Sub-metering | Bauhaus Apartments

Bauhaus Apartments
  • 131 residential lots
  • 4 commercial lots
  • 10 residential levels
  • 5 levels of basement car parking
  • gymnasium
  • roof entertainment area
  • outdoor garden

Measuring energy usage is fundamental to choosing, implementing and evaluating energy reduction strategies. Bauhaus Apartments describe the low cost energy monitoring system they pieced together in this case study.

Bauhaus Apartments has found a simple and inexpensive way to temporarily sub-meter common property electricity circuits. The data collected will be used to:

  • Provide before and after baselines to quantify savings for different energy-saving initiatives
  • Measure energy consumption, which is variable and harder to calculate, for plant & equipment such as lifts, garage doors, water pumps etc


Bauhaus investigated permanent sub-metering solutions in conjunction with the Smart Green Apartments program to measure consumption “before” and “after” implementing energy-saving initiatives.  32 electrical circuits were identified and selected for measurement covering fire stairs, car parking, common residential hallways, gym, management office and service corridors.

Quoted costs ranged from $15,000 to $72,000.  Instead Bauhaus opted for a portable sub-metering solution for a total cost of $2,160 incl GST. 


Two ‘sets’ of data logging equipment were purchased.   Each set can measure 3 circuits simultaneously (3 x single-phase or 1 x three-phase) and comprises:

WattNode Transducer

(measures consumption)
HOBO Data Logger

(gathers data for download via USB cable)
Split-Core Transformer

(measures current through-put on circuit)
HOBOware Pro

(software to manage gathered data)



After installation, the equipment is left in situ for a defined period. Once the data is exported for analysis the equipment can be relocated to the next set of circuits.

WattNode Transducer and HOBO Data Logger in bottom of electrical cabinet
Split-Core Transformers with “red” circuit wire passing through middle of transformer

Sub-metering Project

The project has 3 phases:

1. Measure “BEFORE” data for 32 circuits over 20 weeks:

  • Each circuit measured for 3 weeks
  • Data is logged every 15 minutes
  • Commences 12:15:00am Sunday
  • Concludes 12:00:00pm Saturday
  • Data exported to HOBOware for analysis
  • Two sets of data logging equipment relocated to next set of 6 circuits during ‘off week’ for auto commencement on Sunday

2. Implement energy saving initiatives

3. Sub-Metering  repeated to gather “AFTER” data

Bauhaus’ electrician will relocate the logging equipment at each stage of the project for a total cost of $500.


The first 3 circuits measured in October 2013 shed light on the impact of Voltage Optimisers installed in 2007.

Last Updated: 
Mon 25/01/2016

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