29 Mar 2007

Payback Time

There is an interesting letter in the May edition of Homebuilding & Renovating from Jonathan Belsey, taking me to task for an article I wrote about solar panels, which appeared in the March edition.

He writes:Although the article gave a nice summary of the available technologies, my heart sank when I saw that, as usual, the author (that’s me he’s talking about) was going to focus on return on investment as the major issue of the article. Yes, even with government grants, solar water heating and power generation are expensive and it will take you many years to recoup the money that you have spent. Why is it, though, that only alternative technologies come in for this treatment from the selfbuild press? Why doesn’t your buyers guide on showers in the same issue of Homebuilding & Renovating tell me how long it would take me to earn my money back? Well, of course, for the simple reason that I will never recoup my investment on a new shower. The same can be said of most other items we build into our houses.

It’s not the first time I have heard this criticism levied. And, in truth, I have a certain amount of sympathy with it. But ultimately, it really doesn’t stack up as an argument, because everything you fit into a house serves some purpose. A shower, for instance, is designed to get you clean: there might be cheaper ways of getting yourself clean — a bowl of water, for instance — but they aren’t as good and most people would choose a shower every time. Same with doors, lights, floor covers, kitchen units and stairs: they are all there because they serve some useful purpose.

But what is the point of a solar panel if not to produce hot water or electricity? Solar hot water panels should be looked at together with boilers. When you choose a boiler, you look for something that is reasonably priced and reasonably efficient at what it does. Looks and size may come into it, just, but the choice is largely down to cost effectiveness, with a hopeful look at comparitive environmental credentials as well. Why should you judge solar hot water panels any differently? They are a supplemental heating source, not a piece of environmental sculpture. If you are rich enough to be able to ignore the commercial realities of fitting solar panels, all well and good, but the great majority of selfbuilders aren’t and they have to weigh up the costs very carefully.

So, in my book, payback time remains a critical tool with which to judge all the renewable technologies. Without such an analysis, we have no way of judging which technologies represent good value.

26 Mar 2007

Are you ready for the EcoPod?

Just got back from four exhausting days at the Homebuilding & Renovating national show at Birmingham’s NEC. There is always a buzz about this show but this year was particularly good. The visitors are generally very well informed and the number of really basic (for which read gormless) questions I was asked was almost nil. And we had a few new faces helping to deliver the seminars — Hugo Tugman, Marianne Suhr, Tim Pullen — who were all good and together made a welcome change, especially for David Snell and me, who have been fixtures at these events for longer than we care to admit.

The range of exhibitors hasn’t changed a lot over the last few years but there is an increasing emphasis on smart homes gear and, of course, green building. The abiding image of this particular show will be Aidan Quinn’s EcoPod (pictured), which he hastily assembled the day before the show began.

What the hell is it? Well that was the question I was hearing from the passers-by. And well they might ask. Even after going inside and seeing the tiny kitchen, loo and upstairs bedroom, you are none the wiser. It looked like nothing so much as an discarded prop from the Lord of the Rings. Might make a nice play house for your kids but it is hard to see just what other purpose it serves? A snip at £45,000? I think not.

Still, it got the publicity and it got me to write about it so Aidan must be doing something right.

18 Mar 2007

Eco Bollocks Award: Wales

It must be a sign of the increasingly frantic times, but I am handing out my 4th Eco Bollocks award barely two weeks after Ken Livingstone got No 3. This time the recipient is an entire country, Wales, although it would be perhaps a little fairer of me to give it specifically to their legislative assembly, whose decidedly not-very-low carbon building is pictured here. They seem to have come up with an altogether novel way of combating climate change and that is to start issuing their edicts from another planet, with a view perhaps of taking up residence there sometime soon.

According to the UK government’s Planning Portal website:The Welsh Assembly Government has signalled proposals to achieve zero carbon levels for all new buildings in Wales by 2011, a move which would also entail it taking over responsibility for building regulations. Under these plans they would become a devolved matter. The UK government has already committed to achieving zero carbon standards for all new homes by 2016. The Welsh Assembly Government has stressed it wants to move more quickly.

