Circularity Metrics Now Drive Lighting Specs
The push for a circular economy is now a practical reality for lighting designers, with architects and specifiers demanding TM66 scores at the specification stage. The IALD confirms that modular, repairable luminaires with clear end-of-life strategies are no longer a niche interest but a core requirement for winning high-profile projects. This shift requires designers to embed lifecycle assessment and design-for-disassembly principles from the start.
Developed by the Lighting Industry Association (LIA) and the Chartered Institution of Building Services Engineers (CIBSE), TM66 is a direct response to the industry's shift away from a linear 'make, use, dispose' model. It provides a standardized framework for assessing the circular economy credentials of lighting products, moving beyond simple energy efficiency to consider the entire product lifecycle. This initiative was born from a cross-industry collaboration to create a unified metric where none previously existed. At the core of TM66 is the Circular Economy Assessment Method (CEAM), a tool that translates complex sustainability data into a more straightforward rating. To ensure the credibility of these ratings and combat greenwashing, the TM66 Assured Product Verification Scheme offers independent, third-party verification of manufacturers' claims. This allows specifiers to confidently compare the circularity performance of different products. This focus on circularity is mirrored by upcoming EU regulations like the Ecodesign for Sustainable Products Regulation (ESPR), expected to take effect around 2026. This will expand on current energy-related directives to include requirements for durability, repairability, and the use of recycled materials, likely mandating a Digital Product Passport to document these aspects. Beyond circularity, human-centric lighting standards are gaining prominence in high-end architectural projects. The WELL Building Standard, for instance, uses metrics like Equivalent Melanopic Lux (EML) to measure light's impact on our circadian rhythms. This involves designing lighting to support biological health, specifying minimum light exposures, managing glare, and ensuring high color rendering (CRI >90) and flicker-free performance. To calculate the biological impact of a light source, designers use the Melanopic Equivalent Daylight Illuminance (MEDI) metric, which has a recommended value of at least 250 lux measured vertically at eye level to be effective. This is found by multiplying the visual illuminance (lux) by the Melanopic Daylight Efficacy Ratio (MDER), a value indicating how closely a light source mimics the stimulating effects of natural daylight. The technical backbone for these advanced lighting schemes increasingly relies on DALI-2 (Digital Addressable Lighting Interface). As an open protocol, it ensures interoperability between devices from different manufacturers and integrates with broader building management systems (BMS). Its architecture supports IoT integration, allowing for advanced data monitoring on energy use and predictive maintenance, often through a combination of wired and wireless networks.
