Lighting standards and rising energy costs: is change needed?
Kimberley RileyView bio
The increase in energy prices has made households stop and think about the energy usage in their homes; which of our appliances are the most energy hungry? How can I reduce my lighting consumption? But are businesses doing the same? Reducing energy consumption has been a topic of discussion for some time however has since become a financial need given the vast surge in energy prices in the recent months.
Businesses that are designing office spaces could think about how to reduce energy consumption by providing a lighting design specific to their needs or tasks. As a designer, the first port of call when designing the lighting for any office space would be to refer to the relevant lighting guides.
In previous editions of the indoor lighting guide, the recommendation for office lighting was 500 lux for tasks such as writing, typing, data processing with the SLL LG7 guide providing a lower recommendation of 300 lux.
The most recent version of (BS EN 12464-1: 2021) has significantly increased the illuminance limit past 300 lux and introduced two more modified options that allow for even higher illuminance values. The required task illuminance is now 500 lux and can be modified to a whopping 1000 lux for a multitude of reasons as shown in the table below:
Given the 1000 lux value for “writing, typing, reading and data processing”, this could be open to interpretation when designing for CAT A offices. The worry here is that the designer does not know who will be occupying that space and therefore could provide a blanket level of 1000 lux across the floor plate to cater for all when this is likely, not necessary. As you can see from Note 2, there is a redirection to a daylight section. The guidance takes into consideration daylight and explains that “daylight can supply all or part of the light needed for visual tasks or activities”. Considering there could be a significant reduction in the need for artificial lighting by utilising daylight, there surely should be a table providing reasons for applying a reduced light level – lower than the required 500 lux? Some ideas to develop instantly spring to mind:
1. Let’s utilise the natural light we have when designing buildings. With the new workplace settings since Covid struck, many companies have reduced office sizes and opted for hotdesking rather than fixed desk seating for each employee. Naturally, people are attracted to spaces that have natural light, desks located close to a window with minimal artificial light above will likely be used more than that of a desk in the centre of an office with limited daylight and vast amounts of artificial light. Daylight is supplementary to artificial lighting therefore effective daylight dimming for luminaires located close to windows will reduce energy usage.
2. Task lighting which is controllable by the user could be positioned on each desk. A lower level of light (more in line with the 300 lux from LG7) is to be directed onto the task surface which can be increased by a task light controlled by the user at each workstation. Not only does this reduce energy consumption (providing increased light only when it is required) but also gives users visual comfort when sitting at any workstation.
3. Designing for a specific task. Should a user who primarily works on a computer have the same required light levels as a user who works with pen and paper? Light levels should be considered based on the task requirements.
There is a balance between designing for the user and designing with energy efficiency in mind. Unfortunately, the increase in the “required light level” limits the amount of energy that can be saved from a lighting perspective.
The world is an ever-changing place and guides cannot possibly keep up to date with the difficulties we face in the world; in this instance the energy crisis. It is down to the due diligence of the lighting designer to provide the balance between required light levels and energy efficiency and to educate/ensure the contractors adopt a similar approach and do not simply apply a blanket level of 1000lux across the space.
You can get in touch with the lighting team for more information.