Electric lighting and thermostatically controlled hot air radiators were both fitted. The water supplied to the spray inlet is heated by a thermostatically controlled heater. The heating was thermostatically controlled and windows and air vents provided ventilation. The engine also features a pressurized lubrication system controlled thermostatically. This engine employed thermostatically controlled liquid-cooling by means of a front-mounted radiator. Each room had thermostatically controlled heat with an automatically controlled fresh-filtered air supply. The engine coolant now had a pump and thermostatically controlled bypass. The fan was thermostatically controlled which was still an unusual feature at this time. In scientific literature, these devices are often broadly classified as thermostatically controlled loads (TCLs). This was further improved in 1987, with the addition of a thermostatically controlled fan. These are often broadly classified as Thermostatically Controlled Loads (TCLs). Thermostatically controlled loads comprise roughly 50% of the overall electricity demand in the United States.