18.7: Energy Conservation

Energy conservation refers to reducing energy waste and increasing efficiency. Energy conservation can involve behavior changes as well as technologies. Some examples of energy conservation have no financial impact. These include turn off and unplugging electronics when not in use, turning down the water heater, and driving efficiently (figure \(\PageIndex{a}\)). Additionally, opening blinds on south-facing windows in the morning during the winter takes advantage of a passive solar technology. Relying on the sun for heating and lighting reduces the use of electricity. 

Figure \(\PageIndex{a}\): A plant on the dashboard of this Ford Fusion (right) indicates if the driver's behavior promotes fuel efficiency. In this picture, there is only one leaf on the plant, indicating low efficiency. Some ways to drive efficiently include following the speed limit and adjusting your speed gradually. Image by ogilvyprworldwide (CC-BY).

Other examples of energy conservation require some financial investment, but they quickly pay for themselves with savings on an energy bill. An energy audit is a first step to investigate inefficiencies in one's home. This helps homeowners identify where their home is losing energy, and which problem areas and fixes they should prioritize to save energy and money. For example, an energy audit may reveal places in the home where hot escaping in the winter or entering in the summer. An energy auditor might recommend installing insulation to better seal the home as well as to insulate the hot water heater and pipes. Investing in most high-efficiency appliances also pays for itself relatively quickly (figure \(\PageIndex{b}\)). 

Figure \(\PageIndex{b}\): Energy Star appliances use energy efficiently. Image by MoneyBlogNewz (CC-BY)

This video provides a walkthrough of an energy audit.

Finally, some strategies for energy conservation require sizeable financial investment. They can eventually pay for themselves over extended periods of time. Once example are double-paned, low emissivity (low e) windows (figure \(\PageIndex{c}\)). The two layers of glass trap air between them, which serves as insulation. Additionally, the glass is coated with very small metal dots that allow light to pass through, but infrared (heat) energy is reflected back. If it is hotter outside, heat is emitted back outside; if warmer inside, heat will be emitted back inside. Energy-efficient air conditioners, geothermal heat pumps, and on-demand (tankless) water heaters (figure \(\PageIndex{d}\)) are also examples of energy-conserving technologies that require sizeable investment.

Figure \(\PageIndex{c}\): Anatomy of an efficient window. A double-paned, low emissivity window allows light from the sun to pass through, but tiny metal dots (not visible) reflect heat (labeled "Low-E and/or solar control coating"). The double panes trap air between them, an insulator (labeled "gas fill"). Spacers are between the glass and the sash, which surrounds the glass. The sash can move out of the frame when the window is open, and weatherstipping prevents air from leaking between the sash and the frame. The stop on the outside prevents the sash swinging outward, and the stool extends perpendicular to the wall outside of the stop. Under it is a backer rod, filling the space between the stool and the wall beneath it. The frame consists of the horizontal sill and vertical jamb. The apron/flange is the trim just below the frame. Image modified from U.S. Department of Energy (public domain).

Figure \(\PageIndex{d}\): An tankless water heater (electric demand water heater). Because hot water is not stored, there is no opportunity for it to cool and need to be reheated. This conserves energy. The heating unit is installed in close proximity to hot water use. It is suppled by a power source (110 or 220 volts). Hot and cold water lines run from the heating unit (which contains heating elements) to the sink. Image by U.S. Department of Energy (public domain).

Attribution

Melissa Ha (CC-BY-NC) and Home Energy Audits. U.S. Department of Energy. Accessed 01-18-2021. (public domain)