Energy Consumption of a Desktop Computer

Some people have the habit of keeping the computer switch on for days, specially at the working place. Let's analyse the energy consumption of a desktop computer under various scenarios.

Below calculations are based on the computer I use at work place. It consumes ~70W when in operation. LCD monitor contributes 25W to it.

Assume your team size is 5 (each member has his/her own computer).

Average work hours per day = 11hrs (worst case)
Work hours per week per member = 11hrs * 5 = 55hrs
Total energy requirement per week per member = 55hrs * 70W = 3,850 Wh
Total energy requirement of all the members = 3850Wh * 5 = 19,250Wh

Scenario 1: Member "A" keeps his/her computer switch on for consecutive 2 days. (from [day1] 8AM to [day2] 5PM)

A's consumption = (33hrs  + 11hrs * 3) * 70W = 4,620Wh
Energy consumption of other members = 3,850Wh * 4 = 15,400Wh
Total consumption of all the members = 4,620Wh + 15,400Wh = 20,020Wh
Energy wastage = 20,020 - 19,250 = 770Wh (4%)

Scenario 2: Member "A" keeps his/her computer switch on for consecutive 3 days. (from [day1] 8AM to [day3] 5PM)

A's consumption = (57hrs  + 11hrs * 3) * 70W = 6,300Wh
Energy consumption of other members = 3,850Wh * 4 = 15,400Wh
Total consumption of all the members =  6,300Wh  + 15,400Wh = 21,700Wh
Energy wastage = 21,700 - 19,250 = 2,450Wh (13%)

Scenario 3: Members "A", "B" keep his/her computer switch on for consecutive 3 days. (from [day1] 8AM to [day3] 5PM)

(A+B)'s consumption = 2 * (57hrs  + 11hrs * 3) * 70W = 12,600Wh
Energy consumption of other members = 3,850Wh * 3 = 11,550Wh
Total consumption of all the members =    12,600Wh  + 11,550Wh = 24,150Wh
Energy wastage = 24,150 - 19,250 = 4,900Wh (25%)


I think you can understand these numbers. At least the percent wastage. Sadly, this is the behavior of average worker! Some workers even have the habit of keeping the computer switched on throughout the week. Monday morning switches on and Friday afternoon switches off!

There may be a requirement to keep the machine on while you are not at work. But those situations are exceptional and rather rare.

Do your bit for the country! Do your bit for the environment! Please make sure you turn off your computer when you leave the office!