Remember the 1970s? That’s when Congress blamed automakers and Midwest manufacturing plants for poor national air quality. This ill was ultimately remedied, in part, by legislation, catalytic converter design and smokestack restrictions. The good news is that Americans probably do live healthier lives because of fewer carbon dioxide particles, less acid rain and improved breathing space. The bad news is that other daunting issues have replaced the old.
Today the window treatments and shadings business also faces a call
to arms. Regulation issues aside, some of the same needs for improvement
urged upon the automakers and other industrialists will soon be
standard operating procedure for our businesses as well. Here’s
why: Quite simply, the world can no longer afford to be non-energy
efficient. For a preview, one only needs to look east across the
Atlantic Ocean and study the shading methods of Europeans who have
practiced energy conservation for most of the 20th century.
At the risk of understatement, the deal is simply this. The sun
can be our friend or enemy. Depending on how we treat this power
source, we can make it an energy efficient partner, as the Europeans
do, or a continued lost opportunity with ultimate dire consequences
for our grandchildren and ourselves.
Let’s be honest, no living person would dispute the sun’s
power as a dynamic energy source for all life. Intensity and duration
of natural light not only affect our vision, but also trigger biological,
physiological and psychological responses. It especially affects
melatonin, the blood hormone that influences sleep, waking and the
manner in which we conduct our day-to-day work and leisure activities.
BALANCING FORM AND FUNCTION
Aesthetically, daylight has always been integral to good building
design. It is dynamic because it adds visual interest to interiors
by reflecting various sky conditions. As a result of its cool, blue
temperature color, daylight renders colors quite naturally except
at sunrise and sunset when it is a warm red. It is no wonder that
artists prefer northern daylight as a source of illumination.
The art and science of daylighting design also involves a critical
balance of form and function, particularly when applied to public
spaces, such as malls and lobbies. Because available daylight controls
many natural light considerations, one of the first concerns of
architects and designers is the typical sky at the building site.
Meteorologically, clear skies are defined as those with 0 to 30
percent cloud cover. Cloudy or overcast skies range from 70 to 100
percent. The 30 to 70 percent range contains myriad possibilities
and requires that a design perform well in a variety of conditions.
Were those the only variables architects had to consider, natural
light control might be reasonably simple. However, the planning
process is complicated by a host of other important factors, including
sky conditions, light source (direct sun, sky and/or reflected ground
or surround) and solar position.
Experts must also weigh the critical issue of daylight delivery
systems, architectural elements that permit daylight to enter buildings
and provide a means for distributing light within interiors. The
most common systems are skylights, windows, light sleeves, monitors
and clerestories. The best choice for a particular building (commercial
or residential) depends on space function, design flexibility and
general site daylight conditions.
Daylight control is affected by both exterior and/or interior means.
Most daylighting systems are devoted to the exclusion of direct
sunlight, and therefore, affect the amount, quality and distribution
of general daylight inside buildings to varying degrees. The five
chief exterior means are overhangs, fins, louvers, fenestration
(window systems) and specialty fenestration.
With large glazed surfaces again popular with architects, fenestration
is an overriding element in natural light control. For purposes
here, we define fenestration (from the Latin fenestra for window)
as glass or plastic materials. That includes single-, double- or
triple-pane for insulation and annealed, heat strengthened, tempered
and laminated glass for different degrees of strength and safety.
When considering glaze, architects look at the following performance
parameters in material choice: daylight transmittance, U-value,
shading coefficient, color appearance and glass reflectance.
Specialty fenestration incorporates a variety of glass, plastic
products and other materials. Specialty glass includes fritted,
frosted and block glass. Fritted is a ceramic pattern superimposed
on clear glass. It has clear and opaque areas that offer a distorted
view through an opaque surface. Frosted glass is frequently found
in skylights and is double-layered to diffuse light and enhance
insulation. Glass block is a non see-through decorative material
with outstanding prismatic and insulating qualities that is often
used in public places.
In many applications, plastics and other materials can be suitable
and, in some cases, stronger substitutes for clear glass. Translucent
and insulting properties make them ideal for windows, skylights
and even wall panels. The addition of fiberglass fibers between
glass layers also provides an attractive diffuse effect.
OPTIMAL LIGHT FOR LIVING TASKS
Short of sunglasses, there is no one all-purpose shading system
that allows optimal light for living tasks and accompanying ergonomic
regulation that influences mood, perception and eye strain itself.
As a result, natural light engineers are continuing to explore technological
limits to bring comfort and productivity to a world at home, work
For outdoor leisure activities, visors, hats and sunglasses generally
provide sufficient visual protection and comfort. Inside, most Americans
rely on various shading options (blinds, louvers, etc.) and direct
task lighting to operate productively. Rising energy costs and an
industry response to the burgeoning home automation trend promise
a plethora of new residential natural light control advances.
