a thermostat apparatus for controlling a heat pump with supplemental resistive heating as typically contained in a packaged terminal air conditioning unit is disclosed which provides improvements in energy management by reducing energy usage as much as possible within user guidelines when the conditioned space served by the ptac is not occupied . a reduced setpoint temperature determination is based upon measurements of thermal response within the conditioned space to application of supplemental or resistive heat , and utilizes supplemental or resistive heat in achieving a quick recovery when people enter the conditioned space , thus enabling a more reduced setpoint temperature when the space is not occupied .