28 Feb 2011

The Mackay Calculator gets even bigger

I've probably made a complete fool of myself, but vanity got the better of me last week and I agreed to test drive Prof. David Mackay's 2050 Pathway calculator. That's the spreadsheet (dressed up as a series of checkboxes and natty graphs) which he has created to try and tease out just how we might go about making the UK a low carbon sort of place by 2050 (just in time for my 97th birthday).

The results of my haphazard navigation are about to go on public display at the DECC website and, worse still, I am meant to be taking part in an online debate with some other guinea pigs on Thursday and Friday this week. It's being hailed as an energy-literate conversation, but trying to get to grips with this project is enough to make anyone feel like a numpty. You can't help but come into an exercise like this without carrying baggage, and I anticipated it being a showdown between pro- and anti-nuclear camps, but the funny thing is that, if you tweak the calculations a little, you can very easily arrive at a situation where we are literally swamped with low carbon electricity and are desperately exporting it to all and sundry. You can do this with or without nuclear power, so this particular aspect of the debate rather palls into insignificance.

Much more worrying, for me, is the decision on what to replace oil and gas with. At the moment, Mackay reckons it's biofuels or heat pumps, but of course I don't really warm towards either. That's my baggage. And also, I suspect, the reason I have been asked to guinea pig this stage of the project. "That Brinkley," thinks the Prof, "he hasn't a good word to say about biofuels or heat pumps, and he's always criticising the Renewable Heat Incentive, so let him try and work out how to get to 80% carbon reduction without them, ha!" Indeed, I'm not sure I can, so my immediate instinct is to call foul and to complain that there aren't enough checkboxes for the hydrogen economy which I imagine may ride to the rescue with a train load of fuel cells. Well, 2050 is still a long way off: it's pretty much all speculation, isn't it?

You can of course tweak the demand side as well, which I did with abandon. This makes everything about fifteen times more complicated, but it still leaves a big gap around heating, even if you max out every lever you have.

There's certainly some food for thought here. Take a look after Thursday and see what you make of it. It's going to be somewhere around here.

Mackay gets a nod as well today on a fascinating article about thermal underwear on the Low Tech site. No, really, it is fascinating. What interests them here is the Professor's claim that the average temperature in UK homes was 13°C in 1970. They ask how he knows this. In fact, this claim is expanded upon in the 2050 Pathway explanatory text which suggests the following:

The mean internal temperature of UK homes during the winter months was 17.5°C in 2007, compared with 16°C in 1990.

In fact, Mackay shows a graph of average internal temperature from 1970 to 2050. All good stuff, but just where does this information come from? And can we believe it?

In the meantime, it's off to Ecobuild where I'll be on Tuesday and Wednesday. In fact, I am on the rota to populate the PassivHaus trust stand on Wednesday afternoon, 2-4, so do drop by if you want to upbraid me.

17 Feb 2011

More on Denby Dale: lessons learned

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.

Mark: And?

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....

9 Feb 2011


I've always had this nagging feeling that there was something amiss in the world of SUDS. I thinks the whole acronym thing is a clue here. SUDS stands for Sustainable Urban Drainage Systems. I have even seen it written as Sustainable (Urban) Drainage Systems. It's that Urban bit that stands out. Why in particular should a drainage system be Urban, rather than rural or suburban?

And if it is urban, should SUDS be restricted to urban areas? Are SUDS necessarily a green solution to the problem of surface water run-off? Or just a good solution for densely packed areas where flooding might be a problem?

Maybe it's that word Sustainable at work again, but SUDS have somehow been incorporated into the Code for Sustainable Homes as a must-have feature. You might think that a good old fashioned soakaway would be just the ticket but the Code calls for something a little more sophisticated than this. It requires you to provide robust hydraulic design calculations referred to in key guidance documents such as The SuDS manual (CIRIA C697, 2007) and Preliminary rainfall runoff management for developments (EA/DEFRA, 2007).

Blimey. Sounds like you need an expert! Indeed you do. Suitable professionals may be found in a variety of disciplines, such as engineering, landscape design or hydrology.

Now experts have a habit of recommending complicated solutions and the Code experts have cooked up a real beauty here. It now seems that if your site doesn't pass the porosity test for normal soakaways, then the Code requires that you fit a rainwater harvesting system to act as a holding tank for surface water run-off. Now rainwater harvesting systems are all fine and dandy (or at least many people think they are) but not even their biggest fans think that they are to be confused with SUDS, as their purpose is quite different.

A SUD system is basically just an engineered-but-still-dumb soakaway, whereas as rainwater harvesting system needs a good deal of management and lots of bits added onto it in order to function correctly. As well as being expensive to install (maybe £3,000 per property), they also have to be maintained.

But the way it stands, if you are on a site where conventional soakaways will not work then, in order to get to Code Level 3, you will have to fit Rainwater Harvesting. Not to deliver low levels of water use within the household (for which it is designed) but to act as a SUDS-compliant soakaway (for which it isn't). And that would seem to include sites well away from urban areas.

Have a look at this video of some of the recent Queensland flooding and ask yourself how your rainwater harvesting system would have coped. Or, for that matter, just about any SUDS system you could dream up.