In the workplace, the issue of optimal light levels and proper utilization
of interior controls has a direct effect on energy costs, productivity,
comfort, security, privacy and convenience. It also means less need
for artificial light, which while not the focus of this article
is a discipline unto itself and is of critical concern for architects
and engineers who must integrate these light sources and, ultimately,
for building occupants who must live with the result.
Proper interior natural light control invariably supplies solar
protection, glare and interior heat gain reduction, diffused light
and the elimination of interior furnishing fading. Typical controls
include horizontal and vertical blinds, draperies and shades and
products such as film that can be applied directly to the glazing.
Horizontal blinds are effective on north and south exposures blocking
high-angle sunlight. Vertical blinds work well on east and west
exposures because they mitigate low-angle sunlight. Draperies, while
stylish, are not as effective in admitting sunlight and limit adjustment
In the late 20th century, the emergent choice of natural light control
became exterior and, particularly, interior shades. The trendy term
is performance daylighting, in which the goals are comfort, energy
efficiency, aesthetically pleasing glare reduction and relatively
uniform light distribution.
An early objective for engineers was, and remains, visual comfort.
In either setting, an ideal shading system should permit sufficient
natural light without glare. The most common sources of glare are
direct sunlight, skylight, reflected ground or opposite façade
Manufacturers and trade organizations, such as the Illuminating
Engineering Society of North America (IESNA), have published guidelines
for designing daylighted spaces. For instance, IESNA recommends
a maximum of 3:1 for the ratio of near surround luminance to task
luminance and 10:1 for the ratio of far surround to task luminance.
Adherence to such formulas goes a long way in combating ocular fatigue
and eliminating uncomfortable glare in daylighted space.
Shades also can prevent problems associated with veiling reflections,
i.e., light from external sources that strike work surfaces at mirror
angles with respect to tasks. Examples are desks directly in front
of unobstructed windows or computer monitors situated so that screens
face windows. One solution is to position computer monitor viewing
direction parallel to window faces. Better yet, get some shades.
MAKING EVERY DOLLAR COUNT
Proper management of direct sunlight and the resulting excessive
solar heat gain is one of the continuing challenges faced by today’s
natural light control experts. As a consequence, energy efficiency
is a huge reason shades have become a staple of modern office building
architecture. Not only do they conserve energy by minimizing interior
lighting loads, but they also reduce associated heating and cooling
costs. As modern building elevations return to the use of large
glazed surfaces (that capture natural light and create solar radiation
problems inside buildings), shades have come to be recognized as
a fundamental construction requisite.
Consider this: Normal glazing admits 88 percent of solar radiation,
80 percent of which is transmitted directly. That solar radiation
is absorbed by walls and furniture and is converted to long wave
radiation, which in turn is blocked by the glass creating a greenhouse
effect. In buildings with 50 percent or more of unprotected windows
exposed to the sun, the temperature in closed rooms (which is most
of them) is 10 to 15 degrees higher than those outside. This phenomenon
is known as solar gain. Exterior blocking devices, and especially
solar shades, mitigate that heat, allow for higher temperature settings
and permit visibility. Resulting cost savings for the very largest
buildings can surpass $100,000 a year. An added bonus is that such
interior shades are virtually maintenance free.
Recent studies by the National Engineering School of State Public
Works (ENTPE) in Lyon, France, reveal the following:
• Americans represent four percent of the world’s population
and use 40 percent of the world’s energy.
• Exterior solar screening shades can reduce air conditioning
loads by more than 60 percent.
• Interior solar screening shades can reduce air conditioning
loads by more than 23 percent.
These are impressive numbers, particularly when viewed in the context
of dwindling global resources. Theoretically, we all accept as fact
that someday natural resources will expire. We just don’t know
when. Unfortunately, we conspicuous consumers continue our mode
of ecological brinkmanship hoping against hope that there will be
enough fuel for the Porsche, the powerboat, the furnace and maybe
our grandchildren. Beyond that, our horizon pales, our vision grows
dimmer and level of concern dissipates.
The wakeup call is just around the corner. With architects reconsidering
the role of light and increasingly returning to glazed surfaces,
it is time that we, in the window treatments industry, realize that
we are in a prime position to influence national solar protection
preplanning and energy management.
Here’s a final thought: North Americans are subject to 4,000
hours of natural light per year. Our decision in these first years
of the 21st century is either to capitalize on this gift or disregard
it. Accepting the challenge of conservation offers a far brighter
and more profitable future.
G.A. (Tony) Lovette is president of Specialty Drapery, a major
provider of custom window treatments and solar shading systems to
the design trade and commercial markets in the Mid-Atlantic region.
He is past president of Lutron Shading Solutions by VIMCO, and a co-owner
of VIMCO and has been involved with natural light control through
shading solutions for nearly 15 years working with architects, designers,
window treatment professionals, solar screen fabric manufacturers
and others to efficiently use shading systems to harness the positive
effects of the natural sunlight while reducing its negative effects.
For more information, he can be contacted at: firstname.lastname@example.org.