26 May 2015

Are Eco Homes prone to Overheating?

Earlier this month, stories appeared in the Sunday Times and the Daily Mail about overheating in eco-homes. In particular, Passivhaus was mentioned.

Why exactly should an eco home overheat anymore than any other home? What the stories implied was that because these houses were so well insulated, they wouldn't be able to cool down in summer. Heavy insulation used to keep the buildings warm in winter also traps heat in summer — potentially putting vulnerable residents at risk warns Mail Online. A study at Coventry University found that Passivhaus flats built by Orbit housing association were overheating too often, although the definition of overheating seemed to be set pretty low at 25°C. Lots of people pay good money to go places where the temperatures never drop below 25°C.

But back to the point. Is there something special about eco-homes (and Passivhaus homes in particular) that causes them to overheat? I don't think so. In fact, the Passivhaus standard is rather unique in setting comfort standards for overheating. 25°C for more than 10% of the time is regarded as a Passivhaus failure but I don't know of any other housing standard where such a result would be deemed to fail. Indeed, the existence of a Passivhaus overheating hurdle was the very reason why this study was being undertaken in the first place.

It's difficult for any home to enjoy temperatures lower than the external air temperatures without introducing air conditioning. Without this, the best method of controlling summer overheating is to open lots of windows and cross-ventilate, so that there is a breeze running through the building. This is the standard house cooling method used in hot countries and there is no reason why it can't be employed in eco homes and Passivhauses. Passivhauses also benefit from having mechanical ventilation systems which, used correctly in heat waves, will contribute to night-time cooling. On its own, mechanical ventilation may not be adequate to dissipate all the heat build up but it's not designed to do this. Passivhauses also have windows!

If the building itself is to contribute to the problem, it won't be the insulation that causes the problem but the thermal mass of the structure. If a house is built largely of concrete or brick, these materials will gradually absorb background heat during a prolonged heat wave and radiate this heat back into the house during the relatively cool night time, precisely when the residents don't want it. Low mass materials like timber and insulation don't absorb significant amounts of heat and are therefore not going to contribute to night time overheating. Admittedly, they will also stop heat escaping from the structure at night but set against this is the fact that they will also stop heat absorption during the hottest part of the day. These two effects cancel each other out.

If there is a problem with overheating homes in the UK, it will almost certainly be caused by a combination of having large, unshaded, south-facing glazing (resulting in the conservatory effect of having spaces which are rendered almost uninhabitable during the day time), coupled with inadequate ventilation — probably caused by having too few opening windows. These are design issues which can affect any building during heat waves, regardless of building standards and insulation levels. The editorial decision by two right-wing papers to big this story up as an "Eco House Problem" is unwarranted and probably mendacious.




26 Feb 2015

1998 revisited

I've just had my 500th article published. I started freelancing in 1997 and have mostly written for Homebuilding & Renovating since then. But in the early days, I used to find all kinds of unlikely spots to take my musings and here is one of my earliest pieces dated December 1998, written for the Velux company. It's about the nascent housing crisis and it's interesting to reflect how the slant has changed over the intervening years. Back then, we built twice as many homes as we do now, but mass immigration had yet to take off and become such a political hot potato.

Where will all the new homes go?

The future of new housing in Britain has reached a crucial stage. For the first time, there is a debate about how much housing is needed and where it should go. Until now it has always been assumed that new homes are generally a good thing: no more. We live in an age when many of the previous generation's assumptions are not only being questioned but also being actively rejected.

Until World War II, British housing had been largely developed on a piecemeal, laissez-faire basis. Developers were able to buy land more or less wherever they chose and build houses for either rent or sale. It resulted in a great expansion of towns and cities throughout the country: as we become more prosperous, we wanted more space and builders were happy to meet these demands where they could. The downside of this was that new housebuilding tended to sprawl out along roads in what is now called ribbon development. After the war, the political climate changed and planning controls were introduced. The idea of these was not (and never has been) to prevent building, but to direct it into locations which it was felt would be less damaging overall and it would be easier and cheaper to provide the essential services like schools, shops and medical services. In order to stop ribbon development, green belts were introduced around towns so that post-war housebuilding has tended to be channelled into what are called infill areas, mostly between the pre-war ribbons.

Throughout this post-war period we have been building around 200,000 new homes each year. Some of these have been replacements for older houses but most have added to the sum total of homes in the country which currently stands at around 25 million, one home for every 2.3 people. In 1972, the ratio was one home for every 2.8 people. The statistics here don't lie. Our total housing stock is expanding by nearly 1% each year whilst our population is virtually static.

Why do we need more houses? Haven't we got enough already? Or is there something wrong with the ones we've built to date? The truth is that nobody can answer these crucial questions with authority. Much of the evidence we have is anecdotal and often contradictory. Some sources cite the fact that much of our existing housing stock is simply in the wrong place and that people have a need to live near to their work so the new housing is tending to get built in the prosperous areas. Others say that we are still undergoing a profound social transformation which is seeing the breakdown of the traditional family and the rise of the singleton household and the single parent family. A third theory has it that we are simply getting richer and want more space to store our possessions. What isn't in doubt is that there remains a pent-up demand for new housing of all sizes and in all locations, though the bulk of this demand is coming from South-East England.  

Set against this is an increasingly strong conservation lobby. The government has outlined a target figure of 4.4 million new homes needed between 1991 and 2016 (very similar to the rate we have been building since the 1960s). But, for the first time, this figure is being challenged by many different parties and people are objecting to loosing more and more countryside to housing. Elected politicians have been quick to notice this and have been caught in something of a cleft stick, not wanting to upset either potential new house buyers nor existing residents who are fearful of development. Their response to date has been to try and persuade housebuilders to switch away from the time honoured practise of putting up houses in fields and to get them to concentrate on the conversion of existing buildings into homes — a phenomenon known as brownfield development. 

