Monthly Archives: March 2012

Reflecting on our total home energy usage

The graph of our total gas usage per year doesn’t decrease quite so impressively as our electricity graph, which I blogged about halving over five years. Because the numbers were getting ridiculously big and difficult to compare at a glance, I’ve re-created the electricity graph here in terms of our average daily electricity usage instead of our annual usage (click the graph to see a larger version):

Graph of daily electricity usage per year.


If you compare it with the average daily gas usage graph below, you can see (just from the scales of the y-axes) that we use much more gas than electricity (except in 2007, which was an anomalous year because we didn’t have a gas fire during the winter so we used a electric halogen heater instead):


Graph of daily gas usage per year.

Our gas usage has come down overall since 2005 (from 11280 kWh in 2005 to 8660 kWh in 2011; or 31 kWh per day to 24 kWh per day on average) but not so dramatically as our electricity usage has. Between 2005 and 2011, we reduced our electricity usage by about a half  and our gas usage by about a quarter.

Gas, in our house, is used only for heating rooms and water. So if I were to chart the average outside temperatures of each year, they’d probably track reasonably closely to our gas usage. In 2005 (when we used an average of 31 kWh per day), we still had our old back boiler (with a lovely 1970s gas fire attached) which our central heating installer reckoned was about 50% efficient. In 2006 (26 kWh per day), we replaced it with a new condensing boiler (apparently 95% efficient) but didn’t replace the gas fire until mid-2007 (the dodgy year that doesn’t really count). In 2006, we also had the living-room (our most heated room) extended so it had a much better insulated outside wall, door, and window. These changes could explain the pattern of reducing gas usage year by year up till then.

Old boiler being removed

In 2009, January saw sub-zero temperatures and it snowed in November and December. I think that must be the reason why our usage for the whole year shot back up again, despite the new boiler, to 31 kWh per day. In 2010 (21 kWh per day), it was again very cold and snowy in January; I think the slight dip in gas usage that year compared with both 2008 (25 kWh per day) and 2011 (24 kWh per day) was down to a problem with the gas fire that meant we used the electric halogen heater again during the coldest month. In 2011 it snowed in January but was fairly mild for the rest of the year.

I think 2008, 2010, and 2011 probably represent ‘typical’ years of heating our house with its new boiler and gas fire. Like I concluded about reducing our electricity usage, I think our gas usage went down mostly by getting some better insulation and a more efficient boiler but we did also reduce the default temperature of our heating thermostat to about 17 degrees C (instead of 20 degrees C) a couple of years ago too (we increase it when we need to but it stays low if we don’t), which I think has made some difference but it’s hard to tell when our heating usage is so closely tied to the outside temperature. Also, we don’t currently have any way of separating out our water heating from our central heating, and our gas fire from the boiler.

Of course, what really matters overall is the total amount of energy we use (that is, the gas and electricity numbers combined). So I’ve made a graph of that too. Now we’re talking numbers like 48 kWh per day in 2005 to 33 kWh per day in 2011.


Graph of total daily energy usage per year.

Overall, that means we reduced our total energy usage by about one-third over seven years.

Thanks again to @andysc for helping create the graph from meter readings on irregular dates.

Southampton to Aarhus, booking a train

I just discovered the Deutsche Bahn train booking website. So far it seems really cool!

I’d just been whinging on Twitter about how European governments need to open up their railway data so that companies can set up better pan-European rail booking websites so that it’s easier and cheaper to book journeys that cross multiple countries. And @pete_v replied that he’d used Deusche Bahn:


So I gave it a go. I typed in Southampton Airport Parkway (UK) as the starting point and Aarhus (Denmark) as the destination. Not only had it heard of both stations but it even did text completion on their names! I made up some dates, clicked Search, and within less than a second it had returned a list of possible trains:


And at the click of a button, the full itinerary:


It also provides a comparison with travelling the same distance by car (includes full route planning details and a map – not shown here):


And an environmental report comparing, among other things (not all shown here), carbon emissions from flying or going by car, which is something I think is really useful too:


So, in summary, I think this is a rather cool site! I’ve not yet tried booking anything and you can’t do that online (or at least, not for such a complex journey) but you can book the complete journey by phoning up. You also can’t here see the price (though I have a fair idea of what it’s likely to be based on having played around with individual sites like Eurostar and the Danish railway bookings site) so that would have to be kept as a surprise for when talking to the agent. Presumably, also, it’s not checking actual availability (it’s so quick I don’t think it could be doing) so there are potentially several more steps to go.

But it’s still loads better from a user experience perspective so far than using Rail Europe, or even Eurostar, which throws errors a lot more often than it should. Those two sites, while slow, do at least provide online booking. So Deutsche Bahn still has something to prove. If I do end up going to Aarhus (or elsewhere), I’ll give it a go and report back!

P.S. I also haven’t tried taking a detour through Copenhagen so that I can do a The Killing tour…that should be a real test of it…