It can be hard to convince people to consider their environmental footprints in a struggling economy. It’s hard to push, say, expensive solar panels while many folks are struggling to pay their utility bills.

So I raised an eyebrow when I heard about Denver Mayor John Hickenlooper’s “Take 5 for the Environment“ pledge. Was he asking us to invest time and money we don’t have?

Fortunately, that’s not the case. Hick’s suggestions are not only affordable (many are free); the impacts are so significant they’re tough to ignore. And they’re incredibly simple.

To save energy, replace four compact light bulbs with CFL bulbs, and save 1,760 kilowatt-hours of electricity over the life of the bulbs. (I’m proud to say I’ve already done this one.)

Reduce your shower by 45 seconds and save two gallons of water every day.

To help the air quality, replace one car trip with walking or biking, decreasing carbon dioxide emissions by 520 pounds per year.

Plant one tree in the city to help remove pollutants from the air and create shade to reduce energy use.

To reduce waste, replace plastic shopping bags with reusable ones to eliminate 208 bags a year.

Take a pledge on the Web site, where you can also sign up for a Green Toolkit that offers ideas on how to make your home more eco-friendly.