Selecting HVAC Systems to Achieve Comfortable and Cost-effective Residential Net-Zero Energy Buildings
Wei Wu, Harrison Skye, Piotr A. Domanski
This study investigated the energy, comfort and economic performance of commercially-available HVAC technologies for a residential net-zero energy building (NZEB). An experimentally- validated model was used to evaluate ventilation, dehumidification, and heat pump options for the NZEB in the mixed-humid climate zone. Ventilation options were compared to mechanical ventilation without recovery; a heat recovery ventilator (HRV) and energy recovery ventilator (ERV) respectively reduced the HVAC energy by 13.5 % and 17.4 % and reduced the building energy by 7.5 % and 9.7 %, with a simple payback of 12.7 and 7.0 years. There was no significant difference in thermal comfort between the ventilation options. Dehumidification options were compared to an air-source heat pump (ASHP) with a separate dehumidifier; the ASHP with dedicated dehumidification reduced the HVAC energy by 7.3 %, the building energy by 3.9 %, and the initial cost by $3293. The ASHP-only option (without dedicated dehumidification) reduced the initial investment but provided the worst comfort due to high humidity levels. Finally, ground-source heat pump (GSHP) alternatives were compared to the ASHP; the GSHP with two and three boreholes reduced the HVAC energy by 26.0 % and 29.2 % and the building energy by 13.1 % and 14.7 %, but with long payback periods. The options with lowest initial investments that met the net energy target with good thermal comfort were the ASHP with ERV or HRV and dedicated dehumidification.
Net-zero energy building, HVAC, air source heat pump, heat recovery, ground source heat pump, thermal comfort