Lighting accounts for almost 8% of the world’s energy usage. It makes up around 10-20% of domestic energy bills, with an even higher proportion in commercial premises like offices.
But it still has huge potential for improvement. Technological changes and management of consumer behaviour can greatly reduce energy consumption without sacrificing comfort – and even improve health and wellbeing along the way.
LED lightbulbs marked a huge leap forward in energy efficiency. They can reduce energy consumption by 50-80% in comparison with older technology, but their impact goes beyond energy savings, as by emitting less heat than older bulbs, they also reduce the need to cool interiors.
Type of light also plays a role in our bodies, affecting sleep, attention and metabolism. But its impact mainly depends on intensity. Bluer light – typically emitted by screens and “cold” LED bulbs – can alter the brains’ production of melatonin, which impacts sleep and circadian rhythms. Warmer and properly adjusted LEDs, on the other hand, can minimise this effect. They are also more energy efficient than other systems.
Better lighting doesn’t mean more light
A typical mistake in interiors is total, uniform lighting. We flip the switch and illuminate an entire space without considering how each each area of it will actually be used. But lighting needs are far from uniform. For instance, European regulations state that a hallway needs around 100-200 lux, while a workstation needs around 500.
Dividing up spaces can reduce lighting energy consumption by anywhere from 20% to 40% without affecting visual comfort. And further savings – as much as 20-60% – can be achieved through smart lighting systems that use sensors to automatically adjust lighting depending on where people are within a space.
Excessive lighting is another common problem. Many lighting systems exceed recommended levels without producing noticeable benefits, causing unnecessary energy use.
In short, what we need is to use less energy, and adapt spaces to how people actually use them.
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Benefits of natural light
A building’s most efficient lighting resource is natural light. Outside it can exceed 10,000 lux, while inside it is rarely more than 500 lux. Even so, it is common to leave artificial lights switched on all day, which both increases energy costs and reduces our exposure to natural light.
But an office or residential building design that makes the most of natural light can reduce lighting energy use by 40-70%. It also improves productivity and mood, reduces visual fatigue, and helps to regulate our biological clocks.
At night, artificial light can affect sleep by reducing levels of melatonin, the hormone that helps us to fall asleep. Exposure to natural light during the day helps to improve night time rest and balance our circadian rhythms. Since each person responds differently, it is important to adapt lighting to individual needs.
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Colour temperature also affects the way we feel. Cold light makes us more alert, while warm light is better for rest and relaxation. Dynamic lighting systems allow us to adapt lighting over the course of the day, improving comfort and only using as much energy as necessary.
Sustainability and health certifications
In recent years, energy-efficient lighting has ceased to be an isolated objective, and now forms part of global certification systems that analyse buildings as a whole. The two most important certifications are LEED and WELL.
LEED: energy efficiency and sustainable design
LEED (Leadership in Energy and Environmental Design) has become one of the world’s most widely used standards for evaluating building sustainability.
In lighting, LEED does not just look at energy consumption. It also considers use of natural light, ways of reducing power consumption from lighting, automatic controls and sensors, and the quality of lighting in interior spaces.
Studies show that LEED-certified buildings can significantly reduce global energy consumption, with lighting and heating making a direct impact.
In practice, LEED pushes us towards more energy-efficient buildings, where lighting systems are an integral part of the design as opposed to an isolated, separate element.
WELL: lighting and health
While LEED certification is based on efficiency, the WELL Building Standard looks at human health. In its lighting section, WELL looks at exposure to natural light (including duration), control of excessive light, spectral qualities of artificial light, alterations to circadian rhythms and night-time light exposure, and flexibility of lighting at different times of day.
The WELL Standard illustrates how the paradigm is shifting when it comes to lighting. No longer just a technical parameter, it is now seen as a direct determiner of physical and mental wellbeing. A 2022 study found that following WELL criteria can reduce fatigue, and improve quality of sleep and cognitive performance.
WELL introduces the vital concept that improvements to lighting should not just aim to save money, but also protect our health.
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Interior design and energy efficiency
A space’s design is also decisive in energy consumption. For instance, lighter coloured surfaces reflect up to 80% of light, while darker colours increase the need for artificial light.
Research has shown that certain passive design choices can reduce energy use for lighting by 30-50%, all without any technological changes. These include a building orientation that makes the most of natural light, using materials that reflect light, control of excessive light or glare, and indirect lighting.
Carefully designing a space can save as much energy as renovating its entire lighting system.
The lighting of the future
Reducing energy consumption does not depend on one technological fix, but on a broader, integrated strategy that ranges from the layout of a space down to the type of lightbulbs used.
There is not one official statistic that encompasses the potential savings of all of these measures combined, as this figure also depends on the type of building, climate and use. But we do have estimates. For instance, modernising lighting in an office building can reduce lighting energy consumption by 60-90%, depending on how well it is optimised.
But lighting is not just a question of energy use. It is also a key component of health, productivity and wellbeing. The buildings of the future will therefore not just be more efficient, but also healthier, and certified under criteria that cover energy, use, health and design.
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