Lighting Division

Savings Breakdown

CURRENT SITUATION: 1 set of Batten fitting c/w 2 x 36w tubes each. (2 tube type)

PRPOSED ARRANGEMENT: To delamp each fitting from Two 36w tubes to One 36 w tubes
each and install 1 pc of Delfina Energy Saving Reflector.

ENERGY AUDIT
Calculation based on the following data :
  1. Total fixture in : 1 set ( Two 36w tubes each )
  2. Total Fluorescent tubes : 2 pcs
    ( 2 tubes per fixture )
  3. Wattage per tube : 36w
  4. Wattage per ballast : 12 w
  5. Working hours per day : 24 hours
  6. Working days per week : 7 days
  7. Weeks per year : 52 weeks
  8. Annual operating hours : 24 hours x 7 days x 52 weeks = 8,736 hours
  9. Electricity Rate : S$0.15/kw/hour
  10. Price of reflector : S$52.00/pc
CALCULATIONS
  1. The cost for operating 2 tube per year = (Annual Operating Hrs x Wattage Consumption x Electricity Rate) / 1000
    = (8,736 hrs x ( 72 w + 24 w) x S$0.15/kwh) / 1000 = S$125.80
  2. The cost for operating 1 tube per year = (Annual Operating Hrs x Wattage Consumption x Electricity Rate) / 1000
    = (8,736 hrs x (36 w + 12 w) x S$0.15/kwh) / 1000 = S$62.90
  3. As 1 no. of tube is taken down after installation of the reflector, therefore the resulted annual saving in energy consumption = Annual operating cost of 2 tube - Annual operating cost of 1 tube = S$125.80 - S$62.90 = S$62.90
  4. The estimated payback period = (Total cost of reflectors) / (Annual saving Experienced [Item 3]) = (S$52.00) / (S$62.90)
    = 0.83 = 10 months.
  5. According to the American Society of Heating, Refrigeration Air - conditioning Engineers Journal (ASHRAE) : Each watt saved equal 3,412 BTU's not produced for air-conditioning load, or 3,412 BTU per kw. One ton of AC (TR) equals 12,000 BTU's and require 1.25 kw.
    • ASHRAE = Heat Contributed by tubes that are removed = ((36w + 12w) x 1 tube kw) / 1000 = 0.048kw
      = 163.776 BTU's = 0.0136 TR
    • The electrical power required for every ton of refrigeration = 1.25 kw/TR
    • Therefore power saved on AC system = 1.25 kw/TR x 0.0136 TR = 0.017 kw/TR
    • Annual saving resulted from AC system= Power Saved on AC system (kw) x Annual Operating Hrs x Electricity Rates
      = 0.017 kw/TR x 8,736 hrs x S$0.15/kwh = S$22.28
  6. Reduced maintenance costs due to fewer lamps, ballast and starters to be maintained and replaced and lower maintenance labour required ( about 8% of the savings on the lighting costs ) = Item ( 3 ) x 8% = S$62.90 x 8% = S$5.03
  7. Overall Total Annual Savings ( Item : 3 + 5 + 6) = S$62.90 + S$22.28 + S$5.03 = S$90.21
  8. The Payback Period = (Total Cost of Reflector) / (Overall Total Annual Saving) = (S$52.00) / (S$90.21) = 0.58 = 7 months
  9. Normal life span for the reflector is 15 to 20 years ~ Base on 15 years:
    • Base on the electricity rate of S$0.15/kw/hour for 15 years: The cost for operating a 36W tube per year (refer to item 2) = S$62.90
    • Total saving for 15 years = 15 years x S$62.90 = S$943.50
    • Less initial extra cost = S$52
    • Net Saving over 15 years = S$891.50
  10. Presume that the initial extra cost is $52 for each light fitting with Delfina Energy-Saving Reflectors compared to normal light fittings. The fact that our light fitting will enable you to have a saving of one tube or more, the return ratio is derive as follows:
    • S$52.00 spread over to a minimum of 15 years = S$3.47
    • Saving for each year = S$62.90 - S$3.47 = S$59.43
    • Return Ratio = (S$59.43 / S$3.47) * 100% = 1713%