Do more: lighting vs. energy usage

Perhaps you’re tired of hearing all the buzz about global warming. Perhaps you consider your energy use minimal or typical to that of your neighbors. Can just one person’s effort make any difference to the planet? Does one have to change their lifestyle to minimize energy usage? How about minimizing personal energy use for sake of simply minimizing use, saving energy costs, and decreasing pollution?

To change one must understand their current status quo. Metrics are key in your business as well as your personal life. Where do you exhaust CO2? Surely your vehicle exhausts but what about your home? Your furnace, hot water heater, other appliances, and lights all contribute. Let’s start with a simple example of calculating your home’s CO2 output based solely on your usage rate due to lighting. In case it isn’t obvious, your home doesn’t emit CO2, but the generation of electricity to run your appliances and to light those bulbs does.

For example, to burn a 100 Watt bulb for ten hours requires the generation of 1kWh of energy which expends 1.34 lbs of CO2[i]. This widely accepted value is based on the average emissions of several energy sources including: coal, petroleum, natural gas, and wind. Note however that coal emits up to 2.5 lbs CO2 compared to zero of wind energy and coal-fired power plants account for nearly half of all electricity generated in the US releasing roughly two billion tons of CO2 annually; 33% of US annual CO2 emissions[ii].

Where 1,000 Wh = 1 kWh; 1kWh = 1.34 lbs CO2,For our 100 Watt bulb lit for 10 hours:

(100 W x 10 hr) / 1000 = 1 kWh; 1 kWh * 1.34 lbs = 1.34 lbs CO2 created

Let’s look at an entire house. For a typical mid-size family, their usage might look like this:

6.29 kWh/ day may not seem like a lot of energy, nor does the $210.00 annual cost[iii] of electricity –based solely on daily light usage for 49 weeks. Considering this usage for a city the size of Seattle boasting 61,466 such 3-bedroom homes[iv], usage and CO2 emissions add up to 132,997,672 kWh annually and emissions of 80,198 tons of CO2.

6.29 kWh/day * 365 days/year – 21 days * 61,466 3-bedroom homes =

132,997,672 kWh annually for Seattle’s 3-bedroom house sporting residents

Being more aware of lights on and lowering the hours of light usage will help to lower energy use, however, not changing your family habits and simply replacing some rooms with flourescents will actually return a higher energy savings and lower your household emissions by up to seventy percent. Let’s look again at our typical mid-size family lowering usage by halving their light use:

Verses a typical mid-size family substituting CFLs in some rooms of their house:

By replacing most of the ‘high-use’ rooms with flourescents, this can mean a reduction of almost 1 ton CO2 emitted and $142 savings annually. For a city like Seattle making similar changes, this means a CO2 reduction of 54,086 tons or the equivalent of taking 4,400[v] mid-size SUVs off the highway, one Qatar citizen’s emissions per year[vi], or that of the entire Falkland Islands for one year. Comparatively, the world CO2 output due solely to human activity is 27.2 Billion metric tons[vii].

Create a similar spreadsheet modeling your home’s usage to view actual usage and to compare alternative uses.

Before beginning a comparison of alternative energy savings and lighting, it is important to understand basic differences between fluorescent (CFL) and incandescent light bulbs. The differences are mostly the watts of electricity used and the expected lifetime[viii] of each. Understanding these differences will help ensure that two equivalent light bulbs will be compared. For this study, comparable lumen output bulbs[ix] were compared and bulb life was disregarded. Know that for our typical mid-size family example, all but two rooms would have required multiple replacements of incandescent bulbs over the course of one year, however with CFLs, the most used room would not have required a bulb change in two years, the bedroom lights lasting for four years (calculated life considering the low end of expected CFL life hours).

But, what about the mercury in CFLs? Yes, that is an important and hot issue now. Read more information from Energy Star here: http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf and consider their graph of Mercury output in emissions relative to CFL verses incandescent light energy production: