Also in this section

• Average amount of water used on campus each year: 28,958,937 gal/yr
• Average campus electrical use per day:  100,400 kWh/day
• Average amount of natural gas burned to heat campus in the month of January: 47,781 ccf/month

## 1

Turning lights on and off takes more power than keeping them on.

False. There's a very brief spike when any electrical equipment is started, but it’s short-lived.

## 2

Keeping lights on make the bulbs last longer.

False. A typical office has the lights on 2,000 hours per year. Lamps last 36,000 hours if kept on 24/7. Since there are 8,760 hours in a year, they will last 4.1 years if we keep them on all the time. Lamps and ballasts that Michigan Tech uses do not depreciate much if they are cycled on and off. Let’s say we only keep them on for 2 hours per cycle and they are shut off four times per day—we use them 2,000 hours per year. Cycling will depreciate the life curve, so that average failure now occurs at 28,000 hours. So, we take 28,000 divided by 2,000 and we get 14 years of life. That’s more than three times as long as keeping them on 24/7. And we haven’t even talked about the other 6,760 hours when the lamps are using up energy when no one needs it.

## 3

Shutting off a fume hood when not needed saves a bundle.

True. A fume hood typically uses about \$2,500 per year in steam to heat up replacement makeup air if it is left on 24/7. If it has a three-horsepower electric motor, the electricity costs \$1,400 for a full year. So, the total savings is close to \$4,000.

## 4

Reducing room temperature by even one degree Fahrenheit in winter can save a fair amount of energy and money.

True. Each degree raises a heating bill by about three percent.