Generalization of the Fourier series approach to model hourly energy use in commercial buildings

Development of the accurate models for hourly energy use in commercial buil dings has important ramifications for (I) retrofit savings analysis, (ii) d iagnostics, (iii) on-line control and (iv) acquiring physical insights into the operating patterns of the buildings. Electric and thermal energy uses in commercial buildings, being strongly periodic, are eminently suitable fo r Fourier series analysis. Earlier studies assumed trigonometric polynomial s with the hour of the day as the primary variable and one week as the peri od This model, though suitable on the whole,was poor during certain weekday periods and during weekends. This paper presents a generalized Fourier ser ies approach which, while ensuring a wider range of applicability, also yie lds superior regression fits partly because of the care taken to separate d ays of the year during which commercial buildings are operated differently and partly because of the rational functional form of regression model prop osed. The validity of the approach is verified with gear-long data of twent y-two monitored buildings.