I recently changed all of my incandescent and halogen lightbulbs over to low energy bulbs. I had a few challenges along the way so I thought it would be helpful to share some of my experiences.

The first question I asked myself was whether I should replace the old bulbs progressively as they blew, or change them all over straight away? The environmental answer was probably easiest: given that my electricity supply came partly from non-renewables (something I am in the process of changing by switching to Ecotricity), an immediate switchover would be the best way to reduce my carbon footprint.

But what of the economics? To answer this, I considered the cost of running one of my existing incandescent 40W bulbs versus an equivalent 5W LED bulb. Over ten hours, the former would cost roughly 5p (based on a tariff of 12p/kW). Buying a new bulb would involve additional outlay, but the amortised cost of ten hours of an LED bulb works out at about 0.4p (for a bulb that costs £4 and lasts 10,000 hours). The total cost for ten hours (including energy cost of 0.6p) would therefore be 1p. The answer was clear: I should change all my bulbs immediately!

The next choice was whether to use fluoro or LED bulbs. To be honest, there is not much in this. Both last about the same amount of time; fluoro are cheaper upfront but use about double the energy for the same light. Both would considerably reduce my carbon footprint, but I decided to go mostly for LEDs as they are the most efficient and I prefer the light they give.

The first of my replacements were the standard 22mm bayonet fittings (BC or B22 on most labels). These were the easiest bulbs to source and I got a mix of Philips and NGPS candle bulbs for a bulk price of around £4 each. I bought way too many of these, having not properly assessed all of my (very high) light fittings. It turned out half of them were actually the narrower 15mm fitting (B15). So I returned half of the B22s and tried to find some B15 LEDs. I couldn't find any on the high street, but in the end found some 5W LEDs (40W equivalent) made by Lohas on Amazon (£9.99 for a pack of three). These are all non-dimmable, but I figured replacing my dimmer switches with flick switches was a small price to pay to reduce my carbon footprint*.

Next up were my kitchen spotlamps. I bought a Philips LED 4 Bar Spotlight from Wickes for £50 (including 4X3W bulbs). This was reasonably easy to fit*.

Finally, I did all my bathroom downlights. This proved somewhat more challenging. I bought twenty GU10 5W LED bulbs from Wickes (£20 per pack of 10). The bathroom and the kitchen all fitted fine, but then I got to our shower and found the old halogens had a completely different fitting (two pins that pushed straight in, rather than the newer push-in-and-twist fittings of the bulbs I had bought). So back to Wickes I went to buy some new fittings (£20 for a pack of ten downlight fittings). When I went to put these in, I discovered the old halogens went through a transformer and ran off 12V. So I had to pull all of that out to put in the new fittings*. In the end, I got there and now the whole house runs on low energy bulbs. I don't think it need have been anywhere near as hard as I made it, but now I am there, I thought I'd pass on some of my "learning points" so others don't make the same mistakes I did!

*You should probably get a qualified electrician to do this.