LIGHTING TECHNOLOGY
A more conventional office lighting refurbishment with low energy lighting whilst preserving the quality of light
undertaken:
1. Benchmark the existing lighting installation regarding operational energy use, maintenance costs per annum, and carbon footprint.
Taking the first steps towards decarbonising lighting in offices
In a typical office building, lighting accounts for around 30% of the building’s annual energy consumption, presenting a real opportunity for energy savings and progress towards decarbonisation.
Sophie Parry CEng MIET FSLL
Head of UK Akademie, Trilux Lighting
www.trilux.com N
et Zero Carbon (NZC) is a term currently being defined, along with the tools to measure it, by a consortium of stakeholders
working with the UK Green Building Council. The goal is to determine if a building is truly Net Zero Carbon, in line with the UK government’s Climate Change Act, which aims for the country to be Net Zero Carbon by 2050.
Modern buildings being constructed
or refurbished are still likely to be in operation in 27 years’ time. However, it can be difficult to predict how lighting installed today will support NZC legislation in 2050. Case studies show that the power density limit in W/m², as calculated in 2022, should put investment in low energy lighting on a trajectory to contribute to a NZC outcome. One example demonstrates that a realistic maximum energy density for office lighting is 4 W/ m² (based on the Office case study featured in the CIBSE Journal, January 2023).
This means that lighting installations must be designed with energy
A fully refurbished building where the emphasis is on the quality of light, low energy use and wellness for the occupants
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efficiency in mind, in proportion to the energy consumption of other building services. This way, they can contribute to a NZC outcome while providing immediate savings in operational energy and lower maintenance costs.
Getting the balance right When designing lighting for a new building or renovation, it is important to consider both energy efficiency and lighting quality. There are two project scenarios to consider for internal lighting:
(1) as part of a new build or whole- building renovation. In this scenario, the lighting design will likely be carried out to the client’s performance specification and be designed to meet or exceed all applicable legislation or standards. The minimum requirement is to comply with the requirements of
Building Regulation (England) Part L volume 2, Non-domestic buildings, and use UK Ecodesign-compliant products. Realistically, the Building
Regulations are pretty easy to achieve and are often behind the technology curve of what’s achievable. This ‘beyond the curve’ area will provide the best decarbonised solutions. A professional design team should be employed to ensure the completed project meets the clients’ whole- building performance specifications. (2) as a stand-alone project. This
scenario is a little more extensive, and the client needs to choose their suppliers with care, as often it is just the lighting manufacturer designing and supplying the lighting in conjunction with an installer. The following approach should be
2. Carry out a condition survey to determine if the existing lighting installation meets current applicable legislation and standards, such as Building Regulation Part L for lighting-operational energy and the recommendations found in BS EN 12464-1:2021. For emergency lighting, work to Building Regulation Part B in conjunction with BS 5266- 1, and in particular, the buildings’ current Fire Risk Assessment for any requirements for emergency lighting and escape route signage.
3. If re-using the existing electrical installation, conduct a condition survey to check the installation complies with BS 7671:2018 Requirements for Electrical Installations. The outcome of the surveys will
form the basis of a business case to justify and fund the project.
Next step The next stage of the project is to specify and agree on the scope of works and performance for the new lighting installation in terms of lighting quality, product compliances, and the maximum permitted or targeted operational energy and carbon. Here we should first produce a detailed design and specification for installation. A Programme of Work should include the project impact on the day-to-day use of the building if occupied, removal of the existing lighting, installation of the new lighting, set-up and commissioning, as-built O&M documentation, hand-over/ demonstrations to the client & their FM team and disposal of any waste lighting materials via the WEEE scheme. Sub-meters for lighting energy
will also be required to comply with Part L, allowing the client or their FM team to check after 12 months of using the new installation if the operational energy use is as predicted. If there is a noticeable over-spend, then the lighting control settings and how the building is used should be a consideration to reduce energy use.
Conclusion
Lighting installations that deliver good quality light and use minimal power to contribute towards a Net Zero Carbon building are possible. However, success relies on carefully choosing your lighting design team and supplier. ■
EIBI | FEBRUARY 2024
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