I take a phone call from Geoff Tunstall, owner of the Denby Dale PassivHaus, by now well known to House 2.0 readers as this must be the fourth time I have written about this house. It's also going to be featured in the next (9th) edition of the Housebuilder's Bible, which should be on sale at the Homebuilding & Renovating show at the NEC at the end of March.
Anyway, back to this phone call...
Geoff: I've rung to tell you about February's gas consumption.
Mark: Geoff, are you turning into a nerd?
Geoff: I think I might just be. That last blog post you did, and the comments it drew, caused me to take a much closer look at how we are burning the gas.
Geoff: It's the domestic hot water. I had a look at the settings and it turned out that our system was set to come on in the morning and stay on all day and turn off just at night. I twiddled with it and now it only comes on for three hours in the evening.
Mark: That should be ample. Has it made a difference to gas consumption?
Geoff: Dramatically. Since I did this, on Feb 2, we've used just 250kWh of gas. That's set to be about 500kWh for the month of February, considerably less than we were using in January (650kWh) and November (604kWh).
Mark: How can you be sure it's the adjustment on the hot water settings?
Geoff: I can't. That bloke in Nottingham said we should be metering the separate outputs from the gas boiler, but, hell, we are just a couple of ordinary people who want low fuel bills. In truth, I've also fiddled with the MVHR settings and made the background temperature a degree lower: it was getting a little too hot.
Mark: That might have had a greater effect than changing the hot water settings.
Geoff: I suppose it could have done. But the point I wanted to make it to thank you for writing that post because it caused us to take a look at how we operated the system. And knowing what we know now, I'm pretty certain that next winter we will use a lot less fuel than we did this one.
Mark: That's an interesting point, Geoff, and one that is frequently overlooked. I remember hearing Wolfgang Feist say that the PassivHaus performance standard is only an average consumption figure and that the actual energy usage between similar PassivHauses varied by a factor of five, wholly dependent on how the occupants drove their homes. So if you took say ten PassivHauses in a row, the best one might be getting a score of 8kWh/m2/a, whilst the worst might be as bad as 40kWh/m2/a, but the average score would be around 15kWh/m2/a, which is the target. They would all be built to the same standard: it's just that some people are very frugal and others very wasteful. This difference between best and worst case is mirrored throughout the German housing stock. And presumably the same would go for us.
Geoff: There's another thing that's bothering me?
Mark: What's that Geoff?
Geoff: It's trying to convert gas usage into money. Because of the way gas is charged, the less we use, the more expensive it gets per unit. We don't save as much as we should.
Mark: It's a nightmare, isn't it? I keep referring to gas prices as being around 3.8p per kWh but they are nothing like this, are they? It's the same with electricity. It's meant to be around 12p per kWh, but again it's actually much higher. I have just had my new prices sent through the post from E.on and the first 900kWh are charged at 23.2p/kWh. Only then do they fall back to 11.79p per kWh. Now that first 900kWh at the top rate is the equivalent to a standing charge of £102 a year.
Geoff: So who gains out of that? The utility companies are just confusing us, aren't they?
Mark: They are, Geoff, they are. Why do they have standing charges at all? And why charge for them in this peculiar way? At least the old standing charge was an easy concept to understand, even if it was totally unjustified. The current method of two-tier charging is the most consumer unfriendly set up you could ever dream up. It really is a nightmare trying to disentangle it all.
Geoff: You see, I feel we are not saving as much money as we should be doing because the less gas we use, the more expensive it gets. We are paying on average around 6 or 7p per kWh.
Mark: I'm all for transparent fuel charging, not this muddy soup we now have. I can't believe that they are allowed to get away with it. Hell, I'm off on another rant. Time to go and lie down.
And with that, we bid each other goodbye. But I am left pondering it all. And that leads me to write it down while it's still fresh....