Honda Smart Home uses geothermal for radiant floor heating
The Honda Smart Home US showcases technologies that enable zero net energy living and transportation. The home, located on the West Village campus of the University of California, Davis, is capable of producing more energy on-site from renewable sources than it consumes annually, including enough energy to power a Honda Fit EV for daily commuting.
The Honda Smart Home, construction of which began in April 2013, will serve as a residence for a member of the UC Davis community. The fully furnished home comes equipped with a Honda Fit EV battery electric vehicle for the resident’s daily transportation.
A Honda-developed home energy management system and an energy-efficient design will allow the home’s occupant to use less than half of the energy of a similarly sized new home in the Davis, Calif., area for heating, cooling and lighting. The home is also three times more water-efficient than a typical U.S. home.
The home at UC Davis will function as a living laboratory where the company, along with researchers from UC Davis and Pacific Gas and Electric, will evaluate new technologies and business opportunities at the intersection of housing, transportation, energy and the environment.
UC Davis’s West Village, where the Honda Smart Home is located, is the largest planned zero net energy housing development in the United States. Opened in 2011, West Village is home to the university’s internationally recognized research centers focused on energy efficiency, sustainability and transportation.
Honda home energy management system
The Honda Smart Home US uses Honda’s home energy management system, a proprietary hardware and software system that monitors, controls and optimizes electrical generation and consumption throughout the home’s microgrid. A 10kWh battery energy storage system in the garage, using the same lithium-ion cells that are used in the Honda Fit EV, allows stored solar energy to be used at night, when household demand typically peaks and electric vehicles are usually charged.
Honda’s HEMS leverages the battery to balance, shift and buffer loads to minimize the home’s impact to the electric grid. The system will also enable Honda to evaluate the second life, or re-use, of EV batteries in grid applications, home-to-grid connectivity and other concepts.
The system also is capable of improving grid reliability by automatically responding to demand response signals and providing other grid services. If the electricity grid is overloaded, for example, Honda Smart Home is capable of shedding its load and even supplying power back to the grid. This type of smart grid connectivity will enable the mass deployment of electric vehicles and renewable energy without sacrificing grid reliability.
The Honda Smart Home will seek a number of green certifications, including U.S. Green Building Council’s LEED, National Association of Home Builders’ National Green Building Standard and U.S. EPA’s Energy Star. The home brings together innovative technology and the latest green building concepts:
• Geothermal radiant heating and cooling: In homes and cars, heating and air conditioning systems consume significant amounts of energy. In the ground beneath Honda Smart Home’s backyard, eight 20-ft. deep boreholes allow a geothermal heat pump to harness the ground’s relatively stable thermal sink to heat and cool the home’s floors and ceiling throughout the year.
Researchers from UC Davis will evaluate the performance of the system to determine its adaptability to mainstream use. You can watch a video about the geothermal system and other sustainable features of the home.
• Passive design: The Honda Smart Home is designed to be extremely energy efficient by taking into account local weather conditions, sun direction and the home’s outer shell. Known as “passive design,” these techniques reduce the energy needed for heating and cooling while maintaining comfortable living conditions.
The Honda Smart Home’s south-facing windows are optimized for heating and cooling, while the north-facing windows are positioned to maximize natural light and ventilation. This will keep the home naturally cool in the summer and warm in the winter. Double-stud walls, cool roofing material and a fully insulated concrete slab all contribute to the home’s energy efficiency.
• Solar photovoltaics: A 9.5kW solar PV system mounted on the roof will generate more energy than the home and Fit EV consume on an annual basis, due in large part to the efficient design of the home. All of the energy for space heating, space cooling, ventilation, lighting, hot water, appliances and consumer loads, in addition to the transportation energy for the Honda Fit EV, is supplied by the solar panels on the home.
• Pozzolan-infused and post-tensioned concrete: A naturally occurring substance called pozzolan was infused into the Honda Smart Home’s concrete to replace half of the cement typically needed. A technique called post-tensioning, which uses steel cables to compress the concrete slab, also was used to reduce the amount of concrete and steel needed.
• Advanced lighting: The LED lighting used throughout the home is not only five times more energy-efficient than conventional lighting; it also is designed to support the health and wellness of the home’s occupants. Honda worked with researchers from the California Lighting Technology Center at UC Davis to explore new circadian color control logic.
Mimicking the natural shifts in daylight that occur from morning to night, the circadian-friendly lighting design allows occupants to select lighting scenes that complement occupants’ circadian rhythms and support nighttime vision.
• Sustainable materials and waste management: Sustainable materials were used throughout the construction process. Rather than cover the concrete foundation with wood, diamond pads were used to create a smooth, polished finish. For the roof, metal was selected, which is more recyclable than asphalt.
All lumber used in the construction process was sustainably harvested from forests certified by the Forest Stewardship Council, while advanced framing techniques were used to reduce the amount of material needed. Finally, 96% of the construction waste associated with the project — including drywall, brick, plastics and lumber — was recycled.
• DC-to-DC electric vehicle charging: The Honda Fit EV included with the home has been modified to accept DC power directly from the home’s solar panels or stationary battery, eliminating up to half of the energy that is typically lost to heat during DC-to-AC and AC-to-DC power conversion. When the solar panels are generating electricity at full capacity, the vehicle can fully recharge in approximately two hours directly from sunlight.
Sharing data, technical details
Hundreds of channels of energy data generated by sensors throughout the house will be shared with PG&E and UC Davis researchers. In addition, Honda’s Environmental Business Development Office, in conjunction with Honda R&D, will use the home as a living laboratory to test new technologies and evaluate new environmental business opportunities.
Regular updates on the home can be found at www.hondasmarthome.com. Contribute to the conversation on Facebook and Twitter using the hashtag #HondaSmartHome.
By The Numbers: Emissions and water consumption
The Honda Smart Home is expected to generate a surplus of 2.6 megawatt-hours of electricity over the course of a year, while a comparable home will consume approximately 13.3 megawatt-hours. This results in a net offset of nearly 13,100 lb. of CO2 per year, even when taking into account California’s relatively clean electricity. The excess energy anticipates potential future increases in energy needs, such as the addition of more occupants or electric vehicles to the home, and an increased daily commute.
The savings are even more dramatic when you consider Honda Smart Home produces its own transportation fuel; CO2 savings rise to more than 23,500 lb. per year versus a comparable home and vehicle.
Honda Smart Home is three times more water-efficient than a typical U.S. household. In a typical home, the toilet alone can use 27% of household water consumption. Dual-flush toilets with WaterSense certification, along with low-flow faucets in the sinks and showers and a high-efficiency washing machine and dishwasher, all contribute to water savings.
A technique called xeriscaping is used in the garden, where 30% of a typical home’s water is consumed. Plants that thrive naturally in arid climates were selected, while filtered greywater recycled from the home is the only source of water other than rain.