the energy use or demand estimated by the equation, a constant term in energy units/day or demand units/billing period, the regression coefficient of an independent variable Vn, the independent driving variable.

In general, when creating a whole-building model for a number of different regression models are tried for a particular building and the results are compared and the best model selected using R2 and CV (RMSE). Table 27.16 and Figure 27.7 contain models listed in ASHRAE's Guideline 14-2002, which include steady-state constant or mean models, models adjusted for the days in the billing period, two-parameter models, three-parameter models or variable-based degree-day models, four-parameter models, five-parameter models, and multivariate models. All of these models can be calculated with ASHRAE Inverse Model Toolkit (IMT), which was developed from Research Project 1050-RP.141

The steady-state, linear, change-point linear, variable-based degree-day and multivariate inverse models contained in ASHRAE's IMT have advantages over other types of models. First, since the models are simple, and their use with a given dataset requires no human intervention, the application of the models can be on can be automated and applied to large numbers of build

Table 27.16: Sample Models for the Whole-Building Approach from ASHRAE Guideline 14-2002.152


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