Great move, boys and girls. Bear in mind that the world has yet to see a single zero carbon building. Indeed the world has yet to agree on what the hell a zero carbon building actually is. Hardly have we recovered from the shock of being told that England has become the first country in the world to commit itself to zero carbon housing, then up pops Wales which says “2016 is for wimps. We’ll do it five years earlier.” Do I detect the same macho posturing as displayed by Ken Livingstone who set London a 60% carbon reduction target twenty-five years ahead of the national government? I believe I do. Hence the award of the prize to the Welsh Assembly.

Environment minister Carwyn Jones said: "We will be opening discussions with the UK government on the devolution of the building regulations which would allow us to set out a standard framework, including zero carbon, for all buildings, whatever their source of funding, which is tailor made for Wales."

Well good luck Carwyn, pictured here. And my bullshit detector started twitching again when I read the phrase “we will be opening discussions with the UK government.” How long do you think that process will take? Let’s hazard a guess of, say, five years, which would neatly take us past the 2011 deadline and also provide an A1 excuse for not quite reaching the target.

Carwyn added: "Once these regulations are devolved, it will allow us to move further and faster on achieving zero carbon on all new buildings in Wales."

Take a tip from me. If you really wanted to save carbon emissions, you wouldn’t be pissing about rewriting a Welsh version of the building regulations. What an almighty waste of time and energy. What Europe needs is a single set of standards applicable across all frontiers, not the Balkanisation of red tape.

Low energy housing in Sweden, Denmark & Germany

On Friday, I attended the debriefing session run by the DTI Global Watch Mission, which sent a small party to Sweden, Denmark and Germany in November. It was similar, in many ways, to the PassivHaus study tour, which I went on in February, but it was a longer tour looking at a wider range of low energy housing projects.

The general consensus was also pretty similar to that drawn by the PassivHaus study tour. In all three countries, they were looking at the same sort of things: a small number of exemplar projects, all with the emphasis is on pretty much the same features: massive insulation levels, air tightness, triple glazing, mechanical ventilation with heat recovery and a little booster heating to get things up to par. It’s a recurring theme: you’d be tempted to think that maybe they have the solution to the conundrum of how best to construct low energy housing.

However, there are subtle differences between the three national approaches. In no particular order, here are some of the notes and calculations I made, as a result of attending the session.

• 80% of new homes in Sweden are heated with electric heat pumps, of which over 60% are ground source heat pumps. Remember, Sweden has loads of hydro-electricity, so electric heating makes sense for them in ways it doesn’t in other territories. They use to prefer the cheaper air-to-air heat pumps but people found them noisy and the growth in the market is now happening with ground source heat pumps.

• In Denmark, 60% of homes have a supply of hot water pumped into the house from a district heating system.

• The Germans pay 50 cents (33p) per kWh for renewably generated electricity sold on to the grid. No other nation does this. Consequently, German roofs are covered in PV arrays.

• Micro Combined Heat and Power plant (CHP), fired by the Stirling engine, throw off one unit of electricity for every seven units of heat. You end up with far too much heat for optimal use. However, the next generation of fuel cell-based CHP, which should be commercially available by around 2010, should produce roughly equal amounts of heat and electricity. This should address the output issue, but at the moment fuel cell CHP is anything but micro: it requires a dedicated plant room.

• There is yet another low energy standard that was mentioned that I hadn’t come across before. The 3-litre house. This refers to the amount of heating oil required to provide space heating for each square meter of a house each year. 3-litres is reckoned to be the bees knees for renovations. 7-litre houses are something close to the building regs standard in Germany: in contrast, the PassivHaus standard is lower still, probably around 1.5-lts. This fascinating new take on a performance standard sent me scurrying off to my Excel spreadsheet which analyses our home usage. On this basis, I reckon ours is an 8-litre house! For a house built 15 years ago, that’s not too bad but I am not sure I should boast about it.

• The 2006 Part L building regulation for England & Wales indicates a space heating requirement or around 40kWh/m2/annum. I reckon that could be termed as a 4-litre house. Or maybe it’s nearer 5.

