Change for the better – it’s glaringly obvious

One of the key changes to the standard is that more parameters have been added to the calculation table, particularly with regards to the use of ‘modified illuminance’. Other parts of the table including some text and references have also been updated.

In terms of ‘room brightness’ and calculation areas, illuminances on walls and ceilings, together with surface reflectances, now contribute to luminances and are indicators for ‘perceived room brightness’. Requirements for the ‘visual task area’ are now defined in terms of ‘Em required’ and ‘Em modified’, with ‘room and space’ referred to as ‘Em wall’, ‘Em cylindrical’ and ‘Em ceiling’. The result
of these changes is that room brightness increases under these new requirements. The calculation areas, i.e. work field, near field and surrounding area are also clarified.

The standard states that lighting should be adjustable to the actual needs of users in the building and that the system should ensure that illuminances can be achieved that meet or exceed the recommended maintained illuminance level using only the electric lighting (assuming a worst case scenario without daylight contribution). Illuminance can be achieved by both daylight and electric lighting or any combination of the two. Lighting should also be designed to meet the lighting requirements of a particular task, activity or space in an energy efficient manner. However, it is important not to compromise the visual aspects of a lighting installation simply to reduce energy consumption. The required minimum illuminance levels as set in the standard are minimum values that should be maintained over time.

In Annex A of the new standard, recommended best practice is provided on use of the Unified Glare Rating (UGR) method. The lighting product must be verified with a UGR table to show that the product is suitable for the visual task. This table method therefore helps to curb any discomfort glare from the light fixtures in indoor lighting systems.

Annex B of the new standard refers to the visual aspects of lighting (e.g. room brightness) but also introduces the non-visual effects of lighting, including how lighting affects the circadian rhythm and mood of humans, as well as how lighting can improve their performance and wellbeing.

Annex C of the standard, ‘Lighting Design Considerations’, provides an example of the use of the ‘Em Required’ and ‘Em Modified’ parameters in a typical lighting design calculation for an office in which the majority of employees are over 50 years old.

Interview with Erlend Lillelien and Prof. Dr. Paul Walter Schmits-Reinecke of the Technical Committee for EN 12461-1: 2021

Can you describe the Technical Committee Working Group for EN 12464-1 and how it operates?

EL: The Working Group comprises around 22 to 25 members. We’ve met perhaps 25 times on the new revised 2021 standard, which has taken the best part of five years to complete. On each occasion we meet, there are typically between 10 and 15 members present. Each country is typically supported by one ‘expert’, except the UK and Germany, who have up to three experts in each meeting. The countries represented in the working group are predominantly from Western Northern Europe and include Norway, Sweden, Denmark, Finland, UK, Germany, Netherlands, Switzerland, Austria, Belgium, Italy, France and Spain. We report to the European Committee for Standardisation, CEN Technical Committee 169 for Light & Lighting.

PWSR: The first European standard that we worked on was a challenge, as we had to bring together the different requirements of each member country. This was, and is still, one of our primary jobs on the standards committee. We have to accept that people do things slightly differently compared to your own country and although it has to be copied and followed in the standard, every country still has some freedom to describe, for example, what the size of their ‘task area’ is in a lighting design calculation.

How do you reach consensus as a working group?

EL: We have a convenor who reports to CEN, who is elected by the technical committee. We reach consensus through meetings and discussions. On this 2021 revision alone, we had up to 25 meetings, which are typically two-day meetings held in different locations across Europe. Each member country takes turns hosting the meetings. We reach consensus at these meetings through discussions, often very lengthy ones! During the recent Covid lockdowns, we met online as a group using Microsoft Teams or Zoom. These have proved to be quite useful and worked well.

PWSR: Standards work should always be based on consensus. We all have to agree unanimously on a change or addition to a standard. But after the meetings, this means the country experts may have to accept some compromises. When they return home to their own country, they have to then ‘sell’ the compromise to their national committee, colleagues and co-workers. Having said all this, there are some national deviations in the new standard. We have only one now for Slovakia I believe. The biggest deviation over time for this standard has been Denmark, which had their
own national regulations that stated they could have lower illuminance levels than our standard specified. But these deviations are rare.

