New energy saving gadgets ordered

Following on from today’s earlier post, I’m still searching for ways to make the house more efficient.

Lighting

We currently have some 240V, 50W halogen lighting in the hall, which generate 1000 candelas of light.  Now, there are 8 of these, so that’s 400W when they’re all switched on.

Today I ordered two Philips Master LEDlamps (these things aren’t cheap—over £25 each including VAT), but they do only draw 7W.  They’re also dimmable, and should fit in to the existing sockets.  If they don’t work out, I can still return them and get my money back.

Heating

In addition, I also ordered two electronic radiator control valves, that allow me to programmatically set the temperature a room should be at various times.  The target is the living room with the gas fire.  While the balanced flue fire appears to be around 90% efficient, it’s still easier to heat the lounge with the main central heating.

The plan is to not heat the room at all until 3PM, and then heat it to a base temperature until 8:30pm-ish, when the heating will switch off.  Normally, if we’re in the room, we’ll put on the fire to make it extra cosy, so if no-one’s in for any evening, it won’t keep heating.  When the fire’s on, it will warm the room sufficiently for the boiler to stop supplying heat to that room, and heat the rest of the house instead.

These devices aren’t cheap either (£25 each), and I need to drain the central heating system to add them, but as the current valves are leaking, I need to get a plumber in anyway.

Fingers crossed.  I can’t wait to see what effect these things have.

Solar PV, 3 weeks in

Our solar panels have now been in for exactly 3 weeks, and in that time we’ve generated 140 kWh of electricity.

It’s been a fairly sunny three weeks, but the panels are generating to specification.  If you want to know more, please contact me.

In order to see what is going on, I also purchased an energy monitor, which I’m developing some software for. The monitor measures the current every 6 seconds; measuring what the house is consuming, what the solar PV is generating, and aggregates the data. You can see our usage since I bought the monitor above. I’ve also got sensors on several appliances around the house as well as the under-floor heating, so more measurements should be coming as we enter the heating season in October.

The green dots at the top are the total kWh used by the house each day, and the yellow dots at the bottom are what was generated by the solar panels.   The bar graph is the consumption for two hour periods each day, the the sample immediately after the date line being from 1-3 AM.  The values above 0 are consumption, and the values below are generation from the solar panels.

The monitored values are currently inaccurate, as you’ll notice the generation in the middle of the night.  This is because the current measurement does not correct for power factor, but that is alas another blog post.

The good news though?  Over the last 3 weeks we’ve used almost no net power during daylight hours, averaging just 1.5 kWh.

Another way to cut CO2 and save money

While I had been focusing on the house as a way to cut our CO2 emissions, it was becoming apparent that there would be little we could do to find any more significant reductions in usage.

But, there was something we could change lurking outside of the house.  The cars!

We drive an average amount, and had a Renault Alliance convertible that was 25 years old, and got about 22 mpg in town (though it only drove 3000 miles) and a Chrysler Grand Voyager that got about 30 mpg, that was 10 years old, and starting to cost us quite a bit after we had its gearbox refurbished.

Rather than continue to fret about these two cars, I put my foot down and decided we needed to do something about it.

Now the UK has a scheme where cars that put out less than 100 g/km pay £0 road tax, less than 110 g/km pay £20, less than 120 g/km pay £30, and less than 130 g/km pay £90.

Older cars pay £180 per year.  So, right there, a potential savings of £360 a year, if I an get two cars in the lowest band.

Well, that didn’t happen, but we did manage to get a Citroen C1 (or Toyota Aygo/Peugot 107 depending on which brand you went with) that attracts only £20 road tax, and a Kia Cee’d SW 2 that attracts £90 road tax.  We had tried to buy a Skoda Octavia that is in the £30 bracket, but unfortunately had to cancel the order as delivery slipped.

The C1 has now done 4400 miles since we bought it (and with my son learning to drive in it), and averaged 48 mpg, more than double the 22 mpg car it replaced.

