A building automation system comprising: a building automation controller comprising a plurality of building automation objects each comprising data that may be used to generate a model that includes a plurality of elements, wherein each element is associated with one or more of the building automation objects ; a web server comprising business logic that is adapted to read and subscribe to the building automation objects , wherein each building automation object is adapted to notify the business logic of changes to the data of the building automation object , and to process the data from the building automation objects to provide model update commands based on the changed data; wherein the web server implements an observer pattern to notify the business logic of any changes in the data values of building automation object , the business logic further containing a flag database having a plurality of flags, each flag corresponds to an element of the model and has a first value and a second value, wherein the first value indicates that the corresponding element of the model has not changed, and the second value indicates that the corresponding element of the model has changed, each of the flags being organized hierarchically in accordance with a model hierarchy and the business logic providing model update commands to a client only for the model elements that require updating as identified by the flags; and a client comprising presentation logic adapted to display the model , receive the model update commands from the business logic , update the model using the model update commands, and display the updated model . a building automation controller comprising a plurality of building automation objects each comprising data that may be used to generate a model that includes a plurality of elements, wherein each element is associated with one or more of the building automation objects ; a web server comprising business logic that is adapted to read and subscribe to the building automation objects , wherein each building automation object is adapted to notify the business logic of changes to the data of the building automation object , and to process the data from the building automation objects to provide model update commands based on the changed data; wherein the web server implements an observer pattern to notify the business logic of any changes in the data values of building automation object , the business logic further containing a flag database having a plurality of flags, each flag corresponds to an element of the model and has a first value and a second value, wherein the first value indicates that the corresponding element of the model has not changed, and the second value indicates that the corresponding element of the model has changed, each of the flags being organized hierarchically in accordance with a model hierarchy and the business logic providing model update commands to a client only for the model elements that require updating as identified by the flags; and a client comprising presentation logic adapted to display the model , receive the model update commands from the business logic , update the model using the model update commands, and display the updated model . <EOS>