Free lighting tool
TM66 circular economy pre-assessment
This calculator gives an indicative CIBSE TM66 circularity score for a luminaire from eight yes/no questions covering product design, materials and manufacturing, and the manufacturer's ecosystem of repair and take-back. It is a free pre-assessment for specifiers comparing products, not the CIBSE CEAM-Make or CEAM-Specify tool, and it does not certify anything.
By Nicholas RedicanLast reviewed
What is CIBSE TM66?
CIBSE TM66, Creating a circular economy in the lighting industry, is the CIBSE and SLL technical memorandum that defines how luminaire circularity is assessed. Its Circular Economy Assessment Method (CEAM) scores a product from 0 to 4 across product design, manufacturing, materials and ecosystem, so specifiers can compare products on the same basis.
CEAM-Make is the detailed manufacturer self-assessment, which CIBSE's TM66 Assured scheme can independently verify; CEAM-Specify is the shorter checklist a designer uses at specification stage. Both workbooks are published by CIBSE (cibse.org), not by this site. This page hosts NR Lighting's own eight-question screen: it borrows TM66's themes so the right questions are put to a supplier, but its weightings, bands and rating are a simplification for ranking candidates, not a substitute for the CIBSE method.
How to use the TM66 calculator
- 01Gather the datasheet, warranty terms, any material declaration or Environmental Product Declaration, and the manufacturer's repair or take-back policy: every answer needs evidence.
- 02Answer the eight yes/no questions. Each card shows its category and its weighting of 10 or 15 points. Once all eight are answered the answers are sent to NR Lighting's servers for scoring; no account is needed and the scoring service does not store them.
- 03Read the sidebar: score out of 95, percentage, band (Poor Circularity, Improved, Good Practice or Excellent) and an indicative rating range on TM66's 0–4 scale, with a tick for the top two bands and a cross for the bottom two.
- 04Pro subscribers can add project details and a product name, see an improvement tip under every No, and export a PDF report listing the answers, score, band and up to five improvement opportunities.
- 05Press Reset and score the next candidate. The number only means something relative to the alternatives, so record them side by side.
The method: how the score is formed
Score = Σ points for every Yes answer (maximum 95) · Percentage = Score ÷ 95 × 100 · Excellent ≥ 80 %, Good Practice 60–79 %, Improved 40–59 %, Poor < 40 %
Each question has a fixed weighting: the three that most affect keeping a luminaire in service (a replaceable driver, an adhesive-free assembly, and a repair or take-back route) carry 15 points, the other five 10. A No scores nothing. There is no partial credit and no evidence upload, so the result is only as honest as the answers.
Each band is shown with an indicative rating range on the 0–4 scale TM66 uses (2.5 and above, 1.5–2.5, 0.5–1.5, below 0.5). That mapping is NR Lighting's approximation; a CEAM-Make score comes from a far longer question set and cannot be read off this page.
| Category | Question | Points |
|---|---|---|
| Product Design | LED driver replaceable without permanent damage to the luminaire | 15 |
| Product Design | No glues or adhesives that prevent non-destructive disassembly | 15 |
| Product Design | Warranty of five years or more | 10 |
| Materials & Manufacturing | At least 30 % recycled material by mass | 10 |
| Materials & Manufacturing | Full bill of materials or material passport available | 10 |
| Materials & Manufacturing | Made or assembled within 500 miles of the project site | 10 |
| Ecosystem | Verified repair service or end-of-life take-back scheme | 15 |
| Ecosystem | Disassembly and disposal instructions publicly available | 10 |
Worked example
Two 3000 K recessed downlights are shortlisted for a London retail fit-out. Product A has a plug-in driver, a screw-fixed body with a clip-fit optic, a five-year warranty, a material passport and a take-back scheme, but it is assembled well beyond 500 miles from site and publishes neither a recycled-content figure nor a disassembly guide. Product B is UK-made with a replaceable driver and a five-year warranty, but its optic is bonded and nothing else is offered.
