I've been busy. I've bought a derelict warehouse on a backstreet in Cambridge and am making plans to knock it down and build a house there.
It all came about very suddenly. The site was put on the market at the end of October and, as it was said to be "the last brownfield site in Romsey Town", it attracted enormous interest. There are lots of people in Cambridge who would love the chance to build a house in the city and, in this day and age, any potential city building plot attracts a Grand Designs premium. Conventional notions of what it is worth and whether it stacks up financially go out the window in the stampede to buy into a dream.
Offers poured in during the ten days the site remained on the market and the agent decided to take it to sealed bids. What was unusual was that the vendor didn't want to sell to the highest bidder necessarily but wanted the buyer to build a single family home (rather than student flats) and also wanted the house to be an eco-house. This rather threw me. Although I've been involved in various green building projects over the past thirty-five years, I actually bridle at the term eco-house because to my mind it's indefinable. It's like natural food or organic shampoo: it's a cuddly, friendly sort of term but in the great scheme of things it's also utterly meaningless. A house is basically either a good house or a bad house and I don't think sticking a grass roof on a bad house makes it a good house.
But now was not the time to get bogged down in semantics. So I checked it with my partner, who was game for the adventure, then I checked the various savings accounts and utility company index-linked bonds into which I had parked the proceeds of the sale of my last house four years ago, and knowing I had the wherewithal to make a cash bid, I put in an offer, together with a brief CV and a word about my interest in Passivhaus and the like.
But I didn't win the bid. Mine wasn't the highest bid, but the one that won was lower than mine. Someone had obviously lit the vendor's boat rather better than me. Maybe my mixed feelings about eco-homes had shown through. Anyway, I put it behind me, wrote it off to experience and decided to look again for a city building project.
But then six weeks later, the agent rings me and asks if I'm still interested. Apparently the winning bid had hit problems and was unable to complete in the timescale the vendor was wanting, and so I was back in with a chance. But there was a very demanding condition. I had to complete in a week. There was to be no exchange of contracts, just a straightforward completion in one fell swoop.
I'd never heard of such a thing. Surely the property industry was incapable of working to such tight deadlines? The only good news was that the searches and all the preparation work had been completed and I could buy these from the solicitors. But I had to find a new solicitor and that wasn't straightforward — everybody wants to complete before Christmas and the Cambridge property market is very hot this year. After an afternoon on the phone, I tracked someone down who actually relished the challenge of completing in a week. And the deal was on.
The reality is that city centre building plots are so few and far between that you have to take on inadvisable risk in order to secure them. No planning permission in place. Not even time to talk to planners or anything sensible like that. Just buy a derelict warehouse and see what you can make of it. Only cash buyers need apply as no bank would lend on such a project without planning permission in place. And if the vendor says you have one week, then you have one week.
If I took the trouble to actually read the Housebuilder's Bible instead of simply writing it, I might just have cottoned onto the fact that I've been extremely reckless here. But somehow I suspect that it's not actually that big a risk because the community would very much like to see this site redeveloped and I think the political wind is blowing our way. It helps that the previous week, it was announced that small sites would in future be exempt from S106 planning contributions. That was a potential hidden tax that could have had a crippling effect on the budget.
My hope is to build a delightful house which may or may not qualify with the soubriquet eco-house (I don't mind either way) and also to have some fun doing it. Let's see how it all works out.....
27 Nov 2014
On Sea Level Rise
On Tuesday night this week, I had the pleasure of listening to Prof David Vaughn talking about the work of the British Antarctic Survey where he has worked almost all his adult life. Vaughn is Professor Ice Sheet and he spends his time exploring the goings on in Antarctica, Greenland and the 200,000 plus glaciers that pepper the world's mountain ranges. It's a fascinating area of science and one that's obviously key to our understanding of where our climate and our sea levels are heading.
At this point, I would expect a number of people to rise angrily from their perches and accuse me of listening to a pinko greenie engaged in a conspiracy to pull the wool over our eyes by manipulating the data to suggest we are all doomed. "British Antarctic Survey? British Alarmist Society, more like." I have no doubt that UKIP will be planning to slash their £44m annual budget under their charming "Axe all green subsidies" policy.
