Last updated: 7 ก.พ. 2565 | 742 จำนวนผู้เข้าชม |
Colour Rendering Index (CRI)
This is a measure of how realistic colours look when they are lit by a lamp. A standard incandescent bulb scores 100% as it produces the full spectrum of colours and therefore has perfect colour rendering.
Fluorescent lamps have a lower CRI because they do not produce the full spectrum of light. Good quality 'triphosphor fluorescents' use three phosphors to give off red, green and blue light. This tricks your eyes into thinking they are seeing white, in much the same way as a TV screen works. If you want colours to look good, you need to choose a fluorescent lamp with a CRI of 80% or higher - this will be fine for everyday use. Specialist fluorescents are available with a CRI higher than 90%, but these are slightly less efficient and are usually only used by professionals such as graphic designers or artists.
You should avoid buying tubes for the home if they do not have a CRI rating of at least 80%, as they may be cheap tubes intended for office buildings. These only use a single phosphor that leaves large gaps in the spectrum of light. They have a CRI as low as 50%, which tends to give people's skin a sickly look, and colours just don't look right. They are also now banned under EU regulations. These give energy saver bulbs a bad name, but are greatly out-performed by modern, household fluorescents with a high CRI.
Perceptions of fluorescent energy saver lamps
People often complain that they do not like fluorescent energy saving lamps because of the colour they produce. This is because they buy discounted 2700k lamps from their supermarket or receive free energy saving lamps from their Energy Company; free ones that are paid for out of their energy bill! These 'free' lamps help energy companies hit their 'carbon reduction targets' but of course don’t even have to be installed! Nothing in life is free.