HELIOS is the architect's own home which evolved over time from a passive solar home, to a home which also reduced its hot water needs, to a home with reduced heating and cooling energy loads, and finally to a net zero energy home. Helios was first constructed in 1984 as a passive solar home with the intent of employing proper building orientation, partial earth sheltering, solar gain through a two story sunspace and south facing windows, and building mass to reduce the heating load in rural northwestern New Jersey. This design resulted in a home which consumed only 35% of the energy needed for space heating a comparable conventional home. In 1998 a solar hot water system was added to provide 65% of the hot water needs. With the advent of high efficiency mini-ductless split-system heat pumps, this equipment was installed over time to replace the existing heating systems in the home. When solar photovoltaic (PV) systems became more affordable in 2008, a 4.7 KW (DC) system was installed, and with further economies in solar PV an additional 4.1 KW (DC) system was installed in 2015. The result is a net-zero energy home which has been carefully monitored over a full year of actual use to verify that all energy for space heating, cooling, hot water, and plug loads is provided by solar energy. The only energy not yet covered is the electricity needed to charge the owner's electric car. When community solar is permitted in New Jersey the owner plans to purchase the necessary energy from a community system to also satisfy the electric vehicle.
Single family residence
Basis of Performance Claim
Conditioned Floor Area
2,751 sq ft
Energy Data Type
Renewable Energy System Type(s)
Net electricity usage (purchased)
Annual renewable energy generated
Envelope and Mechanicals
4" concrete slab over 4" XPS insulation over 6 mil polyethylene vapor barrier
Foundation wall assembly
1-1/2" EPS exterior over 8" concrete block
Above grade wall assembly
2x6 stud walls at 16" on center with fiberglass blanket insulation plus 1-1/2" rigid EPS exterior. In addition north wall is poured concrete retaining wall with 2" XPS insulation towards earth side and open to interior (painted dark color to serve as mass wall to store solar heat gain in winter).