Product A: 15 + 15 + 10 + 10 + 15 = 65 points; 65 ÷ 95 × 100 = 68 %, Good Practice (Tier 2), indicative rating 1.5–2.5. Product B: 15 + 10 + 10 = 35 points; 35 ÷ 95 × 100 = 37 %, Poor Circularity. A Pro subscriber sees three improvement prompts against A and five against B. The useful output is that list of questions to put back to each supplier, not the label.
| Question | Product A | Product B |
|---|---|---|
| Driver replaceability (15) | Yes, 15 | Yes, 15 |
| No permanent fixings (15) | Yes, 15 | No, 0 |
| Warranty 5 years or more (10) | Yes, 10 | Yes, 10 |
| Recycled content 30 % or more (10) | No, 0 | No, 0 |
| Material declaration (10) | Yes, 10 | No, 0 |
| Local supply chain (10) | No, 0 | Yes, 10 |
| Repair or take-back (15) | Yes, 15 | No, 0 |
| Disassembly instructions (10) | No, 0 | No, 0 |
| Total | 65 / 95 = 68 %, Good Practice | 35 / 95 = 37 %, Poor |
Limitations, and when to involve a lighting designer
The result is an indicative screening value: not a CEAM score, not certified, and not something to quote in a BREEAM submission, planning statement or specification clause. The official workbooks and TM66 Assured verification come from CIBSE.
Eight questions cannot capture TM66's scope. There is no partial credit for a driver a technician can replace but a client cannot, no weighting for rated life, spares or upgradeability, and no check that a take-back scheme is actually used. Two products can share a band and differ greatly in embodied carbon, which TM66 does not measure; that is TM65's job. Circularity never outranks the lighting task either: the luminaire still has to meet BS EN 12464-1 and the efficacy Approved Document L expects.
I use this screen at the start of a specification to decide which suppliers to press for CEAM-Make evidence, then check that evidence before the shortlist goes into the luminaire schedule. If you need a defensible circularity statement, or a shortlist reviewed against the full TM66 method, get in touch.
Standards and guidance referenced
- CIBSE TM66: Creating a circular economy in the lighting industry, with the CEAM-Make and CEAM-Specify assessment workbooks
- CIBSE TM66 Assured: independent verification of manufacturers' CEAM-Make assessments
- CIBSE TM65: embodied carbon in building services, a calculation methodology, and TM65.2 for lighting products
- BS EN 12464-1:2021: the lighting task (illuminance, uniformity, UGR, colour rendering) a circular luminaire must still meet
- Approved Document L (England): minimum luminaire efficacy and controls for non-domestic lighting
Frequently asked questions
What is CIBSE TM66?
TM66 is the CIBSE and SLL technical memorandum Creating a circular economy in the lighting industry. It explains why luminaires should be designed for long life, repair, reuse and recovery, and provides the Circular Economy Assessment Method (CEAM), which scores a product from 0 to 4 across product design, manufacturing, materials and ecosystem. It is guidance rather than law, but increasingly requested in specifications.
How is the score in this calculator formed?
Eight yes/no questions carry 10 or 15 points each, 95 in total. Every Yes adds its points; a No adds nothing. The total is divided by 95 to give a percentage: 80 % and above is Excellent, 60–79 % Good Practice, 40–59 % Improved, below 40 % Poor. The 15-point questions are driver replaceability, freedom from adhesives, and a repair or take-back route.
What is a good TM66 score?
On this pre-assessment, Good Practice (60 % or more, at least 60 of 95 points) means the product answers Yes to most of the questions that keep it in service; Excellent (80 % or more) means at most one gap. Only a completed CEAM-Make assessment gives a product its actual TM66 score, so treat the band as a ranking aid, not a result.
Is this the official CIBSE CEAM-Make or CEAM-Specify tool?
No. CEAM-Make and CEAM-Specify are published by CIBSE with TM66 and obtained from CIBSE, and manufacturers' CEAM-Make results can be verified under the TM66 Assured scheme. This calculator is NR Lighting's independent eight-question screen built on TM66's themes; its weightings, bands and rating mapping are a simplification for early comparison and should never be presented as a TM66 score.
What is the difference between TM65 and TM66?
TM65 estimates the embodied carbon of building services products in kgCO2e from their mass and material make-up where no Environmental Product Declaration exists; TM65.2 applies it to lighting. TM66 assesses circularity: how well a luminaire is designed to last, be repaired, upgraded, reused and recovered. A product can be low-carbon yet poorly circular, or the reverse, so ask for both.