DOE2.1F is a set of programs for the analysis of energy consumption and cost in residential and commercial buildings. Programs are included to enter input data (Building Description Language Processor), to calculate the heating and cooling loads for each space in a building for each hour of a year (LOADS subprogram), to simulate the operation and response of the equipment and systems that control temperature and humidity and distribute heating and cooling to the building (SYSTEMS subprogram), to model primary energy conversion equipment that uses fuel or electricity to provide the required heating, cooling, and electricity (PLANT subprogram), and to compute the cost of energy and building operation based on utility rate schedules and economic parameters (ECONOMICS subprogram), to display results (Reports subprogram)), and to convert raw weather files into DOE-2.1F compatible weather files (Weather Processor). A library of materials, constructions, and windows is provided.