Energy efficiency

Energy efficiency is the coolest thing. Find out why.

What is energy efficiency?

Engineers define energy efficiency as the ratio between energy input to energy output. It is a rate that describes the ability of a technology to convert energy from one form (raw, primary) to another (refined, useful).

It is expressed as a percentage. For example, saying that the energy efficiency of a wood-powered stove is 40% (not so bad!) means that it can transform 100 calories worth of firewood in 40 calories worth of heat. 60 calories are dispersed with the combustion. Different technologies fare differently when it comes to transforming and utilising energy.

Doing more with less

Improving energy efficiency means achieving a greater final performance at the same energy intake. You are lowering the input-to-output ratio. To this extent, it is a synonym of productivity. The reverse is also true: you can obtain a desired level of useful final work at a lesser energy cost. This is called energy saving, which is an immediate consequence of energy efficiency.

You can then look at energy efficiency as a strategy to cut down waste and save watthours. Combine the effects of energy efficiency and energy saving, and you get the ultimate advantage: doing more with less.

As a rule of thumb, efficiency of solid fuels is lower then liquids or gases. Electricity – a secondary, pure energy carrier – is virtually 100% efficient.

The efficiency of renewable sources is theoretically infinite, as it is the resource. But solar panels, wind turbines, tidal energy machines, etc. have a finite, but ever improving, efficiency rate.

Why is energy efficiency considered a no-cost fuel?

ranking energy technologies by levelised costThis chart from the American Council for an Energy Efficient Economy shows that energy efficiency techniques exhibit the lowest cost per unit of energy delivered, when compared to different energy generation technologies.

Energy efficiency can be envisioned as a free and ubiquitous fuel. It is the most abundant and accessible in nature – virtually there’s always room to upgrade; the most “democratic” – everyone can tap into it, despite the endowment and know-how gaps; and it repays for its own investment.

Why is important to pursue energy efficiency?

Open boxes to see!

Energy is a basic need for humans

Humans need energy to stay warm, grow-process-cook food, sanitise water, lighten spaces, move around. This is true for tribes as well for complex societies.

There is no such a thing as free energy

Energy resources, regardless their origin, are scarce, scattered in nature and costly to produce, convert and distribute. Humans depend on complex technology to harness and make good use of energy, in form of heat, mechanical work or electricity. 

Saved energy is the cheapest of them all...

Energy technology and infrastructure are resource-intensive and take a lot of energy to be built and decommissioned. In general, modern economies are energy-intensive and losses are everywhere as energy flows through them.

Imagine how much heat plants and furnaces – and virtually every small and big combustion reaction – dissipate daily. That energy can be saved and reused in industrial processes and buildings.

A watt saved cost less than a watt produced.

...and the greenest of them all!

Most of Ireland’s energy comes from imported fossil fuels like natural gas (52% of the electricity mix!), followed by coal, peat and oil.

Fossil fuels are responsible for the global humanitarian emergency that climate breakdown is, and their extraction and use is linked with local health and pollution issues.

By reducing the demand of primary energy, energy efficiency can effectively offset these downsides.

Want to know more about energy efficiency?

Keep reading!

The most sustainable of all energy sources is the one that is not produced at all – The cleanest and cheapest watt is the one that is conserved.

Reducing the total (primary) energy requirement of human systems is  critical in a world with finite resources.

But it’s not a matter of restrictions: energy efficiency policies unlock a wide range of monetary and non-monetary benefits at household, firms, State and environmental level.

Benefits of energy efficiency

Besides the immediate financial gains, there has been a lot of emphasis recently on the centrality of energy efficiency interventions in abating heat-trapping emissions, cutting down atmospheric and indoor pollutants (leading causes of respiratory diseases and premature deaths in the world), and stopping energy poverty and energy vulnerability.


To cut it short, energy efficiency acts as a triple-dividend: lightens the utility bill, mitigates health and ecosystem damages and strengthen energy system stability and reliability. Utility-level efficient energy policies displace the need for fossil fuel-generated electricity, particularly coal-fired plants that are usually brought online to meet peak demand. To this extent, energy efficiency is a panacea for the energy trilemma: security of supply, sustainability and equity. And for households in the “eat or heat” impasse, energy efficiency is a life-saver.

Pyramid of future energy system

The energy system of the near future can be represented as a pyramid. The size of each step represents its importance. At the top you have renewables. Post-carbon humanity still has to satisfy its energy needs, and those Terawatthours have to be generated somehow. This is where you deploy a mix of distributed renewables and clean energy assets along with batteries and intelligent grid controls – imagine this flexible and responsive zero-carbon network of peer prosumers operated via blockchain.

But that’s only the small tip of our pyramid. To be at the same time fossil-free and guarantee fair and universal access to the remotest corner of the world, the foundation of our future energy systems must lay on sound efficiency and conservation techniques. No Watt shall be wasted. No calorie dispersed.

How do we conserve energy?

Nothing is lost, nothing is created, everything is transformed

Antoine-Laurent de Lavoisier

XXVIII century French chemist