Lots of technology available to boost our 'negawatt' usage

Reducing energy use through energy efficiency is easier than ever. As we say in the energy efficiency business, a megawatt is the energy you use, but a “negawatt” is the energy you don’t need to use.

Efficiency, as I’ve mentioned before, doesn’t mean that you have to stop using energy-­consuming devices, or even that you have to use them less. It means that you choose systems and controls that enable you to use less energy to get the effect you want. Often, new, energy efficient technologies also offer other advantages over older, less efficient technologies.

Lighting is probably the field in which efficiency has had the fastest recent advances. Incandescent light bulbs became practical in 1878. The earlier commercial models, based on a carbon filament, lasted for about 1,200 hours of use. In the early 1900s, carbon was replaced with tungsten, and good quality bulb life increased to about 2,000 hours … and then technological development stalled for 100 years.

Today, though, lighting technology is advancing fast again. Compact fluorescents have come and gone. The current commercially available state of the art is an LED light bulb that uses less than a sixth of the energy of a similar incandescent bulb. Research is continuing, and it appears likely that today’s LEDs will be replaced in a few years by OLEDs, which are LEDs that are made from a different type of material, and will be even more energy efficient.

LEDs, in addition to using less energy, offer design options that weren’t practical with incandescent bulbs, such as: color-­changing lights, lights that can be tuned to specific frequencies to give warmer light, lights that can mimic natural light cycles and eliminate blue light in the evenings, and even lights that can conform to underlying shapes.

Control technologies are also better than ever. Room-scale and building-scale occupancy sensors and timers have become affordable and reliable. They can ensure that lights are off when they’re not needed. Some advanced commercial lighting systems can even send discount coupons to the phones of customers who have opted in.

Other major energy uses have also advanced very significantly over the last 50 years. Building codes require better insulation, which can be installed when structures are being built at very low additional cost. Building insulation technologies have also improved, with the addition of innovative materials like expandable foam insulation, which makes it easier to seal small gaps and holes, and radiant barriers, which are still underutilized. They’re very inexpensive reinforced aluminum foil sheets that hang under rafters and reflect heat back into a building during the winter, and out of it during the summer.

Windows have improved. Medieval castles had single-pane glass windows. It took centuries to realize how easy it is to add a second pane, which creates an insulating layer of still gas between the panes. Today, windows have insulated frames and transparent coatings designed to optimize heat gain or loss based on local climate. Some windows have three, or even four, panes, and some windows use gases other than air between the panes, to improve insulation even more.

A modern triple-pane, argon-filled, coated window in an insulated plastic frame also offers better transparency and better clarity than a castle window. People in even the worst modern housing have better windows than medieval royalty.