• Don’t say it too loudly, but we use another 4 litres per annum per m2 just to heat our domestic hot water. These extra litres are somehow overlooked from the standard.

• The Swedes, the Danes, the Germans and the Brits all seem to design homes with a 60-year lifespan. Quite where this 60-year figure came from, I have no idea. Why not 50? Or 75? How come everyone settled on 60?

• Having said that, only around 15,000 homes are demolished every year in the UK. That is one tiny number when compared to the 180,000 new ones built and the 25 million homes that currently exist. At that rate, it will take 1667 years before we manage to replace all the existing homes we have built, which is precisely 1607 years more than their design life. Does anyone foresee any problems building up here?

• The NHBC reckon that currently 47% of new homes being built in the UK are apartments. How long are they going to have to last?

13 Mar 2007

Book review: The Planning Game

In recent years, there has been a spate of new books about selfbuild. Many of them have been Me-Too titles, essentially rehashing the same bits of information that the more established books have already covered. Well, I would say that, wouldn’t I! But I think what has been lacking has been titles that drill down into the different aspects of the building process, which will arguably be of more value to the consumer. The long-awaited appearance of Ken Dijksman’s The Planning Game sets out to fill one of the more obvious gaps, its aim being to guide you through the maze of red tape surrounding the granting of planning permission.

It’s a delightfully easy read, which is saying something for a book on planning. I have worked with Ken over many years at the Homebuilding & Renovating shows, where he frequently held court as our Expert Planner. His sympathies have always been with the developer and the selfbuilder and this shows through right from the opening sentences. In fact the entire first chapter is a masterpiece of understated rage against our little-loved planning regime. This is very much the grumpy old man territory.

And, of course, none the worse for it, because if you are trying to win a planning approval you are almost guaranteed to share Ken’s jaundiced view of the whole process. It’s a game to be won or lost, a game with potentially very big stakes, hence the title of the book. It makes no difference whether you are a rookie homeowner, trying to get permission for an extension, or Persimmon Homes, aiming to build a new estate; the feelings that go along with trying to outwit the planners are pretty much the same.

The book takes you on a guided tour of our planning system. You will find out about all manner of planning arcana, such as lawful development certificates, tree preservation orders and permitted development rights. Ken is a very knowledgeable guide, having been a local council planning officer for 17 years before embarking on a more lucrative career as a planning consultant. He sets out to explain what the laws of the game are and in doing so he has created a useful primer that should be read by students undertaking planning courses just as much as homeowners wanting to understand how the system works. My only real gripes are that the illustrations are uninspiring and that there is no index, though in its place is a comprehensive Glossary of Planning terms.

Overall, the Planning Game is a welcome addition to the selfbuild canon and it’s a book that will not only find a place on my main bookshelf but is also guaranteed to become extremely well thumbed.

7 Mar 2007

On David Birkbeck's selfbuild

If you are the head of an organisation that champions good design in housing, you can’t really build box. But David Birkbeck, director of Design For Homes, has ended up pushing the envelope out of the bathwater. He and his wife Clare are just completing a truly heroic selfbuild, pictured here, nestling in a hollow in the Essex countryside, not far from Stansted Airport.

I have visited the site a few times over the past four years but today is my first visit for 18 months. Although they have been living there for well over a year, it still bears all the hallmarks of an overstretched selfbuild: there are still lots of things to be done.

However, it looks fantastic from the outside and it’s not bad from inside looking out either. But this morning David is full of the woes of selfbuild because there are a number of niggly little snags which remain unresolved. A lot of the problems stem from the fact that the house is built around this enormous free-standing spine wall. The structure is in fact a series of lean-tos, built off this wall. The wall is made up of some shiny white building blocks, imported from Germany, which are held together with a glue mortar, rather like the thin-joint blockwork systems.

No one in the UK had ever used this building block system before and rather unsurprisingly it hasn’t been plain sailing. The joint between the lean-to roof and the wall is failing and no one is sure just why. Did the architects design the detail badly? Did the blocklayers leave gaps in the mortar allowing rain to penetrate into the blockwork? Or was the roof detailed poorly? Or could a missing vapour barrier be the culprit? It is notoriously difficult to diagnose damp problems and the diagnosis is even more problematic when the materials being used are unfamiliar.

