Lighting focused on you

Human Centric Lighting, or human-centred lighting, is an approach to lighting planning and application that takes into account not only aesthetics and energy savings, but above all the impact of light on people’s health and well-being.

Lighting design in the Human Centric Lighting (HCL) approach is more complex than traditional lighting, as it must take into account a range of biological, behavioural and environmental factors.

Let’s review some of the key issues that should be considered when designing HCL lighting.

Understanding the diurnal rhythm

The human body operates on a diurnal rhythm that regulates a range of functions such as sleep, appetite, energy levels and even mood. HCL lighting should be designed to support this rhythm, rather than disrupt it. For example, lighting should be brighter and closer to white or blue light during the day to promote alertness, and warmer and less intense in the evening to support natural sleep processes.

Health and safety

HCL lighting should be designed to protect the health and safety of users. For example, it should minimise the risk of glare, reflection and flicker, which can cause eye fatigue and other health problems. It should also be safe to use, especially in areas that are accessible to children.

Personalisation

Everyone has unique needs and preferences for lighting, which can vary depending on age, health, lifestyle and tasks performed. HCL lighting should be flexible and adaptable to meet these different needs. This may include the ability to adjust the intensity, direction and colour temperature of the light.

Sustainability

The design of HCL lighting should also take into account sustainability aspects. This means choosing energy-efficient light sources such as LEDs, as well as minimising light emissions into the environment (known as ‘light pollution’), which can disturb wildlife.

Mimicking natural light

Research has shown that natural light has the most positive impact on human wellbeing and performance. Therefore, HCL lighting design should aim to mimic the variability of natural light, both during the day and at different times of the year. This can include the use of different light sources, such as direct, indirect and reflective light, to create a rich and balanced lighting effect.

Human Centric Lighting (HCL) relies heavily on mimicking the natural rhythm of sunlight, adjusting the intensity, colour and distribution of light throughout the day. Below, we propose an example of a daily lighting cycle that can be based on HCL principles:

Morning (6:00 – 9:00)
During this time, the light should be gradually increased to mimic the sunrise. The colour of the light should be warm, but change towards cooler tones to stimulate alertness and focus. Light intensity should also increase to help the body transition from sleep to wakefulness.

Daytime (9am-5pm)
During the day, light should be bright and cool (usually towards white or blue) to promote alertness and productivity. Light distribution should be such as to minimise shadows and glare, which can cause eye fatigue.

Evening (17:00 – 20:00)
At the end of the day, the intensity and colour of light should gradually change towards warmer tones and lower intensity to mimic sunset and help the body move into rest mode. Lighting should be directed to create a pleasant atmosphere and minimise glare.

Night (20:00 – 6:00)
At night, light should be minimal so as not to interfere with the production of melatonin, the sleep hormone. If lighting is needed (e.g. for safety), it should be very soft, warm and non-intrusive.

Of course, the above schedule is exemplary and should be adapted to the individual needs, lifestyle and diurnal rhythm of the users. It is also important to take into account natural sunlight and how it affects interior lighting.