Energy efficiency

Energy efficiency is a key lever in the fight against climate change and in reducing the carbon footprint. It means using energy more intelligently, delivering the same service or output with less energy. The result is lower greenhouse gas (GHG) emissions and reduced environmental impact, which is why energy efficiency is often described as the cheapest and fastest 'first fuel' of the energy transition.

Why is energy efficiency important for the carbon footprint?

Energy generation is one of the largest sources of GHG emissions worldwide. By improving efficiency, we cut energy demand and the emissions linked to producing that energy, particularly for purchased electricity (Scope 2 emissions). Together with electrification and clean supply, it is a core part of decarbonization.

Energy efficiency measures

Measures can be applied across households, industry, transport and buildings.

At home

• Use energy-efficient appliances and check the EU Energy Label.
• Replace traditional bulbs with LED lighting.
• Improve insulation to reduce heating and cooling needs.
• Make the most of natural light and use efficient heating and cooling systems.

In industry

• Optimise production processes to reduce energy use.
• Implement an energy management system such as ISO 50001.
• Upgrade to more efficient machinery and equipment.
• Integrate renewable energy sources.

In transport

• Promote electric and hybrid vehicles.
• Encourage public transport, cycling and walking.
• Improve logistics and freight efficiency.

In buildings

• Design energy-efficient buildings with recognised certifications (such as LEED or BREEAM).
• Use sustainable construction materials.
• Install building energy management systems.

How is energy efficiency calculated?

Energy efficiency can be measured with different indicators depending on the context, but a common formula is:

Energy efficiency (%) = (useful output energy / input energy) × 100

For example, if a machine uses 100 units of energy to deliver 80 units of useful output, its efficiency is (80 / 100) × 100 = 80%. In carbon terms, improving efficiency means reducing emissions per unit of output, an essential step towards a low-carbon economy.

Benefits of energy efficiency

• Cost savings: lower energy use means lower energy bills.
• Competitiveness: efficient operations cut running costs.
• Job creation: drives employment in clean energy, green construction and energy consulting.
• Public health: less fossil fuel combustion means cleaner air.
• Energy security: lower reliance on imported fuels strengthens energy independence.

Legal and regulatory framework

Energy efficiency is a policy priority across the world. In the European Union, the recast Energy Efficiency Directive (Directive (EU) 2023/1791), in force since October 2023, replaced the earlier 2012 directive. It establishes the 'energy efficiency first' principle and sets a binding target to reduce final energy consumption by at least 11.7% by 2030 compared with 2020 projections, supported by rising annual energy-saving obligations on member states.

In Spain, this obligation is delivered partly through the National Energy Efficiency Obligations System and the Energy Saving Certificates (CAE) scheme created by Royal Decree 36/2023, alongside the National Energy Efficiency Fund. These measures sit within the broader National Energy and Climate Plan (PNIEC).

By implementing energy efficiency strategies, individuals, businesses and governments can cut emissions, save money and drive innovation. At Manglai we help companies measure and track the impact of their efficiency improvements as part of a broader carbon footprint strategy. Discover how Manglai can help you.