Despite the tremendous architectural interest and the large po-
tential energysavings, theactual number of effectivelydaylit
buildings that demonstrably save energy is very small.This is
due to numerous design, implementation,and technological bar-
riers:

Amajorbarriertotheuseofdaylightingistechnological.
Daylightingis unique in that it requires designers to solve not
only complex technical issues on a case-by-casebasis, but also
qualitativeissues as well.Thereare alack ofgoodmodular inte-
grated building systems that perform well across energy-efficiency
andqualitative criteriaandcan be easily used in mostbuildings.
Concepts for innovative technologies need to be comprehensively
tested to determine if they are truly viable and acceptable.Evalu-
ation methods are not well established.

Anintegrateddesignbalancesthecoolingloadofthewindow
againstrequireddaylightilluminancelevels,therebycapturing
bothcoolingandlightingenergysavingswithoutcreatingdis-
comfort.A poor designimposesasubstantial coolingloadand
creates glare.Achieving this balance requires careful and informed
design andengineering.

Daylightingrequirestheparticipationandcooperationofmul-
tipledisciplines--architecture,lightingdesign,mechanicalsys-
temdesign.Since the fenestration systemisapredominantele-
ment that defines the exterior architectural "character" of a build-
ing,windowsareoftendesignedwithoutconsideringthecom-
fortof interior inhabitants.Energy-efficiency standardsmay en-
couragedesignerstosubstituteconventionalcomponentswith
new and better technologies, independent of whole building con-
siderations.Even when the proper components are selected, poor
design and commissioning practices often lead to unreliable per-
formance and uncomfortable work environments.