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THE INGREDIENTS
OF NET-ZERO HOMES
An ecofriendly
home occupied
by a vigilant
owner can make
a profit as it
generates more
net energy than it
produces.
Systems, proper orientation, design,
management and technology
By Lloyd Lee
A full understanding of net-zero housing
implies a recognition that the homebuyer
is paying for a comprehensive and
complete building up-front. This includes
all the energy and utility costs that he or
she would have paid for on a monthly
basis throughout the life of that house.
While the mortgage will surely be higher,
the total monthly costs for owning and
maintaining that house will be effectively
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nil in a world of incessantly rising energy
costs. It is not difficult to achieve a netzero house, but it does take disciplined
decision-making, a systems-oriented
approach, and a greater initial investment
in efficient, quality materials, equipment,
and design.
5 Key Ingredients
of a Net Zero House
Following are five key ingredients of a net-zero
house. The first four can be loosely grouped as
“passive strategies” that promote energy
conservation while the last key ingredient can be
labeled an “active strategy” implying energy
production.
the behavior of the occupant. What good is the bestdesigned eco-home loaded with cutting-edge
technological systems if the occupant forgets to close
a window while running the AC, or forgets to turn
off the lights when he or she is out?
With that being said, eco-builders such as Native,
Occupant Vigilance / Monitoring systems
usually include a user-friendly system of monitoring
equipment as standard procedure. Information can
The first, and most critical step, is to recognize that a be accessed via the internet at any time allowing for
home’s eco-friendliness is ultimately determined by
responsive and proactive behaviors on the part of
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the owner. An ecofriendly home occupied
by a vigilant owner can not only operate off
the grid, but can also make a profit as it
generates more net energy than it produces.
Proper Orientation
Proper orientation of a building combined
with a climate-responsive form is the most
cost-effective way to reduce energy
demand. It is quite simply a matter of good
design and decision-making that translates
to significant energy savings. When
designing a net-zero house, this should be
the first step, keeping in mind that it is far
“greener” and far cheaper to work with
nature rather than fight against it.
in a Texas could get 75 percent of the heat
it needs from the sun. It also allows for
efficient cross-ventilation and takes
advantage of prevailing breezes which
typically come from the south during the
summer.
Responsive Envelope Design
A “building envelope” is effectively the
barrier between the exterior and the
interior of your home. This includes the
walls, windows, doors, and the roof of a
building. Thus, it makes absolute sense to
avoid penny-pinching in this area. One key
aspect of the building envelope is
insulation. We cannot stress how important
adequate insulation, one with a high Rvalue, is. The higher the R-value, the better
your envelope is at keeping out the heat in
the summer and retaining it in the winter.
In Texas, the best form of a house is a long
rectangle oriented with its long sides facing
north-south. This minimizes direct sunlight
thus reducing demand for cooling while
maximizing sunlight during the winter thus Eco-builders, such as Native, employ spray
reducing demand for heating. When
foam insulation as opposed to traditional
designed correctly, a direct-gain solar home batting insulation for its higher R-value and
Proper
orientation of a
building
combined with a
climateresponsive form
is the most costeffective way to
reduce energy
demand.
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its ability to fill in small cracks and crevices fully
sealing the building. Special attention to insulation
must also be paid to windows. Look for double or
triple paned glass windows which typically have
better insulating properties. Also look for glass
coated with a low-e film which reflects certain
spectrums of infrared light thus resulting in less
heat gain. It is absolutely imperative that windows
and other openings in the building envelope be
properly placed and adequately shaded on the
outside.
Xeriscaping and Rain Water Collection
The lush, grassy front lawn is a ubiquitous fixture
of American suburbia. However, they are probably
the worst purveyors of water misuse and waste.
Depending on conditions, a 25-by-40-foot yard can
drink up to 10,000 gallons of water each summer.
In some areas of the Western U.S., lawns account
for 60 percent of urban water use. Keeping
America’s grass perfectly cropped requires 38
million lawnmowers, most of which use two-stroke
engines that generate as much pollution in an hour
as a car does during a hundred-mile trip. Each
year, Americans apply more than 70 million
pounds of pesticides to their lawns, some of which
seeps into groundwater, threatening wildlife and
human health.
This could all be mitigated with the use of
“xeriscaping” which means using drought resistant
landscaping that is adapted to the local climate of
various regions. In Texas, why settle for generic
and unsustainable Kentucky Bluegrass when a
homeowner could have a luxurious prairie
meadow of native Buffalo Grass and wildflowers?
Xeriscaping combined with rainwater storage and
collection systems offered by eco-builders can meet
a net-zero home’s water needs.
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Active Technology (Solar + Geothermal)
The most prominent technologies employed to
achieve net-zero are photovoltaic panels and
geothermal, or ground-source, heat pumps. While
these technologies may be the most glamorous
aspect of a net-zero house, they also contribute
significantly to the cost difference between net-zero
and traditional modes of home construction.
A typical array of solar panels in Texas will cost
around $35,000. However, after generous local
rebates and federal tax credits, the net cost can be
as low as $15,000 with the added gratification of
having virtually negligible monthly energy bills.
Active technologies such as photovoltaic solar
panels provide the sustainable, energy-production
punch needed to completely power all of a
building’s appliances and mechanical systems.
Geothermal heat pumps offer twice the efficiency
of traditional air-source heat pumps found in most
homes. These alternative heat pumps rely on the
enormous thermal mass of the very earth beneath
us to dissipate heat.
However, as impressive as these technological
solutions are, it takes a responsive and welldesigned package of both “passive” and “active”
strategies to create a functional net-zero home.
www.buildnative.com
(512) 970-1401