Analysts at RMI, a Colorado-based think tank, urge federal housing officials to require Fannie Mae and Freddie Mac to incorporate home energy performance data into lenders' appraisal and underwriting standards. Fannie Mae and Freddie Mac are government-sponsored enterprises that together back nearly half of all home mortgages in the US. The RMI team further suggests that Fannie Mae and Freddie Mac could provide incentives for lenders to promote green mortgage products that encourage homebuyers to invest in energy-saving upgrades.