The global energy crisis is approaching. What can we do? Here are some steps you can take. Cooling puts the greatest stress on your summer energy bill and the power grid . Just as t tune-up for your car can improve your gas mileage, a yearly tune-up of your heating and cooling system can improve efficiency and comfort. Clean or replaces filters monthly or as needed. For central air conditioning systems and room air conditioners, look for the ENERGY STAR, the federal government's symbol for energy efficiency. For central air, purchase the system with the highest possible Seasonal Energy Efficiency Raton. (SEER) Use energy-efficient ceiling fans either alone or with air conditioning. Ceiling fans do a great job of circulating air. When used with air conditioning, fans allow you to raise the thermostat  and cut costs. Ceiling fans cool people, not rooms, so before you leave; turn off the ceiling fan. Let a programmable thermostat! "remember for you" to automatically adjust the indoor climate with your daily and weekend patterns to reduce cooling bills by up to 10 percent. You can come home to a comfortable house without wasting energy and cresting pollution all day while you are at work. Try to make your home airtight enough to increase your comfort, make your home quieter and cleaner and reduce your cooling costs up to 20 percent. Gut your air conditioning load, and reduce pollution by planting planting leafy trees around your home and fixing reflective bricks on your roof. Close blinds or shades on south-and west-facing windows during the day, or fix shading equipment to avoid heat build-up. Turn off everything not in use: lights, TVs, computers. And use fluorescent bulbs , which provide bright, warm light while using at least two-thirds less energy, producing 70 percent less heat and lasting up to 10 times longer than incandescent bulbs . Drive the car that gets better gas mileage whenever possible if you own more than one vehicle. If you drive 12,500 miles a year, switching 10 percent of your trips from a car that gets 20 mils per gallon to one that gets 30 mpg will save you more than PS65 per year. Carpool. The average U.S. commuter  could save about PS260 a year by sharing cars twice a week with two people in a car that gets 20.1 mpg---assuming the three passengers share the cost of gas. According to the passage, the thermostat is used to    _   .
make rooms quieter control room temperature turn off the air conditioner reduce room air pollution