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Zero Energy Homes (ZEH) are homes designed to use zero net energy from
the utility grid. The concept is simple — couple the maximum possible
building energy efficiency with the best available renewable energy resources
in a way that maximizes the effectiveness of both
For a glimpse of the houses of tomorrow, one need look no further than
the work of a few forward-thinking production builders. Combining solar
energy technologies with energy-efficient features and energy-saving construction
techniques, these builders are constructing houses that generate nearly
as much electricity as they consume on an annual basis.
Constructing the Zero-Energy Home
A key element in designing a near-ZEH is that the house’s overall
energy use first must be dramatically reduced through a combination of
super-efficient features and advanced construction practices. The use
of these energy-saving building methods ensures that the addition of a
relatively small photovoltaic (PV) solar system (typically 2.4 kilowatts
in capacity) can effectively lower the electricity usage of a house by
half or more compared to a typical new home.
For instance, a typical house has 20 percent to 30 percent duct leakage.
In a near-ZEH, ductwork is sealed and super-insulated or placed in the
conditioned space. Spectrally selective glazed windows reflect the sun’s
heat in summer and reduce heat loss in winter. Mechanically designed HVAC
systems account for bends and turns in ductwork, register locations, duct
length, connections and airflow. Other ways to “tighten up”
residential energy consumption include improved ceiling and wall insulation,
energy-efficient appliances and the use of fluorescent lighting. All of
these efforts are combined in a whole-house approach to designing and
building the ZEH.
Once a house has been made super energy efficient, an array of PV modules
is installed. Usually located on the roof, the array converts sunlight
into direct current electricity, and through the use of an inverter, turns
DC into AC electricity to power the house. Many builders prefer building-integrated
photovoltaic (BIPV) systems, which are built into the roofing materials.
For multiple reasons, mainly aesthetics and to minimize roof penetrations,
BIPV systems are a good choice for productionhouses.
Zero Energy Homes have a number of advantages:
Improved comfort—an energy-efficient building envelope reduces
temperature fluctuations.
Reliability—a ZEH can be designed to continue functioning even during
blackouts.
Security—a home that produces energy protects its owner from fluctuations
in energy prices.
Environmental sustainability—a ZEH saves energy and reduces pollution.
Zero Energy Homes optimize and include the following design features:
Climate-specific design
Passive solar heating and cooling
Energy-efficient construction
Energy-efficient appliances and lighting
Solar water heating system
Small solar electric system.
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