Weather Variables

There are five primary weather variables in the model: temperature, relative humidity, cloud cover, wind speed, and precipitation. Precipitation is itself more a category than a mathematical variable. In some climates, we use only rainfall, typically measured as cumulative amount by hour. In other climates, we use a family of precipitation variables, including rain, snowfall, and other types of precipitation (eg freezing rain).
We also include interaction variables involving weather. This group includes both the interaction among the weather variables themselves (eg the interplay between temperature and humidity) and interactions between weather variables and other measures (eg the interaction between cloud cover and the angle of the sun above the horizon, as a measure of effective insolation).

Further, more extensive discussion of weather variables.

Clock and Calendar Variables

The clock and calendar are wonderful proxy indicators of behavior. People begin and end the day, and vary their energy consumption, in a very regular manner. When the time of day and the calendar are both taken into account, we can tell a great deal about how load will respond: 2.00am [02:00] is a great deal different from 4.00pm [16:00]; and 4:00pm [16:00] on Sunday is quite different from 4.00pm [16:00] on Wednesday, within the same week. The calendar also marks very strong seasonal patterns, as well the breaks in normal patterns that occur on and around holidays.

More discussion of clock and calendar variables in the model.

Ephemeris Data

We use ephemeris data principally to determine how much solar energy, both for heat and for light, is available. When crossed with cloud cover, it also provides a proxy measure of insulation.

More information about the use of ephemeris data.

Special Events Data

Special events are events that have an important impact on load, but which are not predictable from knowledge of the calendar and regular weekends and holidays. Special events include factors such as transportation strikes that affect the daily work and energy use cycles, special sporting events, and the like. They are important for two reasons. First, by taking them into account we prevent the results from an "unusual" day from influencing the model when an otherwise similar day occurs. Second, while while one may not be able to predict such events themselves far into the future, careful treatment of the event gives some insight into what would be the likely consequences of a similar event in the future.

Economic and Demographic Measures

Economic and demographic variables are used to track and project system scale. The model operates on an hourly basis, while economic and demographic variables may be available only quarterly or annually, and then on a regional basis that is normally not congruent with the service area being analyzed. However, we have developed methods to integrate economic and demographic data within the model; this is particularly useful for projecting on a medium to long-term basis.

More information on economic variables in the model.

 

Send mail to tony.baker_AT_teslaeurope.com (replace _AT_ with @) with questions or comments about this web site.
Copyright © 2006 Tesla, Inc and Tesla (Europe) Ltd