6.13 Energy Conservation

Energy conservation is any choice that reduces energy use, such as turning off lights, lowering the thermostat in winter or biking instead of driving.

Energy efficiency means doing the same job with less energy, such as an LED bulb that gives the same light as an old incandescent bulb while using at least 75 percent less electricity. Efficiency improvements save energy without asking people to give anything up.

Every unit of energy saved is fuel that doesn't have to be mined, drilled or burned, so conservation cuts air pollution, CO₂ emissions and the land and water damage from extraction.

A typical fossil fuel plant turns only about 35 percent of its fuel energy into electricity, and a few more percent is lost as heat in power lines. Work it out: to deliver 1 kWh to your house, the plant has to burn fuel holding about 1 ÷ (0.35 × 0.95) ≈ 3 kWh of energy. So every kilowatt-hour you save at home saves roughly three kilowatt-hours of fuel energy, plus the pollution that would have come with it.

Utilities also care about when you use energy. Demand peaks on hot summer afternoons, and extra, often older and dirtier, power plants are switched on just to cover those peaks. Programs that shift use to off-peak hours, smart thermostats and time-of-use prices cut how many of those plants are needed.

• Adjust the thermostat: a few degrees cooler in winter and warmer in summer saves a lot of heating and cooling energy.
• Insulate walls and attics, seal leaks around doors and windows, and use double-pane windows.
• Switch to LED lighting and choose ENERGY STAR (high-efficiency) appliances.
• Use passive solar design: south-facing windows (in the Northern Hemisphere), thermal mass and overhangs (topic 6.8).
• Green building features such as natural lighting, efficient heating and cooling systems, green roofs and smart thermostats.
• Save water, especially hot water: low-flow showerheads and full loads in the dishwasher and washer cut the energy used to heat and pump water.
• Landscape for energy savings: shade trees on the sunny side of a house cut summer cooling, and windbreaks of evergreens cut winter heating.
• Run appliances outside peak hours and unplug devices that draw power on standby.

• Corporate Average Fuel Economy (CAFE) standards are US rules that set the average fuel economy, in miles per gallon, that each automaker's fleet of new cars and light trucks must meet. Raising them pushes companies to build more efficient vehicles.
• Hybrid vehicles combine a gasoline engine with an electric motor and battery. The battery recaptures energy when braking (regenerative braking), so hybrids burn less fuel, especially in stop-and-go traffic.
• Battery electric vehicles have no tailpipe emissions; their total emissions depend on how the grid's electricity is made.
• Public transportation, such as buses, subways and light rail, moves many people using far less energy per person than individual cars. Carpooling, biking, walking and building denser, mixed-use neighborhoods do the same.