GEED is a Research & Development for Low Carbon Infrastructure
Building energy usage is a multi- variant and non- linear situation. Previously this kind optimization of one parameter with respect to the other is thought to be highly un-predictive and complex and considered only an academic/research work. But with the advent of robust energy simulation codes like Energy plus, DOE-2 and ESP-r these problems become simple and can be addressed effectively for a solution with acceptable speeds. For getting a holistic view of a generic situation of building energy use optimizations, consider a situation of two variable i.e. lighting (KWh) and HVAC (KWh) energy use which needs to be optimized for a minimum annual energy usage for a subject building. It is easy and understandable fact that glazing is usually a major source of heat load and natural light in any air conditioned building, but the former is not desirable and it also vary inversely with each other. Light is desired to reduce lighting energy consumption in day light saving times. At the same time increasing windows and sky light would also increase the ingress of heat into the building. As a results one can think of an optimum point of window to wall ratio that would optimize the energy annual energy use for a proposed envelop. Thus the minimum cost curve will be a deciding factor for acceptable window to wall ratio.
