6.13 - Energy Conservation

Learning Objectives

I. Small Scale Energy Conservation Methods

• Adjusting thermostats: Turning down the heat. A programmable thermostat can be used to set predetermined temperatures, which allows for less overall energy use.
• Real numbers: The U.S. Department of Energy says turning your thermostat back 7 to 10°F for 8 hours a day (while you sleep or are away) can save as much as 10% a year on heating and cooling.

• Improving home insulation and efficiency:
• Better insulation: Insulating homes better means heat generated by the furnace stays inside, so less overall energy is needed for heating or cooling. Insulation traps heat or air conditioned air and minimizes loss to the environment.
• Efficient appliances: Using appliances that perform the same task but consume less total electricity.
• Look for the ENERGY STAR label. LED bulbs use at least 75% less energy than old incandescent bulbs and last up to 25 times longer (DOE).

• Sustainable home design (passive solar and deciduous trees):
• Deciduous shade trees: These trees provide shade in the summer months, which decreases the need for electricity to cool the home. In winter they lose their leaves, letting sunlight through for natural warming.
• Passive solar design: Includes using materials like brickwork or dark colored flooring to absorb the sun’s natural heat. Double or triple paned windows help trap that heat, using a “greenhouse effect” to warm the home in cooler months.

• Water conservation: Conserving water is a way to conserve energy, because electricity is often required to purify and pump water to homes.
• Native vegetation: Replacing turf or grass with native plants. Native plants are adapted to the surrounding climate and require significantly less water.
• Low flow devices: Using low flow shower heads, low flow toilets, or low water appliances like dishwashers.
• Rain barrel use: Capturing rainwater in a rain barrel and using it to water gardens, wash sidewalks, or wash cars. This avoids using water that had to be treated and pumped by a municipal plant.
• Conservation landscaping: The CED's term for planning a yard to save water and energy: native or drought-tolerant plants (called xeriscaping in dry places), mulch to hold moisture in the soil, and trees placed to shade the house in summer or block cold winter winds.

II. Large Scale Conservation Methods (Transportation and Building)

A. Transportation (State or National Level)

• Transportation accounted for 28% of total U.S. energy use in 2019.

• CAFE standards: The Corporate Average Fuel Economy (CAFE) standards measure the average miles per gallon that vehicles sold in America must achieve. Raising these standards over time forces automakers to produce more fuel efficient vehicles, which lets people travel the same distance using less gasoline.
• Status as of 2026: In July 2025, Congress set the penalty for missing CAFE standards to $0, and in September 2026 NHTSA finalized lower standards (about 34.9 mpg fleetwide by model year 2031, down from about 50 mpg projected under the 2024 rule). In October 2026, California led a group of states, cities, and counties in a lawsuit challenging the new rule (pending as of late October 2026).

• Hybrid and electric vehicles (EVs):
• Hybrid vehicles like the Prius use both a gasoline engine and an electric motor. The electric motor assists the gasoline engine, which lets the car travel further on less gasoline. Many hybrids charge their battery through the braking system rather than requiring a plug-in electrical source.
• Battery electric vehicles (BEVs) run only on a battery charged from the grid, with no gasoline engine and no tailpipe emissions. Electric cars turn over 77% of the electricity from the grid into motion at the wheels, while gasoline cars turn only about 12% to 30% of their fuel's energy into motion (fueleconomy.gov). Plug-in hybrids (PHEVs) have a battery you can charge plus a gas engine for longer trips.
• Incentivizing EVs: Governments can subsidize or offer rebates to companies that build electric vehicles and charging stations, which makes them cheaper and incentivizes consumers to buy them. That decreases gasoline consumption. Note that EVs are only as sustainable as the electricity used to fuel them.

• Public transit and carpooling: Investing in public transportation (buses, light rails) or encouraging carpooling drastically decreases the amount of energy spent on transportation, because it moves a mass amount of people in one vehicle.

B. Sustainable Large Scale Building Design

• Green roofs and walls: Adding plants to the roof or side of a building.
• The plants absorb sunlight, which helps keep the building cool and reduces the electricity needed for air conditioning.
• This also helps decrease the urban heat island effect, which occurs when dark surfaces like asphalt and concrete absorb the sun’s heat.

• Natural lighting: Using skylights or floor to ceiling windows to bring in more natural light, which reduces the electricity needed to light the building.

• Recycled materials: Using recycled materials during construction, such as glass, wood, or fly ash, a powdery byproduct of coal-fired power plants that can replace some of the cement in concrete. (Much of the gypsum in drywall also comes from coal plants: it is made in the scrubbers that remove sulfur dioxide from their exhaust.)

• Green building certification: Programs like LEED (Leadership in Energy and Environmental Design) rate buildings on energy and water use, materials, and indoor air quality. Common green design features include thick insulation, efficient windows, heat pumps, rooftop solar, and the features above.

III. Managing Peak Demand and Smart Grid Technology

• Peak electricity demand: This occurs when demand for electricity is highest, typically when people arrive home at night, turn on devices, and solar electricity goes offline. Peak demand can also happen during hot weather when air conditioning use is maxed out.
• If demand exceeds supply, it can cause rolling blackouts.

• Variable price systems (tiered rates): A system designed to manage peak demand by discouraging high energy use.
• Users pay a different, higher rate per kilowatt-hour if their monthly usage exceeds a certain threshold.
• This incentivizes users to conserve energy, buy more efficient appliances, or use smart thermostats.
• Time-of-use rates: A system aimed right at peak demand. Electricity costs more per kWh during peak hours (often about 4 to 9 p.m.) and less late at night, so people shift things like running the dishwasher or charging an EV to off-peak hours.

• Smart grid concept: An integrated system that uses computers, smart thermostats, and smart meters to improve the electricity system.
• Decentralized production: Unlike old grids that relied on a few large power plants, a smart grid uses many decentralized producers, like community owned solar or wind farms.
• Integration and two way flow: It includes integration tools like batteries to store electricity, and it allows for two way direction of electricity. For example, extra electricity generated by rooftop solar can be sent back to the grid for other consumers to use.

IV. Practice Calculations

Big picture: Energy conservation happens through individual actions like setting programmable thermostats and using low flow fixtures (which matters because of the energy needed to treat and pump water), and through passive sustainable home design using features like deciduous shade trees and proper insulation. Large scale efforts focus on reducing transportation energy by promoting public transit and raising CAFE standards for vehicle efficiency. Finally, smart grids are critical for managing electrical supply by integrating decentralized renewable energy production and using variable price systems to discourage peak time consumption, which keeps supply stable and efficient.