High excitation purity light sources
Approved document L, Conservation of Fuel and Power, Volume 2: Buildings other than dwellings, 2021 edition incorporating 2023 amendments, defines high excitation purity light sources as:
Colour-tuneable light sources that can be set to at least the colours listed in Table A1 and which have for each of these colours, measured at the dominant wavelength, the minimum excitation purity shown. Intended for use in applications requiring high-quality coloured light.
Table A1 High excitation purity light sources
| Colour | Dominant wavelength (nm) | Minimum excitation of purity (%) |
| Blue | 440–490 | 90 |
| Green | 520–570 | 65 |
| Red | 610–670 | 95 |
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