Patent ID: 11965664
Assignee: TYCO FIRE & SECURITY GMBH
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F  G | IPC F  G

Claim 3:
4. A method of monitoring building efficiency, comprising:
establishing a current building efficiency state value of a current run cycle of a heating, ventilation, and air conditioning (HVAC) system based on a first building efficiency reference value corresponding to a start of the current run cycle and a second building efficiency reference value corresponding to an end of the current run cycle, wherein the first building efficiency reference value is based at least in part on a first temperature difference value between a first supply temperature value and a first return temperature value at the start of the current run cycle of the HVAC system, and wherein the second building efficiency reference value is based at least in part on a second temperature difference value between a second supply temperature value and a second return temperature value at the end of the current run cycle of the HVAC system, the current building efficiency state value is further based on an average of the first temperature difference value and the second temperature difference value and based on a constant value and an airflow value of the HVAC system, and the current building efficiency state value is determined according to a product of the constant value and the average of the first temperature difference value and the second temperature difference value multiplied by the airflow value;
determining a building efficiency state deviation value based on a difference between an average building efficiency state value of a set of previous building efficiency state values and the current building efficiency state value;
comparing the building efficiency state deviation value to a building inefficiency threshold value; and
providing an indication including an inefficiency status to a device associated with the HVAC system based on a determination that the building efficiency state deviation value exceeds the building inefficiency threshold value.