Subject: Energy Ideas - Thermal Env.

From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:42 PST

ENERGY IDEAS -- Building Envelope (Vol. 1, No. 4, October 1992)

This issue of Energy Ideas focuses on the thermal envelope of a
building -- the windows, walls and roof.  A great deal of energy
can be transferred through a building envelope, requiring a
greater expenditure of energy to maintain comfort.  

Infiltration of hot, humid air in the summer requires additional
cooling as well as dehumidification.  Infiltration of cold air in
the winter requires additional heating.

Aside from air infiltration, conductive and radiative heat loss
and gain add to heating and cooling loads.  Proper insulation of
walls and the roof, as well as the installation of low-
conductivity windows, will minimize conductive transfer. 
Installation of radiant barriers and low-emissivity (low-E)
windows will minimize radiative transfer.  This issue will cover
these topics in greater detail.

To read a particular article, enter <index #>.<article #>

1.  Introduction
2.  Windows - minimizing conductive and radiative losses
3.  The Heat Island Effect - are our cities getting warmer ?
4.  Energy savings with Insulation
5.  Radiant Barriers - enhancing insulation performance
6.  Resources

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From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:42 PST

Jonathan Kleinman, Editor (202) 387-8034, [email-masked]
Eleanor Lewis, Director, Government Purchasing Project
Ralph Nader, Founder, Center for Study of Responsive Law

SEALING THE ENVELOPE

A building shell, also known as a building "envelope," plays a
crucial role in the energy efficiency of a structure.  Many
buildings constructed in the 1950s and 1960s lose a tremendous
amount of energy through their shells.  Properly insulating,
sealing and coating a building dramatically improves its energy
performance in all seasons.

Each component of the building shell has the potential to allow
heat to leak through it.  For example, windows, while they
contribute to occupant comfort, also contribute to energy loss. 
According to the Solar Energy Industry Association (SEIA), office
buildings account for about one-third of all energy used yearly
in the United States.   These same buildings lose approximately
25 percent of their energy by unwanted gain or loss of heat or
the infiltration of unwanted air through windows.  According to
the Alliance to Save Energy, almost two-thirds of our commercial
space has no more than single-paned windows.  As a result, every
year, an amount of energy equal to the annual oil flow through
the Alaskan pipeline leaks through windows, cooling buildings in
the winter and heating them in the summer.  Also, uninsulated
ceilings, walls and roofs allow the conduction of heat and the
infiltration of unwanted hot or cold air.

Many technologies, both standard and innovative, can improve the
ability of a building to minimize heat transfer.  Insulated
windows ~ either aerogel or multiple-paned ~  can prevent the
conduction of heat through glass.  Low-emissivity (low-E) windows
and window films allow windows to reflect heat rather than
transmit it, keeping rooms cool in the summer and warm in the
winter.  Fiberglass insulation in walls, ceilings and roofs will
limit temperature gain and loss.  Buildings can use natural
sunlight to illuminate and heat workspaces.  And radiant barriers
can prevent radiative heat (the heat traveling as infrared light
which can be felt far from an object), which insulation does not
stop, from entering or leaving a building.  

New technologies can significantly improve the thermal
performance of buildings.  For example, part of Rocky Mountain
Institute operates from a 4,000-square-foot house in Old
Snowmass, Colorado.  By using super-insulation, "tight"
construction and passive solar design, the building, which
includes a large library, a computer room, 20 work stations,
seven computers, two photocopiers, a fax machine, a plotter, two
laser printers and the home of Amory and Hunter Lovins, has a
total utility bill of five dollars per month.  According to Amory
Lovins, Executive Director of Rocky Mountain Institute, on a
January day without solar heating, the building will only lose
about 0.8 degrees fahrenheit in temperature.

This issue of Energy Ideas presents available and developing
technologies which improve the thermal performance of building
envelopes.

---

From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:42 PST

WINDOWS - A NEW LOOK AT AN OLD SCENE

Known as "glazing," glass areas on a building shell are a
necessary part of a pleasant work environment.  Offices with
windows are, almost without exception, considered to be the most
desirable.  Being able to see out and to fill an office with
natural light makes office space feel more relaxed and natural. 
Windows also provide unique opportunities to use sunlight to
reduce lighting and heating loads.  Unfortunately, most buildings
today suffer from poor glazing design, resulting in increased
heating and cooling loads.  New design techniques and glazing
products have been developed to use sunlight to increase building
energy efficiency.

