To focus on energy efficiency is to make present ways of life non-negotiable. However, transforming present ways of life is key to mitigating climate change and decreasing our dependence on fossil fuels.
Energy efficiency policy
Energy efficiency is a cornerstone of policies to reduce carbon emissions and fossil fuel dependence in the industrialised world. For example, the European Union (EU) has set a target of achieving 20% energy savings through improvements in energy efficiency by 2020, and 30% by 2030. Measures to achieve these EU goals include mandatory energy efficiency certificates for buildings, minimum efficiency standards and labelling for a variety of products such as boilers, household appliances, lighting and televisions, and emissions performance standards for cars. 
The EU has the world’s most progressive energy efficiency policy, but similar measures are now applied in many other industrialised countries, including China. On a global scale, the International Energy Agency (IEA) asserts that “energy efficiency is the key to ensuring a safe, reliable, affordable and sustainable energy system for the future”.  In 2011, the organisation launched its 450 scenario, which aims to limit the concentration of CO2 in the atmosphere to 450 parts per million. Improved energy efficiency accounts for 71% of projected carbon reductions in the period to 2020, and 48% in the period to 2035.  
What are the results?
Do improvements in energy efficiency actually lead to energy savings? At first sight, the advantages of efficiency seem to be impressive. For example, the energy efficiency of a range of domestic appliances covered by the EU directives has improved significantly over the last 15 years. Between 1998 and 2012, fridges and freezers became 75% more energy efficient, washing machines 63%, laundry dryers 72%, and dishwashers 50%. 
However, energy use in the EU-28 in 2015 was only slightly below the energy use in 2000 (1,627 Mtoe compared to 1.730 Mtoe, or million tonnes of oil equivalents). Furthermore, there are several other factors that may explain the (limited) decrease in energy use, like the 2007 economic crisis. Indeed, after decades of continuous growth, energy use in the EU decreased slightly between 2007 and 2014, only to go up again in 2015 and 2016 when economic growth returned. 
On a global level, energy use keeps rising at an average rate of 2.4% per year.  This is double the rate of population growth, while close to half of the global population has limited or no access to modern energy sources.  In industrialised (OECD) countries, energy use per head of the population doubled between 1960 and 2007. 
Why is it that advances in energy efficiency do not result in a reduction of energy demand? Most critics focus on so-called “rebound effects”, which have been described since the nineteenth century.  According to the rebound argument, improvements in energy efficiency often encourage greater use of the services which energy helps to provide.  For example, the advance of solid state lighting (LED), which is six times more energy efficient than old-fashioned incandescent lighting, has not led to a decrease in energy demand for lighting. Instead, it resulted in six times more light. 
In some cases, rebound effects may be sufficiently large to lead to an overall increase in energy use.  For example, the improved efficiency of microchips has accelerated the use of computers, whose total energy use now exceeds the total energy use of earlier generations of computers which had less energy efficient microchips. Energy efficiency advances in one product category can also lead to increased energy use in other product categories, or lead to the creation of an entirely new product category.
For example, LED-screens are more energy efficient than LCD-screens, and could therefore reduce the energy use of televisions. However, they also led to the arrival of digital billboards, which are enormous power hogs in spite of their energy efficient components.  Finally, money saved through improvements in energy efficiency can also be spent on other energy-intensive goods and services, which is a possibility usually referred to as an indirect rebound effect.
Beyond the rebound argument
Rebound effects are ignored by the EU and the IEA, and this might partly explain why the results fall short of the projections. Among academics, the magnitude of the rebound effect is hotly debated. While some argue that “rebound effects frequently offset or even eliminate the energy savings from improved efficiency” , others maintain that rebound effects “have become a distraction” because they are relatively small: “behavioural responses shave 5-30% of intended energy savings, reaching no more than 60% when combined with macro-economic effects – energy efficiency does save energy”. 
