Artificial Lighting in a Net Zero Carbon Building

Although the amount of energy consumed by artificial lighting has decreased substantially over the past 20 years with the introduction and adoption of energy-efficient LEDs, lighting is still a major consumer of electrical energy and a producer of emissions and pollutants.

The efficiency of LED light sources continues to increase, but lighting is still a long way from being net zero. The United Nations Framework Convention on Climate Change states that “Electricity for lighting accounts for approximately 15% of global power consumption and 5% of worldwide greenhouse gas (GHG) emissions”.

Replacing traditional lighting systems with LED remains an important aim and will dramatically reduce the amount of energy consumed when a building is in operation, but until recently the environmental impact of sourcing the raw materials for lighting, the manufacture and transportation of components to the factory, and the transportation of luminaires to site, has largely been ignored. It is vital that we consider the whole life cost of lighting systems and the future reuse and recycling of modern fittings, including the disposal of old lighting which may contain mercury and other contaminants.

General adoption of LED luminaires over the last 20 years has seen both old and new technologies sent to landfill at their end of life because they are not readily maintainable and reusable. Typical LED lamp life is 50,000 hours, which equates to only ten years of regular daily use, and may be significantly less with replaceable bulbs. Technology and efficiency has also been improving so rapidly that on occasion LED luminaires have become obsolete between being specified on a project and orders being placed.

Light fittings are often manufactured from a mixture of metals such as aluminium, stainless steel, bronze and brass, with components made of glass and plastics, held together by glues and finished with a powder coated or painted exterior. The LEDs themselves are manufactured from compounds such as gallium arsenide and phosphor. All these materials have to be sourced from a largely unregulated global market and at the end of their lifespan have been dumped into landfill, with very little recycled.

CIBSE (Chartered Institution of Building Services Engineers) has been working closely with leading lighting designers and manufacturers to develop “TM66 - Creating a circular economy in the lighting industry”. This report, published in 2021, gives guidance and tools to manufacturers to deliver a circular and more sustainable approach to luminaire manufacture. The document details how to design, source and manufacture luminaires to be more sustainable and recyclable, and therefore reduce their embodied carbon. The figures below, extracted from TM66, outline the current lighting recycling model and the circular economy model.

As designers there are further ways we can reduce the carbon impact of artificial lighting in buildings, by making informed decisions throughout the design process, such as:

• Ensuring daylighting is the primary source of illumination in a building during day light hours through careful design of fenestration, space planning and building envelopes.
• Ensuring spaces are illuminated with artificial light only where and when required. If fewer luminaires are required, fewer resources will be needed in their manufacture. Not all spaces need to be evenly illuminated.
• Designing systems which allow individuals to use locally controlled task lighting to lower overall light levels within a workspace, reducing energy consumption.

• Being fully aware of the principles of circular economy, and comparing the EPD (Environmental Product Declarations) certificates of different manufacturers luminaires. Now manufacturers are producing EPD certificates, information should be requested from manufacturers and compared to assess the performance of similar products.

• Thinking about how might a space or building be used in the future, in another configuration. Designing for flexibility and longevity.
• Encouraging clients to think about lighting as part of their overall strategy and social responsibility, as part of their own Net Zero commitments. Without the support of clients, the likelihood of contractors substituting sustainable lighting for cheaper, less sustainable alternatives remains high.

• Considering refurbishment of existing luminaires. Lots of manufacturers are offering to upgrade or refurbish luminaires and provide new warranties.

• Thinking about specifying lighting which is 3D printed, or manufactured from waste/recycled materials, cardboard or plywood.

• Considering the use of wireless control, reducing cabling and installation complexity. Wireless installations only need 3 core cables, so there is a reduction in material to be made from 5 core cabling used in a comparable DALI installation.

• Try rationalising driver quantities - drivers need not be specified in a 1 to 1 ratio with downlights.

• Specifying control systems to dim lighting in response to daylighting and internal occupancy.
• Specifying sensors to switch lighting off when areas are not in use.
• Switching lighting OFF when a building is unoccupied. Our towns and cities are full of buildings with their lights on after business hours.

The value of daylight and artificial light has never been greater. Research continues to inform us about the effects of daylight and artificial lighting on our psychological and physiological wellbeing. We also now understanding the impact of light pollution on the night skies and the negative impact on ecology.

By educating ourselves and becoming more informed about the life cycle of lighting and through working cohesively with lighting manufacturers we can positively contribute to the design of a net zero building whilst ensuring that the buildings lighting enhances a user’s wellbeing and experience.