3. External Shading. ASHRAE 90.1-1999 is unclear as to how to account for efforts to providing landscaping that reduces solar gain in summer and increases solar gain in winter. The project in question is being landscaped with large trees that have been selected for their shading characteristics. Existing trees are being preserved with the new parking areas being designed to fit with existing landscaping features. The goal is to reduce cooling loads and to reduce the heat island effect. DOE2.1E has the capability to model shading from trees and other landscaping features. ASHRAE 90.1-1999 intimates that the base building should be modelled with the same external shading by landscaping - but it is not explicit on this point. Does LEED allow for the proposed model to be credited for landscaping efforts to reduce gains?
Shading contributions by landscape is accepted under the LEED Energy Modeling Protocol. The modeler should include the differences between the Budget and Proposed cases as appropriate in the Submittal table of model variables. It is encumbent on the modeler to describe assumptions such as the tree species, canopy size, opacity, etc. used to model the shading effects. Applicable internationally.