Rounding out the HVAC system is a heat-recovery ventilation (HRV) system, which is required to meet LEED Platinum indoor air-quality standards. The system simultaneously exhausts stale, humid indoor air to the outside and introduces fresh, outside air to interior spaces. Heat between the two air streams is exchanged, reducing heating energy losses due to ventilation. A solar wall along the southwest corner of the home was considered for heating ventilation air but ultimately ruled out. The findings showed that the solar wall would have reduced the cost of the PV array (by approximately $1,150), but the construction costs for the wall would have been significantly greater than the PV cost savings.