This is a brilliant free book packed with data and understandable by even me http://www.withouthotair.com/ . By David JC MacKay, a Professor in the Department of Physics at the University of Cambridge

Amongst many possible quotes - this one showing a bit of the contradictory thinking that surrounds GSHPs: "In Britain, the main purpose of heat pumps would be to get heat
into buildings in the winter. The ultimate source of this heat is the sun, which replenishes heat in the ground by direct radiation and by conduction through the air. The rate at which heat is sucked from the ground must satisfy two constraints: it must not cause the ground’s temperature to drop too low during the winter; and the heat sucked in the winter must be replenished somehow during the summer. If there’s any risk that the natural trickling of heat in the summer won’t make up for the heat removed
in the winter, then the replenishment must be driven actively – for example by running the system in reverse in summer, putting heat down into the ground (and thus providing air-conditioning up top)."

And another:
".... each country’s cumulative emissions of CO2, expressed as an average emission rate over the period 1880–2004. Congratulations, Britain! The UK has made it onto the winners’ podium. We may be only an average European country today, but in the table of historical emitters, per capita, we are second only to the USA" (9% less)

Posted By: fostertom
And another:
".... each country’s cumulative emissions of CO2, expressed as
an average emission rate over the period 1880–2004.
Congratulations, Britain! The UK has made it onto the winners’ podium.
We may be only an average European country today, but in the table of
historical emitters, per capita, we are second only to the USA"
(9% less)

Umm... seeing as the industrial revolution started here, why should that be a surprise?

For that matter, why should we feel guilty about the emissions of our great grandfathers? For them, the science and understanding of the environment was negligable, and coal was cheap and plentiful. Should we be punished for their ignorance?

It would be far more meaningful (but sadly less sensationalist) to give our emissions per capita for each of the recent years - to show how we currently compare with other nations, and how that has changed since environmental awareness has been pushed to the fore.

It would be far more informative to see where we are now, and how far environmental measures have affected our impact, than to wring our hands over the failures of people long, long since dead.

Edited to add - that said, the book is fascinating. The analysis of the viability of various schemes puts the difficulty of 'going green' into context.

I suspect he gives demand reduction little thought because, as others have pointed out (and Monbiot also mentions) there are few conceivable circumstances under which it could happen to a useful extent.

No politician would dare enforce it. Even those who have proposed the current dramatic targets are failing to achieve the year on year reductions needed to meet them. They set the targets sufficiently far off in the future that they are safe from having to be seen to do something right now.

No economic crisis yet experienced has achieved such reductions - except on the micro scale (such as Cuba).

The general public are not experiencing anything that leads them to feel they must impose hardships on each other or themselves. Witness the current credit crisis - everyone is focused on finding the means to get back to 'business as usual' rather than reducing their long term consumption.

Demand reduction is not technologically possible either right now. Our main loads are heating, and without upgrading the entire building stock, they will continue at much the same levels. Other significant loads are hot water and cooking - both of which would require radical lifestyle changes to usefully reduce. Microgeneration is simply not viable on a large and economically achievable scale at the moment. Most of the other attempts at demand reduction (energy saving bulbs and switching to standby) have marginal effects at best.

I'm not saying that any (or all) of these cannot lead to some demand reduction. However, even in aggregate, the actual demand reduction that we could expect to achieve in a 'perfect storm' falls far short of that needed to make renewables (as the current technology exists) viable as a sole source.

Jared Diamond's bestseller Collapse http://www.amazon.co.uk/Collapse-Societies-Choose-Fail-Survive/dp/0140279512/ref=sr_1_1?ie=UTF8&s=books&qid=1227735847&sr=8-1 is a brilliant study of those many societies that slid open-eyed and helpless into collapse, and those few that found the will to change radically in the nick of time.

Posted By: marktimeWell the yawning gap between haves and have nots that spawns the desire of the plebs to buy more and more tat is glaringly absent in Cuba. Make up your own mind whether that is a good or bad thing, (i.e. the capitalist "dream"), but bear in mind that on an evening in downtown Havana you'll see more smiles and social interaction than in any similar sized UK borough.

I feel that the equation "have less = happier society" is a little simplistic. Look at Russia, and compare the high levels of corruption and antagonism with the 'smiles and social interaction' of Cuba. Some societies cope better with shortage than others, and some remain more socially coherent in the presence of excess.

Social problems in the UK are as much to do with education, seismic shifts in industrialisation and labour markets, and oddities like the rise of benefits culture - none of which can be blamed on capitalism. It's wonderful that cuba has been isolated from much of this by it's unique situation, but that doesn't mean that it's social coherence can be reproduced in other societies.

Posted By: fostertombe replenished somehow during the summer. If there’s any risk that the natural trickling of heat in the summer won’t make up for the heat removed in the winter, then the replenishment must be driven actively – for example by running the system in reverse in summer, putting heat down into the ground (and thus providing air-conditioning up top)."

Remember, all reverse running for the above reason will lower the COP and a need for summer cooling suggests bad building design does it not? I have yet to be impressed by this book and am finding plenty of contradictions. Maybe a better title would be 'Sustainable energy - let's put the cart before the horse!'

This book is about giving those who do not have the education or ability to do the sums. David is not trying (mostly) to tell us what to do, but to let us know the options available and whether or not they stack up. Yes, there are going to be issues with reverse running of heat pumps, but these are still options. He He is not trying to give us the answer but to let us decide what the issues are. He does spend significant time illustrating how changing behaviour can have a dramatic effect on energy consumption mainly through his personal energy use.

