JSutils for Computer Energy Saving and Energy Use Calculation  
Updated: 30-Apr-2008
JSutils Compact Disk

EnCalcE Formulae

Latest Version: 3.3
Size: 418KB
Released
1-May-2008
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EnCalcE uses the following formulae to calculate the results:

Hours Used = Payback Period * 365 * (Normal Rate Hours On + Cheap Rate Hours On)

Standby Hours Used = Payback Period * 365 * (Normal Rate Standby Hours + Cheap Rate Standby Hours)

Number Of Replacement Items = Hours Used / Item Life
(Rounded up to next whole number - Assumes that Standby Time does not affect Item Life)

Item On Cost per Day = ((Normal Rate Hours On * Normal Rate * (100 + VAT) / 100) + (Cheap Rate Hours On * Cheap Rate * (100 + VAT) / 100)) * Item Wattage / 1000)

Item Standby Cost per Day = ((Normal Rate Standby Hours * Normal Rate * (100 + VAT) / 100) + (Cheap Rate Standby Hours * Cheap Rate * (100 + VAT) / 100)) * Item Standby Wattage / 1000

Item Cost per Day = Item On Cost per Day + Item Standby Cost per Day + (Item Cost * No replacements) / (Payback Period) * 365)

Item Standby Percentage = Item Standby Cost per Day / (Item On Cost per Day + Item Standby Cost per Day)

Item Cost per Quarter = Item Cost per Day * 365 / 4

Item Cost Over Payback Period = Item Cost per Day * 365 * Payback Period

Item CO2 Generated Over Payback Period = (((Normal Rate Hours On + Cheap Rate Hours On ) * Item Wattage / 1000 ) + ((Normal Rate Standby Hours + Cheap Rate Standby Hours ) * Item Standby Wattage / 1000 ) ) * CO2 Conversion Factor * 365 * Payback Period

Note 1: VAT is not applied to Item1 or Item 2 cost.
Note 2: If the currency selected is not UK Pounds (£) or Euros ( €) then VAT is changed to TAX.
Note 3: The CO2 generated does not take into account the CO2 generated in manufacturing and supplying an item.