Technical Information:
Project: Z6 House (Single Family)
Year: 2006
Area: 230 m2
Budget: € 1.029,69
Location: Santa Monica, California,
EUA
Architect: Ray Kappe Architects
Rated by LEED (Leadership
in Energy and Environmental Design) for Homes v.1 in 2006, achieving the level
Platinum.
The Z6 House is a
single-family residence that was added to a multifamily-zoned lot with an
existing duplex. It
has 4 bedrooms, 2 complete baths and a service bathroom. The house serves as
both a residence and a model home for a line of green, modular, single-family
dwellings offered by the owner's (Steve Glenn) company - LivingHomes.
The house is
constructed of factory-built modules that were erected on the site-built
foundation over a period of 13 hours; the structural slab-on-grade serves as
the finish floor for the first level. A roof deck offers views and a green roof with vegetation. Plantings on
the roof are native species of southern California, mostly sedums, native
grasses, and rushes. The site also includes a small
vegetable and herb garden. The landscaping around the house consists of newly
planted native groundcover, shrubs, and trees.
The house was built
in a dense neighborhood with single-family and multifamily houses in the
surrounding blocks. Because the neighborhood was originally sited on sand dunes
that were paved over for development, creating hills, the project site is
sloped. Site drainage, stormwater use, and stormwater infiltration on site are
important issues in this ecology. Rainwater collected from the roof, combined
with stormwater diverted from site drains and swales, is stored in a cistern
and used to irrigate the gardens.
There are public
transportation stops within a quarter-mile of the house, and the use of
bicycles for transportation is common in the neighborhood. Grocery stores,
restaurants, banks, schools, parks, a theater, and other conveniences are all
available within short walking distance of the house. Regardless, local code
requires the house to have a two-car garage.
Environmental
Aspects
A commitment to
minimizing the project's ecological footprint informed all aspects of the
home's design. The project team used the phrase "six zeroes" to
describe the goals of the project: zero waste, zero energy, zero water, zero
carbon, zero emissions, and zero ignorance.
The design
maximizes the opportunities of the mild, marine climate with a passive cooling
strategy using cross-ventilation and a thermal chimney. A 2.4-kilowatt
photovoltaic array and a solar hot-water collector take advantage of the sunny
location, as does the daylight strategy for the interior.
To create flexible
interior spaces, all bedrooms have moveable wall partitions that can be opened
to common areas for more space. Large exterior doors and large expanses of
glass connect the inside to the outside, allowing the living space to expand to
the outdoors. This flexibility between indoor and outdoor living spaces is
traditional in southern California architecture.
Bioclimatic Design
The most important
climatic issue to address for a residence in this climate is mild heating in
the winter. Air-conditioning is generally not needed, but it is important to
have good passive solar orientation and shading and to take advantage of
natural ventilation. The breezes from the coast, from the southwest and
northwest, are fairly constant and predictable.
The home is
oriented 45 degrees from a north-south axis. There are operable windows and
doors on the southwest, southeast, and northeast faces that provide natural
ventilation. The design incorporates an open plan and two-story volume that
helps the air move throughout the house. A whole-house fan located at the top
of the stair tower leading to the roof helps draw hot air out of the building.
The chimney effect is in evidence on a warm day.
Each of the
southwest, southeast and northeast facades also have large deck overhangs to
prevent solar heat gain from the summer sun. In the winter, the southeast
glazing admits direct sun, which heats up the concrete floors at the first
level; this warms the house into early evening on a sunny day. Glass ceilings
in the upstairs bathrooms capture heat from the sun in the winter and shading
devices divert the heat in the summer months.
The house has an
evacuated-tube solar hot water collector. This collector runs to a heat
exchanger that heats water for domestic use and for a radiant floor heating
system. There is no air conditioning. The climate is dry and humidity control
is not a concern. Natural ventilation and the whole house fan are effective in
cooling the house.
Light & Air
As the building
envelope is 73% glazing, by area, all rooms receive plenty of daylight. Operable
windows or exterior sliding doors provide every room with natural ventilation
and views to the exterior. Skylights bring light into the two upstairs
bathrooms. The southwest, southeast, and northeast facades have operable
windows and doors, while the northwest facade has a translucent insulated panel
for daylight transmission in a direction without desirable views.
Protecting occupant
health and comfort was among the goals for the project, so the team selected paints
and sealants with low levels of volatile organic compounds (VOCs). No carpet
was used, and the house features an indoor garden to improve air quality.
Water Cycle
The 13.250 liters
water cistern sits below grade; collected water is pumped up to irrigate the
roof garden. The irrigation system on the roof consists of boxes lined with an
EPDM membrane and filled with evaporative-control-system chambers that help
keep moisture in the planting medium, which is a mixture of sand and perlite.
The bottom 8 centimeters of each box is kept moist; water is pumped up to the
roof as needed to maintain this level. Excess water flows out of the boxes and
back to the cistern.
The ground-level
landscaping is watered with graywater from the showers, tubs, bathroom sinks,
and clothes washer, via a subterranean irrigation system. All irrigation is
controlled by a device that monitors humidity in the atmosphere and prevents
irrigation when it is raining.
Low-flow plumbing
fixtures throughout the house further reduce the home's use of potable water.
The owner of the residence has installed a monitoring system that tracks
the performance of the photovoltaic array and solar hot-water collector as well
as the building's use of water and energy.
Energy
The Z6 house has a
very low energy profile in part because it has no forced-air heating or
cooling. The building takes advantage of natural ventilation from the
prevailing breezes, with an open plan and a whole-house fan drawing air up
through the top of the home. The house was designed to optimize passive solar
heating, with glazing to admit winter sun and balconies placed to shade the
house from summer sun. A radiant floor heating system is powered by a solar hot
water collector.
All of the appliances
are Energy Star rated and the lighting system is a low energy usage LED system
that is controlled by an integrated home automation system. A 2.4-kilowatt
photovoltaic (PV) array above the roof acts as a shade canopy for the roof
stair access. The
PV array was designed to provide 60-75% of the homes energy usage, and includes
battery storage. This, and the operable windows and doors in every room, will
make the house habitable during a blackout. Architects expect the
energy-efficient features, such as PV arrays, to save the owners enough money
in energy bills to pay for themselves eventually. In this case, that payback
should take 8 to 10 years.
Most daytime
lighting is handled with natural light from skylights and floor-to-ceiling
glass.
Materials
Building the home
in a factory and assembling it on site significantly reduced the project's use
of material resources. In a conventional wood-framed home, 30%–40% of the
materials used end up in a landfill; the construction waste for the Z6 House
was 10% of that for a comparable, conventional home.
Because the goals
for the project included maximizing views, daylighting, and passive solar
heating, the home features large areas of glass; to maintain a high level of
energy efficiency, the team selected high-performance, low-emissivity glass.
Other materials in
the house were chosen based on the environmental impact of their manufacture or
harvest. Wood certified according to Forest Stewardship Council (FSC) standards
was used for exterior siding, exterior decking, interior wood ceilings, and
millwork veneers. Cork, a rapidly renewable material, was used for the floor.
The structural steel frame, countertops, and porcelain tiles include recycled
content. Aggregate was used in the concrete floor slab and foundation.
Sources:
http://www.discovery.com/tv-shows/curiosity/topics/9-z6-house/
http://www.buildinggreen.com/hpb/mtxview.cfm?CFID=42848283&CFTOKEN=84801276
http://www.aiatopten.org/node/136
http://www.public.asu.edu/~kroel/www558/Living%20home%20model%20home.pdf
