Due to the sheer number of existing buildings, it’s not enough to focus solely on reducing greenhouse gas (GHG) emissions through new construction. And wider implementation of energy-efficient systems through retrofitting will have a massive impact. Moreover, retrofitting presents opportunities to address longtime inequities in the housing sector, providing broader access to energy-saving measures. The most common barriers are capital costs, and owners’ lack of knowledge that today’s reliable technologies pay dividends far into the future.