Sunny days and consumed energy

This paper describes experiment based on calculation of heat consumption for part of the town during the winter season. It is based on historical data analysis in the view of the nature of the sun activity. The relationship between heat consumption and outside temperature is sought and expressed in linear formulas. These relations are then improved by the inclusion of the information about sun activity during a day. The main idea is to separate sunny and common days and then describe heat consumption individually for them. This contribution also shows simple method substituting sun intensity measurement by the comparison of temperature differences.