Load-based testing methodology for fixed-speed and variable-speed unitary air conditioning equipment

A load-based methodology for testing and rating the performance of unitary air conditioning equipment has been developed and demonstrated using a laboratory psychrometric chamber test facility. The methodology simulates representative sensible and latent loads of a commercial building as well as the thermal and latent capacitance of buildings using psychrometric chamber test facilities. The advantage of the proposed test methodology is that there is no requirement to disable the native control systems designed by equipment manufacturers. This results in more realistic representations of the installed performance of equipment that include interaction of their embedded controls with the building. The load-based control approach is described and applied to the control system of an existing psychrometric chamber test facility. Results using the developed test methodology collected from fixed-speed and variable-speed RTUs show significant differences between actual part-load performance and steady-state performance at equivalent ambient operating conditions. A test procedure that includes interaction of the equipment controls with a virtual building could enable future equipment ratings that are both climate and building-type specific. This would not be possible for the current testing approaches that override native controls with no building interaction.