How to Persuade Strangers to Turn Off Lights and Reduce CO2 Greenhouse Gas Emissions

The shared laundry room in my apartment building has a fluorescent ceiling fixture with 2 T8 lamps.

The light is left on in the empty room about half the times I walk past. I turn off the light, but who knows how long it's been on, and how much CO2 has been generated?

Today I set out to find an impressive number to put on a little label I can stick to the wall plate for the light switch.

1. How many Watts does the fixture burn?
   Assuming 2 x 48 in. T8 32W lamps and average electronic ballast:
   A web search turned up typical total fixture wattage of 59W and 65W.
   I'll say 60W.
2. How much CO2 does 1 marginal kWh generate?
   My utility, PG&E, publishes a report, Greenhouse Gas Emission Factors: Guidance for PG&E Customers April 2013 [PDF]. In a footnote, the report notes that "The California Air Resources Board (ARB) uses a marginal emission factor for California of 944 lbs CO2e/MWh."
   So, 0.06 kWh * 0.944 lbs CO2/kWh = 0.05664 lbs CO2. That doesn't look very impressive.
3. How many liters in one pound of CO2?
   One pound of CO2 is 0.2294 cu meters, or 229.4 liters, so 0.05664 lbs CO2 * 229.4 liters / lb = 12.993216 liters.
   Call it 13 liters CO2 / hour! That's pretty impressive.

I'll try posting this number and see what happens.