22 August 2006
BENEFITS OF DAYLIGHT. Daylight in interior spaces has multiple benefits.
Daylighted environments provide a connection to the outdoors, are healthier for
occupants and have the potential to save energy. Research has shown that children
learn better1, retail stores sell more product2, and office workers are more productive3 4
in daylighted environments. Since daylight also helps to regulate our circadian cycle5,
introducing daylight into interior spaces is a top priority. Daylight is a natural resource
that is more efficient than electric light and should be utilized to its fullest potential
(Refer to Chapter 5, "Lighting Equipment" for efficacy of light sources).
PROJECT TYPES THAT BENEFIT FROM DAYLIGHT. The introduction of
daylight into any space has the potential to provide these benefits for the occupants as
well as reduce building energy use. However, some project types are better suited than
others to take advantage of daylight.
Open spaces with high ceilings such as hangars, warehouses, recreation
centers, and maintenance areas offer good opportunities for toplighting with skylights
Perimeter spaces such as offices, lobbies, classrooms, cafeterias, and
residential areas are all good sidelighting applications.
DAYLIGHTING ECONOMICS. The use of daylight can produce more
comfortable work environments. This benefit may be difficult to quantify, but the energy
saved by dimming or switching electric light in response to daylight can be quantified.
The implementation of skylights and clerestories as well as lighting control equipment
such as dimming ballasts and photocells all increase initial cost. Additionally, for DoD
facilities in areas of high threat, Antiterrorism (AT) criteria (see UFC 4-010-01) increase
the required strength of all glazing. Therefore, the addition of glazing may significantly
increase the cost over a commercial building. Careful analysis must consider these
costs to determine the payback of daylighting strategies. The following case studies
describe projects where daylighting strategies and energy efficient lighting and controls
have been added to an existing building.
The Heschong Mahone Group, "Daylighting in Schools", <http://www.h-m-
The Heschong Mahone Group, "Skylighting and Retail Sales", <http://www.h-m-
g.com/Daylighting/summaries%20on%20daylighting.htm#Skylighting and Retail Sales>
California Energy Commission. (2003). Windows and Offices: A study of office worker performance and
the indoor environment (Catalogue No. P500-03-082-A-9).
"Design Objectives, Productive", Whole Building Design Guide, 22 August 2002
New Buildings Institute, Inc. "Lighting and Human Performance", Advanced Lighting Guidelines, Chapter
2. 2001 Edition, p.2-12-13