David seems naturally keen to decide what the problem is and to then get the culprits to fix it at their own expense. But this in itself may prove difficult because, like many selfbuilders, David has acted largely as his own contractor, hiring in trades as and when needed. Paul Rogatski from Hanson was with us and he made a telling comment: “If you are working with materials or systems that are new to everyone concerned, there is really only so much design you can undertake beforehand. You have to work out a lot of the details onsite.”

It reminded me of a witty little aphorism I had heard a couple of years earlier (I don’t remember where): “The water gets in through the gap between the design and the workmanship.”

It’ll get sorted. Eventually it’ll be all just so and the leaks will be forgotten. In the meantime, a project like this serves as both an inspiration and a warning. If you want to try something different, be prepared for lots of grief along the way.

OK, you know that already. But sometimes it doesn’t hurt to repeat it.

4 Mar 2007

Eco Bollocks Award: Ken Livingstone

Thanks to an alert reader, I have been delving into the real London Climate Change Action Plan, not the Evening Standard’s bastardized version that I was reading on the underground the other day.

It’s a deeply depressing document. On the surface, it looks as though the Mayor, Ken Livingstone, is hitting all the right buttons and he has been widely praised for this by the greenerati for coming up with a plan to reduce London’s carbon emissions by 60% by 2025. But the devil is always in the detail and when you start analysing the proposals, it is pretty obvious that a) there is actually very little Ken Livingstone can do about the situation and therefore b) he is simply spinning a green fantasy. So Ken, I have no choice but to award you my third Eco Bollocks Award for this work of fiction, The Mayor’s Climate Change Action Plan.

Why has Ken’s tour de force so irked me? Put very simply, the math is wrong. The figures don’t add up. And the great bulk of the savings are to be derived from actions over which the Mayor has no control or influence.

If you make a bold claim that you can reduce London’s CO2 emissions by 60%, you have to have some figures to back it up. And there are lots of figures in the Plan. The unit of measurement we have to get our heads around here is the “million tonnes of carbon dioxide released per annum.” For clarities sake, I will refer to these as MTCAs.

London as a whole is reckoned to currently produce around 45 MTCA. If the headline in the plan is to be believed then, by 2025 this figure should have fallen by 60%. The accompanying chart indicates how this will work. If you can’t see it clearly, click on it and it should open in a resizeable window.

Two points to note here. Firstly, the second grey bar shows that under a Business As Usual scenario (BAU), that far from falling, London’s carbon emissions are set to grow to 51 MCTA by 2025. This is accounted for by the new homes and offices that are due to be built. No worries. The cunning Plan will just shave it all off again in order to get the 2025 figure down to 18MCTA, the target figure which represents 60% of the 1990 figure. To its credit, this chart does at least make this clear.

The second point is that you will note that the carbon reduction measures are split into two parts. The first, 19.6 MCTA is described a savings achievable through the Mayor’s Plan whilst the second, 13.4 MCTA, are additional savings required to meet the 60% target.

So already, the Mayor has admitted that around a third of his carbon reduction target is out of his control. In fact, the Plan as a whole is remarkably coy about how these additional savings might be achieved. It merely calls for the rapid introduction of comprehensive carbon pricing across all sectors, including aviation. This is crucial to create incentives for widespread take-up of carbon reduction measures and to drive development of new technologies.

Reading between the lines, what this is saying is that carbon needs to be either heavily taxed or rationed. It needs to be so expensive that people are coerced into changing their behaviour. This is something it is clear is beyond the powers of the Mayor and may well require widespread international co-operation in order to become effective, as its not something one country could do unilaterally.

You could lie in bed all day arguing the merits of carbon rationing as opposed to carbon taxes but it doesn’t really get you anywhere and it doesn’t contribute anything to London’s Climate Change Plan. A more honest appraisal would state that “we simply have no power to influence events in these areas and therefore we will not make claims that we can.” An even more brutal appraisal would say that if comprehensive (for which read punitive) carbon pricing was introduced across all sectors, as the Plan suggests it needs to be, then the Climate Action plan would be superfluous, as everything suggested elsewhere in the Plan would be implemented as a matter of course.

