Converting to LED lights: everything you need to know

I'm 100% LED now - even my fridge light is LED. You don't need to go that far - I'm a little obsessed! It has taken me a couple of years of learning to get it right.

The most important lesson has been light 'temperature'. This is measured in Kelvin (you'll find it on the packet of any light bulb). I like a warm white, much like the old-fashioned tungsten bulbs. This is about 2700 Kelvin (K).

It's interesting that folks from colder climates tend to favour a warm light, while folks from hotter climates prefer something more white or blue. Now I understand the colour I like, I generally get the right bulb each time.

One of the reasons I switched to LED is that I have solar panels on my roof, which contribute to the electricity demand of my house during the day. However after I bought a real-time energy meter I quickly learned that I was using a crazy amount of electricity at night - when my panels don't help. With a bit of investigation I realised my lighting was drawing a lot of electricity. But my electricity bill for my three-bedroom house is now £7 a month, and upgrading my lighting played a big role in that. Even if you don't have solar panels, lighting uses a lot of power. The good news is, it's one of the easiest things to change.

Knowing which colour you like is important.

My personal preference is for 2700. A nice warm light.

I am assuming that these are the spotlight type bulbs.

It depends if they are low-voltage or mains. You can tell this as low voltage bulbs have 'pins' (right - see below) to connect them and mains have 'pegs' (left). If they are pegs it's not a problem, but I'd suggest you replace them all anyway. Halogen bulbs use so much electricity for the light they produce - just feel their heat - that it's a false economy to wait until they blow to replace them.

If they are low voltage (pins) it's a bit more complicated. They will have a transformer either in the ceiling or light fitting. Some LED bulbs, like the Philips Master LED range, have in-built circuitry that can deal with most (but not all) transformers, so you don't have to change them.

In other cases, you need to replace the transformer with an LED driver. This is because the transformers are too overpowered for the small amount of electricity that LEDs need. You will need an electrician for that.

Lots of people tried LED lighting when it was first available and it often produced dim, cold puddles of light.

Those memories still persist, so in fact a lot of what I do is to persuade people that this is no longer the case. I take a selection of bulbs to people's homes so they can see the range of colours, brightnesses, fittings and so on, so they can try before they buy. That way they get what they want without making costly mistakes. It blows the old 'bad bulb' stereotype to bits and the people I know have so far been universally delighted.

There are still some challenges on packaging that don't make it easy to choose right bulb for its purpose, but there's a growing lobby for non-nonsense labelling, so hopefully things will change. Take a look at my guide at the end of these questions for a step-by-step approach to getting it right.

Throw them away or recycle them if you can. You can find more information of where to recycle here. Please note that you should never throw CFL (compact flourescent tubes) into your general waste, as they contain mercury - another good reason to replace them!

The energy you save by replacing them will far outweigh any embedded carbon in the production of the old lightbulbs.

There are still some energy savings, as LEDs do use less energy than CFLs. But you are right, they are nowhere near as great as if you were replacing old-fashioned light bulbs.

If you are happy with the light there is no need to, but as you replace them you could go LED. You can buy a good quality non-dimmable spot for as little as £4 now (IKEA's range are well priced and produce a great quality light). The other benefit, as you mention, is they are 'instantly on' - no hanging around while your bulbs warm up.

I see what you mean - you only have to stand under those bulbs in a bathroom or kitchen to feel the heat pouring off them!

But this would be an incredibly inefficient way of heating your house, for a number of reasons. First, you don't always want heat, so in the summer for instance, you are heating your house when you probably want it to be cooler. Second, heat rises, so heat from ceiling lighting will stay close to the ceiling and therefore won't benefit the occupants of a room at all. Third, it's much cheaper to heat by gas, or biomass, than electricity, and your boiler will have a thermostat to control the level of heat.

I always find it hard to recommend suppliers as it's really a personal choice. Generally, it is worth remembering you get what you pay for, so with a few exceptions, very cheap LED bulbs won't perform well or last long.

I use energybulbs.co.uk and ledhut.co.uk as they have great returns policy and a good choice. I am also a fan of IKEA's new LEDARE range as they produce a warm and bright light. Do bear in mind this is just my personal recommendation.

Yes – dimmable LED lights are very reliable now. There are a few things to bear in mind.

You may have to get your dimmer switch changed to a 'leading edge' or LED compatible dimmer. This is because they handle much lower loads. For example if you changed a '4 x 60 watt bulb central light' to LED you would go from switching a load of 240 watts to nearer 30 watts.

Some bulbs have built-in circuitry to manage dimmers; some don't. They best way to find out is to install them and if they don't dim well, or flicker, you will know to replace the dimmer. They are no more expensive than 'regular' dimmer switches.

I have dimmable lights in my kitchen and living room and they work perfectly. Just make sure, when you buy bulbs, they have the dimmable logo on the box or that it states they are 'dimmable'.

Poor quality, cheap bulbs don't last long. My experience is that if you buy quality they do last.

