GreenLight Alliance: The Next Step

26th October 2021

Bob Bohannon and Kristina Allison give us an insight into the newly published CIBSE SLL Technical Memorandum, TM66, which offers advice and guidance on how to create a circular economy in the lighting industry.

The life expectancy of some commercial buildings is just 30-40 years. Whisper it quietly, but Bob is not a huge fan of some Victorian architecture, but driving past Hampton Water Pumping station the other day, he realised that this glorious building appears to have beautifully performed its function for some 150 years. Alarmingly, building and demolishing a series of 40-year buildings, rather than a single 150 year one, often yields a higher GDP figure. We don’t measure the environmental impact.

We have to make better use of the resources embodied in our lighting equipment, an unthinking linear economy of Take (resources from the environment), Make (products in factories), Waste (dispose of products into the natural environment) is increasingly no longer acceptable. Product durability and adopting the Circular Economy is the part of the solution to maximising resource usage, keeping (in our case) lighting assets at their highest value, i.e., as an effective luminaire for as long as possible. 

A team of us got together and we started listening, consulting, learning, engaging and what is soon to come out of that process is a document and a suite of three tools. The objective being to give information to all, not to tell people they are doing it wrong, but to show how they can do it better. We wanted to enable supply push by creating a nuts-and-bolts tool for manufacturers and to stimulate demand pull by giving specifiers and clients the questions they need to ask.

The document is CIBSE SLL Technical Memorandum TM66 on Creating a Circular Economy in the Lighting industry, to be published October 2021. It describes the background to the Circular Economy in general, including the drivers behind its adoption, but most importantly it gives guidance on how the circular economy affects each sector of the industry, what opportunities it may bring them and what to do next.

At the same time comes the publication of SLL’s Circular Economy Assessment Method for Manufacturing (CEAM-Make) which allows manufacturers (or specifiers if they so wish) to assess the performance of their luminaire and its supporting ecosystem in terms of its Circular Economy performance. The tool accepts the complexity that sustainability questions bring, but converts that to a simple, easy to understand star rating. The objective is to move as many products and manufacturers from zero to hero (4) as quickly as possible by giving them the detailed issues to consider. The assessment method is weighted to cover differing products, comprehensive and covers product design, manufacturing, materials and supporting ecosystem.

The CEAM-Make may be a little too in depth for a busy specifier to use every time they need to choose between luminaires, or in the transition period where manufacturers have not yet fully completed their CEAM-Make assessments. Therefore, we created CEAM-Design, being a specifier support tool. You could almost think of it as a triage tool, being essentially the most important questions to ask a manufacturer.

All the tools in the suite have been created in full consultation with people knowledgeable in the field, from manufacturers to product designers, lighting designers and end users. The tools will be updated, but the hope is that they will deliver the practical know-how, understanding, and a level playing field for claims that make an already green industry in terms of its product’s in-use energy performance, truly sustainable.

Roger Sexton, Stoane Lighting

For Stoane Lighting, TM66 couldn’t have been more welcome.

We needed a metric on the Circular Economy to be certain there weren’t holes in our approach and to market our luminaire designs mapped on a neutral foundation. We had carried out embodied carbon analyses on certain luminaires with CIBSE’s TM65 and, at a whole company level, had accreditations from B Lab and EcoVadis. It’s the specific Circular Economy assessment on our products that we lacked. 

Honoured to test drive TM66, we put part of our ZTA range through the CEAM process. It took considerable time to compile our ‘book of evidence’ for the four blocks of questions. Skimming from the 66 number of questions, below we just highlight one per section to give a flavour of the topics covered.


Repairability and upgradeability are focused on. ZTA design permits easy access to (no glue) and replacement of light sources, optics and drivers with common tools and without damaging the luminaire (as also called for in Article 4 of Eco Design Regulation 2019/2020). The ZTA range has extra fixing holes to facilitate subsequent use of different component types due to discontinuation of originals, to harness improved technologies (e.g., LED modules becoming more efficient, or gear losses decrease) or to cater for a changed need at the installation. For the same reason there is also some leeway mechanically and thermally.


Localisation sliders, e.g. ‘Geographical Distance from Final Assembly to Site’ needed some thought. For our submission we assumed Edinburgh to London, but we think this question leads the way to a ‘CEAM Project’. We scored well with the ‘Average Supply Chain Partner geographical distance from final assembly location’ question. With Stoane Lighting, all of our parts are designed and made in-house or we use local specialist machinists, paint shops and anodisers, etc. Only the optic, driver and LED module come from overseas. 


Recycling is questioned here. The main material used in the ZTA luminaire is aluminium, which is infinitely recyclable. The aluminium we buy (from Derbyshire) has a recycled content of 65-85%. Recycling components comes down to modular design. If components are common across the ranges, or even indeed across multiple ranges, then the likelihood of being able to reuse components increases. 


The norm for remanufacturing involves a factory return – but what if this isn’t possible? Say a building is in constant usage. This section therefore questions related services that are available. Stoane Lighting can drive a mobile workshop to installation to carry out repairs or upgrades. 

We appreciated the thoroughness of the TM66 review and scored well. But we can see where we must make improvements – we did not score high marks everywhere. We do not use, other than for making prototype parts, 3D printing (we are not convinced yet by 3D printing of aluminium but watching progress in that industry). In terms of recycling our own waste we are making our very first steps with melting down machine room offcuts and using gravity die casting to make 100% recycled aluminium pendants. 

I will be interested to see how generally the industry and standardisation bodies evolve in the context of the Circular Economy. The market reaction to our uptake of TM66 has been positive. We are being asked for TM66 assessments of our luminaires before the guide’s publication. One such request came from Buro Happold who want to use our Tadpole luminaires for an installation connected with COP26 this year in Glasgow which will be covered in a future article in this series.