1.7 As a consumer interested in reducing your carbon emissions, (a) which should you do: (1)
install more efficient lighting for your home or (2) buy a car that gets higher miles per gallon?
To answer this, consider that a 100W light bulb that is run 3 hours a day every day will use
around 100 kWh a year. A high efficiency light uses about 25% of a conventional light bulb.
Replacing it with a 25W Compact Fluorescent Bulb would save 75 kWh a year. This would
equal 150 lbs of carbon dioxide or the same amount of carbon dioxide emissions associated with
burning 7.5 gallons of gasoline. (b) Given that the average US household uses 10,000 kWh a
year of which 8.8% is lighting, how many gallons of gas and lbs of CO2 could be saved by
switching all of the bulbs in a home? (c) For comparison, if you drove 12,000 miles a year and
upgraded from a car that gets the national average of 20 mpg to one that got 30 mpg, how much
would you reduce your gas consumption and CO2 emissions on an annual basis? (d) What if
you upgraded from a car that gets 30 mpg to 37 mpg? (combustion of 100 gallons of gasoline
releases 2,000 lbs. of carbon dioxide).
Solution:
a. You would choose an answer depending on your house, your lighting habits, your type of car
b.
c.
d. Switching from a 30 mpg vehicle to 37 mpg vehicle results in a 10 mpg savings.