Climate zones are areas that are divided and categorized by the temperature, amount and type of precipitation, humidity, and the passage of seasons. These zones are divided based on general temperature related to longitude and delineated by intervals up from the South Pole and down from the North Pole. Climate zones are divided under the presupposition that although the weather varies in each particular location day-to-day, the overall weather patterns will typically stay the same over years at a time.
Climate zones are central to the IECC. Climate zones dictate many of the energy efficiency measures that a building must include, and they are especially relevant to the building envelope. Climate zones are based on weather factors like winter and summer temperatures along with humidity and rainfall (to define the "Dry" and "Marine" sub-climates). The climate zone map had not changed since the 2003 IECC.
As you can see from the map, climate zones are divided from county to county. For example, here in New York City we are considered a “climate zone 4 county,” yet the rest of New York state is a climate zone 5 or 6.
Knowledge of climate zones is crucial in the construction process due to the fact that climate plays such a big role in what materials you will be using. It will also dictate your overall energy consumption when the building is completed. As temperature definitely plays a large part in proper construction in your climate zone, you can see the specific moisture delineation specified as ‘Marine,’ ‘Dry,’ and ‘Moist’ is equally as critical to defining your climate zone. Beyond these basic forms of factors, a deeper explanation dives into what we call ‘degree days,’ which compares the mean outdoor temperatures for a location to a standard temperature, typically based at 65 degrees fahrenheit.
It is always in your best interest to find professionals to help you with permitting and codes specific to your city or county. Knowledge of your climate zone is a crucial part of ensuring a safe and energy efficient building.