Most Americans think that they can save energy (and help the planet) by making small changes to their behavior that don’t  offer much savings in reality, according to a new study in PNAS. Nearly 20% of participants named activities such as turning off lights, which don’t actually result in very much energy savings. People neglected to mention much more important actions, such as buying energy efficient appliances or weatherizing their homes.

“Switching to efficient technologies generally allows you to maintain your behavior, and save a great deal more energy,” according to lead author Shahzeen Attari. She said switching to high-efficiency light bulbs, which can be kept on all the time, will save more energy than minimizing the use of low-efficiency ones.

The study, Public Perceptions of Energy Consumption and Savings is available for free from PNAS.