Light sources: types and specifications

Lamp that produces light by heating a tungsten lament until it is made red hot (incandescent) by the electrical current owing through. The light emitted tends to be warm. Since 1st September 2009, the European Union has applied a gradual ban on this type of lamp, replacing it with sources that reduce environmental impact and offer greater lighting efficiency and longer life.

Direct evolution of the incandescent lamp, this lamp offers greater efficiency and longer life as well as better colour yield. They can be used with power from the mains and 12V power supplies and are available in cold and neutral colour temperatures. Low efficiency halogen lamps will be banned as of 2016.

Lamp that emits indirect light. Normally such lamps are tubular and are available in different colour temperatures. To function, these lamps require a transformer (ballast) and thus cannot be connected directly to the power mains. In the compact version (best known, most widespread of the so-called energy saving lamps), the ballast is incorporated.

These lamps have good chromatic performance and rather high efficiency which makes them suitable for many applications. They produce a warm light although there are some drawbacks such as the time required to reach maximum illumination and needed to turn them back on, as well as the fact they cannot be dimmed. Moreover, they require a ballast to operate so they cannot be connected directly to the mains voltage.

LED bulbs are replacing traditional incandescent bulbs (section 5.1) or halogen bulbs (section 5.2) since they are preferable in terms of efficiency and energy savings (energy classes A to A). They usually have the same shape and socket as traditional bulbs (e.g. E27, E14, GU10, GU5.3 etc.), integrating LED diodes and electronics (driver) required to guarantee operation. Currently there are no official technical rules that regulate the operation of this type of bulb. Since the behaviour of light bulbs with integrated electronics is different from that of simple light bulbs, most manufacturers provide lists of compatible dimmers, which allow you to select the most suitable dimmer. It is advisable always to use transformers and dimmers specific for LED bulbs and to check whether they are compatible and operating properly. When using traditional dimmers, it is advisable always to check that they have been tested and approved by the manufacturers of the light bulbs you intend to use and the maximum number of LED bulbs that can be dimmed. In fact, these dimmers work with high minimum loads and do not read the low loads of LED bulbs: the electronics integrated in the light bulbs must be able to ensure the dimmer perceives the minimum load required. Therefore a dimmer that is not designed specifically for LED light bulbs might dim a smaller quantity of bulbs than a LED- specific dimmer would (e.g. a generic 300W dimmer can dim up to a maximum of 10 x 4 W LED light bulbs for a total of 40W, while a LED- specific dimmer with a maximum power of 100W can dim up to 25 up to a maximum of 100W precisely. LED lamps also contain various electronic components that, in unfavourable conditions, may generate acoustic noise. Catellani & Smith uses, recommends and checks the high-quality LED light bulbs of the leading suppliers on the market (e.g. Philips, Osram, Soraa, Idealed, etc.) and cannot guarantee the proper functioning of its luminaires with low-quality LED bulbs or those from unknown LED bulb manufacturers.

Given their high luminous efficiency, life and colour rendering, in recent years LEDs have become the light source of choice for manufacturers and lighting designers and for consumers who are increasingly sensitive to energy savings and environmental protection. The light emitted by the LEDs we use tends toward the various tonalities of white: cool white, neutral white and warm white.
According to market availability, Catellani & Smith pledges to ensure that the LED light sources in its own luminaires can be replaced (see section 5.12 LED life cycle).

See “colour temperature”.

Generally measured in degrees Kelvin (K), it commonly refers to the colour tone emitted by a light source.

Often confused with colour temperature, colour rendering is the qualitative evaluation of the chromatic aspect of the objects being illuminated. In other words, it is a measurement of how “natural” the colours of the objects appear. The value is established as a percentage according to the CRI (Colour Rendering Index).

See RA.

On the chromaticity diagram of the CIE (International Commission on Illumination), MacAdams ellipses refer to the regions defining the human eyes’ ability to distinguish the different colours at the centre of the ellipse. They are used as an index in selecting the colours for LED diodes.

As opposed to conventional light sources, LEDs do not “burn out”, rather, in time, the intensity of the light emitted declines. Although there is as yet no standard de ning the life of a LED, its life is generally deemed terminated when the light emitted declines to 80% of the initial level. Since it is not possible to test a LED until total extinction, LED manufacturers are required to state the parameters used to estimate time before the luminous ux of a LED light source falls below that percentage. The life of a LED is generally counted in hours; however, this always depends on the type of use: continuous (typical of a business where the lamp remains on all the time) or occasional (as in households where the lamp is on for a few hours a day). For example: if a LED guaranteed for approximately 30,000 hours remains on 24 hours a day, it will last 3 years while, if it is only on for 3 hours a day, it could last up to 40 years.