Providing Light with Daylight

Smart buildings can take advantage of sunlight to reduce their
electricity consumption for lighting.  According to the U.S.
Department of Energy (DOE), more than 20 times the light required
to light building interiors is available from natural sunlight. 
Conventional window placement does not take full advantage of the
available light.  Simply placing windows in outer, or perimeter,
offices only illuminates those offices.  However, direct sunlight
which enters those windows will also increase the room
temperature.  This is helpful in winter but it adds substantially
to cooling loads in summer.  Traditionally, interior offices have
not been lit by windows.  

New glazing techniques provide lighting to all offices while
avoiding overheating from direct sunlight.  These technologies
are very cost-effective in new construction.  However, the design
techniques require integration with the building's layout and
heating, ventilating and air conditioning systems.  Consequently,
these retrofits are extremely costly.  The notable exception to
this is the replacement of inefficient windows.

Atria

One new building design, the atrium, provides a bright and
pleasant central area for office buildings and also creates a
light source for interior offices.  An atrium is an area in the
center of a building which is open from the ground floor to the
roof and is illuminated by natural light.  Interior offices with
windows facing an atrium need lower levels of electric lighting. 

Light Shelves and Clerestories

Perimeter offices may be illuminated by new window arrangements
which admit diffused and reflected light while blocking direct
light (which causes unwanted heating and glare).  Light shelves
project outward from windows in perimeter offices.  Located about
a third of the distance from the top of the windowthey reflect
light through the upper portion of the window.  A light-colored
ceiling will scatter this light, illuminating the office without
heating it.  Clerestories are skylights where the glass has been
mounted perpendicular to the roof (see photo on page two). 
Mirrors on the roof reflect light into the window and the inner
surface of the clerestory diffuses the light and directs it
downward into the building.  The clerestory may also contain
photocells to activate artificial lights when natural light falls
below a certain level.

New Developments

Two new technologies can transport light into interior office
spaces.  The first, light "pipes," reflect sunlight along their
length, similar to a optical fiber, and allow some light to
escape with each reflection.  These pipes are excellent light
sources for hallways and cubicle offices.    The second,
holographic films, refract light to change its direction.  A
holographic film on a window can make light appear as if it is
shining directly into the room regardless of the angle at which
it strikes the window.  Thus, even incidental light can be
projected 30 feet into a hallway or office space.

Controlling Heat Transfer through Windows

All objects emit light at different frequencies; the hotter the
object, the more light emitted at higher frequencies.  Relatively
cool objects, such as ourselves, sun-warmed asphalt, warm rooms
and other objects near 80 degrees fahrenheit, primarily emit
infrared radiation (IR), which we experience as heat.  All
objects seek a state of equal radiation; the net result of this
radiation is that cooler objects will get warmer.  Since glass is
transparent to IR, warm rooms will lose heat through radiation in
winter and cool rooms will absorb IR heat in summer.

IR is not the only way that glass facilitates energy transfer. 
Energy may be transferred by visible light as well.  When
sunlight shines directly into a room, all of the energy
associated with that light is absorbed by dark surfaces in a room
(carpeting, desks, chairs, etc.).  These surfaces get warm and
radiate heat in the room.  This will reduce heating loads in
winter, but it will increase cooling loads in summer.  

Lastly, windows allow heat transfer by conduction.  Glass has a
very low thermal resistance.  While a fiberglass-insulated wall
typically has an R-value (a measure of thermal resistance) of 15,
called "R-15," single-paned glass windows have R-1 or, at best,
R-2.  Thus, these windows allow warm rooms to lose heat in winter
and cool rooms to gain heat in summer.

Low-Emissivity Windows Block IR

Low-emissivity (low-E) windows minimize the entrance of infrared
radiation into a room while permitting the passage of visible
light.  Emissivity is a material property.  An object with a low
emissivity has a highly reflective surface; it neither absorbs
nor emits radiation.  A low-E window will bounce radiant heat
back to its source; warmth in a room on a cold day will be
trapped inside while warmth outside on a warm day will be kept
outside.  According to Lawrence Berkeley Laboratory (LBL), these
windows cost about $2/square foot and will pay back their
investment in two to six years, depending upon climate and energy
costs.  Low-E films may also be placed directly on existing
windows as part of an efficiency upgrade.