Some of my LED bulbs are more than 5 years old and still going strong. If your bulbs are blowing on a regular basis there may be something else wrong - loose connections in lamp holders, faulty connections to light switches, over-heating a bulb in a small confined space and so on. If this happens elsewhere in your home it could be a general issue; if it is in just one room, a local one. In either case it might be worth contacting an electrician to investigate it for you.

While there are energy efficiency advantages to 'voltage optimisation' (this lowers the voltage in your house to about 220v, which nearly all appliances now work on and thus saves money), I suggest you find out what's causing the problem, as these systems cost a fair amount and may not solve your issue.

They are not quite as cheap as low energy bulbs yet but they are getting there.

When I think about how much a bulb costs, it is also worth thinking about the running cost. For example, lets say you have four spotlights in your kitchen, it costs £80 a year to run those, whereas LEDs will cost £7 a year to run. The 'payback' time calculation is important. It might be tempting to buy the cheap non energy-efficient bulbs, but in the long term you will be better off.

You can buy them in many places now - all DIY stores, lighting shops and online. Have a look at my guide at the end to making the right choices for you. There is nothing wrong at all with using modern low-energy bulbs (the new ones come on instantly too) if that is what our budgets lends itself to.

The elusive perfect bulb - a quest close to my own heart!

Ok, first things first: if you want a warm light you need to choose something with a Kelvin count of 2700 or less. Any higher than this and it will be a colder light.

Next, choose the light output you want. As a general rule of thumb most people know that a 100w bulb is bright and suitable for a main light, that a 60w bulb is suitable in a lamp, and 25w bulb works where we want soft and gentle light. LED bulbs use about 10% of the energy of traditional bulbs – so 10w will give you the equivalent light output of an old 100w bulb, 6w of a 60w bulb, and so on.

This one, from Ikea (again just a personal suggestion) might suit your purposes. If not, armed with the information above, you should be able to get what you need.

Incidentally, if your fitting is a bayonet fitting, you can easily buy converters on places like eBay that allow you to use a screw fitting in your bayonet lampholder. In this case you would need a B22 to a E27 converter.

Is it possible to replace GU3 halogen bulbs (the sort with two thin pins at the back) with LED lights, without ripping out the entire system? I have asked this question before, and was told no, but technology is changing all the time.

Yes, it is possible. The GU tells us that the base has a bi-pin cap, meaning that it has two pins and the number, the distance between the pins - in your case 3mm.

So it is simply a matter of finding an LED replacement bulb that meets that specification.

I had a quick look online and it is possible to source them as more and more LED bulbs are now being introduced. Remember, these are generally low voltage bulbs so you will need to ensure that they are compatible with your system. See my other answers (and guide below) about replacing low voltage lighting.

When you are replacing very specific bulbs, see you if you can get an 'exact match' or 'perfect fit' labeled bulb so that you know they will fit into the existing aperture.

What's on?It sounds obvious, but the best place to start is to work out which lights are on the most, and replace them first. In this way, you will maximise your saving.

How much light? Light is measured in lumens, but this is too complicated to work out every time you buy a bulb. So as rough guide, if you want the equivalent of an 'old school' 100w light bulb, go for 10w, 60w – 6w, 40w – 4w. The mathematicians among you will spot a rough 10% rule. For spotlights, replace a 50w GU 10 with a 4w LED bulb.

Which colour?Light temperature (colour) is measured in Kelvin (K). The lower the number, the warmer the light. Because I like a warm light, 2700K is my preference – it's like the light from an old-fashioned bulb. 3000K is less warm, and then as you go up the light becomes cooler and whiter – anything approaching 5000k will be nearly blue. Sometimes these are called 'warm white' or 'cool white'. So, depending on your preference, check the packet to make sure have the right colour for you.

Do you want to dim your lights?You will have to pay a little more for dimmable bulbs, but they are available across the range. Look for the 'dimmable' symbol on the packet. Just a word of warning – occasionally, because LED lights use so little energy, you may need to change your dimmer switches too (ask a qualified electrician to do this for you).

Got the right fitting?You will have a range of light bulbs in your home with different fittings – just make sure you match the fitting to the one you are buying. The best way to do this is to take the old bulb along with you. If you are replacing down-lights or spotlights, take one out (when it is cold and switched off) and see if it has 'pegs' or 'pins'. If it has pegs, this is mains voltage (a GU10 fitting) and is no problem to change. If it has pins, this is low voltage lighting and is a little more complicated. You may need some advice from a professional as to which bulbs will work in your home.

Finally, when you are changing your lighting, think of it like re-decorating a room, where you would buy a paint tester pot to see if you like the colour first before you paint the whole room. When you are investing in new bulbs, buy one first to see if you like it before you replace the rest. And remember, most places will exchange the bulb if it is the wrong one for you.

Once you have changed your bulbs, you can sit back (you won't need to get up to change them for an average of 15 years) and bask in their glow – and be smug in the knowledge you're quids in.

Interested in finding out more about how you can live better? Take a look at this month's Live Better Challenge here.

The Live Better Challenge is funded by Unilever; its focus is sustainable living. All content is editorially independent except for pieces labelled advertisement feature. Find out more here.