This year, the Energy Policy Act (EPAct) extends daylight saving time (DST) in the United States by four weeks. The idea behind this change is to see if it will reduce energy consumption. The U.S. Department of Energy (DOE) will study the affect of daylight saving on energy consumption and report the results of the study to Congress no later than December 31, 2007. After reviewing the study findings, Congress can revert back to the traditional American DST schedule if warranted.
DST was first implemented by the German government around World War I, then the United Kingdom and other Allied countries followed. The purpose was to better align work hours with daylight hours and therefore reduce the need for electric lighting in offices and factories. DST moves sunrise and sunset forward by one hour during that time of year when there are the most daylight hours (late spring, summer, and early fall). It would shift the hour from early morning to evening, better matching waking time with daylight hours.
Benefits of daylight
Anjali Joseph, PhD, completed a study for The Center for Health Design in August, 2006, titled, “The Impact of Light on Outcomes in Healthcare Settings.” She found that light reduces depression among patients, decreases length of stay in hospitals, improves sleep and circadian rhythm, lessens agitation among dementia patients, eases pain, and improves adjustment to night-shift work among staff. There is also a direct correlation between work environment satisfaction and access to daylight in that environment.
A combination of electric lights and daylight can provide the light necessary for the health and well-being of patients and staff. However, natural light does not cost anything and is in the form most people prefer.
Green Guide for Health Care
The Green Guide for Health Care Version 2.2 offers several suggestions under the Environmental Quality Section Credit 8.1. The intent is stated as providing building occupants with a connection between the outdoors and indoors by providing daylight and views into the building's regularly occupied spaces. The suggested design practices include:
Provide access to daylight in diagnostic and treatment areas.
Provide access to daylight in inpatient units by providing window configurations that allow visual connection to the outdoors for private and semiprivate patients, even when cubicle curtains are closed.
Provide access to daylight for 75% to 90% of regularly occupied staff work spaces and non-inpatient room spaces.
Design strategies to maximize windows include:
Building orientation—Northern exposure usually provides the best light source because the light is mostly glare-free and diffuse. Southern exposures may need overhead shielding from high midday sun angles. West and east windows have a greater risk for direct sun glare.
Shallow floor plates for better light penetration into the space.
Increased building perimeter for more window opportunities.
Courtyards and atria to open up the interior of the building for windows (figure 1).
The floor plan (A) of patient rooms overlooking a two-story atrium (B) at Wuesthoff Medical Center in Melbourne, Florida.
Wall color—Internal walls influence window design and placement. Highly reflective—but not glossy—light-colored walls will spread daylight back from sidewalls. Jewel-toned walls will absorb more light and may require more supplemental lighting sources.
As a rule of thumb, if the walls of a building are more than 25% glass, the building can benefit from solar control glass. The further south and the higher the percentage of glass, the higher the percentage of solar energy that should be blocked. The energy efficiency of spectrally selective glazing means that architects who use it can incorporate more glazing area than was possible in the past within the limitations of codes and standards specifying minimum energy performance.
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