A new type of window, an electrochromic window, has recently been
developed which could reduce a building~s energy costs by 30 to
50 percent.  According to a September 29, 1992, article in the
New York Times ("Researchers Develop ~Smart~ Window to Cut Energy
Consumption," p. C4), the electrochromic window uses an electric
current to react to heat and light changes.  The window consists
of seven very thin layers: the two outer layers coat the window;
the next two layers function as positive and negative terminals
for current flow through the window; the next two layers contain
a metal which changes color in response to an electric current;
and the central layer contains an ion conductor.  As the two
metals change color in response to a electric current, the amount
and type of radiation which passes through the window may be
controlled.  These electrochromic windows may be placed between
two panes of glass to increase further the insulating value of
the window.  

Casting Shadows Can Also Save Energy

Light-blocking structures can prevent the entrance of direct
sunlight through windows.  Exterior blinds prevent light from
striking a building during the day (though that eliminates the
view).  According to Energy & Economics: Strategies for Office
Building Design (see Resources, page seven), these blinds add
very little to the construction cost of a building (less than 1
percent) and can reduce energy consumption by 10 percent.  At a
modeled cost of $60,000, the estimated payback time for a
60,000-square-foot building is six years.  Other less expensive
devices, such as awnings,  may be more cost-effective, depending
upon their effectiveness at blocking direct sunlight.  Exterior
window plants provide shade in summer and allow sunlight in
winter.  Interior blinds are not as effective in preventing heat
gain, since the heat has already passed through the window before
it strikes the blind, though they can prevent heat loss at night
in cold climates.

Improving Window R-Values

The thermal resistance of windows may be improved by adding panes
of glass and by filling the space between the panes with a
non-conducting gas.  Multi-paned or storm windows filled with an
inert gas (such as xenon, krypton or argon gas have an R-value (a
measurement of thermal resistance) of R-6.
Windows may also have "aerogel" placed between the individual
panes.  Aerogel is a solid and transparent material made of
nearly pure silica which contains millions of microscopic air
cavities.  These cavities increase the resistance of the
material.  Just one-half inch of aerogel between two panes of
glass can increase the R-value of a window by 500 percent, making
a window more resistant to heat conduction than a wall.

CASE STUDIES:

Mt. Airy Public Library, North Carolina
In 1982, the town commissioners of Mt. Airy, North Carolina,
sought to construct a library which would consume 70 percent less
energy than a conventional building.  By using clerestories
across the top of the library, the building provides glare-free,
diffuse light to all corners of the library without allowing the
stacks to be directly illuminated, thereby preventing damage to
the books from sunlight.  The building design also incorporates
insulation and air lock areas (see pages 5-6) and a zoned system
of heat pumps.  Electricity used for lighting accounts for only
one-eighth of the energy consumption in the building.  The
library uses 90 percent less energy than the Mt. Airy City Hall,
a building of comparable size (about 13,000 square feet).  The
construction cost was $88 per square foot as compared to $79 per
square foot for a conventional building, but was within the range
of other innovative and uniquely-designed libraries.  After
construction, the library was found to use 53 percent less energy
that was estimated for a conventional design.  (Contact: Ralph
Cooke, 838 Cross Creek Drive, Mt. Airy, NC  27030).

Abrams Elementary School in Bessemer, Alabama
In designing a replacement for a condemned elementary school, the
Board of Education in Bessemer made quick energy-saving
adjustments to conventional designs.  Since heating and lighting
account for almost 70 percent of the energy used in a typical
elementary school, the school was designed with modified
clerestories.  These shine light directly onto water-filled
plastic pipes placed in the ceilings of the school~s 20 hexagonal
teaching areas.  These tubes intercept and diffuse light.  Other
energy-saving measures led to the construction of a building
which consumes 60 percent less energy than a similar, non-solar
building.  (Contact: Stuart Wells, Passive Solar  Industries
Council, 1511 K Street NW, Suite 600, Washington, DC  20005,
(202) 371-0537.)
Elementary Schools in Laveen, Arizona
As a part of a major energy retrofit, in 1991, Laveen replaced
inefficient, leaking aluminum windows in one school with a glass
block window wall system.  The project also added insulation to
the roofs and walls of the building.  The school superintendent
reported that the improvements in the quality of lighting, air
distribution, air temperature and noise level in buildings has
improved the learning environment.  The projects were repeated in
two additional buildings in the summer of 1992.  (Contact: Dennis
Umber and Associates, 5535 Osborn Road, Suite 203, Scottsdale, AZ 
85251 (602) 423-8474.)