The Kia has been travelling all over the country with a boat on top for my daughters sailing, and despite that, has averaged 47.6 mpg over the 7000 miles it has travelled.

So, the Chrysler generated 58% more CO2 than the Kia and the Renault generated 118% more than the Citroen.

How much CO2 have we saved?  A ton!

On the Kia, 647 l * 2.7 kg / l * .58 = 1013 kg
On the C1, 416 l * 2.3 kg/l * 1.18 = 1129 kg

That’s a 55% reduction in CO2 caused by travelling, and that’s assuming we had the same cars.  In fact we’re actually driving less now too.

And how much money since last October?

Kia: £871.26 * .58 = £505 + £90
C1: £519.46 * 1.18 = £612 + £160

Grand total: £1367 in the 10 months we’ve had the cars.

An update on energy use

I haven’t updated the blog for 2 years, so here are the last two years worth of figures and the previous year for reference.

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

Our energy usage appears to have stabilized; here’s the daily average usage in kWh.

	Low Rate Electricity	High Rate Electricity	Gas	Average Total	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

What happened in 09-10?  My wife was away skiing, and it was also very cold.  I took the opportunity to tape over the open fire in the lounge with cardboard and duct tape.  I had planned to stick a picture of some flames on top too, but never got around to that part.

That simple measure dropped our usage by over 10%.

In November 2010 we replaced our open fire with a balanced flue system, installed additional installation over another part of the loft, and installed new double glazed french doors.  Despite this, it appears that our usage actually increased, though that may have been caused by a large family Christmas last year.  We also actually used the fireplace, and the loung was a little warmer.

It certainly felt like a colder winter last year, despite the number of degree days being lower, and we had long period of snow and sub zero temperatures.

Alas, because of the balanced flue, we began to have some problems with condensation, because air wasn’t being sucked out of the chimney, so we also began using a dehumidifier for some of the year to prevent condensation.  It turned out reorganizing the loft to add additional insulation had blocked the airflow, and that was actually the cause, so we now rarely use the dehumidifier.

Again, I also tracked our neighbours usage (with their permission of course)

	Average Daily Total kWh	Per Degree Day @ 19.5
08-09	106.70	8.50
09-10	98.93	7.95
10-11	94.74	7.76

This autumn, we install Solar PV, as I mentioned earlier today.  Fingers crossed we can bring down the energy usage even more.  I’ve also started a campaign to hibernate off PC’s when you’re not actually sitting at them.

Solar PV

Earlier this year I wrote:

I keep hearing people tell me that it's crazy not to install PV on our house, especially with feed in tariffs that pay back almost 40 pence for each kWh generated, so I thought I'd look into it at bit.

So, start with the assumption that we fit about 2.1 kWp to the house, that means that on a perfect day, the solar grid would produce 2.1 kW of power. It turns out that where we are, the expected output of that panel would be around 1750 kWh per year. That currently costs us about £150 for that amount. Now, the feed-in-tariff would also pay an additional £720 per year (tax free? maybe let's assume it is).

Now, the installed cost for this system is £8700, which the solar websites tell me would make me £29,000 better off after 25 years, and that I break even after 8 years and 6 months. Really? Where do I sign up, and do you have a bridge you want to sell me too?

Sure, the government currently promises that we'll get the subsidies over 25 years, but I'm not sure I trust promises from governments.

Now, what's the real payoff time?

Well, first of all, the opportunity cost on the money is missing. Let's say that you take your savings out of a nice safe bank account to pay for it, and that it's currently paying you 1% interest.

The lost interest costs you £87 per year, so that now takes you 13 1/2 years to break even.

But I know you manage your money better than that. You can get 3% really easily here in the UK, and interest rates are soon to rise. At that rate it's 13.5 years, but if you think you can pull off 4.5%, it goes all the way out to 18.5 years. Don't even think about taking out a loan at 7.5% to pay for this; if you do, payback goes out to 31.5 years!

