Honda Smart Home: A Net Zero Home

Jyothsna Giridhar, Aug 4rth 2014

Honda Smart Home, a joint Initiative between UC Davis and Honda, is a net Zero energy home that was constructed in March 2014. The home gets all its energy from solar PVS, and has incorporated a number of technologies and passive design strategies to minimize the energy use. The home is currently unoccupied. Project leader Michael Koenig says the home could be occupied by UC Davis faculty members or students in a few months. In this article we focus on the green design features of the home.

Honda Smart Home: A Net Zero Home1

 

Passive Design

The home is designed to block direct solar radiation in summer to minimize cooling loads, while allowing heat to warm the house during colder months. The envelope ( walls, roof, windows and floor slabs) is designed to minimize heat loss and air leakages. The home employs radiant heating and cooling and the floor slabs are insulated to control heat loss from radiant systems.  Air leakage is minimized by sealing the envelope using an aerosol system. The home is located in the valley which is characterized by warm afternoons and cooler evenings, and employs ventilation to take advantage of this temperature swing. 

 

Wall

R-31 Assembly

Slab insulation

R-10 under slab insulation

Glazing

Triple pane windows. U value 0.15 btu/h ft2°F

(Koenig, 2014)

 

HVAC and HOT Water Systems

The house employs a Ground Source Heat Pump (GSHP) - radiant system combination that takes care of necessary heating, cooling and hot water requirements. Radiant systems run through the concrete slabs, walls and ceiling. The water in the radiant system is sent back to the four underground bores of 20 feet depth each housing a tank filled with grey water. The ground is warmer in winter and cooler in summer, and this stable temperature adds heat to the system in winter, and removes heat in summer.

Honda Home uses other integrated strategies such as extracting heat from the mechanical ventilation system and transferring it to the hot water system. According to project leader Michael Koenig, the home uses two high efficiency ventilators capable of maintaining acceptable ventilation rates in the house. Additionally, efficient ceiling fans are used. He further explains that the systems utilize temperature sensors to stabilize climate control.

 

Lighting Systems

All the lighting fixtures in the home are LEDs. The home employs a circadian lighting system that replicates the natural light throughout the day, which encourages healthy living cycles and maximizes comfort. Additionally, high reflectance surfaces, allow daylight through high efficiency windows and clerestory . These minimize the requirement for artificial lighting. According to Koenig, the lighting systems are controlled by motion sensor, daylight sensor and an astronomical switch  for the shades, and manual overrides especially for night time control.

 

Smart Homes

 

 

Smart Homes 2 Home Energy Management System

The project uses a Home Energy Management System (HEMS) to control the transfer of energy to the grid. HEMS harvests energy from the home’s 9.5 KW solar array and stores it in batteries, enabling nighttime use to meet peak energy demand. The HEMS monitors grid load and transfers excess energy back to the grid. HEMS uses battery power to transfer energy to the grid when the available solar energy is low. Thus the HEMS not only benefits the home but the community as well.

 

Other sustainable features

 

Smart Homes 4

 

Materials: All cabinets, wood framing and hardwood flooring are certified by Forest Steward Council . Selection of material finishes take the occupants’ health and wellbeing into consideration. For example all paints have low Volatile Organic Compound (VOC) content. The house uses gray polished concrete for flooring. Much of the construction waste is diverted away from landfills by sending it to recyclers.

Water conservation: Xeriscaping comprises much of the landscaping. Xeriscaping is selection and usage of drought resistant native or adapted landscaping species. Such vegetation requires little or no irrigation, as they are well suited for the local conditions. The irrigation water for the landscaping is sourced from gray water and rainwater. The landscaping uses pebble ‘paths’ that channelize rain water into rain gardens,  thus preventing it from going in to drain.

 

Acknowledgements

We would like to thank Michael Koenig, Honda Smart Home Project Leader, for participating in this interview.
Interview conducted May, 2014, Davis, CA by Jyothsna Giridhar

Images courtesy of Matt Sloutcher, Corporate Affairs & Communications, Honda North America

For more information please visit Honda Smart Homes.

 

 

 
 
 
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