Office Complex in Southfield, Michigan
In 1992, The Northland Towers Office Complex added a blue low-E
film to the outside of 39,000 square feet of window space on
their two towers.  The previous film on their glass, which
accounts for 90 percent of the building~s exterior, had begun to
peel.  The project cost $69,960.  While reflective film lowers
the cooling load in summer, it increases the heating load in the
winter because the reflective film prevents sunlight from
entering and warming rooms.  The net annual savings are 
estimated at $22,571, resulting in a payback of 2.8 years. 
(Contact: Chris Pedigo, Executive Vice-President, Northland
Towers Management, 15565 Northland Drive, Suite 510 West,
Southfield, MI  48075, (313) 569-3180.)

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From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:42 PST

THE HEAT ISLAND EFFECT

Light-colored surfaces mitigate what is known as the "heat
island" effect.  According to a September 1990 article in
Scientific American, downtown temperatures in Los Angeles are
over five degrees fahrenheit warmer than they were in 1940, and
they are increasing at a rate of nearly one degree every 10
years.  

This is attributable to the increased use of asphalt across the
city.  Asphalt is dark and absorbs heat very effectively.  The
use of asphalt also displaces trees which cool the air by
evapotranspiration.  The net cost in Los Angeles from the effect
is estimated to be $100,000 annually in additional cooling costs. 
Lightening asphalt and roof surfaces and replanting trees  in
urban areas can reduce the amount of heat which a city will
absorb.

Light-colored surfaces also improve the energy efficiency of
individual buildings.  According to the Solar Energy Corporation
of New Jersey, a white roof will stay 30 degrees cooler on a
sunny day than a dark roof.  The cooler roof temperature results
in a smaller cooling load in the upper floors of a building. 
However, white surfaces radiate as effectively as a dark surface
and will radiate heat into a building.  Low-emissivity surfaces,
such as radiant barriers (see page six), are more effective at
reflecting the heat from sunlight.

CASE STUDY:

Light-Colored Roofing in Mesa, Arizona
The City of Mesa replaced or re-coated the roofs of four
buildings with light-colored insulation board and spray styrofoam
as part of an energy retrofit for each building.  Prior to the
retrofit, each of the buildings had a dark green or black roof
and no insulation.  The heating and cooling load attributed to
the roof is expected to be reduced by 20 to 30 percent.   The
estimated payback for the project is quite long, about 20 years. 
However, this project was completed as part of a major retrofit,
including energy efficient lighting and heating, ventilating and
air conditioning (HVAC) improvements, which had much shorter
paybacks.  By performing all energy improvements at the same
time, the city of Mesa included a project which was not highly
cost-effective but still energy-efficient.  (Contact: Larry Kell,
City of Mesa, Box 1466, Mesa, AZ  85211-1466, (602) 644-3287).

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From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:43 PST

PROVIDE CLOTHING FOR YOUR BUILDING -- INSULATE IT

Proper insulation in a building is important because it prevents
the transfer of heat between a building and the external
environment, as well as between sections within a building. 
Attempting to control the temperatures in different zones of a
building will not succeed if heat can travel freely throughout
the building.  

All Parts of a Building Should Be Insulated

Walls, ceilings and roofs should all be insulated.  The payback
time for insulation depends upon the amount of insulation
currently in place.  Buildings which have no insulation can
expect a project to pay back in energy savings in a few years. 
Wall insulation has the longest payback because of the cost of
repainting.  

Floors should be insulated as well.  Slab-on-grade floors should
be insulated around the perimeter with rigid board or foam.  The
board or foam should be placed vertically along the outside edge
of the floor and should extend down at least two feet below the
surface of the floor.
Insulation of structural members, the steel beams which support
the building, is also important.   According to Energy &
Economics, uninsulated structural members can reduce the
performance of roof and wall insulation by up to 20 percent. 
Improper insulation also causes water to condense on cool beams,
causing a structure to deteriorate.