May I suggest that, before they do, they spend an hour listening to David Vaughn talk. He dresses very conservatively, he talks very quietly, he is polite almost to a fault. In fact, he comes on like an accountant, which perhaps is what he is actually is, albeit one with some very sophisticated measuring kit. He just weighs ice and measures sea levels. He looks for trends and patterns and he peers into the future to try and work out where things are headed, but he steers clear of making suggestions about what we should or shouldn't be doing — "that's for economists and politicians to decide".
What was interesting to me is the huge strides that have been made in our knowledge in the past few years, between the IPCC reports AR4 in 2007 and AR5 in 2013. We now have two satellites (the Grace mission) which are measuring gravitational variations caused by changes in mass at surface level. If the mass of an ice cap is changing, Grace will pick it up. Clever stuff.
And the mass of ice sheets is changing. As you might expect, it's decreasing, although the picture isn't uniform nor necessarily easy to interpret. Thus far, the changes are fairly moderate and are occurring at the margins, but what scientists fear is that there might be a sudden catastrophic event. One area on the Antarctic coast is of particular concern because there the ice sheet rests on bedrock which is far below sea level and there is a possibility that relatively small changes in sea temperature could cause it to all slide into the sea. How big an area? The size of Cornwall? Belgium? Norway? No one knows, but Vaughn probably has a better handle on it than anybody else. If we can afford MI5 and MI6, then I think we can afford the BAS.
Back at the height of the last ice age when ice sheets covered much of the northern hemisphere, the global sea level was 120m lower than it is today. The Mediterranean was not there and there was a land bridge between Britain and France. The temperature was approximately 7°C colder than it is today.
Still locked up in the Greenland Ice sheet is another potential 7m of sea level rise and in Antarctica it's 60m, so if we were to head for a 4°C increase in global temperatures, which is within the bounds of possibility (though far from certain), then we could anticipate a much higher sea level, though it might take 500 years to play out.
What is known today is that global sea level is currently rising at 3.2mm per annum. It the last century, it averaged around 2mm and in the 19th century, they think it was around 0.8mm. There is no hiatus in sea level change — the rise is pretty much constant. 3.2mm may not sound like much, but that still equates to 300mm by 2100. In fact best estimates are rather more than this at present but it's a field open to a lot of doubt and speculation. (Sea level is affected by a number of factors beside ice sheet melt.) It's probable that the relatively small amount of climate warming that we've already seen has locked in sea levels rises of several meters, but the timescale on which it will all happen is contentious.
The questions are can we manage this? Can we arrest it? And over what timescales are we talking? Should we be planning now to mitigate sea level rises which won't be fully played out till maybe the 25th century? What exactly are our planning horizons? This isn't the stuff of blind panic: it's good old risk assessment played out over a very long timescale. It does however ask some very uncomfortable questions about whether our actions now are making things better or worse for our distant descendants and what exactly we are hoping to achieve on Planet Earth.
In the shorter term, what is likely to happen is that storm surge events like the one that accompanied Hurricane Sandy are going to get worse and more frequent, but we already know that our coastal cities (New Orleans) and infrastructure (Fukushima) are at much greater peril than we care to think about. Sea level rise simply changes the odds and, if you like, makes coastal protection more expensive. Right-wing commentators who claim that it's simply too expensive to stop burning fossil fuels should bear this in mind. The longer we keep bingeing, the bigger the hangover.
At this point, I would expect a number of people to rise angrily from their perches and accuse me of listening to a pinko greenie engaged in a conspiracy to pull the wool over our eyes by manipulating the data to suggest we are all doomed. "British Antarctic Survey? British Alarmist Society, more like." I have no doubt that UKIP will be planning to slash their £44m annual budget under their charming "Axe all green subsidies" policy.
May I suggest that, before they do, they spend an hour listening to David Vaughn talk. He dresses very conservatively, he talks very quietly, he is polite almost to a fault. In fact, he comes on like an accountant, which perhaps is what he is actually is, albeit one with some very sophisticated measuring kit. He just weighs ice and measures sea levels. He looks for trends and patterns and he peers into the future to try and work out where things are headed, but he steers clear of making suggestions about what we should or shouldn't be doing — "that's for economists and politicians to decide".
