With a substantial fraction of the population insulated from energy price signals in bulk-metered apartment and condominium buildings, some jurisdictions are exploring mandatory metering of individual suites to encourage electricity conservation. This study finds that sub-metering in a Toronto condominium building reduces electricity usage by 20 percent. However, the costs of metering and customer service largely offset the electricity cost savings, and so the private net benefits are small or negative. The social net benefits depend strongly on the value assigned to externalities from generation. Social net benefits in our baseline results are closer to 5 percent than to 20 percent, and could be negative in many buildings.