Kelcroft energy audit case study II
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Energy Audit Case Study II saving money

energy audit case study
by John A. Herbert

This energy audit case study is part of a Kelcroft energy audit, it is only one element of a comprehensive energy audit report conducted by Kelcroft E&M Limited.

Date: February 2005
Location: Central, Hong Kong
Type: Composite Commercial

A kelcroft energy audit uncovered several opportunities to conserve waste energy, lower operating expenses and save money. One particular discovery, is an interesting an example because Kelcroft philosophy, namely details matter.

hong kong energy audit case study

It also demonstrates that a relatively small modification can create substantial savings over time.

The Kelcroft energy audit uncovered an alarming fact, the entire building’s central chilled water plant was regularly started every Sunday to serve a single room.


The building has a standard air conditioning plant arrangement, a central chilled water air conditioning system comprising:

  • air-cooled liquid chillers
  • chilled water pumps (2 duty/1 standby)
  • pressure compensated bypass valve
  • common riser serving fan coil units
  • control on/off 2-port control valve

Building Characteristics

Building operation were outsourced to a building management company, plant stop/start operations was conducted manually.

One tenant required air-conditioning for a single room (approx. 500 sq. ft.).

Therefore the building management company started the chilled water plant, including pumps and ancillaries, and operated same for four hours, every Sunday to provide comfort cooling.

The system turndown ratio was unable to cope with the "load" creating gross energy inefficiency. The control system was hunting, and causing operational instabilities.

Numerical Analysis

Energy auditing is economics driven; the goal to identify feasible energy and cost savings.

Calculations indicated that corrective action would save more than HK$40,000 per annum, with a payback period of less than one year. In addition, a corrective action would save more than 2,400 Kg carbon dioxide emitted every year.

Other savings accrue, extended life of the equipment and reduced maintenance costs.


The air-conditioning system had been operated inefficiently, causing stability (hunting) problems, and calculations validated the significant waste of money.

Since operating requirements, characteristics are not static, and vary throughout the lifespan of a building, is a timely reminder to conduct an annual energy audit.

Call Kelcroft to order your energy audit today!

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tags: energy, Hong kong, Energy audit case study