Light Bulbs

You would think it was simply a matter of buying the bulbs to fit your lamps and light fittings but there are a few things to bear in mind:

  • Limiting the size and types of bulbs you use in your home means you can buy in bulk and save money.
  • It also means you are more likely to have a spare bulb to fit, should one be is required.
  • Mainstream or common bulb size tend to be cheaper and come in more variants (colour temperature, beam angle, etc.).

Typically we have tried to limit the bulbs in our house to these four main variants based on bulb type and voltage:

  • 240V ac bulb in 21W low-energy form - these are used in rooms with a central ceiling rose, where we want a lot of light and these are equivalent to 150W filament bulbs. The other advantage of these is that you can fit them in fittings and shades that would otherwise be restricted to a 60W filament bulb.
  • 240V ac Megaman low-energy candle 9W with a BC fitting - this is the 'universal' bulb that we use around the home as it fits in pretty much any type of lamp and has good light output and reaches maximum light output quickly. These are also available in a 7W version. We are now migrating away from these to LED equivalents but they provide a more even light pattern than most LED bulbs, which limits their use in some wall lights.
  • 12V ac/dc MR16 (50mm diameter) 20W halogen. Used in the kitchen and bathrooms. Slowly replacing with LED equivalents.
  • 12V ac/dc G4 10W halogen. Used for specialist fittings such as cabinets. Also slowly migrating these to LED equivalents.

Choosing A Bulb

Control

The first thing you need to consider when buying a bulb is how you intend to control it. If all you want to do is use a light switch, then you have a huge wider choice of bulbs.

We would argue against buying bulbs that have in-built control capability unless you want to enable quite complex lighting arrangements, with each bulb being controlled individually. So called 'smart bulbs' have many limitations:

  • Higher cost - Smart bulbs are currently very expensive compared to their dumb equivalents.
  • Increased power usage - Our LIFX bulbs uses nearly 3W of power when 'off'.
  • Need to be left on - Smart bulbs need a permanent power source and won;t work if someone switches them off at the light switch. This limits where they can be used.

Cost

When you factor in the cost of a bulb, you must consider the 'whole life' cost. This includes the initial purchase price, the energy used over its lifetime and the lifetime of the bulb itself. The initial high cost of LED bulbs is often offset by their high efficiency and long lifetime, making them the best financial investment longer term.

You should also consider the environmental cost. Many bubs use rare earth metals and have toxic chemicals inside them.

Light Output

Light is the first thing you should be looking for in a bulb and it is measured in lumens.

  • A standard 60W incandescent bulb puts out about 860 lumens.
  • A 14W fluorescent bulb is about 900 lumens.

Be very wary of claimed outputs and what they are equivalent to. Some bulb manufacturers have very optimistic views of their bulbs when compared to incandescent equivalents.

Another thing to bear in mind is the beam angle or distribution of light output. MR16 down-light bulbs vary significantly and you need to choose a beam pattern to match your requirements. It can also look very odd when bulbs with different light patterns are use together in one room, especially if they project onto a wall.

Fitting & Voltage

Obviously you need to buy a bulb that has the right fitting for the ceiling rose, lamp or enclosure being used. Most light fitting are specific to a particular voltage, which ensures you don't plug a 12V bulb in to a mains voltage fitting.

Form Factor

The form factor is the second thing you need to be looking for in a bulb. There are many standard fitments but, bulbs vary in size and shape. Some may not fit the space inside a shade of fitting.

Dimmable

All bulbs can be switched on or off but few have the capability to be used with a dimmer switch and thus have a variable light output. If this is important to then you need to ensure that the chosen bulb is compatible with a dimmer switch and is clearly marked as such.

This issue is further complicated by the fact that not all dimmer switches or lighting controllers are capable of workign with all types of bulbs. Most cheap dimmer switches have a minimum load requirement and this measn that they often only work with filament bulbs.

The definition of 'works' also varies. Whilst some combinations may work, they may also be noisy or result in bulbs that flicker.

Colour

All bulbs emit light with different wavelengths or spectrum of colours. Even white bulbs vary and usually have a declared colour temperature. The colour temperature of a 'white' bulb will change the mood and affect the way coloured objects are perceived by the human eye.

It is best to choose a colour temperature (e.g. warm white) for each intended application. Mixing bulbs can look very odd, e.g. having bulbs with different colour temperatures in your kitchen ceiling.

Some bulbs are called 'daylight' bulbs and emit a spectrum of light very close to that which comes from the sun. As an example, we use a daylight bulb in our daughter's bedroom ceiling as it makes clothes and makeup appear more naturally, as they would appear when viewed outside.

