D.C. Mun. Regs. tit. 29, r. 29-6243
The facility shall provide heating and cooling systems, which shall meet all applicable codes. All heating systems shall be installed with safety devices to prevent fires, explosions, carbon monoxide release and other hazards.
The facility shall be adequately heated and cooled.
The facility shall maintain a temperature of between sixty-eight (68) and seventy-two (72) degrees Fahrenheit, except during winter months, when the facility may maintain a temperature of no lower than sixty-five (65) degrees Fahrenheit during sleeping hours.
Heat sources, such as hot water pipes, fixed space heaters, hot water heaters and radiators exceeding one hundred twenty (120) degrees Fahrenheit that are accessible to residents shall be equipped with protective guards or insulation to prevent residents from coming in contact with the heat source.
D.C. Mun. Regs. tit. 29, r. 29-6243