9
Special topics
9.8
Case study for energy saving
The cost savings from implementation of energy saving measures depend on the existing energy performance of the
shopping mall, the scope of the saving measures, and other factors such as the mall size, usage pattern, site constraints,
etc.
For a better understanding, a case study of a typical shopping mall in Hong Kong has been carried out. Estimated cost
savings from implementation of various energy saving measures are highlighted for reference.
The basic information about the shopping mall in this case study is listed below:
- Total GFA: 10,000m
2
- Leasing area: 60% of GFA
- Landlord area (front of house): 30% of GFA
- Landlord area (back of house): 10% of GFA
- Annual operating hours: 5800 Hours
- Year of the mall: 15 Years (with minor renovation only)
The shopping mall is now undergoing major renovation works and the various energy saving measures relating to lighting
and MVAC will be carried out. The following table summarises the estimated cost savings and the payback period.
Lighting saving measures
Annual cost saving (HK$) Simple payback
Adopt energy efficient lighting
- T5 Instead of T8 c/w electronic ballast
-
instead of Incandescent lamp
$200,000
3 – 5 years
Proper lighting control zones
$35,000
3 – 5 years
Lux sensor to dim parameter lighting or lighting under/adjacent to skylight $35,000
3 – 5 years
Use self-luminous EXIT sign vs. traditional fluorescent EXIT sign
$15,000
4 – 7 years
Occupancy sensor control for infrequent occupied
$15,000
4 – 7 years
TOTAL :
$300,000
Saving measures for air conditioning system
Annual cost saving (HK$) Simple payback
Use of
(against air cooled chiller)
$300,000
1 – 3 years
Variable speed chiller
$100,000
1 – 3 years
Variable chilled water flow
$30,000
3 – 5 years
Variable speed
$150,000
3 – 5 years
Increase space temp by 2°C
$30,000
3 – 5 years
Increase chilled water supply temp. by 2°C
$20,000
3 – 5 years
Optimum fresh air flow rate
$10,000
3 – 5 years
Regular maintenance of chiller (e.g. tube cleansing, water treatment)
$30,000
4 – 7 years
Free cooling design
$100,000
4 – 7 years
Optimum chilled water pipe diameter
$20,000
4 – 7 years
Optimum chilled water pipe insulation
$10,000
4 – 7 years
TOTAL :
$800,000
The estimated annual energy cost for a shopping mall is about HK$3,000,000. Based on the above, the implementation
of the saving measures can reduce the annual energy cost by around HK$1,100,000 (i.e. 37% saving).
9.8.1 Professional help
It is important to engage professionals for detailed consultation on the implementation of energy saving projects in
shopping malls and shop spaces. The following is a list of references for obtaining professional help:
• Authorised persons (AP) & registered structural engineers (RSE) – Appendix A (2)
• Registered professional engineers (RPE) in the building services discipline – Appendix A (4)
•
Appendix A (7)
9.8
Case study for energy saving
Hong Kong Green Building Council 203