Examples

MR16

MR16 halogen bulb
The MR16 halogen bulb is the most common 12V bulb used in UK homes. It usually comes in 20W or 35W versions. These bulbs are 50mm in diameter.

LED equivalents are slowly coming onto the market that can start to compete with these halogen bulbs on light output. The colour spectrum is still someway short but they are improving. Depending on the situation a good 3W LED equivalent will provide as much light but they are not cheap. At the top end of the range 5W LED bulbs are appearing on the market and claim to be able to match a 50W halogen bulb for light output. These bulbs are typically over £20 each though.

The good thing about using MR16 bulbs and light fittings is that you have lots of options and the technology is improving all the time. One thing to watch out for is that 12V lighting generally assumes an AC supply and not all bulbs can be used with a 12V DC supply. Some also feature a regulator to enable them to be connected to higher voltages (i.e. a 12V lead-acid battery).

MR11

MR11 halogen bulb
The MR11 halogen bulb is essentially a smaller version of the MR16 12V bulb and these bulbs are 35mm in diameter.

240V BC Low-energy Candle

Megaman candle BC
The Megaman low-energy candle bulb with a BC fitting comes in 7W and 9W versions. It has a good colour spectrum, being quite warm and reaches maximum light output quite quickly. There are also versions available that are dimmable.

G4

G4 Halogen
These small 12V bulbs are using in small light fittings, where it is difficult to fit much else. In our home this typically means in the conservatory lights and in designer lighting and decorative fittings, where we are looking for a sparkle effect. These types of lights tend to feature crystal glass and use some form of reflection and light dispersion. Typically these are either 20W or 10W in halogen form.

We have found that the frosted versions look nicer than the clear bulbs, giving a softer and more difuse light. To reduce our energy consumption we are slowly changing these over to LED equivalents but LEDs provide much lower light levels, a colder light and tend to be much more directional.

You can generally get these G4 bulbs in 20W, 10W and 5W versions. They can also be clear or frosted. Finding LED replacements is currently very challenging. You can read more about our G4 LED bulb dilema on our hall light project page.

Style

Light bulbs don't have to be boring, functional looking devices and they certainly don't need to be ugly. There are bulbs emerging onto the market now that are elegant and stylish.

Hulger

Hulger Plumen compact flourescent bulb
Hulger is a USA company producing elegant compact flourescent bulbs.

Lighting Panels

LEDlite lighting panel
LED lighting panels offer another way to lite up a room.

Brands & Models

LeDenQ

LeDenQ
The LeDenQ is a wireless LED bulb that can be controlled by touch panel and push button controller, using the Z-Wave technology, to adjust brightness and change the colour (about 20,000 supported).

LIFX

LIFX
LIFX is a WiFi enabled, multi-colour, energy efficient LED light bulb that you control with your iPhone or Android. It started out as a Kickstarter project (our review).

Lumen Smart Bulb

Lumen Smart Bulb
The Lumen Smart Bulb is another one seeking funding, this time via indiegogo. It aims to be the first RGBW, Bluetooth 4.0 controlled LED smart bulb. Unlike the other RGB lightbulbs which mimic "white" light by combining red, green and blue light, the Lumen has a 6W white LED light that generates over 400 lumens of light.

Philips Hue

Philips Hue LED bulb
In November 2012, Philips started selling their Hue LED bulbs. The bulbs cost 179 for a starter pack that includes broadband connection equipment (ZigBee hub) and three bulbs.

Philips claims that the bulbs are equivalent to a 50W filament bulb (600 lumen) but use just 8.5W. This light output is noticably less than a normal bulb though. The bulb is capable of producing nearly every colour of light in the spectrum (16 million colours to be exact). They currently come in a ES screw fitting only and an adapter is required to use them in a more typical UK, BC bayonet fitting.

Initially, the bulbs will only be available through the Apple Store and can only controlled by an iOS or Android app (plus web interface). Philips hopes that software developers will create their own apps for Hue, which uses an open standard called ZigBee Light Link.

Bulbs like this are not really as smart as they are claimed to be. These types of bulbs need a permanent power supply, in order to be able to control them. The Philips Hue bulb can only be contrrolled via the Smartphone app for now, though people are already hacking the control protocols. If you do put it in a normal light fitting and switch it off, that's it, no more remote control. At least they have designed it to come on with full 'warm white' brightness when power is reapplied, so it will work like a normal bulb. Don't underestimate how much of a chore it will be to get your iPhone out to turn a light on!

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