**BTU / Energy Measurement**

Btu/ energy measurement is important in applications such as AHU (Air Handling Unit), FCU (Fan cooling Unit), Chiller, Cooling tower, and other chill water building cooling system to monitor the energy consumption and efficiency of the system. Btu/ energy measurement is done with BTU calculator that collects data from flow meter and temperature sensors.

**Working Principles**

A BTU meter calculates energy consumption by flow rate and temperature difference, the formula

is:• Q : Heat / cold consumption (Joules)

• qm : Unit weight of water passed flow meter (kg/h)

• qv : Unit volume of water passed flow meter (m3/h)

• ρ : Density of water (kg/m3)

• Δh : Enthalpy of water (J/kg)

• τ : Time (unit: h)

When the water or other liquid passes through the pipe line, the flow meter measures the instantaneous flow rate ‘q’ and sends it to the iSOLV BTU meter then the temperature sensor measures the return pipe temperature ‘T1’ and supply pipe temperature ‘T2’ and also sends it to BTU meter.

According to above formula, iSOLV BTU meter integrates the cooling or heat consumption. If T1>T2, integrates cooling consumption, otherwise integrates heat consumption. Finally, the iSOLV BTU meter stores the data and displays on LCD.