Those who downplay rebound effects attribute the lack of results to the fact that we don’t try hard enough: “many opportunities for improving energy efficiency still go wasted”.  Others are driven by the goal of improving energy efficiency policy. One response is to suggest that the frame of reference be expanded and that analysts should consider the efficiency not of individual products but of entire systems or societies. In this view, energy efficiency is not framed holistically enough, nor given sufficient context.  
However, a few critics go one step further. In their view, energy efficiency policy cannot be fixed. The problem with energy efficiency, they argue, is that it establishes and reproduces ways of life that are not sustainable in the long run. 
A parellel universe
Rebound effects are often presented as “unintended” consequences, but they are the logical outcome of the abstraction that is required to define and measure energy efficiency. According to Loren Lutzenhiser, a researcher at Portland State University in the US, energy efficiency policy is so abstracted from the everyday dynamics of energy use that it operates in a “parallel universe”.  In a more recent paper, What is wrong with energy efficiency?, UK researcher Elizabeth Shove unravels this “parallel universe”, concluding that efficiency policies are “counter-productive” and “part of the problem”. 
According to some critics, efficiency policies are "counter-productive" and "part of the problem".
To start with, the parallel universe of energy efficiency interprets “energy savings” in a peculiar way. When the EU states that it will achieve 20% “energy savings” by 2020, “energy savings” are not defined as a reduction in actual energy consumption compared to present or historical figures. Indeed, such a definition would show that energy efficiency doesn’t reduce energy use at all. Instead, the “energy savings” are defined as reductions compared to the projected energy use in 2020. These reductions are measured by quantifying “avoided energy” – the energy resources not used because of advances in energy efficiency.
Even if the projected “energy savings” were to be fully realised, they would not result in an absolute reduction in energy demand. The EU argues that advances in energy efficiency will be “roughly equivalent to turning off 400 power stations”, but in reality no single power station will be turned off in 2020 because of advances in energy efficiency. Instead, the reasoning is that Europe would have needed to build an extra 400 power stations by 2020, were it not for the increases in energy efficiency.
In taking this approach, the EU treats energy efficiency as a fuel, “a source of energy in its own right”.  The IEA goes even further when it claims that “energy avoided by IEA member countries in 2010 (generated from investments over the preceding 1974 to 2010 period), was larger than actual demand met by any other supply side resource, including oil, gas, coal and electricity”, thus making energy efficiency “the largest or first fuel”.  
Measuring something that doesn’t exist
Treating energy efficiency as a fuel and measuring its success in terms of “avoided energy” is pretty weird. For one thing, it is about not using a fuel that does not exist.  Furthermore, the higher the projected energy use in 2030, the larger the “avoided energy” would be. On the other hand, if the projected energy use in 2030 were to be lower than present-day energy use (we reduce energy demand), the “avoided energy” becomes negative.
An energy policy that seeks to reduce greenhouse gas emissions and fossil fuel dependency must measure its success in terms of lower fossil fuel consumption.  However, by measuring “avoided energy”, energy efficiency policy does exactly the opposite. Because projected energy use is higher than present energy use, energy efficiency policy takes for granted that total energy consumption will keep rising.
That other pillar of climate change policy – the decarbonisation of the energy supply by encouraging the use of renewable energy power plants – suffers from similar defects. Because the increase in total energy demand outpaces the growth in renewable energy, solar and wind power plants are in fact not decarbonising the energy supply. They are not replacing fossil fuel power plants, but are helping to accommodate the ever growing demand for energy. Only by introducing the concept of “avoided emissions” can renewables be presented as having something of the desired effect. 
What is it that is efficient?
In What is wrong with energy efficiency?, Elizabeth Shove demonstrates that the concept of energy efficiency is just as abstract as the concept of “avoided energy”. Efficiency is about delivering more services (heat, light, transportation,…) for the same energy input, or the same services for less energy input. Consequently, a first step in identifying improvements depends on specifying “service” (what is it that is efficient?) and on quantifying the amount of energy involved (how is “less energy” known?). Setting a reference against which “energy savings” are measured also involves specifying temporal boundaries (where does efficiency start and end?). 
