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Energy Audit
Case Study II
Date: February 2005
Location: Central, Hong Kong
Type: Composite Commercial Building
This sanitised energy audit briefing is one element of a comprehensive energy audit report
An 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.
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.
Synopsis
The building was fitted with a standard 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.
Conclusions
The air-conditioning system had been operated inefficiently, causing
stability (hunting) problems, and calculations validated the significant
waste of energy.
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.
This briefing is one element of a comprehensive energy audit report
Energy Audit
For professional, independent energy audit, energy
surveys and energy engineering advice call Kelcroft today.
For further information regarding energy efficiency and energy conservation call Mr
John Herbert telephone (852) 2335 9830, facsimile (852) 2335 9862 or
email us