What was interesting to me is the huge strides that have been made in our knowledge in the past few years, between the IPCC reports AR4 in 2007 and AR5 in 2013. We now have two satellites (the Grace mission) which are measuring gravitational variations caused by changes in mass at surface level. If the mass of an ice cap is changing, Grace will pick it up. Clever stuff.
And the mass of ice sheets is changing. As you might expect, it's decreasing, although the picture isn't uniform nor necessarily easy to interpret. Thus far, the changes are fairly moderate and are occurring at the margins, but what scientists fear is that there might be a sudden catastrophic event. One area on the Antarctic coast is of particular concern because there the ice sheet rests on bedrock which is far below sea level and there is a possibility that relatively small changes in sea temperature could cause it to all slide into the sea. How big an area? The size of Cornwall? Belgium? Norway? No one knows, but Vaughn probably has a better handle on it than anybody else. If we can afford MI5 and MI6, then I think we can afford the BAS.
Back at the height of the last ice age when ice sheets covered much of the northern hemisphere, the global sea level was 120m lower than it is today. The Mediterranean was not there and there was a land bridge between Britain and France. The temperature was approximately 7°C colder than it is today.
Still locked up in the Greenland Ice sheet is another potential 7m of sea level rise and in Antarctica it's 60m, so if we were to head for a 4°C increase in global temperatures, which is within the bounds of possibility (though far from certain), then we could anticipate a much higher sea level, though it might take 500 years to play out.
What is known today is that global sea level is currently rising at 3.2mm per annum. It the last century, it averaged around 2mm and in the 19th century, they think it was around 0.8mm. There is no hiatus in sea level change — the rise is pretty much constant. 3.2mm may not sound like much, but that still equates to 300mm by 2100. In fact best estimates are rather more than this at present but it's a field open to a lot of doubt and speculation. (Sea level is affected by a number of factors beside ice sheet melt.) It's probable that the relatively small amount of climate warming that we've already seen has locked in sea levels rises of several meters, but the timescale on which it will all happen is contentious.
The questions are can we manage this? Can we arrest it? And over what timescales are we talking? Should we be planning now to mitigate sea level rises which won't be fully played out till maybe the 25th century? What exactly are our planning horizons? This isn't the stuff of blind panic: it's good old risk assessment played out over a very long timescale. It does however ask some very uncomfortable questions about whether our actions now are making things better or worse for our distant descendants and what exactly we are hoping to achieve on Planet Earth.
In the shorter term, what is likely to happen is that storm surge events like the one that accompanied Hurricane Sandy are going to get worse and more frequent, but we already know that our coastal cities (New Orleans) and infrastructure (Fukushima) are at much greater peril than we care to think about. Sea level rise simply changes the odds and, if you like, makes coastal protection more expensive. Right-wing commentators who claim that it's simply too expensive to stop burning fossil fuels should bear this in mind. The longer we keep bingeing, the bigger the hangover.
21 Nov 2014
Lighting the future
I visited LuxLive on Wednesday to see where the lighting industry is headed. As you might expect, it can be summed up in 3 letters — LED. They were everywhere and there was very little of anything else. For someone used to writing about construction, where the pace of change is lugubrious, it's quite exciting to see an industry undergoing a rapid transformation. For most players in this space, it is a question of how to add value to a product which is both dropping in price and increasing in quality all the time. It's not enough to just sell LEDs: the future market is just too unpredictable.
And many so-called experts turned out to be almost as clueless as me. I was told on good authority that dope growers have no use for LEDs because they can't do ultra-violet light. A quick Google afterwards revealed dozens of really cheap UV LEDs. In fact, we may be about to be entering a world where growing all manner of plants at home becomes a whole lot easier and more productive.
For the past ten years or so, much of the emphasis in the lighting industry has been on increasing energy efficiency both by squeezing more performance out of the lamps themselves and by adding better control gear and better design. The arrival of cheap and very efficient LEDs has already made much of this work look pointless. Cree, the NASDAQ-quoted LED powerhouse, have now produced an LED that delivers 300 lumens per watt, which is about eight times more efficient than the best compact fluorescent, and although it's not yet in commercial production, it seems just a matter of time before the bar is raised again. In five years time, maybe 1,000 lumens per watt will be possible. By then lighting will have become so cheap to run, that it will be nearly-free. An old-fashioned 60-watt bulb could be replaced by an LED running on less than half a watt. A whole house could be lit by as little as 10 watts at a cost of maybe £5 per annum.