1st beef: It’s not really a 60% reduction, it’s just 31%. The rest requires action at national or international level.

Still 31% is still a hell of a big reduction, 19.6 MCTA. Well worth having if it helps slow climate change.

Now as everybody knows there are only two ways to cut carbon emissions. One is to reduce demand; the other is to supply power from carbon-free (or carbon-lite) resources. The Plan is full of lots of suggestions for improvements to be made in both areas. But when you get down to look at the details, you find that the policies to be implemented will have only a marginal impact.

Let’s look at the plan for housing and development. There are no less than 28 pages in the Plan devoted to tackling the 16.7 MTCA from London’s existing 3.1 million homes. It starts by making a bold claim:

Londoners can still do everything they want and need to do at home - staying warm, watching TV, cooking, etc. You don’t have to reduce your quality of life to tackle climate change, but you do have to change the way you live.

Sounds fine, doesn’t it. Painless carbon reductions all round. Then, on p 35, it looks at the targets.

Taking the target of a 60 per cent reduction from the 1990 baseline, to be achieved by 2025, the domestic sector would need to emit 12.2 MTCA less by 2025 (including savings from a reduced carbon energy supply and more energy efficient new building). Achieving this reduction will be extremely challenging, and realistically requires the establishment of a UK carbon pricing system. However, in the current policy environment, a saving of 7.7 MTCA is achievable by 2025.

There’s no point delving into the bit of the jigsaw that can only be done with a “UK carbon pricing system” again, but let’s look instead at how the Plan hopes to save the 7.7MTCA that is says is achievable.

So how is this 7.7MTCA made up? Figure 16 (illustrated) indicates just how it’s to be delivered. Amazingly, 5% is said to derive from future housing becoming more energy efficient. The fact that these houses will still be net contributors to the overall emissions is hidden elsewhere in the calculations.

But that still leaves around 7 MTCA to account for. The plan claims that around half this figure can be met by a combination of the following:

• 70% improvement in energy efficiency from lightbulbs and appliances in 70% of households
• 10% reduction from simple changes in behaviour in 60% of London households (e.g., switching off lights, turning down thermostats)
• 15% increase in thermal efficiency in 40% of London households

To back this up, look at the claim (on p42, widely repeated in the media) that If every lightbulb in every London home was energy efficient, London could save 575,000 tonnes of CO2

and that If all appliances in homes were energy efficient, this could translate into savings of £150 million off electricity bills and cut 620,000 tonnes of CO2 emissions annually.

Combine these two totals and you would have a saving 1.2 MTCA. But the plan isn’t suggesting that this is feasible and is only talking about a 70% improvement in 70% of households, which halves the theoretical saving from 1.2 to 0.6 MTCA. That’s just 8% of the total required to meet the 7.7 MTCA reduction the Plan says it can implement. Yet Figure 16 suggests that the savings on lighting and appliances should account for 23% of the total. 8% or 23%? Which is it, Ken?

Figure 16 also suggests that 18% of this 7.7 MTCA can be found by behavioural changes, otherwise known as switching off lights and turning down thermostats. No figures are presented to back up this claim but it seems highly unlikely that London will save 1.4 MTCA from behavioural changes if they can only save half this amount by a huge switchover to energy efficient lighting and appliances.

The third claim is that there will be a 10% saving (0.8 MTCA) from an increase in thermal insulation, basically cavity wall insulation, better loft insulation and double-glazing. This figure seems plausible but it isn’t verified elsewhere, though there is an interesting chart, Figure 28 on p 47, which shows how few London homes actually have cavity walls (about 15%) and that 60% of these already have their cavities insulated. Double glazing has already penetrated 55% of the possible market and 90% of London’s lofts are already insulated, though only 5% comply with current best practice (around 300mm depth of mineral wool).

