Climate-Specific Design

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.

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.

In some locations, it may be apparent that both average and high temperatures have changed over the last 5 years. For example, 9 of the 10 hottest years on record have been in the last decade. Whatever the case, likely minimum and maximum temperatures are essential in sizing heating and cooling equipment, determining how much insulation is appropriate, and making a variety of other decisions about the structure.

A wind rose, which shows the direction and strength of wind at the site, can be used to design natural ventilation into the house. It is surprising that most houses are deigned without regard to cross-ventilation. For many designers, windows are primarily architectural features rather than functional elements that have the potential to reduce energy use and increase comfort. Deciding where to install a wind turbine on the site to generate electricity is impossible without accurate wind records.

Rainfall records are important in two respects; first, when designing a water catchment system, and second, when determining which plants, vegetables, and fruits are appropriate for the site, Ideally, outdoor plants should be native to the area; they'll need a minimum of care and very little additional water. Moreover, backyards can be converted into gardens that provide food.

Know Your Climate

House design should start with a sense of place:

  • What are the outstanding qualities of the climate (hot-dry, warm-humid, cold-windy, Mediterranean-mild)?

  • What are the average high temperatures in the summer and average lows in the winter?

  • How many months of the year MUST the house be air-conditioned?

  • When the weather is mild (spring and fall) from which direction does the wind blow?

  • What is the latitude of the site?

  • What is the angle of the sun off the horizon on June 21 and December 21?

  • How high is the water table?

  • What kinds of insects in the area may affect the building (termites, carpenter ants) or the inhabitants (mosquitoes)?