3 Feb 2011

Lost in Translation

Hats off to the Department of Communities and Local Govt for publishing these forgotten documents commissioned by the old government. Mel notes that the cost of these 16 documents was £691k. I was curious. What was in them?

Here's one called Behavioural change approach and the housing sector: a scoping study. It seems to come from Sheffield University's Town Planning Dept.

And here's the first paragraph of the executive summary: This project explores the potential benefits from applying a behavioural economics approach to the analysis of the attitudes, perceptions and decisions of actors operating in the housing sector. The central features of this methodological approach emphasised here are that: economic agents operate under bounded rationality and sometimes use rough rules of thumb to negotiate uncertainty; the limitations of incompleteness of knowledge can be compounded by creative and imaginative capacities; individuals are socially embedded; durable rules, habits and norms are significant and shape beliefs and attitudes; and emotions are a key part of ‘rationality’. This contrasts markedly with the methodological individualism and narrow economic rationality associated with the mainstream economics approach.

What the fuck does any of that mean? Planning, but not as we know it.

Or how about this one?

Collaboration, innovation and value for money: final report of the call-down project, which seems to have come out of the Department itself.

What are they on about here?

Our research suggests the following definition: “Innovation is the collaborative development and implementation of new ideas, knowledge, products, services or ways of working that significantly enhance previous activities, drawing on the resources and skills of a range of partners and users to create partnership-based financing, decision making and production systems to improve performance and outcomes”.

What twaddle!

And here's another curious one. A study to determine whether it is possible to produce Gross Value Added data for upper tier local authorities from Cambridge Econometrics, which I know as a rather smart little building next to the Six Bells off Mill Road. I've always been curious to know what they get up to and now I do. Or rather, I don't. Here is their methodology statement:

NUTS level 3 are currently the lowest geographical unit which the Office for National Statistics produce Gross Value Added figures. NUTS3 areas vary in size, in some cases equivalent to upper tier authority boundaries; in other cases equivalent to groups of upper tier authorities. The purpose of this study is to assess whether Gross Value Added can be produced for all upper tier authorities – i.e., including upper tier authorities which are part of a wider NUTS3 area. This methodology described below is an adaptation of the existing method used by the Office for National Statistics Regional Accounts, applied to a smaller geography. It provides details of the data sources, the current availability of data and the indicators used to apportion the individual components of NUTS3 Gross Value Added.

This is altogether fun and a great way to waste a few hours. I can't understand any of it and I doubt that Eric Pickles can either. But it does give you a little insight into the workings of Whitehall under Blair and Brown. This is what all those "Consultants" were up to.

1 Feb 2011

How Denby Dale weathered the cold snap

Snow started falling in Denby Dale in the last week in November and lay on the ground right through Christmas. There was a ten day spell in early December when the temperature in Denby Dale never got above freezing, and it dropped right down to minus 18°C on the coldest night. At last, a meaningful test for the Denby Dale PassivHaus. How did it fare? Geoff Tunstall, the man who lives there with his wife Kate, takes up the story.

It all went just fine. I had to adjust the ventilation system a little, that’s all. The MVHR unit has a night temperature lowering setting which is set to run from 10pm to 6am and this left us with an internal temp of around 18°C in the morning, which we regard as a little chilly. But I changed the default setting and ran it on the day-time setting throughout the 24 hours during the cold snap and that did the trick. The internal temperatures went back up to 21°C. In fact, we overshot, and started to get too hot at one point.

Bear in mind, our gas boiler does three things: heats the hot water, runs the 3kW post heater in the ventilation system and heats a radiator and two towel rails in the bathrooms. In addition to this, we also have a gas hob for cooking. The post heater and the radiators were working throughout the cold snap, and our gas usage reflects this.

We burned just over 1600kWh of gas during December, which cost us around £100. But the months before and after the cold snap were more typical of Yorkshire winters, and in these months we used much less gas — 604kWh in November and around 650kWh in January. Our total gas usage for the five months from late August to late January was only 3394kWh (costing £210 including VAT), so that four-week cold snap accounted for nearly half the total we used. Our average monthly gas bill for the first eight months we have lived here including the cold snap is still only going to be £25 a month. In a more normal winter, it would be as little as £18. Our total electric bills for the first six months were just £108.

How does the performance of the Denby Dale house stack up against the key PassivHaus standard of 15kWh/m2/annum? It’s not a big house — it’s around 120m2 internal floor area, which translates to (120 x 15) to 1,800kWh heating a year. But (you cynics say) they burned nearly this much (1,600kWh) in December alone !

Yes and no. The PassivHaus standard is for space heating only, not for domestic hot water or for cooking, so you have to strip out something for these. Hot water probably accounts for about 250 to 300kWh per month in the winter (they have solar panels for the summer months), and gas cooking perhaps 20 to 40 kWh, especially over Christmas. You can see that the November and January space heating totals are probably around 300kWh a piece and that, had the entire winter consisted of months like these, the total space heating requirement would have easily come inside the 1,800kWh suggested by the Passivhaus standard. The fact that December in Yorkshire resembled what you might normally find in Russia or Quebec is by-the-by. The standard is not absolute, it’s relative to the location and the Tunstall’s home was designed as a Yorkshire PassivHaus, not a Russian one.

But do bear in mind, these are not “homes-without-heating”. Just not very much heating!