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Views towards the outside areamong the most important criteriafor the acceptance of buildings.While providing varietywithin the everyday routine oflife, they also help to preventfeelings of claustrophobia.that occupants also supplement daylightwith task lamps. It is possible that electriclight, whether ceiling or task, reduceslighting contrasts on work surfaces thatmake some visual work difficult.A post-occupancy evaluation of thefirst LEED Platinum building in the US,the Philip Merrill Environmental Center,shows very high satisfaction with daylight,despite concerns with visual discomfort(Heerwagen and Zagreus, 2005). Thissuggests that people may value the psychologicalbenefits of daylight even whendaylight creates difficulties for work dueto glare and uneven light distribution.Certainly, the kinds of visual tasks weperform in today’s work environmentsare very different from our ancestors’daily tasks. Cooking, tool making, conversing,foraging, and hunting could beeffectively carried out over a wide rangeof luminous conditions. In contrast, readingand computer work require a muchgreater degree of visual acuity that maybe more difficult in some daylit environments.Yet a uniformly lit environmentthat may be appropriate for office worklacks the psychological, and perhaps biological,value of daylight.Attitudes toward Daylight andElectric LightA study of office workers in a Seattlehigh-rise building asked respondents tocompare the relative merits of daylightand electric light for psychological comfort,general health, visual health, workperformance, jobs requiring fine observation,and office aesthetics (Heerwagenand Heerwagen, 1986).The results show that the respondentsrated daylight as better than electric lightfor all variables, especially for psychologicalcomfort, health and aesthetics. Theyrated daylight and electric light as equallygood for visual tasks.At the time of this study in 1986, therewas little evidence connecting daylight tohealth. Since that time, however, therehas been a surge of research on the link betweenlight and health, much of it focusingon the circadian system and seasonalaffective disorder. Much of this work hasbeen conducted in clinical settings withphototherapy. Since a review of this topicis provided elsewhere in this issue, it willnot be addressed here.However, it is worth noting a laboratorystudy that investigated lighting preferencesof subjects with Seasonal AffectiveDisorder (SAD) compared to subjects thatdid not experience seasonal changes inmood or other behaviours (Heerwagen,1990). Those who experienced seasonalchanges chose significantly higher levelsof brightness for all lighting sources comparedto those who did not. This suggeststhat people experiencing SAD may indeedbe ‘light hungry’ and could benefit fromindoor environments with high daylightlevels, such as atria, sunrooms and locationsadjacent to windows.But what do we know about otherhealth impacts of daylight in the builtupenvironment? Research in hospitalsettings, looking at the relationship betweenroom daylight levels and patientoutcomes, found that bi-polar patientsin bright, east-facing rooms stayed in thehospital 3.7 fewer days on average thanthose in west-facing rooms (Benedettiand others, 2001). Similar results werefound by Beauchamin and Hays (1996)for psychiatric in-patients; those in thebrightest rooms stayed in the hospital 2.6fewer days on average. However, neitherof these studies provides data on the actuallight levels in the patient rooms or lightentering the retina, so it is difficult to drawconclusions about exposure levels.More recent research in a Pittsburghhospital actually measured room brightnesslevels. Walch and others (2005) studied89 patients who had elective cervicaland spinal surgery. Half the patientswere located on the bright side of thehospital, while the other half were in ahospital wing with an adjacent buildingthat blocked sun entering the rooms. Thestudy team measured medication typesand cost as well as psychological functioningthe day after surgery and at discharge.The researchers also conducted extensivephotometric measurements of light ineach room, including light levels at thewindow, on the wall opposite the patient’sbed, and at the head of the bed (which presumablywould have been at or near the20 D&A SPRING 2011 Issue 15