Even if you rent instead of own, an understanding of long-term savings on green household choices can help you better select your next rental property (or encourage your current landlord to make some beneficial changes). To owners out there who may want to make green changes in their living but think it's all just costly confusion: take note of Green and Save's master ROI table. The research on the site looks substantial, offering a calculated rundown of all types of green 'tune-ups' in your home. One of our favorite, sometimes overlooked remodeling elements is the high efficiency skylight. Green and Save calculates a modest cost ($70) and a modest annual savings ($30), for a 42.9% return on investment. This is one of dozens of examples given on the site - and the 40% range appears to be the average ROI, with 3 years the average payback time for most upgrades. Anyone making big green changes lately? Tell us how you're going green (or how you hope to)!