Wednesday, 20 January 2010

Finally, LED replacements for 12-volt halogen spotlights!

It's almost 3 years since I replaced the many mains-halogen GU10 bulbs in my house with compact fluorescent alternatives. At about £8 each they were a significant investment but they have been paying me back in reduced bills ever since.

I was still stuck with about a dozen 12-volt halogen lights known as MR16. No CFL alternative exists and sufficiently bright LEDs have only recently started to come to market. I have now found suppliers for LED bulbs that are bright enough to replace MR16 halogen bulbs, at £10 - £25 each. I can't spare £25 a bulb but I am happy to pay £10 a pop to get rid of my remaining, wasteful MR16 halogen lamps.
There is a catch, however! Buried in the small print on the LED bulb packaging is the warning that they must not be used with standard, 12-volt halogen power supplies. Instead, they must be run using dedicated "LED drivers" which will not supply excess voltage when using such small loads.

There are two solutions to this situation:

1) If you have room above or behind the light fitting, for example in a recessed downlighter, you can simply rip out the MR16 socket and its 12-volt power supply, and fit a GU10 connector in its place.

This photo of our bedroom shows 4 LED bulbs (240 volts, GU10 fitting), each using just 3 watts - that's 12 watts in total. Each has a single LED and a lens to focus the light. While they are less bright than the halogen bulbs they have replaced, they do project the same lighting shapes on the bedroom wall and are as aesthetically pleasing.

They have replaced 4 halogen spotlights (12 volts, MR16 fitting) and 4 separate power supplies, using over 200 watts. Total saving 190 watts, at a cost of £50 for the bulbs and the GU10 connectors.

If these 4 LED lights are used for 3 hours a day, they will save £25 a year on electricity (paying for themselves in just 2 years) and avoid 90 kg of CO2 emissions annually.

2) Many halogen light fittings are multi-spot designs. It is not possible to switch these over to mains operation, using GU10 connectors. Instead, you can buy an LED driver (mine cost £8 from TLC-Direct) and wire it up inside the light fitting in place of - or alongside - the existing 12 volt power supply.

Then replace the halogen bulbs with MR16 LED lights, as shown in the "flying pig" multi-spotlight on the ceiling of my son's bedroom. These LED bulbs and drivers are using 9 watts in place of 60 watts that the original halogens consumed.

Once converted to LED lighting, you must ensure that halogen bulbs are never refitted in place of the LEDs as this would destroy the LED driver and could cause a fire hazard.

While it is straightforward and legal for a competent, non-qualified person to fit LED lighting in place of halogen lights, as described in this blog, you should pay a qualified electrician to do the job if you are not sure of your capabilities. If you are doing it yourself, make sure the lights are off before you start work and that nobody will wander in and turn them on!

Here is the third and final example of LED lighting that I have fitted this week. Our very dated drinks cabinet incorporates three incandescent light fittings, each with a 30 watt striplight. I was able to replace these with 2 watt LED striplights for £10 each, from RS Electrical, saving 84 watts. If used for 3 hours a day, the annual savings resulting from this conversion will be £11 and 40kg of emissions.

Monday, 11 January 2010

What I paid the chlidren

You may recall that I promised my children the full financial benefit of our home's energy savings in 2009, as an incentive for them to concentrate on switching things off, avoiding standby, and so on.

At the end of November I predicted a 10% saving, worth £100 to my kids. In the event, December turned very cold and we had to use much more gas than expected. Still less than last year, however! The annual gas usage fell by 374 kWh, just 2.6% of our total.

We did much better on electricity - saving 728 kWh vs. 2008, that's a reduction of 12.1%. Overall, our 2009 energy usage was 5.4% less than 2008 and resulted in a 7% reduction in CO2 emissions.

So what did the kids earn? £44 each. Good for them, they helped reduce energy wastage throughout the year. Hopefully, this will become instinctive for them as they grow up and make their own ways in the world.

Now for the 10:10 challenge! Since September I have invested in serious loft insulation and replaced the undercounter fluorescent tubes in our kitchen with LED striplights. For Christmas I was given the Fit-PC 2 net top computer (running Windows XP) which has completely replaced my 6-year old Mesh PC tower. This little black box (10cm X 12cm X 3cm) runs silently on just 8 watts, compared with up to 200 watts for my old Mesh monster. If your desktop is left on 24/7, replacing it with a Fit-PC would pay for itself within 3 years. Of course, the first thing to do is stop leaving it on 24/7 - as I did a couple of years ago - but even so, I can now take great delight in running spreadsheets, email, music, videos and internet as fast as ever, but for less power.

With other tweaks around the house, I have managed to halve my baseload electricity consumption (ie., everything off apart from landline phones, built-in appliances, hard-drive recorder, etc) from 160 to 80 watts.

I am setting the benchmark for my 10:10 challenge, at home, as the year to Christmas eve 2010. To cut our emissions from home energy use by 10%, compared with the same period in 2009, our targets will be 17,425 kWh in total (4,770 kWh electricity, 12,655 kWh gas), resulting in household emissions of 4.5 Tonnes CO2e.