If you instead ignore the government subsidy, even at a paltry interest rate of 2% on your money, you're losing £24 a year every year.

Never mind you've invested your capital so if it breaks, you lose your investment, unless you insure which costs you money, making payback worse.

So, for me, I've decided to put this on the back burner again, until something else changes.

What’s Changed?

My old college roommate installed the panels on his house, and they are producing electricity as expected.  Based on the quotes he received I did the above calculations.

However, when I actually came to have someone quote me, the installed system price was just over £6500, giving me a payback time of shortly over 7 years.

The parts are guaranteed for 10, so even if it all goes wrong, it looks like the system should pay for itself, so we’ve given the go ahead, and in just over 4 weeks time, we should be generating a quarter of our electricity.

Winter came and went

We're now just past midsummer, and I still haven't updated the blog. I guess I must have been saving time.

I'm most of the way through reading "Sustainable Energy-without the hot air".

This book is really good, and best of all, it's available free online at http://www.withouthotair.com if you want to be really light on your resource consumption.

2008-2009 Heating season

For my records, the heating season started last year around September 29, and ended April 20, 2009. I'm defining the heating season as a week where we used on average more the 50kWh per day of gas, our primary heat source. We installed a new 90% efficient condensing boiler in February 2008, and unbelievably it actually did use 20% less fuel than our previous boiler that was installed when the house was built in 1985.

I also installed a weather station just over a year, ago, and using software from http://www.wieser-software.com/metstats calculate that the number of degree days during the same period was 2134 calculated against a base temperature of 19.5°C. That's an average of 10.51 degree days per day for the 203 day period.

During the period, we averaged 16.3 kWh of electricity between 7AM and 12:30 AM and 7.2 kWh during the off peak hours. We also averaged 71.9 kWh of gas per day. So, our total energy usage was 95.4 kWh per day, or 9.08 kWh per degree day.

I've also been keeping track of a neighbours house, but they keep their thermostat at 19.5°C, which comes out to an average of 12.51 (by adding 2 to our degree day figure, due to the temperature difference). Their usage was 106.7 kWh per day, or normalized for degree days 8.5 kWh per degree day.

Conclusions

Their house is a different shape from ours, and has recently been practically rebuilt with to new building code standards. It looks like our house is 6.8% less efficient than theirs, however due to our house being heated to two degrees less, we managed to consume only 93% of the energy they did, so it's proof it is worth turning your thermostat down, if you want to save money.

Next year's challenge: See if we can cut next season's kWh per degree day.

Notes:

This calculation isn't strictly correct yet. To do this completely accurately, the base line load for each house when zero degree days are seen should be subtracted before the calculations, to only include the extra cost of heating.

Looking at the figures from the beginning of June, both houses used an average of 26 kWh per day during the non heating season, bringing their house to 6.45 kWh per degree day, vs our house at 6.6 kWh per degree day, making our house only 2.3% less efficient than theirs.

Why won’t Word 2007 save my documents in pretty HTML

Back in older versions of word, you could get an add-in to save to Export to Compact HTML.

Word 2007 includes built in saving of filtered HTML, but it's not without its problems.

While trying to update an online file, I found that word was generating the document in one language, and then setting the style of every paragraph to be

lang="EN-GB"

That was eventually solved by changing the default UI language of the program, but I can't see why the UI input should be connected to the output when I save a file.

The old version of word was happy to export the file without all the noise, but the new version insisted on decorating every line. It also insisted on decorating the bullets and numbering with a hardcoded font reference to Times New Roman 7 point, and added an nbsp tag. Eventually I found the adjust list indents, and replaced it with a simple space, instead of a tab, which was the cause of that particular problem.

Of course, blogging isn't easy either

Not having wasted enough time today, I decided to start using my blog. Well, hey-ho, I can't upload to blogger either.

It looks like it's because I haven't yet saved my file in docx format, and therefore it can't be uploaded!