A system and method for controlling the air temperature of a building using a control plan based on a target time. The system includes a controller which may be connected to a number of indoor and outdoor heating ventilation and air-conditioning units. The system may include a thermostat. The system may also operate without a thermostat. The method includes determining a control plan to reach a desired temperature in a target time. The method also includes updating the plan by comparing the actual time to reach the desired temperature with the target time.