Online Energy Consumption Measurement

Monitoring and management of electricity consumption in NTUA buildings (Zografou & Patision)

The Zografou Polytechnic Campus building complex concerns facilities with an area of ​​262,000 m², which are spread over an area of ​​approximately 1,000 acres. The existing electricity supply network consists of installed low and medium voltage fields in which there are analog voltage and current measuring instruments.

The measured quantities concern phase voltage and current, active and reactive power per phase, total energy as well as total power factor.

In addition to the Zografou Polytechnic Campus complex, electricity meters have also been installed in the Patisia complex in the Tositsa, Averof and Bouboulinas buildings with a total area of ​​26,000 m².

A total of 70 energy meters are installed in the buildings of the two complexes. Data from the meters (kW, kWh, A, V, PF, etc.) are collected at regular intervals (15′) and stored in databases.

Specifically, to monitor energy consumption for heating, cooling and lighting, the following have been installed:

• 70 electricity meters
• 58 power converters
• 23 analog to digital converters
• 2 PLC

While for monitoring the thermal comfort of a typical -pilot- office, they have been installed

• 4 temperature sensors
• 4 lux meters
• 4 relative humidity sensors

To assess the comfort conditions in workplaces, four temperature/humidity measuring devices were installed in the reception area of ​​the secretariat of the School of Mechanical Engineering. The temperature sensor is of the PT100 type with a measurement range of -20 to 100 °C. The humidity sensor measures absolute humidity, dry and wet bulb temperatures, with a measurement range of 0 – 100%RH, accuracy of ±1.5%RH and instrument resolution of 0.1 % RH.

The network of meters and controllers is given in the following figure, while a screen was placed in the NTUA Library to display the buildings' consumption in real time. The screen displays the data collected by the automatic data collection system and informs users/visitors in real time about the consumption in the entire complex.