines grown against walls on building surface temperature; the effects of vines grown on pergolas and trellis systems on both building surface and air temperature; the effect of sod and other vegetated roof types on roof temperature; the effect of aquatic vegetation on water temperature of ponds: the ability of vine shaded ponds to reduce temperature in interior spaces. The experiments described in this dissertation demonstrate that all of the strategies studied; vine shading, landscape ponds, and vegetated roofs, have the potential to reduce heat gain significantly and perform well as bioclimatic elements in cooling strategies for buildings. Landscape ponds and vegetated roofs were shown to be able to function as passive cooling systems as well. That is, they have the potential to reduce average indoor temperatures to below the outdoor average. Landscape strategies can be used to make new buildings perform well in hot climates, but may be even more valuable in improving the performance of existing buildings, since most landscape elements can be added without changes to the building itself. The strategies studied here could be used on buildings of almost any size or type.