WHEELER ON HVACR: 0% Greenhouse Gases — Is It Possible?
by Jim Wheeler
June 1, 2007
The
final success of such a project comes down to the human element.
Everywhere you go you’ll find people who are
worried about and talking about the need to reduce energy consumption, and thus
global warming, but they’re all waiting for someone else to do something about it, or for some
invention to come along, or for some government regulation to be passed to get
the job done; that may or may not happen. Rather, reducing energy consumption
must be done on a personal level, and believe it or not, many of the tools and
means to accomplish this goal are already at hand.
The American Institute of Architects (AIA),
the American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE), Architecture 2030, the Illuminating Engineering Society of North
America (IESNA), and the U.S. Green Building Council are now in the process of
developing a handbook of guidelines, which is initially targeted for the design
of retail stores and light commercial buildings (but can be adapted to homes),
that if implemented, could reduce energy consumption by these buildings an
average of 30%. And it is their goal to keep on revising the guidelines as new
technology becomes available, with the eventual target goal of 0% greenhouse
gases by the year 2030.
Understand that reducing energy use doesn’t necessarily come easily or
inexpensively. Rather, it requires a whole new way of thinking and building
designing. Yet, many of the means are currently at hand and are not at all
expensive to implement.
Of course, reducing the use of energy in residential and commercial buildings
isn’t always as simple as purchasing some new product, for the guidelines
mentioned above cover every step of construction from the design and orientation
of the structure, to the pouring of the foundation, and up to the building’s
eventual use and maintenance. Yet, new products can be found and purchased and
simple operational procedures implemented that can presently go a long way
toward reaching the 30% goal!
Lighting
One of the simplest and least expensive changes that
brings immediate results is to lower the wattage of the lighting inside the
building (change the light bulbs). The lighting levels in most residences and
commercial buildings are currently much higher than we actually require in
order to see well. Changing from incandescent lighting to high-efficiency fluorescent bulbs can
achieve a lighting energy reduction of as much as 80%!
The guideline goal is to reduce the output of all lighting to just the required
levels for the occupied space. Also, just turning off the lights when they
aren’t needed and employing sunlight wherever possible is inexpensive, easy to
do and necessary.
Replacing manual
switches with motion sensors to turn on lights only when people are present is
a good idea for rooms where turning the lights off is often neglected (such as
public restrooms and conference areas).
It’s interesting that tests show reduced lighting wattage to be one of the best
energy savers in all of the different design zones across North America,
because reducing lighting wattage also reduces the need for air conditioning.
For instance, every 12 100-watt bulbs (in a retail store, for example) require
an extra third of a ton of air conditioning to remove the heat they create.
Air Conditioning
Also,
in areas where air conditioning plays a significant role in energy consumption,
just making sure that the units are properly sized so as to not exceed the
expected loads is a very important goal (most are oversized), and adding extra
duct insulation and stopping duct leakage is vitally important, because most
air conditioners don’t actually reach their rated efficiencies due to duct air
leaks into unconditioned areas, such as attics.
Depending on the local climate, even total
replacement of the air-conditioning system can be done economically, because
the current higher efficiency systems can often recoup their replacement costs
in energy savings in less than five years. For, whereas the minimum efficiency
of such systems was 6-SEER (6 Btus of cooling per watt of electricity) just 10
years ago, the minimum efficiency for new residential air conditioners is now
set at 13-SEER, resulting in more than a 53% energy savings when the old
systems are replaced with new ones. Also, some air conditioners are now
available that provide an efficiency of 23-SEER (thanks to new compressor
technology), which can cut the energy consumption below that of old existing
systems by as much as 74%!
Heating
The
minimum efficiency for most gas and oil furnaces was raised from 60% to 78% by
the federal government back in the mid-1980s, and many of the old furnaces have
already been replaced. However, systems with efficiencies into the 90% range
are now available, and eliminating duct leaks on forced-air systems and
slightly reducing temperature settings can provide significant energy savings
in colder climates. Also, in some cases, changing the entire system from a
fossil fuel to a high-efficiency electric heat pump (and especially a
ground-source water heat pump) may achieve even greater energy reductions.
Water Heating
Yet,
simply replacing an old or leaking water heater for one of several available types
of higher efficiency models can also significantly reduce energy
consumption.
The efficiency of gas and oil water heaters, like gas and oil furnaces, has
been raised from the 60% range to as high as the 90% range over the past 20
years, but there is even more to this story. This is because almost all of the
old water heaters lost a larger portion of their energy because they weren’t
properly insulated and through the uninsulated connecting hot water pipes. So,
adding insulation to hot water pipes (where possible) throughout a building,
and employing new highly insulated water heaters can achieve much greater
energy savings than the listed ratings would imply.
Unfortunately, not much (other than adding insulation) can be done to raise the
efficiency of electric water heaters, because the output of electric resistance
is constant (3.414 Btus per watt) and can’t be changed. Yet, new water heater
designs that seem to have originated in Japan have added higher efficiency
options here. Rather than heating water in a tank, which loses energy as it
sits there, a new concept is to heat the water as it is being consumed in
small, tankless, wall-mounted heaters. These are also available for use with
gas as the heating fuel. In addition, one manufacturer from Montreal, Canada,
has come up with a tankless electric water heater that uses highly efficient
microwaves to do the heating.
Other Energy-Saving Ideas
Of
course, simply adding more insulation to a house or commercial building will
reduce energy consumption, as will changing the color of the exterior walls and
roofing (lighter colors in warm climates, darker colors in cool
climates).
Since windows lose (or gain) more heat than walls, reducing the window and
exterior door area of a building will save energy. And replacing existing
windows with those that have evacuated (had the air removed between) multiple
panes and with those that have automatic shades is also a good way to reduce
energy consumption. Adding overhangs (such as awnings) to provide shade when
the sun is at its highest (summer) position in the sky, and to allow its warmth
to enter when it’s at its low winter
position, will carry the savings a step further.
Of course, it’s impossible to cover all the energy-saving options (such as energy-recovery
devices, set-back thermostats, timers, zoning, etc.), but here are some of the
simple and obvious ways to personally reduce global warming, by reducing energy
consumption in our homes and in our work places. They will be covered in the guideline when it becomes available
sometime next year. But after all is said, the final success of such a project
comes down to the human element — to how we personally use and conserve energy,
and to how we maintain the energy-saving methods and systems that we purchase,
install and employ.
For more information on the coming energy guide, contact Don Colliver at colliver@bae.uky.edu.
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