Importance

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Abstract

An apparatus and method for controlling the operation of (HVAC) equipment or other climate control equipment. The method is executed by a conventional computer with a memory storing a program. The system determines whether the space is not occupied and if the temperature drifts outside an allowed margin, then the system allows the temperature to drift to a maximum allowable margin, or to a newly determined margin, whichever is less. The newly determined margin is based upon a determination of the maximum temperature margin to which the system can drift and still drive the temperature back substantially to the use set point within a predetermined maximum recovery time. The recovery time is calculated based upon past temperature-vs.-time data stored for previous cycles of drift and drive. The system can further increase the energy savings by augmenting the allowed recovery time and/or maximum drift range when the ratio of the incremental drift time to the consequent required drive time exceeds a predetermined, programmable amount, i.e. when the added drive time required to return to a certain temperature is small relative to the added allowed drift time for the space, during which the HVAC equipment is not operating and hence no energy is being consumed. Savings and usage of energy over time are stored, and are output to the user upon request to the control computer. The stored data can also be used to determine whether the HVAC equipment's efficiency is deteriorating, and thus whether corrective maintenance is needed.

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First Claim