COMMERCIALARCHITECTUREMAGAZINE.COM APRIL 2019 23Visual benefits include the industry’s traditional focus on good visi-
bility, visual comfort, safety, and orientation. Biological benefits in-
clude alertness, concentration, cognitive performance, and stable sleep.
Emotional benefits include improved mood, increased energy, better
relaxation, and impulse control.
LightingEurope quantified the economic value of these benefits for
various building types in a landmark 2015 study conducted by A.T.
Kearney, Chicago, in which HCL was estimated to offer significant
potential cost savings related to enhanced worker productivity and few-
er errors, absences, and accidents.
ENABLERS
What makes HCL possible is technology properly applied to spaces
through design best practices that, in turn, are promoted by standards.
First, let’s look at technology. Traditionally, aside from special appli-
cations such as boardrooms, lighting systems were installed as static
light producers. After installation, light output and color quality more
or less remained fixed. Aside from changing failed lamps, lighting was
largely forgotten.
With LED technology, this has changed.
Most LED luminaires are either dimmable as a standard feature or a
standard option, with a negligible cost premium. This dimming pro-
vides inherent flexibility in adjusting light levels in response to daylight
or occupant needs. Further, it allows control of the luminaire’s color
output through:
- separately dimmable arrays of warm- or cool-white LEDs
- color-mixing arrays of red, green, blue, and amber LEDs
- adding separately dimmable LEDs to white LEDs.
These approaches provide a range of capability from limited adjust-
ment of correlated color temperature across a set of channels to produc-
ing any shade of white light (from very cool/bluish to very warm/red-
dish), plus a virtually limitless range of saturated colors.
Various general lighting products are now available that provide
manual and programmable color tuning, imitate the warm color of
incandescent lamps while being dimmed, and/or offer precise color
matching between LED products and calibrate to maintain constant
color output over their life. What all of this has in common is that how
a space appears depends on how it’s lighted. Change the color quality of
the light source, and you change how the space appears, with associated
effects on visual rendering, perception, and mood.
Now let’s switch to application and design. These capabilities could
be applied in many ways, ranging from the cosmetic to utility:- changing color output to accommodate changing retail displays and
to ensure merchandise appears visually vibrant and appealing - signaling time for different activities in a classroom
- using saturated color to indicate occupancy and availability of private
office users - changing color, or CCT (correlated color temperature) to adapt light-
ing to different situations for the medical environment, e.g., examina-
tion rooms versus reducing patient stress in a hospital - tuning color to saturated colors to transform a functional space into
an entertainment venue - altering color output to precisely match space decor after final mate-
rials and furnishings are installed in a hospitality space, with future
retuning available if new furnishings are installed - adjusting white-light temperature to adapt a restaurant space based
PROJECT | lighting & electrical
The A.T. Kearney 2015 study shows a
number of micro and macro benefits
for the medical sector. For a hospital
with 1,000 beds and 1,500 employees,
the study indicates that human-centric
lighting can increase capacity utilization
through higher attractiveness for new
patients and can cut treatment costs
through reduced treatment times. In
addition, sick leave taken by care staff
could go down, and employee satisfac-
tion, and therefore staff retention, could
go up.