Shove’s main argument is that setting temporal boundaries (where does efficiency start and end?) automatically specifies the “service” (what is it that is efficient?), and the other way around. That’s because energy efficiency can only be defined and measured if it is based on equivalence of service. Shove focuses on home heating, but her point is valid for all other technology. For example, in 1985, the average passenger plane used 8 litres of fuel to transport one passenger over a distance of 100 km, a figure that came down to 3.7 litres today.
Consequently, we are told that airplanes have become twice as efficient. However, if we make a comparison in fuel use between today and 1950, instead of 1985, airplanes do not use less energy at all. In the 1960s, propeller aircraft were replaced by jet aircraft, which are twice as fast but initially consumed twice as much fuel. Only fifty years later, the jet airplane became as “energy efficient” as the last propeller planes from the 1950s. 
If viewed in a larger historical context, the concept of energy efficiency completely disintegrates.
What then is a meaningful timespan over which to compare efficiencies? Should propeller planes be taken into account, or should they be ignored? The answer depends on the definition of equivalent service. If the service is defined as “flying”, then propeller planes should be included. But, if the energy service is defined as “flying at a speed of roughly 1,000 km/h”, we can discard propellers and focus on jet engines. However, the latter definition assumes a more energy-intensive service.
If we go back even further in time, for example to the early twentieth century, people didn’t fly at all and there’s no sense in comparing fuel use per passenger per kilometre. Similar observations can be made for many other technologies or services that have become “more energy efficient”. If they are viewed in a larger historical context, the concept of energy efficiency completely disintegrates because the services are not at all equivalent.
Often, it’s not necessary to go back very far to prove this. For example, when the energy efficiency of smartphones is calculated, the earlier generation of much less energy demanding “dumbphones” is not taken into account, although they were common less than a decade ago.
How efficient is a clothesline?
Because of the need to compare 'like with like' and establish equivalent of service, energy efficiency policy ignores many low energy alternatives that often have a long history but are still relevant in the context of climate change.
For example, the EU has calculated that energy labels for tumble driers will be able to “save up to 3.3 Twh of electricity by 2020, equivalent to the annual energy consumption of Malta”. . But how much energy use would be avoided if by 2020 every European would use a clothesline instead of a tumble drier? Don’t ask the EU, because it has not calculated the avoided energy use of clotheslines.
Neither do the EU or the IEA measure the energy efficiency and avoided energy of bicycles, hand powered drills, or thermal underwear. Nevertheless, if clotheslines would be taken seriously as an alternative, then the projected 3.3 TWh of energy “saved” by more energy efficient tumble driers can no longer be considered “avoided energy”, let alone a fuel. In a similar way, bicycles and clothing undermine the very idea of calculating the “avoided energy” of more energy efficient cars and central heating boilers.
Unsustainable concepts of service
The problem with energy efficiency policies, then, is that they are very effective in reproducing and stabilising essentially unsustainable concepts of service.  Measuring the energy efficiency of cars and tumble driers, but not of bicycles and clotheslines, makes fast but energy-intensive ways of travel or clothes drying non-negotiable, and marginalises much more sustainable alternatives. According to Shove:
“Programmes of energy efficiency are politically uncontroversial precisely because they take current interpretations of ‘service’ for granted… The unreflexive pursuit of efficiency is problematic not because it doesn’t work or because the benefits are absorbed elsewhere, as the rebound effect suggests, but because it does work – via the necessary concept of equivalence of services – to sustain, perhaps escalate, but never undermine… increasingly energy intensive ways of life.” 
Indeed, the concept of energy efficiency easily accommodates further growth of energy services. All future novelties can be subjected to an efficiency approach. For example, if patio heaters and monsoon showers become “normal”, they could be incorporated in existing energy efficiency policy – and when that happens, the problem of their energy use is considered to be under control. At the same time, defining, measuring and comparing the efficiency of patio heaters and monsoon showers helps make them more “normal”. As a bonus, adding new products to the mix will only increase the energy use that is “avoided” through energy efficiency.