Not that LEDs are without their issues. The light itself is produced from a very focussed source which means there is a glare issue. Lots of work is going into shielding and diffusing this glare and making it more acceptable in every application. Backwards compatibility with existing light circuits is not always guaranteed and there are issues with dimmers not working with LEDs though, again, technology seems now to be producing LEDs that will work with existing dimmers.
One of the neatest and simplest ideas I saw was at the Megaman stand where they had adapted a dimmer so that the colour appearance of the lamp got warmer as the light level was decreased. I'm not sure this is commercially available yet, but it seemed like a very simple way of addressing the issue of the colour appearance of the lamps which exercises some people quite a lot.
The future of cabled switching also seems to be in question. Lots of stands had wireless switch plates for lighting and Megaman were also displaying a wireless home automation system which allowed you to control the heating system as well, all from your smartphone. If this is really advantageous remains to be seen — I think most people will still want a physical switch or thermostat as well, if only because smartphones get misplaced or run out of battery or break down. Wireless switching really comes into its own when you want to pre-program your lighting or heating or switch it remotely, but how many people actually want that function? We will see.
In the meantime, the wireless switchers are not being helped by a protocol turf war rumbling away in the background. Wi-fi v Bluetooth v ZigBee v Z-wave. It's all very well have Z-wave enabled kit, but how do you know the world won't have gone fully wi-fi by 2025? You could end up being Betamaxed, although, to be fair, you won't exactly run short of content, so it may not be quite so critical as all the existing protocols will be supported for decades, even if they stop being used for new applications. Nevertheless, it doesn't help matters that it isn't clear which home wireless system will prevail.
And many so-called experts turned out to be almost as clueless as me. I was told on good authority that dope growers have no use for LEDs because they can't do ultra-violet light. A quick Google afterwards revealed dozens of really cheap UV LEDs. In fact, we may be about to be entering a world where growing all manner of plants at home becomes a whole lot easier and more productive.
For the past ten years or so, much of the emphasis in the lighting industry has been on increasing energy efficiency both by squeezing more performance out of the lamps themselves and by adding better control gear and better design. The arrival of cheap and very efficient LEDs has already made much of this work look pointless. Cree, the NASDAQ-quoted LED powerhouse, have now produced an LED that delivers 300 lumens per watt, which is about eight times more efficient than the best compact fluorescent, and although it's not yet in commercial production, it seems just a matter of time before the bar is raised again. In five years time, maybe 1,000 lumens per watt will be possible. By then lighting will have become so cheap to run, that it will be nearly-free. An old-fashioned 60-watt bulb could be replaced by an LED running on less than half a watt. A whole house could be lit by as little as 10 watts at a cost of maybe £5 per annum.
Not that LEDs are without their issues. The light itself is produced from a very focussed source which means there is a glare issue. Lots of work is going into shielding and diffusing this glare and making it more acceptable in every application. Backwards compatibility with existing light circuits is not always guaranteed and there are issues with dimmers not working with LEDs though, again, technology seems now to be producing LEDs that will work with existing dimmers.
One of the neatest and simplest ideas I saw was at the Megaman stand where they had adapted a dimmer so that the colour appearance of the lamp got warmer as the light level was decreased. I'm not sure this is commercially available yet, but it seemed like a very simple way of addressing the issue of the colour appearance of the lamps which exercises some people quite a lot.
The future of cabled switching also seems to be in question. Lots of stands had wireless switch plates for lighting and Megaman were also displaying a wireless home automation system which allowed you to control the heating system as well, all from your smartphone. If this is really advantageous remains to be seen — I think most people will still want a physical switch or thermostat as well, if only because smartphones get misplaced or run out of battery or break down. Wireless switching really comes into its own when you want to pre-program your lighting or heating or switch it remotely, but how many people actually want that function? We will see.
In the meantime, the wireless switchers are not being helped by a protocol turf war rumbling away in the background. Wi-fi v Bluetooth v ZigBee v Z-wave. It's all very well have Z-wave enabled kit, but how do you know the world won't have gone fully wi-fi by 2025? You could end up being Betamaxed, although, to be fair, you won't exactly run short of content, so it may not be quite so critical as all the existing protocols will be supported for decades, even if they stop being used for new applications. Nevertheless, it doesn't help matters that it isn't clear which home wireless system will prevail.
