When Thomas Edison started his electricity company 129 years ago, it served 59 people in a tiny section of Manhattan. Nowadays, Consolidated Edison makes juice for some 3 million residents of the New York metro area. That’s a lot of people using a lot of watts, and sometimes the utility has to slow the flow. When a heat wave settles in, and the threat of an overloaded power grid looms, Con Ed has the authority to remotely control the central air-conditioning units of more than 20,000 customers. The company doesn’t take this lightly—in fact, it follows bureaucratic and techn...