In short, neither the EU nor the IEA capture the “avoided energy” generated by doing things differently, or by not doing them at all – while these arguably have the largest potential to reduce energy demand.  Since the start of the Industrial Revolution, there has been a massive expansion in the uses of energy and in the delegation of human to mechanical forms of power. But although these trends are driving the continuing increase in energy demand, they cannot be measured through the concept of energy efficiency.
As Shove demonstrates, this problem cannot be solved, because energy efficiency can only be measured on the basis of equivalent service. Instead, she argues that the challenge is “to debate and extend meanings of service and explicitly engage with the ways in which these evolve”. 
Towards an energy inefficiency policy?
There are several ways to escape from the parallel universe of energy efficiency. First, while energy efficiency hinders significant long term reduction in energy demand through the need for equivalence of service, the opposite also holds true – making everything less energy efficient would reverse the growth in energy services and reduce energy demand.
For example, if we were to install 1960s internal combustion engines into modern SUVs, fuel use per kilometre driven would be much higher than it is today. Few people would be able or willing to afford to drive such cars, and they would have no other choice but to switch to a much lighter, smaller and less powerful vehicle, or to drive less.
Making everything less energy efficient would reverse the growth in energy services and reduce energy demand.
Likewise, if an “energy inefficiency policy” were to mandate the use of inefficient central heating boilers, heating large homes to present-day comfort standards would be unaffordable for most people. They would be forced to find alternative solutions to achieve thermal comfort, for instance heating only one room, dressing more warmly, using personal heating devices, or moving to a smaller home.
Recent research into the heating of buildings confirms that inefficiency can save energy. A German study examined the calculated energy performance ratings of 3,400 homes and compared these with the actual measured consumption.  In line with the rebound argument, the researchers found that residents of the most energy efficient homes (75 kWh/m2/yr) use on average 30% more energy than the calculated rating. However, for less energy efficient homes, the opposite – “pre-bound” – effect was observed: people use less energy than the models had calculated, and the more inefficient the dwelling is, the larger this gap becomes. In the most energy inefficient dwellings (500 kWh/m2/yr), energy use was 60% below the predicted level.
From efficiency to sufficiency?
However, while abandoning – or reversing – energy efficiency policy would arguably bring more energy savings than continuing it, there is another option that’s more attractive and could bring even larger energy savings. For an effective policy approach, efficiency can be complemented by or perhaps woven into a “sufficiency” strategy. Energy efficiency aims to increase the ratio of service output to energy input while holding the output at least constant. Energy sufficiency, by contrast, is a strategy that aims to reduce the growth in energy services.  In essence, this is a return to the “conservation” policies of the 1970s. 
Sufficiency can involve a reduction of services (less light, less travelling, less speed, lower indoor temperatures, smaller houses), or a substitution of services (a bicycle instead of a car, a clothesline instead of a tumble drier, thermal underclothing instead of central heating). Unlike energy efficiency, the policy objectives of sufficiency cannot be expressed in relative variables (like kWh/m2/year). Instead, the focus is on absolute variables, such as reductions in carbon emissions, fossil fuel use, or oil imports.  Unlike energy efficiency, sufficiency cannot be defined and measured by examining a single product type, because sufficiency can involve various forms of substitution.  Instead, a sufficiency policy is defined and measured by looking at what people actually do.
A sufficiency policy could be developed without a parallel efficiency policy, but combining them could bring larger energy savings. The key step here is to think of energy efficiency as a means rather than an end in itself, argues Shove.  For example, imagine how much energy could be saved if we would use an energy efficient boiler to heat just one room to 16 degrees, if we install an energy efficient engine in a much lighter vehicle, or if we combine an energy saving shower design with fewer and shorter showers. Nevertheless, while energy efficiency is considered to be a win-win strategy, to develop the concept of sufficiency as a significant force in policy is to make normative judgments: so much consumption is enough, so much is too much.  This is sure to be controversial, and it risks being authoritarian, at least as long as there is a cheap supply of fossil fuels.
Kris De Decker
Illustrations by Diego Marmolejo.