Energy efficiency is the right thing to do. But it is not often thought of as "sexy" in the same way as its cutting-edge clean energy cousins like wind or solar. Yet investments in energy efficiency can offer astounding returns, and efficiency-focused innovations have already avoided huge amounts of fossil fuels from being burned. So much so that is is sometimes referred to as "the fifth fuel."

In an article called The Invisible Fuel, The Economist sets out just how significant these savings are: 

The cheapest and cleanest energy choice of all is not to waste it. Progress on this has been striking yet the potential is still vast. Improvements in energy efficiency since the 1970s in 11 IEA member countries that keep the right kind of statistics (America, Australia, Britain, Denmark, Finland, France, Germany, Italy, Japan, the Netherlands and Sweden) saved the equivalent of 1.4 billion tonnes of oil in 2011, worth $743 billion. This saving amounted to more than their total final consumption in that year from gas, coal or any other single fuel. 
Indeed in the UK alone, energy efficiency savings since 1980 amount to 28G, the equivalent to the output of 14 power stations according to a report from the Association for Decentralized Energy

Yet these savings may be just the tip of a very big, very cool iceberg. And this metaphorical iceberg may just help us save the real ones from melting. 

Even though the savings achieved so far are huge, they've also been held back by a number of factors. Skills, for one, have sometimes been in short supply. Technology, from light bulbs to cars, has often focused on performance, convenience and/or initial sticker price over efficiency and conservation. And from draft proofing to insulation to switching out light bulbs, homeowners and businesses have often lacked the motivation to pursue the myriad of potential efficiency savings because, while collectively they may add up to significant savings, each individual action was not seen as worth the effort.

This situation is beginning to change, however. We may be entering a time when energy efficiency becomes truly mainstream. Here are some of the factors that are driving that change.

Maturing technologies 
While older compact fluorescent light bulbs saved money compared to their incandescent counterparts, they were never drop-in replacements for old-fashioned bulbs and often faced complaints about light quality, delays in turning on and/or reliability issues. LED lighting, however, offers none of these compromises. And as LED pricing continues to drop and performance and the range of products continues to improve, they are becoming the light bulb of choice, not just for treehuggers but mainstream consumers too. From more fuel efficient cars to consumer electronics, these innovations are happening across the board and show few signs of slowing down. 

In fact, a whole new set of radically disruptive technologies may be just around the corner as designers abandon incremental improvements in favor of rethinking the basic parameters of a particular design. The Xeros washing machine, for example, utilizes reusable plastic beads and just one cup of water to clean a load of clothes, meaning less energy is used to heat water or to dry the clothes afterwards. Similarly, British insulation manufacturer Kingspan is promoting its Zer0 Energy Lighting System, which combines high efficiency LEDs with daylighting, motion and light sensors and solar panels to use artificial light only when needed. The return on investment is said to be a matter of three years for your average commercial installation.

Better, more accessible data
I recently wrote about my experiences with the Nest Learning Thermostat. And while this beautiful (and expensive!) gadget includes some clever efficiency features like "early on" programming and "auto away," I suggested that one of its most powerful features may be simply that it provides a more accessible, intuitive and on-going feedback loop telling you what your heating and cooling systems are doing. While I used to set the thermostat to X degrees and forget about it, for example, I can now look at my energy history (available online, through a mobile app and in emailed reports) and see how different settings impact how often the system runs. Nest's acquisition of, a site that allows users to track their overall utilities spending (natural gas, electric and water) in one place, suggests the company takes this portion of its offering seriously. 

Similarly, there is a growing industry of energy efficiency professionals who can help provide detailed, data-driven recommendations about how to improve your building performance. Lloyd Alter at TreeHugger has already written about why the caulking gun and thermal imaging camera are the best weapons in energy waste, showing how even a green-minded architect like himself was surprised at where some of the biggest air leaks in his home were occurring. Some start-ups are even taking the Google Street View approach to energy audits, taking thermal imaging shots of buildings from the outside, across entire neighborhoods, and then using them to identify where savings could be made.

A favorable legislative environment
The improvements in LED lighting and car fuel efficiency didn't happen by magic. While derided by some as "a war on the light bulb," tightening government standards on lighting efficiency have driven innovation and provided manufacturers and retailers alike to collectively up their game. Similarly, President Obama's efforts to tighten fuel economy standards are playing a significant role in changing the MPG ratings of the cars and trucks we now see on the road, and may even help to keep gas prices low as demand flattens out. 

What's particularly interesting about legislating for efficiency is the fact that tighter rules on one jurisdiction can mean improvements elsewhere. When California bans inefficient TVs or takes a lead on electric cars, they spur innovation — and that innovation will have benefits even in states and countries less willing to intervene in the markets, albeit at a slower pace.

New financing models
Money has always been a factor too. Efficiency may indeed save people money, but are they willing to shell out now for savings that will accumulate only gradually? That's particularly true for low income households, despite the fact they spend a larger share of their income on energy and often live in relatively inefficient homes. Similarly, it's true of businesses where day-to-day decisions that impact efficiency may be taken by managers who are not held accountable for a company's spending on energy. That's where new financing models come in, offering money upfront to improve building performance or install new technologies, and that money is then recouped as the saving come in. The aforementioned Kingspan Zer0 Energy Lighting, for example, can be financed using Power Purchase and/or Shared Savings agreements. Many governments are also offering subsidized loan programs to promote energy efficiency, and then innovative platforms like WEfficiency are helping individuals to finance efficiency improvements as a way to support their chosen nonprofit.  

The growing cost of fossil fuels
This last factor may seem like an odd one, at a time when oil prices have been plunging unexpectedly, but most analysts expect the cost of most conventional fossil fuels to keep rising — especially if legislators begin to factor in the true cost of climate change and put a realistic price on carbon. Even if that doesn't happen, there's a simple dynamic at play: Efficiency and renewables are (mostly) an emerging suite of technologies, and the cost of technologies tends to fall as they mature. Coal, oil and gas, on the other hand, are resources and the cost of resources tends to go up as they are consumed.

There are, of course, exceptions to that rule. As the recent oil "boom" in America has shown, advancements in extraction technologies can bring down costs and make previously uneconomic reserves commercially viable — at least temporarily. But then the advancements bring falling prices, and the falling prices bring decreased profits until — guess what? — you've got a boom-and-bust cycle that hurts communities, turns off investors and provides even more room for your competition. 

It seems fair to say that energy efficiency will play an increasingly important role in cutting carbon emissions, reducing energy costs and balancing the demands of an ever more diverse energy grid. Now excuse me, I have to turn this computer off and go caulk some baseboards. 

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