14 Nov 2014
Eco Bollocks Award No 9: Clear Heater Units
Recently, I've become aware of some striking claims being made for electric radiant heating. Like a new way of heating homes has been discovered that is way more efficient than anything else that we have come across before. I think not.
The practice of using radiant heating is not new and it seems to work very well in many places. But claims that is somehow magically more efficient than other forms of heating is, in my opinion, pure baloney.
Take a look at this website. Clear Heater Systems have a neat looking wall panel radiator which they claim will save you a pot of money. They claim that you can save up to 65% against gas heating on a three-bed semi, and up to 90% on electric heating on the same house. Impressed? Let's investigate.
Their claims are apparently backed-up by a piece of academic research by a chap from Leeds University which, at first glance, looks very compelling. It concludes: Overall, the results that we have produced show the Logicor Clear Heating System in a good light. They certainly do.
However, if you read the report carefully, you can see that it's not quite all that it appears to be in its conclusion. The report is based on an analysis of the energy used in 53 properties in the north of England which have been fitted with the Clear Heater units. The results are, however, not being compared with properties heated by other methods, but with an estimated heat loss for each of these 53 properties, based on their own calculations using standard U-values. What this tells you is not how efficient Clear Heater units are but how inaccurate U-value calculations can be if used inappropriately. They are a useful tool for working out maximum heat loads, but not for predicting annual heating bills.
The methodology is even made explicit within the report. Buried away on page 4, under the heading Statistical Analysis, the author states that the study is not a measure of savings against competing heating systems but rather a measure of performance against theoretical heat losses. With the emphasis on the word theoretical.
You'd have to be a bit of a Sherlock Holmes to figure out that the apples here are not being compared with other apples, but with a load of dodgy oranges. And it's on this basis that they claim that you can save pots of money against gas heating. Which is frankly incredible because the Clear Heater Units are electric radiators, albeit with a very thin carbon ceramic heating element sandwiched between two sheets of toughened glass. Much as they would have liked to, Logicor haven't managed to change the laws of physics and, for just hinting that they might have, they get a House 2.0 Eco Bollcocks award.
The practice of using radiant heating is not new and it seems to work very well in many places. But claims that is somehow magically more efficient than other forms of heating is, in my opinion, pure baloney.
Take a look at this website. Clear Heater Systems have a neat looking wall panel radiator which they claim will save you a pot of money. They claim that you can save up to 65% against gas heating on a three-bed semi, and up to 90% on electric heating on the same house. Impressed? Let's investigate.
Their claims are apparently backed-up by a piece of academic research by a chap from Leeds University which, at first glance, looks very compelling. It concludes: Overall, the results that we have produced show the Logicor Clear Heating System in a good light. They certainly do.
However, if you read the report carefully, you can see that it's not quite all that it appears to be in its conclusion. The report is based on an analysis of the energy used in 53 properties in the north of England which have been fitted with the Clear Heater units. The results are, however, not being compared with properties heated by other methods, but with an estimated heat loss for each of these 53 properties, based on their own calculations using standard U-values. What this tells you is not how efficient Clear Heater units are but how inaccurate U-value calculations can be if used inappropriately. They are a useful tool for working out maximum heat loads, but not for predicting annual heating bills.
You'd have to be a bit of a Sherlock Holmes to figure out that the apples here are not being compared with other apples, but with a load of dodgy oranges. And it's on this basis that they claim that you can save pots of money against gas heating. Which is frankly incredible because the Clear Heater Units are electric radiators, albeit with a very thin carbon ceramic heating element sandwiched between two sheets of toughened glass. Much as they would have liked to, Logicor haven't managed to change the laws of physics and, for just hinting that they might have, they get a House 2.0 Eco Bollcocks award.
24 Oct 2014
Whither Passivhaus?
Last week I attended the 4th Annual Conference of the UK Passivhaus Trust. On many levels, it's all been a super success with the number of UK projects burgeoning towards the 250 mark and expected to get to 1,000 sometime in 2015. Interest is growing far and wide beyond the little core of activists who launched the trust back in 2010.
