Monday, 19 March 2012

More energy price hikes

I just got notice that my current tariff for electricity is set to end.

Lo and behold!  Prices are now going to go up 12% for electricity, and 6% for gas for me if I switch to their cheapest deal.

Or I can opt for a fix until July 1, 2013, at about the same levels as I’m currently paying.

Does anyone think prices might actually drop over the winter period before then, as that’s the period where we use the bulk of the electricity?  If so, let me know.  At this moment, I’m tempted to go for the fixed rate based on the cynical winter price rises we’ve seen for the past few years.

By the way, for anyone interested in the existing rates from Scottish power.

Your energy details at a glance

Electricity prices Your current prices Your new prices from
1st May 20121
Your alternative Offer2

Online Energy Saver 13* Standard monthly Direct Debit* Online Energy Saver 18*
First 225kWh used each quarter 21.006p 22.267p 20.975p
All/Day remaining kWh 9.777p 11.706p 11.027p
Night Units per kWh 5.174p 5.837p 5.498p

Gas prices Your current prices Your new prices from
1st May 20121
Your alternative Offer2

Online Energy Saver 13* Standard monthly Direct Debit* Online Energy Saver 18*
First 670kWh used each quarter 6.730p 7.606p 7.164p
All/Day remaining kWh 2.992p 3.382p 3.185p



Energy consumption down, but efficiency is too

It’s been a warmer than average winter, only 75% as cold as last year according to an independent source, and my calculations bear that out too.

Season Degree Days @17.5C Average Per Day
2008-2009 2134 10.51
2009-2010 2121 10.45
2010-2011 2072 10.21
2011-2012 1567 7.71

This smaller temperature difference  complicates things, as we now have a much bigger effect from our baseline usage, which had been ignored in previous calculations.

  Low Rate
High Rate Electricity
Per Degree Day
08-09 7.20 16.30 71.90 95.40 9.08
09-10 7.09 16.18 62.52 85.79 8.21
10-11 7.14 18.46 60.73 86.33 8.46
11-12 5.49 15.38 50.42 71.29 9.24

As you can see, our total energy use per degree day has actually increased, despite the changes made with better lighting and timed radiator valves.  In addition, we reduced the heating to only 7.5 degrees in a 3m x 4m room at the back of the house with 3 outside walls which uses electrical heating.  I have to admit, I’m disappointed.

Maybe if we look at the numbers differently.  Our baseline gas usage appears to be about 12 kWh/ day, and our electricity usage about 8 kWh for high rate, and 4 kWh for low rate.

Below is the table with units of kWh per degree day.

  Low Rate
High Rate Electricity
10-11 0.307 1.024 4.772 6.104
11-12 0.193 0.958 4.983 6.134

While this is better, you can see that the overall usage is still the same, with no measurable effect from the changes, though High Rate electricity is actually down 7 per cent, and low rate is down 38 per cent, but gas usage is actually up 4 per cent, overall though we used 0.5% more energy per degree day than last year.

I’ll have to put this down the the fact that we have the gas fire on in the lounge in the evenings, and it is really toasty in there.

The other good news though is that we did manage to generate .45 kWh of high rate electricity per degree day over the period, which is included in the consumption figures above.

So in terms of fossil fuels, our consumption has dropped by 7% over the period.

In terms of absolute cost, we used 18%  less energy we did in the previous heating season, but that was unfortunately offset by an 18% rise in prices over the same period, so costs were similar to the previous year.

Friday, 2 March 2012

LED Lighting photos

Yesterday, my sister complained there weren’t any pictures.  Well, here they are:


First, the light fixture the LED’s were replaced into in the bathroom.  The one on the right is the LED, as is the one you can’t see on the left.  I had to leave one halogen, so left it in the middle pointing to the mirror.  This fixture used to be 60W, it’s now 26, and the light appears to be the same warm color from both the LEDs and the halogen.  Output is 285 Lumens, but they are not dimmable.


The photo on the right is of the lamp directly above the mirror.

This is a 240V 50W halogen equivalent led drawing 6W with a GU10 fitting.  Again, the light is a very warm color.  You can see in the reflection on the tiles, the 3 individual LEDs.

This was done before, and isn’t counted in the costs below.


P1000059Finally, the rebuilt desk lamp that had failed.  The old plastic head is on the desk for comparison, with its 20W capsule halogen, compared to the new 3W LED.

You can see that the clamps cause the arms to splay out slightly, but it doesn’t appear to be putting any excessive strain on the fitting.

The lamp is quite a bit larger than the one that was originally in this fitting, but I don’t think it looks too bad from the angle I see it from most of the time.

The total cost of this project was £17.94, and given I replaced a desk lamp that was broken, I think was very good value.  And £10 of the total was an Amazon gift voucher for using their credit card!

Payback time on the project on energy costs alone looks like this:

Old wattage: 60+20 = 80 W
New wattage: 3 + 20 + 3 + 3 = 29 W
Difference = 51 W

Cost savings per hour at 51W = £0.0055

so £17.94 / £0.0055 per hour = 3261 hours

At two hours a day that’s 5 years, and a CO2 saving of 1400 kg to boot.  Lifetime of the lamps is forecast to be 50000 hours, so I should never have to replace them.  We’ll see how they cope in the moist environment of the shower room.

Thursday, 1 March 2012

More LED Lamps

Yesterday, I ordered some new 3W LED 12V bulbs to replace the 3 20W lamps currently in the kids bathroom.  I had been warned that I might need a new transformer, and that they might not work without changing it.

My brother-in-law is an electrician in France, and I asked him about the likelihood that they wouldn’t work, and he thought it would probably be worth a shot, but he had said that electronic transformers might not like such a low current draw.

Well, I plugged all three in, and it appeared to work, however after a short time, I noticed a distinctive hum.

The solution of course is to plug in one of the original 20W halogens, taking the load of the light from 60W to 26W with the new bulbs.  Still a big improvement!

As for the third bulb, I happened to have a failure simultaneously of my halogen desk lamp, which has a transformer, and two antennae which carry the 12V AC.  And from our redecoration of the kitchen several years back, I had kept an old halogen light fitting that clamped onto two rails.

So, a quick unscrew of the old fitting, and a clamp on of the new and I have a new desk lamp that also draws only 3W!