HELIOS Passive & Active Solar Home - Net Zero Energy
HELIOS Passive & Active Solar Home
General Process
The architect designed his own home in 1983 to be a passive solar home providing up to 65% of space heating. The design included orientation of all rooms to the south, a 2 story sunspace to act as a buffer to the conditioned spaces, and earth sheltering to the north. Heating performance was monitored for several years and energy modelling (using Energy 10) substantiated a 65% benefit over a conventional home in the same location. Later solar hot water system was added and monitored to demonstrate that two-thirds of the home's hot water needs were provided by solar. Finally solar photovoltaic systems were added to the design with mounting on flat and sloping surfaces of the original roof planes to provide a 9.4 KW (AC) system.
Software Tools
Software Tools:
General modeling information: Originally "Energy 10" was used to model the original passive solar design with conventional heating and cooling systems. Later "BeOpt" (EnergyPlus is simulation engine) was used to model the home retrofitted with heat pumps and solar systems.
Lessons Learned
Outcome of project goals: 1. Earth sheltering is very helpful to reduce heat loss and infiltration (but humidity needs to be controlled).
2. A two-story sunspace with vertical glass is an excellent buffer for conditioned spaces of the home.
3. Mass floors and walls work well to stabilize indoor temperatures in winter and summer.
4. A solar hot water system with a heat pump water heater as backup works very well to provide all hot water needs.
5. A solar PV system (with micro inverters in locations with some trees) can provide all the power needed to achieve a net zero energy home.
6. Decentralized heating and cooling utilizing mini ductless split system heat pumps is an excellent way to achieve high efficiency.
Discrepancies: The energy models predicted higher performance than actually achieved. Since this home was originally constructed in 1984 some materials were not as efficient, and air leakage has diminished the expected building performance.
General Process
The architect designed his own home in 1983 to be a passive solar home providing up to 65% of space heating. The design included orientation of all rooms to the south, a 2 story sunspace to act as a buffer to the conditioned spaces, and earth sheltering to the north. Heating performance was monitored for several years and energy modelling (using Energy 10) substantiated a 65% benefit over a conventional home in the same location. Later solar hot water system was added and monitored to demonstrate that two-thirds of the home's hot water needs were provided by solar. Finally solar photovoltaic systems were added to the design with mounting on flat and sloping surfaces of the original roof planes to provide a 9.4 KW (AC) system.
Software Tools
Originally "Energy 10" was used to model the original passive solar design with conventional heating and cooling systems. Later "BeOpt" (EnergyPlus is simulation engine) was used to model the home retrofitted with heat pumps and solar systems.
Lessons Learned
1. Earth sheltering is very helpful to reduce heat loss and infiltration (but humidity needs to be controlled).
2. A two-story sunspace with vertical glass is an excellent buffer for conditioned spaces of the home.
3. Mass floors and walls work well to stabilize indoor temperatures in winter and summer.
4. A solar hot water system with a heat pump water heater as backup works very well to provide all hot water needs.
5. A solar PV system (with micro inverters in locations with some trees) can provide all the power needed to achieve a net zero energy home.
6. Decentralized heating and cooling utilizing mini ductless split system heat pumps is an excellent way to achieve high efficiency.
The energy models predicted higher performance than actually achieved. Since this home was originally constructed in 1984 some materials were not as efficient, and air leakage has diminished the expected building performance.