Interesting paper by another person from my home department: she notes that renters probably aren't even aware of investments made by landlords in energy efficiency, so landlords have no incentive to make their properties more efficient. She notes that people don't even notice the type of fuel they're going to be using while renters, which makes a cost difference, and argues that if people don't even notice that, they certainly won't be willing to pay much for other amenities that have a smaller impact on their bottom lines. Makes sense to me!