A New Development: Gas-Filled Panels

A new type of insulation developed for insulating roofs and walls
is the gas-filled panel (GFP).  GFPs consist of low-emissivity
multilayer baffles enveloped by a sealed barrier and filled with
a low conductivity gas (such as argon or krypton) or air.  These
panels are twice as effective as fiberglass insulation; they
provide R-7.5 per inch thickness, as opposed to R-3 to R-4 per
inch thickness for fiberglass.  In addition, GFPs can replace
CFC-blown foams.  Lawrence Berkeley Laboratories has almost
completed a manufacturing prototype of a GFP building insulator.
Insulation Does Not Cause Poor Air Quality

While insulation definitely improves the thermal performance of a
building, many believe that over-insulating prohibits adequate
ventilation in buildings.  Alarm over indoor air pollutants,
particularly radon, has caused people to believe that leaky
buildings provide more fresh air and improve indoor air quality. 

Hunter Lovins of the Rocky Mountain Institute strongly disagrees. 
"The answer to indoor air pollution," she stated in an
Architecture article, "including radon, is stopping the poisons~
entry, or, failing that, then ensuring a constant supply of fresh
air prewarmed through heat exchangers.  It is a myth that old
leaky buildings are more healthful than tight superinsulated
buildings.  Research at Lawrence Berkeley Laboratory shows that
you can get much higher concentrations of radon in leaky
buildings than will ever occur in tight buildings with constant,
controlled ventilation.  With heat exchangers, you get
energy-efficient control over the ventilation rates and flow."
("The Performance of Some 1970s Energy Savers," Architecture,
March 1989).  (Contact: Rocky Mountain Institute, 1739 Snowmass
Creek Road, Snowmass, CO  81654, (303) 927-3851.)

Choosing  a "Green" Insulation

Many insulating materials are made using dangerous chemicals. 
Polystyrene, itself a known carcinogen, is usually blown into an
insulating foam with chlorofluorocarbons (CFCs) or
hydrofluorocarbons (HCFCs), both of which deplete atmospheric
ozone and contribute to the growing ozone hole.  Fiberglass must
be handled carefully because splinters of the glass can enter the
lungs.  Cellulose is a safer alternative, but must be treated
with flame retardants.

CASE STUDIES:

Insulating the High School in Yuma, Arizona
The Yuma Union High School District installed R-30 batt
insulation above new suspended ceilings in classrooms at Kofa
High School and R-11 batt insulation in the walls.  Prior to the
installation, the high school had only R-2.5 insulation.  The
building has 360 tons of chiller capacity.  To meet its daytime
cooling demand, the facility manager arranged to make ice at
night to lower the peak electric demand during the day.
Unfortunately, the cooling load had been so large the chillers
had to operate both day and night.  The insulation should allow
the chillers to idle during the day, lowering the peak demand of
the school.  This would entitle the school to a lower electricity
rate with the utility, increasing energy savings.  An additional
benefit is that the chiller plant runs better and will last
longer.  The project cost $55,000 and will eliminate 50 tons of
cooling load in the building.  The energy savings alone, not
including a shift to the lower electric rate, should pay back the
investment in just under three years.  (Contact: Richard
Jernigan, Yuma Union High School District, 472 South 9th Ave.,
Yuma, AZ  85364, (602) 783-0905.)

National Audubon Society Headquarters
As a part of an energy retrofit at its national headquarters in
New York City, the National Audubon Society insulated its walls
with "Air Krete" insulation.  This insulation, which consists of
air bubbles trapped in a magnesium oxide cement mixture, improved
the R-value of the walls to between R-12 and R-16 (up to three
times the New York Code requirement), depending on the thickness
of the insulation.  This insulation is non-toxic and does not use
CFCs in its manufacture.  (Contact: Kirstin Childes, Croxton
Collaborative Architects, 1122 Madison Avenue, New York City, NY 
10028, (212) 794-2285.)

