Many evaluation and research projects that deal with energy use also need weather data. Weather is one of the primary influences on the level of energy consumption for space heating and cooling and energy use data often needs to be normalized for weather before trying to estimate other causes of changes in use, such as energy efficiency programs or demand response programs or economic effects.

The National Oceanic and Atmospheric Administration (NOAA) is a federal agency of the United States that collects hourly weather data from around the country and the world. Daniel has created a Web site which is map-based and provides easy access to NOAA's collection of hourly data. Everyone is welcome to use this free Web site to access NOAA's free database. Click on http://www.klosenergy.com/weather/index.html

After the raw data is downloaded from NOAA, work has to be done to clean and condition the data for use in analysis. Often, temperature and humidity values are combined into a Composite Temperature Humidity Index (CTHI). The CTHI puts the combined effect of temperature and humidity over a build-up period of several hours or several days into a single value, and it often performs better at estimating air-conditioning use on very hot days than any other single weather variable can.

It is also often an important part of energy use studies to determine what impacts would be under normal weather conditions. Many years of historical weather data are needed to determine appropriate weather normals.

Mary and Daniel have used weather data for many demand response, dynamic pricing and energy efficiency program evaluations. It is needed whenever air-conditioning or space heating is being affected, and it is also helpful for water heating and total bill evaluation. Sunrise and sunset times are helpful for daily and monthly modeling of lighting loads.