Paper Conference

Proceedings of eSim 2001: 1st Conference of IBPSA-Canada


DOE2.1E GEOMETRIC MODELLING: The Basic Geometric Approach vs. The Complex XYZ Approach

Christopher Jones, Curt Hepting

Abstract: The DOE2.1e energy modelling program provides differ­ ent approaches for defining the geometry of a building. The simplest approach involves defining the length, width and direction of building surfaces (basic geome­ try approach). A more complex model involves defining the coordinates of all surfaces (XYZ or detailed geome­ try approach). The perceived reason to use the XYZ approach is to better capture the effects of solar shading and day-lighting. The XYZ approach can directly model building shades and shading from other parts of the building. However, DOE2 also provides a simple facility for defining horizontal and vertical window shading devices. The amount of time required to model a building depends on the approach and tools available. The basic geometric approach takes less time than the XYZ approach. This paper examines the building energy use differences for two projects modelled using both approaches. It also compares building energy use and peak loading for both methods following a series of XYZ simplification" steps. For the two projects examined