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From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:43 PST

RADIANT BARRIERS - ENHANCING INSULATION PERFORMANCE

Insulation is capable of stopping the conduction of heat but it
cannot prevent heat transfer by radiation.  When sunlight strikes
the roof of a building it can increase the temperature of the
roof up to 190 degrees fahrenheit on a black roof or 160 degrees
on a white roof.  Both the outer and inner surface of the roof
are at this temperature.  The placement of insulation beneath the
roof prevents the conduction of heat from the roof into the
building.  However, since insulation has a non-reflective
surface, it will absorb heat radiated by the roof until it
reaches the same temperature as the roof.  The hot insulation
then warms the air surrounding it.  Rather than being a barrier,
the insulation has become a heat source.

Radiant Barriers Block Radiant Heat

Radiant barriers prevent the roof~s radiant heat from reaching
below the building insulation.  A radiant barrier is essentially
a low-emissivity (low-E) surface.  Since low-E surfaces neither
absorb nor emit heat radiation very effectively,  radiant
barriers reflect infrared radiation.   A 1985 Solar Age Magazine
article states that a radiant barrier will reflect up to 97
percent of the incident radiation.  

Placement of Barriers in Buildings

Since commercial buildings generally have their insulation, if
any, as a part of their roof structure, barriers must be
installed on top of the roof.  Weathering and dust accumulation
will reduce the effectiveness of a barrier over time.

Exterior Barriers for Buildings

Two types of radiant barriers exist on the market.  The first is
a sheet of low-E material, such as aluminum foil.  The foil is
normally laminated to a rigid scrim (a coarse fabric) to
facilitate installation.  The second is a paint which may be
applied to any surface.  The paint is only slightly less
effective than foil in its performance, but it can also be
applied externally and to a surface of any shape.

CASE STUDIES:

Application of Paint Barrier in Arkansas
In 1987, a radiant barrier paint was applied to the
28,000-square-foot roof of an egg production facility. The
application of the barrier reduced the roof temperature by 40
degrees fahrenheit.  The production facility was closed but in
1990 the coating was still in good condition and the interior
temperatures of the building were lower than adjacent untreated
buildings.  (Contact: Bob Aresty, Solar Energy Corporation, 129
Walters Avenue, Trenton, NJ  08638, (609) 883-7700.)

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From: Essential Information <[email-masked]>
Date: 31 Dec 92 12:43 PST

RESOURCES

The Passive Solar Industries Council is a national association
devoted to providing practical information on energy conscious,
passive solar design and construction throughout the United
States building industry.  PSIC provides accurate and easy-to-use
guidelines, software and general information about energy
conservation measures (ECMs), energy efficient equipment and
appliances, daylighting and passive solar architecture.  PSIC
will be publishing  Smaller Commercial Building Guidelines in
mid-1993.  Contact PSIC at 1511 K Street NW, Suite 600,
Washington, DC  20005, (202) 371-0357.

The National Audubon Society has published a packet of
information, Building for an Environmental Future,  on the
retrofit of their national headquarters.  The packet details the
ECMs included in the retrofit and the environmental benefits
associated with each ECM.  The packet also provides a listing of
environmentally conscious architectural firms.  In addition,
Audubon has published a Technical Guide which provides specific
information on how to incorporate environmentally sound
principles into any building project.  Contact the National
Audubon Society, Conservation Information Department, 950 Third
Avenue, New York City, NY, 10022, (212) 546-9195.

Energy & Economics: Strategies for Office Building Design is a
guidebook for design professionals which contains strategies for
designing efficient buildings.  The book examines specific
projects for improving the efficiency of lighting, building
envelope design, heating, ventilation and air conditioning
(HVAC), and much more.  Each example is examined for its cost and
energy savings.  Contact the Northeast Utilities Service Company,
Conservation and Load Management, P.O. Box 270, Hartford, CT 
06141, (203) 721-2976.

The Department of Energy established in January 1989 mandatory
standards for all new federal commercial building construction. 
For a copy of the guidelines contact the Office of Codes and
Standards, CE-43, U.S. Department of Energy, 1000 Independence
Ave., SW, Washington, DC  20585, (202) 586-9127.

Lawrence Berkeley Laboratories (LBL) has pioneered the research
of a number of energy-efficient technologies.  In particular,
they have been working on gas-filled panels and low-emissivity
windows. For more information, contact LBL, Center for Building
Sciences, Mail Stop: 90-3111, Berkeley, CA 94720, (510) 486-4800.