Whether the house is new construction or a retrofit, local weather patterns are a basic planning tool for a zero energy home. Data should include precipitation records, average temperatures by month and preferably by day over the last several years. Local airports often keep detailed weather records, and a local college or university may be able to provide projections of weather patterns and the potential for regional climate change.
Energy in your home has to be designed as a system. Whether or not you think about it, your home is always interacting with the environment. Hot sunny days create one response from your home’s cooling system; cold snowy days create a totally different response from your heating system. When you consciously question your environment (When does the sun rise? What rooms does the sun shine into and when? In what direction does the wind blow in different seasons?), you create design requirements that are more efficient than automated systems because they are in tune with your specific environment.