There are a few things that can be done to improve the air quality in urban neighborhoods, but all of them involve financial investments. Public transportation vehicles using electric or natural gas have alleviated air pollution in several cities. Some tree species are known to remove pollutants from air. Higher octane fuel, though more expensive, burns hotter and therefore eliminates some of the byproducts of incomplete combustion. Of course, not needing to use vehicles in the first place will greatly reduce the air pollution from vehicles. If cities are re-designed to be more pedestrian or bicycle friendly, such that people can reasonably live close to their workplace, many vehicles become all but obsolete.
RESIDENTIAL AND COMMERCIAL SECTOR The residential and commercial sector—homes and buildings— consumes 11.57 percent of the primary energy used in the United States today. We use energy to heat and cool our homes and buildings, to light them, and to operate appliances and office machines. In the last 40 years, Americans have significantly reduced the amount of energy we use to perform these tasks, mostly through technological improvements in the systems we use, as well as in the manufacturing processes to make those systems.
Heating and Cooling More energy is used for climate control in a home or commercial building than for any other use. Keeping our living and working spaces at comfortable temperatures provides a healthier environment, but uses a lot of energy. Forty-three percent of the average home’s energy consumption is for heating and cooling rooms. The three fuels used most often for heating are natural gas, electricity, and heating oil. Today, about half of the nation’s homes are heated by natural gas, a trend that will continue, at least in the near future. Most natural gas furnaces used in the 1970s and 1980s were about 60 percent efficient—they converted 60 percent of the energy in the natural gas into usable heat. Some of these furnaces might still be in use today, especially in homes that are rented by tenants or owned by people who cannot afford to replace them. Depending on maintenance and homeowner use, these furnaces could last for over 20 years. New furnaces manufactured today can reach efficiency ratings of 98 percent, since they are designed to capture heat that used to be lost up the chimney. These furnaces are more complex and costly, but they save significant amounts of energy. Electricity is the second leading source of energy for home heating and provides almost all of the energy used for air conditioning. The efficiency of air conditioners and heat pumps has increased 50 percent in the last 35 years. In the 1970s, air conditioners and heat pumps had an average Seasonal Energy Efficiency Ratio, or SEER, of 7.0. Today, the new units must have a SEER of 13, and highefficiency units are available with SEER ratings as high as 18. These highly-rated units are more expensive to buy, but the money saved by lower energy bills covers that higher cost within 3 to 5 years.
Lighting Lighting is essential to a modern society. Lights have revolutionized the way we live, work, and play. Lighting accounts for a little more than seven percent of the average home’s total energy bills, but for stores, schools, and businesses, the figure is slightly higher. On average, the commercial sector uses about 10 percent of its energy for lighting. ©2020 The NEED Project
Energy, Climate, and You Student Guide
Four major types of lighting are used in homes, with a fifth being used in commercial buildings. Incandescent lights are the original style of lamp perfected by Thomas Edison in 1879. These bulbs emit light because the filament inside gets so hot that it glows, or incandesces. Incandescent bulbs are extremely inefficient, with 90 percent of the energy used being released as heat rather than light. Most common incandescent bulbs have been phased out since 2014, but appliance bulbs, some vehicle lights, and many other specialty bulbs are still sold as incandescent lights. A more efficient style of light is the halogen-incandescent bulb. This bulb still works the same way as traditional incandescent, but the filament is encapsulated and surrounded by a gas that makes the bulb more efficient. While the old-style incandescent bulbs produced only 14 lumens per watt, halogen bulbs produce 22 lumens per watt. Around the turn of the twenty-first century, compact fluorescent light bulbs began appearing in stores. A smaller version of the large fluorescent tube lights you see in schools and businesses, these bulbs, called CFLs, resemble soft-serve ice cream cones with their distinctive spiral. CFL bulbs produce up to 70 lumens per watt. Their high efficiency and longer life made them very popular through the 2010s. Today, however, most people prefer LED bulbs.
INCANDESCENT BULB
HALOGEN BULB
CFL BULB
LED BULB
LEDs offer better light quality than incandescent bulbs and halogens, last 25 times as long, and use even less energy than CFLs. LEDs now have a wide array of uses because technology has improved and costs have decreased. CFL use has greatly decreased as LED prices have reached similiar prices as other bulbs.
How Do Bulbs Measure Up? Talk to your parents and you’ll learn that they used to shop for bulbs by the wattage, or power, that each bulb used. Only one type of light bulb was available, so the higher the wattage, the brighter the bulb. When incandescent bulbs were phased out, people needed a good way to compare bulbs and purchase the correct brightness for the lighting application. Fortunately, physics always had a good unit available – the lumen. Lumens measure the intensity of the light leaving a light source; the higher the lumen rating, the brighter the bulb. Using lumens to shop light bulbs is a better way of comparing light bulbs since different technologies produce different numbers of lumens per watt of power used.
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