Here Time Comes to Save the Day

Daylight saving time (DST), attributed by many to Benjamin Franklin, seems like a great idea. Since the advent of standardized time, the beginning of our waking hours has been much closer to noon then their end. By shifting time so that noon is no longer the center of the daylight hours, we won’t be wasting sunlight while we sleep.

In practice, it isn’t clear how to best implement DST. In most of North America, DST lasts from the 2nd Sunday of March to the 1st Sunday of November. Up until 2007, it was about a month shorter. In most of Europe, DST lasts from the last Sunday in April to the last Sunday in October. Outside of North America and Europe, few countries observe DST at all.

(1)    Estimate for Americans the number of hours annually of daylight and darkness while they are awake and the number while they are asleep under the current DST rules used in North America.

(2)    Arguments in favor of DST often point to energy savings through reduced use of electrical lighting. Develop a model to estimate the electrical lighting energy use under different DST schedules. Use this model to compare national energy use due to lighting with no DST to the current DST schedule.

(3)    Recent studies, including studies of the 2006 implementation of DST in Indiana, suggest that other sources of energy use (such as air conditioning) may increase with DST and overwhelm the savings from lighting. Make a recommendation for an optimal implementation of DST to be used nationally based on an expanded model which considers heating and cooling as well as other factors you think should be included, such as daylight during commute to reduce traffic accidents and psychological/social costs to the time switch.

History and links to several studies: http://energy.ca.gov/daylightsaving.html
Cost calculator for different types of lighting: http://darkskysociety.org/lightcost/index.php

Problem submitted by Paul Taylor, an associate professor in the department of mathematics at Shippensburg University, Pennsylvania.