RT Journal Article SR Electronic T1 Selecting Trees for Shade in the Southwest JF Arboriculture & Urban Forestry (AUF) JO JOA FD International Society of Arboriculture SP 35 OP 43 DO 10.48044/jauf.1989.009 VO 15 IS 2 A1 E. Gregory McPherson A1 Eileen Dougherty YR 1989 UL http://auf.isa-arbor.com/content/15/2/35.abstract AB Shade trees in the Southwest can provide large potential energy savings for cooling and enhanced comfort for outdoor living. However, water costs for shade trees may offset space cooling savings in water-scarce regions. Computer simulation was used to calculate potential residential heating and cooling savings from several shading scenarios in Tucson, Arizona. Energy savings were compared with water costs to derive net savings for six tree species commonly used in Southwest landscapes.Dense shade on west walls reduced annual energy costs by 10-12% ($55-121), depending on the type of building construction. A surprising finding was that tree form appears to have a greater effect on energy savings than crown density and, hence, merits more attention during the tree selection process. Annual water costs were equivalent to about 20% of annual energy savings for low-water-use species, and ranged from 53-261% for the high-water-use species. Water requirements are an important factor to consider when selecting shade trees for Southwest landscapes.