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Outdoor light bulbs types

By March 21st, 2024No Comments

Choosing small light sources permits the use of luminaires hidden discreetly among planting and landscape features.

Visible light is the light that our eyes detect, and the aim of artificial lighting is, on the whole, to provide conditions that approximate to natural light, so that we can see objects at night as we do during the day. To introduce a lighting system into your garden, you do not need to know that visible light is one of the types of radiation in the electro-magnetic spectrum; nor do you need to know that the visible light spectrum ranges through the colours of the rainbow. It will be helpful, however, if you understand the properties of light that affect the way that artificial light can be used. If you appreciate how these properties can be used and exploited within your garden, lighting design can become truly creative.

Light, lamps and luminaires
The terminology used to describe lights and lighting can be confusing. It has developed in a haphazard way and is defined differently in professional and in day-to-day usage. In addition, it varies from country to country. In this book the following terms are used.
Light is a visual phenomenon; it is the
beam or glow that is emitted by a lamp.
Lamp is the source of light. It is commonly (if imprecisely) referred to as a ‘light bulb’, but the word can also apply to a tube, globe, reflector lamp and capsule.
Luminaire is the housing or body containing the holder or socket of a light source or lamp.
Measures of light
Light levels in the garden at night contrast sharply with daylight levels: the brightest moonlight has only a fraction of the intensity of direct sunlight, but even at this level the human eye can perceive shape, colour and detail, and it is generally the minimum level for pathlighting domestic gardens. Against the background of such low ambient light levels in the garden at night, it is no surprise that even low levels of lighting achieve dramatic results.
The standard measure of output for lamps is called a lumen. The amount of illumination that a lamp provides is measured in lux, which is the number of lumens per square metre. Bright moonlight is 1-2 lux. In North America the term ‘footcandle’ is used. One footcandle is equal to about 10 lux. In lamps with reflectors, it is the intensity of the beam that matters, and that is measured in candelas.

In creative garden lighting it is always important to avoid glare, which will instantly ruin an otherwise well-lit scene. Brightness and glare, however, are two sides of the same coin. A beam of light does not necessarily stop at the subject on which it is focused, and poorly positioned lighting or the wrong choice of lamp beam or wattage can result in light straying in unwanted directions to produce glare. A common mistake is to place luminaires with over-bright lamps near a front door in the belief that bright lighting is always good lighting. Although a high level of lighting is often intended to help the home-owner identify a visitor, lighting the person rather than the entrance and its approach is intimidating rather than welcoming, because it produces glare at eye level. The light itself becomes the focus of attention rather than the area or object that it is meant to illuminate.
Glare from the wrong kind of lighting is as bad as no lighting at all. There are two main types of glare.
Discomfort glare is the name given to the type of light in which it is possible to perform a desired function but with some degree of discomfort. We have to squint through the glare towards an object or shield our eyes with a hand in order to see the illuminated area below or beyond the glare.
•Disability glare is the term for the light in which normal vision is impossible, and perception of the brightness of light depends to some extent on what other lighting is around it: a single accent light will appear brighter if there is little ambient light than if there are other similar areas of light nearby. This is because the human eye adapts to light and dark by opening and closing the iris. This may all seem complicated, but in succeeding chapters we will see how flexibility in a lighting design will allow us to experiment with, and customize, the lighting effect.
The word reflectance is used to describe the percentage of light reflected from a surface. Dark colours reflect much less light than lighter colours and also absorb more light than they reflect Rough surfaces scatter light and significantly reduce the amount. reflected towards the eye compared to smooth surfaces. The box on page 15 indicates the reflectance of various materials common in gardens and the practical implications when choosing which lamp power to use. The concept may seem academic, but the result is practical-for example, what brightness of lamp do you need to light a white marble statue in your garden and how is this light requirement affected if you replace it with a dark bronze subject?
Choosing lamps
Good lighting is fundamentally about choosing the right lamp for the job. The lamp, traditionally known as a “light bulb’, provides an all-round light output appropriate for lighting around a patio, illuminating the route from the car to the house or providing lighting around the front door. Wall lights are typical uses for tungsten light bulbs. Tubular and compact fluorescent lamps and many of the types used in street lighting come into this category of light sources; they provide an all-round light that diffuses in all directions unless controlled or directed by an external reflector. Garden lighting is principally about creating effects, and it requires a considerable degree of control and direction of the light source. Creative garden lighting cannot generally be achieved by diffusion light sources; instead, we use reflector lamps. These are lamps that use a reflective coating or a shaped mirror surface to project a controlled beam of light. Only a few diffusion light sources are used in garden lighting, including metal halide lamps, and their small size makes them suitable for use with external reflectors to produce controlled beams of light.
Colour rendering We take the natural colour of daylight for granted and assume that artificial lighting should strive to match it, a phenomenon known as colour rendering. Lamps are rated on a scale out of 100, and the higher the number the more natural the lit subject appears-80+ out of 100, for instance, means the light provides good colour rendering. Colour rendering is not always the most important factor in the choice of lamps, however. Street lighting mainly uses sodium lighting, as its high energy-efficiency and long lamp life out- weigh its awful orange-coloured light out- put. Fortunately, most other light sources aim at a closer approximation to daylight.
Metal halide sources and tungsten
halogen lamps provide particularly
good colour rendering.
Colour temperature
Another measure for lamp types provides a relative indication of the colour of light This is the colour temperature, which is expressed in degrees Kelvin or K (273K is equal to 0°C/32°F), What might be thought of as warm colours – yellows and oranges are, in fact, at a lower temperature than the cool blues (see table below). Tungsten halogen and the 3000K metal halide lamps are among the most pleasing to use in garden- lighting design because their fairly white light tends to flatter the natural colours of flowers, foliage and building materials and fits in with our perception of ‘natural’ colour. Fluorescent lamps are available in a range from warm to cool white for different applications. Warm white is favoured in most gardens because it resembles the colour of tungsten lighting which has a mellow look. Cool white, on the other fand, tends to look harsh.