EL: A lot of people who read the new standard forget, or are not aware of, the difference between a standard and a guide. We are writing a standard and these are basically a minimum solution that you must adhere to in order to reach a certain level. We try very hard not to describe the actual lighting solutions, but instead we describe the performance levels that you must reach. We’re not saying what type of light you should be using, for example, downlights or wallmounted lights, but simply about the levels of lux you must attain. Many readers buy the new standard and are
disappointed because they need local country-specific guidance on how to interpret the new standard. They expect guidance on a lighting solution directly from the standard itself, but that is not part of our remit. This is where the National guides come into play, which help each country interpret the new standard and bring more detail into what the standard means for that particular country.

Due to cost issues, at least half of the working group members are employed by manufacturers. The other half typically represent the standards organisations. A few, like myself, are independent consultants. Trying to develop standards without the involvement of the manufacturers and lighting designers would be virtually impossible.

How did you end up with the ‘Em Required’ and ‘Em Modified’ values in the new standard?

EL: This was a long process indeed, which took three to four years. It went through a lot of iterations before we ended up where we are now. The lighting controls aspect, for example, the use of dimming, for me this was very important because I didn’t want us to specify that you must use the ‘upper’ or the ‘modified’ value if certain conditions were in play. For instance, perhaps your workforce is generally older, which is very likely in the future. I didn’t want this aspect to increase the energy consumption unnecessarily. So to me, it was critical to specify the ‘upper’ value and the ‘modified’ value together with the use of a lighting control system. The standard states that you may use a control system if you’re using the modified value.

Now that the visual and non-visual effects of lighting have become part of the scope of the new standard, can you elaborate more on the process that has led this forward?

EL: At the beginning of the five-year review process, Lighting Europe sent a letter to us suggesting that we incorporate ‘Human Centric Lighting’ [HCL] into the new revised standard. So one of our first tasks was to review this aspect. We realised quite quickly that there was not enough empirical data to support HCL to enable us to add a new column to the calculation table with new values. There was no conclusive data at that time to support this addition. So we rejected Lighting Europe’s request to include this in the whole table. However, we did add wording on HCL and adjustable lighting controls, but these were general formulations and hints rather than actual requirements.

PWSR: In order to gain consensus and one voice within the working group, there are two factors we must always consider: regulations that we define and add to the standard must be scientifically-based. HCL at the time wasn’t and so it was left out. Also, any of the member countries joining the European standard are not allowed to have their own regulation that is not in line with the standard. So what we did in this revision was provide some hints, tips and guidelines on HCL, but we cannot make it part of the standard yet. However, we cannot ignore that there is currently a big discussion going on in the industry about this. So we felt we had to bring this aspect into the new standard, but not as a requirement, only as some informal references. If we had left this out, people would say that we have not even acknowledged its importance. So it’s been a compromise I suppose. Now the standard is bigger although there is nothing really significantly new in it. The thinking has changed but not the standard itself. The substance didn’t change at all. It looks different, but the same ingredients are in there.

The use of light management systems is mentioned and recommended in several parts of the new standard, particularly with respect to modified light levels. Can you tell us more
about how the standard recommends the use of dynamic and smart lighting controls?

PWSR: Yes, lighting controls and dimming are mentioned in the new standard, but this is not new; it was in the previous version too. There was always a possibility to bring lighting levels up if the workforce is older or to allow for a specific visual task. With the new standard, we are now asking lighting designers to look at this and we want to push them further, for example, there may be a reason to include higher lighting levels that they should consider.

And this brings us to what is behind this new keyword ‘modified’. Too many people were looking at the old standard and saying, “I mustn’t go below the minimum or above the higher value”. This was never intended by the old standard to give them a fixed number. With illuminance, planners have the option of using the table and the context modifiers to define and argue the illuminance themselves. So the new standard in my opinion is very educational.