California is well known for the splendor of its natural environment.
Over the years, California has taken steps to protect that environment,
including limiting vehicle emissions.
One way California is acting to address global warming is by setting a goal
that all new single-family homes should be built to a Zero Net Energy standard by 2020.
The city of Santa Monica has already implemented the standard in their progressive community.
Zero Net Energy, or ZNE, means that a home is designed and built to generate as much
energy as it consumes over the course of a year.
A practical way to achieve ZNE in new home construction is to follow the balanced approach
to energy system design that utilizes renewable electricity and natural gas together.
This balanced energy approach combines rooftop photovoltaic solar panels with smart building
techniques and high-efficiency natural gas appliances to effectively achieve ZNE while
providing the comfort and reliability home buyers prefer.
In order to reach ZNE, we have to rethink how we design and build homes.
It takes an integrated process with set goals and careful planning.
It’s a team effort from the start, and every stakeholder in the project needs to be
engaged early to make it happen.
While there’s no single way to design a ZNE home,
the ideal way to start if for architects and builders to orienting the structure to maximize
solar power generation and take advantage of cooling winds and natural shade.
A critical part of ZNE is the energy efficiency of what’s called “the building envelope”
Generally, the exterior walls and attic space.
Thicker than most traditional walls, the high-performance walls of a ZNE home
have foam board behind the outside layer to minimize heat transfer…
And quality insulation properly installed inside the wall cavity to prevent air gaps
and reduce thermal variations.
High-performance walls also include high-efficiency windows that reduce heat transfer and reflect
solar radiation.
To seal the building envelope from above, ZNE homes typically have high-performance attics.
The ceiling over the living space is well insulated to control heat gain and loss.
While a radiant barrier or insulation below the roof deck keeps the attic cooler in summer
and warmer in winter.
Light-reflective material on the rooftop above creates a cool surface that deflects the heat
of the sun and helps keep the home comfortable inside.
The building envelope design works with the home’s high-efficiency heating and cooling system;
for example, a natural gas furnace and electric air conditioner that are well-maintained,
to provide year-round comfort.
The system’s efficient fan quietly directs conditioned air through well-sealed ducts.
To save energy and conserve water resources, ZNE homes often have a high-efficiency water heater.
The water heater connects to insulated pipes in a compact distribution system that maintains
water temperature and quickly supplies hot water for cleaning, bathing and laundry.
An important part of reaching Zero Net Energy is choosing high efficiency appliances for the home.
In a ZNE home, appropriately-sized photovoltaic solar panels
usually supply the home’s electric needs by day,
easing demand on the utility and lowering monthly bills.
With the right planning and commitment, Zero Net Energy is well within reach
for Santa Monica and all California cities, and well worth the effort!
It's good for the homeowner, good for the city, and good for the planet!
ZNE will help California preserve and protect its natural environment, for generations to come.