The three P's (people, planet, profit) are often referred to as the "Triple Bottom Line" when describing sustainability. It is important to utilize these principles when determining sustainable practices.
At the City of Tempe our facilities division is constantly looking for ways to promote sustainability by reducing both electricity costs and greenhouse gas emissions.
We identified several large structures that were using metal halide lights. The first area identified was the Kiwanis Wave Pool. We replaced fifty-four 400 watt metal halide lights with fifty-four 188 watt LED lights. Annually, we will use 75,114 less kilowatt-hours (kWh's) and save $15,321 in electricity costs.
Another area identified was the City Hall Parking Garage. We replaced 240 metal halide lights with LED's. Annually our kWh savings will be 178,688 while our electricity savings will be $17,868.
Here are some other facts about LED's verses metal halide lights you may not know. According to the U.S. Department of Energy, LED lights use approximately 54% less electricity. A typical 400 watt metal halide light produces 20,000 Lumens when newly installed and greatly dissipates after they are initiated. In fact, metal halide lights lose 50% of their Lumens after a mere 10,000 hours and have a 16,000-20,000 life expectancy. However, they continue to use 456 kWh's. By contrast, LED light fixtures produce 18,000 Lumens while only using 213 kWh's. LED's maintain 92% of their Lumens for 60,000 hours and have a life expectancy of 100,000 hours.
This reduction in kilowatt-hours and electricity usage results in reduced costs and power plant emissions.
LED's promote the "Triple Bottom Line' by producing better lighting longer; therefore increasing our ability to see (people), use less kilowatts, contain no known disposal hazards and reduce greenhouse gases (planet) and use much less electricity (profit).
The U.S. Department of Energy (http://www.energy.gov/eere/femp/lighting-energy-conservation-measures) is an excellent resource for investigating the advantages of LED's. Here’s a link to a great video that highlights the LED streetlight program that the City of Los Angeles completed http://bsl.lacity.org/led.html.
City of Tempe
Facilities Maintenance Manager