  We present an integrated, three dimensional, model of urban canopy, building
energy and radiosity, for early stage urban designs and test it on four urban
morphologies. All sub-models share a common descriptions of the urban
morphology, similar to 3D urban design master plans and have simple parameters.
The canopy model is a multilayer model, with a new discrete layer approach that
does not rely on simplified geometry such as canyon or regular arrays. The
building energy model is a simplified RC equivalent model, with no hypotheses
on internal zoning or wall composition. We use the CitySim software for the
radiosity model. We study the effects of convexity, the number of buildings and
building height, at constant density and thermal characteristics. Our results
suggest that careful three dimensional morphology design can reduce heat demand
by a factor of 2, especially by improving insolation of lower levels. The most
energy efficient morphology in our simulations has both the highest
surface/volume ratio and the biggest impact on the urban climate.
