Abstract: An energy efficient heat pump includes a variable capacity compressor and a controller communicatively coupled to the variable capacity compressor. The controller is configured to receive a call for heating, determine an upper discharge pressure limit of the energy efficient heat pump, determine a lower discharge pressure limit of the energy efficient heat pump, determine a target discharge pressure value, where the target discharge pressure value is less than or equal to the upper discharge pressure limit and is greater than or equal to the lower discharge pressure limit, and modulate operation of the variable capacity compressor such that a detected discharge pressure of the heat pump approaches the target discharge pressure value.