Figure 16 suggests that these three areas — i.e. better lights and appliances, behavioural changes and thermal improvements — will have to account for half of the total savings, which would be around 3.3 MTCA. Whilst the thermal efficiency figure of 0.8 MTCA is credible, the lighting and appliances figure are just plain wrong and the behavioral changes figure is just speculation. It looks extremely unlikely that the actual savings would be more than half the 3.3 MTCA suggested.

2nd beef: The figures for energy demand reduction in housing don’t add up. The text suggests a saving of around 2 MTCA, the chart requires 3.3 MTCA in order to work.

Figure 16 also shows a 44% saving in CO2 emission from London’s housing from greener energy supply. Just how is London’s existing housing stock going to save 3 MTCA from its energy supply?

Energy supplies are dealt with in a separate chapter. It starts by admitting that less than 10% of London’s electricity and 5% of its heat is generated in London itself, so once again its hard for London to have much impact on its energy generation mix. The Mayor’s plan is to:

move as much of London as possible away from reliance on the national grid and on to local, lower-carbon energy supply (decentralised energy, including combined cooling heat and power networks, energy from waste, and on-site renewable energy - such as solar panels). This approach is often termed ‘decentralised energy’. The Mayor’s goal is to enable a quarter of London’s energy supply to be moved off the grid and on to local, decentralised systems by 2025, with more than half of London’s energy being supplied in this way by 2050.

Sounds good. But how would it work? And would decentralised production really save that much energy? The targets are set out in Figure 44, shown here. There is the same growth in CO2 emissions shown between now and 2025 on the Business as Usual principle, pushing London CO2 emissions up from 34.7 MTCA in 2006 to 39.4 MTCA in 2025 which it suggests will be driven by the projected growth in both the number of dwellings and net energy consumption per capita. Figure 44 then shows two red bars, the first bit describes energy which can be saved through the Plan and the second, once again, is those additional savings requiring external intervention.

No matter. At least a 7.2 MTCA reduction would be still be useful. How does the mayor plan to deliver this? Well, almost half of London’s 7.2 MTCA savings turn out not to come from London’s actions at all but from:

projected changes to the mix of fuel sources in the national grid, which includes the achievement of the Government’s target of 20% of energy from renewables sources, would save 3.4 MTCA by 2025.

It also probably includes a contribution from new nuclear power plants, but somehow this fact is glossed over, as nuclear power is something the Mayor opposes.

So let’s get this straight. The Plan’s energy production policy requires a total of 13.8 MTCA to be saved in order to deliver the overall 60% saving. But 6.6 MTCA is coming from external government action, and now 3.4 MTCA is coming from the greening of the National Grid, which incidentally will only happen as a result of external government action. So London itself now only has to contribute the remaining 3.8 MTCA, just 28% of the total.

But 3.8MTCA is still a large and useful contribution. This is to be made up from:

• an increased contribution from combined cooling, heat and power. CCHP generated in London would save 2.2 MTCA by 2025
• an increased contribution from energy from waste and biomass. Energy generated from waste and biomass using non-incineration based technologies and used to fuel biomass CCHP would save 1.1 MTCA by 2025
• an increased contribution from micro generation in London’s homes
and businesses including micro-wind and PV would save 0.5 MTCA
by 2025

I don’t know enough about the workings of combined heat and power and biomass generation to pass any judgement on whether these savings are realistic, but I suspect there is an element of double accounting going on here. The savings are likely to be expressed in terms of how much better they are in efficiency terms compared to today’s grid generated electricity. But grid electricity in 2025 is set to be a whole lot greener (that’s where the 3.8 MTCA savings are coming from) and I suspect that the savings from generating decentralised electricity will by then be much smaller relative to the national grid. Combined heat and power is not a renewable power source. It burns mains gas and the benefit you derive is that it throws off some electricity as well as heating hot water. But it has to be very well matched to its end user demand in order to make significant savings.

Interestingly the Plan refers to CCHP, not the more usual CHP. The extra C is for cooling, an admission that there is already large demand for air conditioning. The fact that this is set to grow as the climate gets warmer is addressed only in passing (on p 86) and natural ventilation as a cooling strategy doesn’t feature as a significant aspect of the Plan. An interesting omission.