But of course it's still very small fry when set against the total amount of building going on and there were voices to be heard saying that maybe, just maybe, Passivhaus isn't quite the way forward we thought and hoped it would be. It sets out to be an exacting target and therefore an expensive one to meet. Whilst for new builds it looks eminently achievable and economically justifiable, in the retrofit market Passivhaus has the feel of being overkill. The structural changes you have to undertake in order to get an existing house to EnerPhit, the reduced retrofit standard, are so great that you begin to wonder whether it is really be worth the bother. Only a very keen energy wonk is ever likely to undertake an EnerPhit conversion: fuel prices would have to be an order of magnitude greater than they are now to make economic sense. Even the environmental sense is questionable.
There were lots of very interesting presentations. Caroline Martin of WARM caught my attention with her analysis of post-completion testing of a number of Passivhaus homes in the West country. The usual spread of outcomes was on display — there always seems to be a joker in the pack who leaves all their windows open throughout the winter and shows up as a total energy hog, and Caroline's sample didn't disappoint in this respect.
But there were also a handful of homes where the heating hadn't been put on at all during the winter. "Was it a particularly mild winter in Exeter?" she asked herself. Weather stats showed that it hadn't been — it was very average. So these homes hadn't just met the fabled Passivhaus space heating standard of 15kWh/m2/annum, they had scored zero kWh/m2/annum. This set me wondering whether they hadn't been over engineered. The design idea is not to eliminate heating costs altogether, merely to reduce them to a very low number and presumably the cost of getting the score down below this is deemed to be money wasted.
In general, the Passivhaus standard is responsive to weather data, thus making it easier and cheaper to build in warmer climates, certainly as regards the amount of insulation to be built in. Conversely, it is much harder to build in colder climes and this has led to a revolt in North America where many low energy enthusiast feel that the standard is just a little too German and that different climates would be better served by variations on the standard. Their specific beef is that when you get into the far north of the US and Canada, the wall insulation becomes unrealistically (and pointlessly) thick. They argue that it would be far cheaper and more cost effective to generate a little electricity on site than to build to an arbitrary standard which is optimised for central Europe.
Now Passivahusers have long desisted from offsetting their heating standard with renewable energy. "No green bling, let's keep it simple" went the oft repeated refrain. But now it appears that the Passivhaus Institute in Darmstadt is about to jump aboard the green bling bandwagon and start offering alternative Passivhaus standards which incorporate on-site energy generation. Watch out for Passivhaus Plus and Passivhaus Premium. Old die hards will have to make do with Passivhaus Classic.
It seems that politics is at work here. I couldn't quite get to the bottom of it, but the EU is pointing us towards a new target, the Nearly Zero Carbon Building, and it will be requiring that these have some form of onsite electricity generation. In this light, if Passivhaus is to stay relevant it has to bring PV into the equation. It also has to take into account not just the primary energy used (a lesser known target of the Passivhaus standard) but the carbon intensity of that primary energy. Hence the new versions of the standard referring to carbon intensity of energy used.
But in doing this, the Passivhaus standard starts to resemble other standards (like the Code for Sustainable Homes) which no one much loved. I fear they may be a small backlash amongst British and Irish enthusiasts who set their stall out on the simplicity and robustness of the original standard. But a full scale American-style tea party revolt? I don't think so. You might not guess it from our newsprint, but I think we are just a little too European for that.
But of course it's still very small fry when set against the total amount of building going on and there were voices to be heard saying that maybe, just maybe, Passivhaus isn't quite the way forward we thought and hoped it would be. It sets out to be an exacting target and therefore an expensive one to meet. Whilst for new builds it looks eminently achievable and economically justifiable, in the retrofit market Passivhaus has the feel of being overkill. The structural changes you have to undertake in order to get an existing house to EnerPhit, the reduced retrofit standard, are so great that you begin to wonder whether it is really be worth the bother. Only a very keen energy wonk is ever likely to undertake an EnerPhit conversion: fuel prices would have to be an order of magnitude greater than they are now to make economic sense. Even the environmental sense is questionable.
There were lots of very interesting presentations. Caroline Martin of WARM caught my attention with her analysis of post-completion testing of a number of Passivhaus homes in the West country. The usual spread of outcomes was on display — there always seems to be a joker in the pack who leaves all their windows open throughout the winter and shows up as a total energy hog, and Caroline's sample didn't disappoint in this respect.