I expect few of you have seen the development of this book over the last few years. You should have. He does not like cars (and called them invalid carriages in previous versions!) and in many respect was trying to sell the green agenda. Over time the book has developed into more of a factual book - with the sums that allows us all to check what he says.

Admin, I'd be very interested in you letting us (and David) know of the contradictions you find. I can't say I've seen any - from my view point of the book being about giving us information for us to make the choices.

This book is a breath of fresh air in an area full of...well, hot air, on all sides.

Well it is shown that it might just be possible (although of course totally unrealistic) that renewables might just allow each of us 125kWh/day! I guess David simply took the decision not to go down the route of exploring demand reduction beyond explaining his own experience in his own house - that's another book. But remember he did give us the power generating options - and also showed they are not realistic. Conclusion - demand reduction.

He has given us the sums and we can see they don't add up but in many places is does talk about demand reduction, but not overtly. As I mentioned, he's giving those who cannot do the sums the tools to do them. It is a clear conclusion we cannot live sustainably as we are currently. Well, to me anyway.

You will find sections in the book where he explains he is not going down the path of government policy etc. Personally, I like just energy - no politics, not too much preaching etc. But then I would!

The biggest thing, for demand reduction, that few have got their heads round, is heat recycling, i.e. to look always for ways that the waste heat from one process can be the heat feed to another, instead of usually, so far, burning fuel to create heat, using a bit and throwing the rest away, for each individual process.

This means an awareness and 'husbandry' of the 'grade' of the heat at all stages - it's so easy to lazily grab unnecessarily high-grade heat relative to the use e.g. to burn a flame at a v high-grade 400oC then massively dilute and down-grade the heat you've created because all you need is air at 25oC to dry clothes. Equally easy to lazily dilute and down-grade your waste heat e.g. the v high-grade heat immediately surrounding a saucepan is diluted by a blast of cool room air - or even ducted-in outside air, down to useless low-grade temp before being exhausted.

Once down-graded, there's no way to re-up-grade it, except by e.g. heat-pumping back up to a higher temp. The quantity of heat energy may remain the same, but it can be in useful high-grade form (a little mass at high temp), or in useless low-grade form (a lot of mass at low temp).

Heat shd be recycled, many times in rank order of the grade of heat truly reqd for each process, so its grade gradually works down the scale by stages from high-grade requirement (cooking) to medium-grade requirement (dhw) to low-grade requirement (space heating) until finally exhausted as genuinely no-longer-useable low-grade heat. That's the way to achieve spectacular demand reduction right across the scale, from steel making through power generation to domestic and horticulture - use x amount of liberated heat three or four times over, instead of throwing it away and starting again four times over.

This subject comes under the heading of Exergy http://en.wikipedia.org/wiki/Exergy - it's about awareness of the entropy gradient, which we're all tumbling down helplessly all the time because we don't even know it's there.
down-grade

Start reading - http://en.wikipedia.org/wiki/Exergy - you'll easily find yourself ahead of the game.

Take the option to start thinking about

Posted By: fostertomthe v high-grade heat immediately surrounding a saucepan is diluted by a blast of cool room air - or even ducted-in outside air, down to useless low-grade temp before being exhausted

Invent a way to recover cooking heat so x amount of heat is contained in as small mass as possible, thus is preserved as high-grade (high temp) as possible, and so is readily useful and useable as input to some domestic (or commercial catering) process that only requires medium-grade heat. And so on.

Posted By: robJHAdmin, I'd be very interested in you letting us (and David) know of the contradictions you find. I can't say I've seen any - from my view point of the book being about giving us information for us to make the choices.

I certainly will. I need to finish reading it first! So far I have just dipped into the bits that I see as most controversial - heat pumps and an ever-growing demand for electricity.

In a perfect world everything would be run by electricity but frankly. MacKay et.al should really know better than to (perhaps inadvertently) encourage people into using electrical appliances at this point in time. The authors and those that move to unquestioningly praise this book should understand that people will skip the data and just cherry-pick what they want to hear from this.

Posted By: dave45Heat recycling is a great idea, but we need to know how.... apart from letting the bathwater go cold before pulling the plug

Get one of these:
http://gfxtechnology.com/

And an air, mechanical heat recovery and vent unit.

That is two clawbacks there and then. Then make the place air-tight and superinsulate, or as much as possible.

Posted By: PaulTYou should be carefull about putting up statements like "get one of these"

He was referring to a drain water heat recovery unit - there's no problem with these in winter.

Posted By: PaulTI have not looked at the product BUT if a heat exchanger can recover 90% of th etemperature difference between indoors outdoors where is the rest of the energy coming from?
Particularly in winter when any more energy extraction would result in frost inside the sytem.....

I thought your were a propoent of MHRV? If you can recover 90% of the ventilation loses then you need less heat from other sources surely. As for winter operation, we have one in our new house and we had a daytime average temperature of -21C over the last week - no problems with frost buildup as the unit we have periodically defrosts itself.

As for the book, one might not agree with the conclusions, but it certainly puts a lot of "bit number" issues into perspective - e.g. the turning off of phone chargers and the like - as much as this is a "feel good" thing to do , in the grand scheme of things, it's irrelevant. People in the UK would be better off each drinking one cup of tea less per day!!!

Paul in Montreal.