What about micro generation? That does feature in the plan and the summary reckons it can save as much as 0.5 MTCA. Given that it is now established micro wind turbines contribute approximately zero power because they don’t work, this puts most of the workload onto roof-mounted solar panels, which do. But just how many would be needed to produce 0.5 MTCA of savings? It’s a good question. Here is the maths:

• A 1kW rated PV roof mounted array would expect to produce around 800kWh of electricity each year
• Each kWh, at the current UK electricity production efficiencies, releases 0.43kg of CO2
• So a 1kW PV array, producing 800kWh of electricity each year, would save 0.34t of CO2 per annum. That’s a third of a tonne.
• The cost? About £10,000 per kW is the market price, though 50% grants are currently available, if you are lucky. The grant system is currently falling apart but that’s another story.

Now the Mayor’s plan is looking to save 0.5MTCA from micro generation, so the maths suggests with each array saving just a third of a tonne of CO2 a year, that London will need no less than 1.4 million PV arrays by 2025. Or the equivalent in other similar technologies, which may be a little bit cheaper, but not a lot.

Remember there is only 3.1 million homes in London and many of these are flats which don’t even have roofs.

But then read what the plan has to say on p113:

Micro-generation technologies are already available and functioning. 1.5 MTCA of CO2 could be saved by 2025 if 25% of homes and new commercial buildings installed solar PV or micro-wind.

This is utter bollocks. It’s virtually an order of magnitude out in its inaccuracy.

It continues:

The Mayor’s vision of London in 2050 is one where every building is fitted with some sort of micro-renewable generation.

Not to mention the garden sheds as well. To get to 1.5MTCA, you’d need no less than 4.2 million installations, greater than the number of buildings in London.

And who is going to pay for all this? Funnily enough, the only mention of grants says that they must be maintained in order to encourage take-up. However, funding these renewables seems to be something the Plan is quite happy to leave to central government. Why does that not surprise me.

3rd Beef: The claims made for decentralised energy in general and micro renewables in particular are utterly unrealistic.

I would argue that pretty much the same could be said of the Mayor’s Climate Action Plan as a whole. It just doesn’t stand up under scrutiny. It would be far more useful and practical exercise to look at what could be achieved, even if it was only to illustrate just how difficult a task it is going to be to bring about meaningful reductions in CO2 emissions. But that of course wouldn’t make for a good headline. Better for all to believe that somehow the Mayor can conjure up a 60% reduction, like pulling a rabbit out of a hat. This way we can all sleep happy in our beds at night, safe in the knowledge that our future is in good hands.

The reality is that the actions set out in this plan are unlikely to have more than a marginal effect on London’s carbon emissions. The plan still envisages growth and new homes, new offices and more people equate to more carbon emissions. This is, if you like, the big lie at the centre of this debate and the one that is increasingly troubling me, as regular blog readers will be well aware.

4th Beef: the 60% CO2 reduction figure is fantasy.

Not that this seems to have stopped lots of people jumping on the bandwagon and declaring Ken Livingstone some sort of green visionary.

• John Sauven, director of Greenpeace, is quoted as saying the following: "Ken Livingstone is showing how the largest city in Europe can combat climate change. No other leader is on the same page. The Government talks about cutting emissions, but is unwilling to confront the vested interests in the power sector, the building industry, the aviation lobby and the motor industry. Ken Livingstone is prepared to lead and take risks in responding to the challenge of climate change."

Yeah, right on John.

• Tony Juniper, director of Friends of the Earth, quoted in the Guardian: “The government must now follow the mayor's lead and ensure that its forthcoming climate change bill requires cuts in UK carbon dioxide emissions of at least 3% every year.”

Tony, read the text. The Mayor is still projecting dynamic growth for London. His energy saving measures are unlikely to offset the effects of this growth. This 3% annual reduction is fantasy.

• Chris Church, head of London 21 Network said the Plan was “probably the best city-level plan of its kind in the world".

Have you been at the Carlsberg, Chris? I don’t even know if any other cities have ever adopted a climate change strategy, but if they use London’s as a model for how to go about it, then God help them!