But there were also a handful of homes where the heating hadn't been put on at all during the winter. "Was it a particularly mild winter in Exeter?" she asked herself. Weather stats showed that it hadn't been — it was very average. So these homes hadn't just met the fabled Passivhaus space heating standard of 15kWh/m2/annum, they had scored zero kWh/m2/annum. This set me wondering whether they hadn't been over engineered. The design idea is not to eliminate heating costs altogether, merely to reduce them to a very low number and presumably the cost of getting the score down below this is deemed to be money wasted.
In general, the Passivhaus standard is responsive to weather data, thus making it easier and cheaper to build in warmer climates, certainly as regards the amount of insulation to be built in. Conversely, it is much harder to build in colder climes and this has led to a revolt in North America where many low energy enthusiast feel that the standard is just a little too German and that different climates would be better served by variations on the standard. Their specific beef is that when you get into the far north of the US and Canada, the wall insulation becomes unrealistically (and pointlessly) thick. They argue that it would be far cheaper and more cost effective to generate a little electricity on site than to build to an arbitrary standard which is optimised for central Europe.
Now Passivahusers have long desisted from offsetting their heating standard with renewable energy. "No green bling, let's keep it simple" went the oft repeated refrain. But now it appears that the Passivhaus Institute in Darmstadt is about to jump aboard the green bling bandwagon and start offering alternative Passivhaus standards which incorporate on-site energy generation. Watch out for Passivhaus Plus and Passivhaus Premium. Old die hards will have to make do with Passivhaus Classic.
It seems that politics is at work here. I couldn't quite get to the bottom of it, but the EU is pointing us towards a new target, the Nearly Zero Carbon Building, and it will be requiring that these have some form of onsite electricity generation. In this light, if Passivhaus is to stay relevant it has to bring PV into the equation. It also has to take into account not just the primary energy used (a lesser known target of the Passivhaus standard) but the carbon intensity of that primary energy. Hence the new versions of the standard referring to carbon intensity of energy used.
But in doing this, the Passivhaus standard starts to resemble other standards (like the Code for Sustainable Homes) which no one much loved. I fear they may be a small backlash amongst British and Irish enthusiasts who set their stall out on the simplicity and robustness of the original standard. But a full scale American-style tea party revolt? I don't think so. You might not guess it from our newsprint, but I think we are just a little too European for that.
30 Sept 2014
On LED Lighting
Last week, I was in my local Medlock's looking for a replacement lamp for a downlighter. The one which had gone was about five years old and was a compact fluorescent — not a comfy fit in a GU10 lamp but it worked OK until it died. I showed the dead lamp to the man behind the counter and he said they did have a replacement but that it would be both cheaper and better to switch to an LED. "They are just about the only lamps we sell now" he said. "The halogen bulb has all but disappeared and the compact fluorescent seems to be going the same way."
Then on Sunday I am at the Homebuilding & Renovating show at Olympia in London and I visit a stand called SavingCO2 which sold nothing but LED lamps. LED GU10s for downlighters, LED bulbs for where we used to put tungsten bulbs, even LED tube lights. Just about any and every bulb and fitting you have ever come across is now available in an LED version at a wattage around half of that achieved by compact fluorescents, and close on a tenth of what we have been using with tungsten and halogen, and with a light quality that most people would readily prefer.
Now admittedly, these LEDs are still a lot more than a halogen lamp — TLC is selling these for less than £2 — but the promise is that these LED lamps will last longer and, if anything, give off a better light. What is more, an interesting article online on Optics.org states that LED prices are falling by about 9% a year, but speculates that quality may suffer in the race to the bottom. There is a danger that if the quality remains too high, then manufacturers will lose the replacement market.
There is also significant money to be saved here. If a typical house has 40 lights and each light runs for an average of 800hrs/annum (about 2.5hrs per day), then the house will consume
• 2,000 kWh/annum if everything was lit with tungsten bulbs (cost £250/annum)
• 1,000 kWh/annum if it's a mix of halogen, CF and tungsten (cost £125/annum)
• 250 kWh/annum if every light fitting was replaced by an LED (cost £30/annum)
And 40 LED bulbs would currently cost around £500, so there is a reasonable payback on offer.
