Algorithms for computing end-use and performance parameters on site are discussed. These algorithms are being used in a large northwestern monitoring program. They help to disaggregate end use, quantify HVAC thermal/ventilation performance, and building occupancy status. These algorithms sometimes reduce needs for sensors or enable otherwise impractical measurements.Monitoring typically produces periodic averages and totals of data. However, some phenomena are ill described by averages or totals. Aggregated energy end-use, thermal, and other HVAC parameters exemplify this. Heat pumps operate in several modes. Direct measurements to disaggregate these modes frequently are costly or impractical.Algorithms are assembled in modular fashion to achieve desired results. They are invoked by specifying algorithm type and user-specified arguments. Arguments may be measured parameters, user-specified constants, or outputs of other algorithms.Development, validation, field experience, and sensor needs for algorithms useful to building energy researchers are presented.Units: Dual