Go into any hardware store and try to buy a light bulb for your living-room lamp that has just ‘popped’ you into darkness - I have stood there looking at the bewildering array of bulbs and been confused at the choices, and have often taken the dead bulb along for comparison! Where once the only choices you had to make were the brightness (40w, 60w etc) and either screw fit or bayonet fit (apparently called ‘the cap’), now there are thin screw caps, fat screw caps, incandescent, halogen, fluorescent, LEDs, some are ‘warm white’ or ‘cool white’, and now something called ‘lumens’ - and to complicate matters even more, you might want one that will work in a dimmer switch!
Lighting is pretty important in a room, either because you need good lighting so you can see what you are doing in the kitchen, or, for example, to set the mood in your living room to help you relax, or light up that gloomy corner where the spiders lurk.
I have experienced that sinking feeling when I have the wrong bulb when switching on to find a cold white light that’s more suitable for an operating theatre than a warm cosy living room, but now there’s the ‘Kelvin’ scale to help, which grades light from candlelight right up to pure sunlight and is actually a scale of temperature. The Kelvin Scale was invented by Lord Kelvin (1824-1907). I started to look up what this is, and in all truthfulness, I got lost after the first paragraph, so would recommend you put on your scientist hat and read up on it yourself if you want to know more! We have become used to the warm yellowy light given out by the old incandescent bulb, which is 2,700k on the Kelvin scale. At the bottom of the scale is candlelight at around 1,600k and by comparison, midday sunlight is about 5,000k.
The original incandescent light bulb was invented by Thomas Edison and has a filament inside surrounded by an inert gas that’s heated to the point that it glows, which gives us light. They weren’t very energy efficient, got really hot (yes, we have all burned our fingers trying to change a bulb!) and lasted about a year. These are now being phased out, but you can still buy them if you know where to look.
Halogen lights were first introduced in 1959, and are an adaptation of the original incandescent bulb, but are filled with halogen gas. It was the first real step towards creating an energy-efficient bulb, and have an increased lifespan by two to three times the standard incandescent light bulb length. They are tiny and give a bright white light, but also can get hot, and are commonly used for spotlights, car headlights and outdoor lighting.
CFL’s (compact fluorescent lights) are energy-efficient bulbs that can emit a wide range of colours depending on the model you choose. Their light is produced by ionising mercury vapour, which excites the bulb’s coating and gives us light. They were slow to light up when first introduced, but have improved over the years. They are less expensive than LED lights and can last longer than incandescent lights. Because of the mercury, you’ll need to handle them carefully, but once they burn out, they are recyclable. They use about 75 percent less energy than incandescent bulbs and last six to 15 times as long. Tubelights use the same technology and are commonly used under cabinets in kitchens or in the garage.
LEDs (Light Emitting Diodes) use almost 90% less energy than a traditional incandescent, making them the most energy-efficient type of lighting by far. LEDs, whilst initially more expensive to buy, can apparently last up to 25 years, so in the long term, they are the cheapest option.
Initially, brightness was measured in watts, but since energy-efficient bulbs can produce the same amount of light with less wattage required, the new metric measurement is lumens. Lumens are the amount of light radiated or the brightness of the light bulb. Brighter bulbs have a higher lumen. The higher the rating, the brighter the light.
So are you any wiser? Probably not! I think I will go back to my method of taking the old bulb with me when I need a new one but will take a good look at the packaging before getting to the cash desk - everything I need to know will be on it!