It's interesting to compare LEDs with PV. PV installation costs have also fallen significantly during the past few years so that, today, PV is costing around £1,500/kW to install and each kW of PV produces about 800kWh/annum in the UK climate. That 800kWh/annum is similar to the amount of energy saved per annum by converting all your lamps to LEDs, for a third of the cost.
It's also interesting to note that the building regs have been left behind by the onward march of LED lighting. Currently, the lighting requirements for Part L in England are covered in a supplement called the Domestic Buildings Services Compliance Guide: 2013 edition. It is still batting on about having to have dedicated light fittings to stop recalcitrant consumers ditching their unpopular CF lamps and reverting to tungsten bulbs at the drop of a hat. The guide requests that 75% of the light fittings in a new build should be energy-efficient (defined as at least 40 lumens per circuit-watt). But with LEDs achieving over 100 lumens per circuit-watt, this definition is already looking out of date.
To its credit, there is a supplementary clause in the guidance which sates that light fittings whose supplied power is less than 5 circuit-watts are excluded from the overall count of total numbers of light fittings. As most of the halogen-replacing LED GU10 lamps are rated at 3 or 4 circuit-watts, this neatly side steps the issue and allows you to put in as many as you want. My guess is that then next version of this guide will probably do away with lighting guidance altogether, as by then LED lighting will have become ubiquitous in new installations.
The big question is will LED lamps really last the 40,000 hours or so the manufacturers claim? Or will the market take them down a route towards built-in obsolescence?
Then on Sunday I am at the Homebuilding & Renovating show at Olympia in London and I visit a stand called SavingCO2 which sold nothing but LED lamps. LED GU10s for downlighters, LED bulbs for where we used to put tungsten bulbs, even LED tube lights. Just about any and every bulb and fitting you have ever come across is now available in an LED version at a wattage around half of that achieved by compact fluorescents, and close on a tenth of what we have been using with tungsten and halogen, and with a light quality that most people would readily prefer.
Now admittedly, these LEDs are still a lot more than a halogen lamp — TLC is selling these for less than £2 — but the promise is that these LED lamps will last longer and, if anything, give off a better light. What is more, an interesting article online on Optics.org states that LED prices are falling by about 9% a year, but speculates that quality may suffer in the race to the bottom. There is a danger that if the quality remains too high, then manufacturers will lose the replacement market.
There is also significant money to be saved here. If a typical house has 40 lights and each light runs for an average of 800hrs/annum (about 2.5hrs per day), then the house will consume
• 2,000 kWh/annum if everything was lit with tungsten bulbs (cost £250/annum)
• 1,000 kWh/annum if it's a mix of halogen, CF and tungsten (cost £125/annum)
• 250 kWh/annum if every light fitting was replaced by an LED (cost £30/annum)
And 40 LED bulbs would currently cost around £500, so there is a reasonable payback on offer.
It's interesting to compare LEDs with PV. PV installation costs have also fallen significantly during the past few years so that, today, PV is costing around £1,500/kW to install and each kW of PV produces about 800kWh/annum in the UK climate. That 800kWh/annum is similar to the amount of energy saved per annum by converting all your lamps to LEDs, for a third of the cost.
It's also interesting to note that the building regs have been left behind by the onward march of LED lighting. Currently, the lighting requirements for Part L in England are covered in a supplement called the Domestic Buildings Services Compliance Guide: 2013 edition. It is still batting on about having to have dedicated light fittings to stop recalcitrant consumers ditching their unpopular CF lamps and reverting to tungsten bulbs at the drop of a hat. The guide requests that 75% of the light fittings in a new build should be energy-efficient (defined as at least 40 lumens per circuit-watt). But with LEDs achieving over 100 lumens per circuit-watt, this definition is already looking out of date.
To its credit, there is a supplementary clause in the guidance which sates that light fittings whose supplied power is less than 5 circuit-watts are excluded from the overall count of total numbers of light fittings. As most of the halogen-replacing LED GU10 lamps are rated at 3 or 4 circuit-watts, this neatly side steps the issue and allows you to put in as many as you want. My guess is that then next version of this guide will probably do away with lighting guidance altogether, as by then LED lighting will have become ubiquitous in new installations.
The big question is will LED lamps really last the 40,000 hours or so the manufacturers claim? Or will the market take them down a route towards built-in obsolescence?
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