Lamp life
Lamp life is another factor to consider, particularly for lighting that is in regular use- for example if it is switched on every night by a timer or photocell. Lamp life is rated in units of 1000 hours and is given by manufacturers as an average lamp life (see table on page 17). Think of 1000 hours as being the equivalent of switching on your garden lighting for three hours every night of the year a lamp with a life of 1000 hours will, therefore, last roughly a year. Both tungsten and tungsten halogen lamps produce light by incandescence- that is, passing electricity through a filament to heat it until it glows. Other types of ‘discharge lamps produce light by using electricity to strike an arc through a gas-filled tube or envelope in such a way that either the gas or a coating on the inside of the envelope fluoresces’ or glows. These lamps also use less energy and are becoming increasingly popular for wall lights and lantern fittings. Long- lived, high-intensity discharge lamps, such as the metal halide types, are used for uplighting large trees.
Energy efficiency Energy efficiency another advantage of tungsten halogen over tungsten lamps. Not only do tungsten ha capsule and reflector lamps run on 12 vots a safe voltage to have outdoors -but they are also very efficient, Use of halogen gas inside the gen capsule ound the flament recycles tungsten shed by the flamere and enates the lamp to operele at a higher temperature and for longer This doubles both the lampe and the light output per watt compered to a typical tunglen lame Compact fluorescent lamps typicaly use about 20 per cent of the power of a tungsten lamp for the same light output. For higher power applicatio such as uplighting large trees, a tal hatide lamp will typically save more than 85 per cent of the energy of a tungen lamp or 75 per cent of the egyuta linear haligen floodlight ling doing the same job
Choosing a system Depending your quants, ch type of commonly sad lighting syste hes its advantages and disadvantage in tents of cost, colour, y efficiency and fe
Tungsten projector lamps The mainstay of garden gezing for many years was the PAR type of lamp. PAR stands for Parabolic Aluminized Rufactor, and the most common example is the PAR38 lamp a reflector lamp, 120mm (4 in diameter, usually with an Edison scrow base of cap and intended fo use in a mains voltage also known as line voltagel spike or wall-mount halder This type of lamp has always been relatively live and widely available, and requires little specialist wladge to ina and create a simple lighting scheme. One drawback is that It is mainly available in higher
wattages, from 60 watts upwards, but it is a popular lamp for the general lighting of bees. In this role, a spot or food han sutab for lighting columnar and spreading trees. It is available with colour coatings, usually green, red, yellow and blue, but this kind of colour treatment of natural subjects in a garden often produces a garish effect, which overwhelms rather than reinforces the natural appearance of foliage, stone and timber. A green lamp tends to make a specimen tree or shrub look like a plastic Christmas tree.
Tungsten halogen dichroic lamps Creative garden lighting has recently come to be dominated by the MR16 low-voltage halogen lamp. This 50mm (2in) diameter lamp features a miniature halogen capsule lamp mounted in a multi-mirror reflector to provide a controlled beam of light with little peripheral light spill. These lamps run on 12 volts, so, although transformers must be installed, they permit flexible wiring configurations and easy adjustment.
The MR16 is twice as energy efficient as the PAR38 tungsten lamp. The dichroic’ reflector reflects all the light forward, while allowing much of the heat to dissipate through the rear of the lamp- that is, it projects much less heat towards your planting or down on to the dining table. MR16 lamps are available in wattages from 10 to 75 and beam angles from 7 to 60 degrees, giving much more choice in accurately and precisely lighting subjects without glare. The wide range of lamp choice is reinforced by its small size: it is less than half the diameter of a PAR38 lamp and about 10 per cent of its overall size. Using MR16 lamps means that luminaires can be much smaller and yet produce more light than old-fashioned tungsten fittings, allowing much greater flexibility in their use.
When you are choosing subjects to light in a garden, it does not necessarily follow that a higher wattage lamp will produce a brighter effect. Spotlighting by using a narrow-beam halogen lamp will produce a more intense circle of light than a wider beam of the same wattage, and a narrow-beam reflector more tightly focuses the light emitted by the halogen capsule into a higher concentration in a smaller circle. This not only makes best use of the wattage capability of a lamp but also serves to make the subject that is being lit more prominent than the other objects around it. A narrow-beam, 20-watt lamp can provide a much higher light level in the centre of its beam than a wide-angle, 50-watt lamp in which the light is not focused so tightly. Perhaps surprisingly, therefore, higher-wattage, wide-beam lamps are often used for the general illumination of mature shrub borders and spreading trees, while lower- wattage, narrower-beam lamps are used to accent individual features. The table below summarizes and compares the characteristics of tungsten PAR38 and tungsten halogen reflector lamps and details the advantages and disadvantages of using each. There is also an indication of the ways in which each lamp can be used in the garden.

George Gitau

Meet George, an advocate for traditional craftsmanship. I will provide you with educational content, techniques and ideas for your next garden and home improvement project. Together, let's create beautiful spaces that are not only beautiful but also functional

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