According to a new study done by the University of Chicago, energy efficiency upgrades still keep the planet green, but probably won’t put too much green back into your pocket.

The University set up a controlled trial of 30,000 households in Michigan, telling ¼ of them to make residential energy efficiency upgrades (with assistance) and compared their energy savings to those who did not upgrade. Households were provided $5,000 in weatherization upgrades (furnace replacement, attic and wall insulation, and weather stripping). Unfortunately, the cost of putting these upgrades into place was nearly double the difference in their energy costs. Although energy consumption fell by a noticeable 10 to 20%, the upgrades only translated into $2,400 in savings over the life of the upgrades—less than half of the costs to input them.

Of course, from an environmental standpoint, such upgrades are still a big win. But its portrayal as a “double-win” as the University of Chicago calls it, is unfounded.

From a real estate perspective, particularly real estate sales, having a green home can still do a lot to attract a buyer to your home over someone else’s non-efficient home. But the direct ‘bottom-line’ approach shows that the investment is not giving as much return as advertised.