Quality CFLs contain a maximum of 5mg of mercury sealed within the glass tubing, that's less than 1% of the mercury found in an amalgam dental filling.
Metal halide lamps
Quick Guide
Luminous efficacy Up to 85lm/w
Lifespan 6,000-20,000 hours
Features
High luminous efficacy
Reasonable lumen maintenance and colour maintenance.
Use them
Retail displays (certain types will accurately display true colours)
Where high light levels are required, eg. factories, sports stadiums
Street lighting applications
Don't use them
On dimmers
Where you need light instantly
Where you expect to switch on and off regularly
Brief description
Metal halide lamps are a compact, powerful and efficient light source. Originally used in industrial applications, they are now available in a range of shapes and sizes. Some even come with built-in reflectors.
New reflector-type metal halide lamps are available in similar sizes to low voltage halogen lamps – they typically last three times longer and consume 25% of the energy.
Advantages
High light output from a small point source. White light with generally good colour rendering ability depending on type. Lamp output not temperature dependant
Disadvantages
Inability to give light instantly – so you can't flick them on/off repeatedly. Prone to colour shifting over time. Require special light fittings and are not a retrofit option for most applications
Ongoing development
Manufacturers are working on even higher lumen packages thanks to new pulse start technology. Their goal is high lumen maintenance and colour rendering in the order of 90% (comparable to that of fluorescents).