Just how many brownfield sites there are suitable for redevelopment is itself a matter of dispute. At one extreme, Friends of the Earth claim that there is the potential to create over 7 million new homes without touching an acre of greenfield: at the other end of the spectrum, many are saying that the government's own target of 60% of new homes to be built on brownfield sites is hopelessly optimistic and that many of the potential brownfield sites are located in areas where there is little demand for new housing. 

To date, the debate about the future of housing has concentrated on the simple numbers of new homes that should be built. It is just as important — yet so far it has been largely neglected — to look at the size and amenity of the houses that will get built. As discussed, one of the driving factors behind the growth in household formation is said to be the shrinking sizes of families and the increasing number of single person households. Logically you would expect the demand for new housing to be largely met by small homes, perhaps one or two bedroom flats. However, the actual demand seems to be spread much more evenly across the spectrum and, indeed, in recent years there has been a significant growth in the numbers of large four and five bedroom homes being built. It would seem that many one or two person households would actually very much like to have some extra space, perhaps a study to work from home or a hobby room. Just because households are getting smaller doesn't mean they are all getting poorer and it is beginning to look as though our individual space requirements are actually growing. If this is so, then one way of reducing the overall demand for numbers of new homes would be to build larger houses. 

Now in the minds of the conservation lobby, the large executive-style houses are the worst offenders of all because they invariably sit in their own grounds and all built with garaging, driveways and other space hungry features. It's a very low density form of housing and, worse still,  it tends to get built on greenfields. The actual living space in such homes is often surprisingly small and it has been shrinking over many years. A four bedroom house built today in a typical greenfield site has between 1100 and 1500 sq.ft of internal floor area: an equivalent built in the pre-war years would have been around 30% larger. 

Greenfield housebuilding isn't going to cease, whatever the wishes of the conservationists. However, it could greatly reduce it's demand for greenfields if it adopted design and building techniques which would allow a greater development density. The high cost of building land has tended to concentrate the minds of housebuilders on shaving actual build costs down to a bare minimum and this has, paradoxically, caused them to build smaller and smaller houses. Furthermore the the methods of construction used nowadays tend to prohibit extension of the dwellings once built. The floor plan is often so very tight that it becomes difficult to build a useful extension at the side or the rear and the loft space is constructed in such a way that it is virtually impossible for the householder to use the space for anything more than storage of suitcases and cardboard boxes. The Victorians and Edwardians habitually built homes with cellars and attics, giving the homeowner the option of expanding the living space as and when circumstances dictated. In contrast, the twentieth century Elizabethans have specialised in creating a form of housing that is both cramped and inflexible. The standard response to needing more space is to move house rather than to adapt what is already there.

It therefore seems likely (though of course it can't be proved) that part of the demand for new housing is being driven by a general dissatisfaction with what we are currently building. Were we to rediscover some of the techniques and designs of our forebears, we could be building extendible housing which would reduce the overall demand for new homes which would, in turn, save many greenfield sites from development. 










20 Jan 2015

Security Tips for Selfbuilders

The average private dwelling currently suffers an attempted break-in every 12 years and over half of these attempts are successful. Of course, it all depends on where you live. Some quiet locations still exist where no one locks their front doors, whilst there are some inner city areas which seem to get burgled regularly.
Wherever you live and whatever the future holds, burglary is not a problem that is likely to go away and anyone considering building a new house would be foolish not to consider the matter very carefully. 

The burglar
As you might suspect, the typical burglar is a young male but you might be surprised to learn that he is not part of a well-organised gang but usually a lone wolf whose break-in is often done on the spur-of-the-moment, when he sees the opportunity arise. There is really no reason to adopt a fatalistic attitude because, although it’s entirely true that if someone really wants to get into a house they can, most of the time they won’t bother if you go to the trouble of making life difficult for them. 
Our young burglar’s main concern is not to get caught in the act and to this end he values being able to get in, and out, quickly and preferably unseen. Another surprising statistic thrown up is that as many as 40% of burglaries take place while the home is occupied. You’d think this would be amazingly risky for our burglar but it only takes a few seconds to come in through an open door and walk out again with something and you may not even realise that you’ve been burgled. If you are worried about this sort of thing happening, get a dog.
With regard to new housebuilding, current thinking focuses on the following areas:
• Site layout
• Preventing access to the rear of the house
• Decent locks fitted to ground floor windows and doors
• Burglar alarms where risk is high
• Security lighting.

Site layout
Although this area has more relevance to estates than to single dwellings, it’s worth mentioning what they are on about. Dark corners and unlit alleyways should be avoided and houses should be sited where their neighbours can see who is coming and going. There is often little the individual housebuilder can do about this, though it is possible that consideration can be given to the issue when there are two or more houses to be sited near each other.
One obvious point that the professionals have tended to overlook is to locate the most widely used room in the house – usually the kitchen – at the front, so that the occupants can see who is coming and going out on the street. However, this arrangement remains an extremely unpopular layout in this country; we still prefer our kitchens to be by the back door.

Restricting access 
The rear of the house is the preferred area of entry for burglars. This is largely because the back of the house is almost always more private and is often screened from neighbours. A burglary often starts with a casual casing of the front of the house; if it looks as though there is no one at home, the second stage will be to go round the back and take a closer look. Only when they’re convinced the coast is clear will the break-in proceed. If access to the back of the house is impeded, then the would-be burglar may abort the job at this early stage in the hope of there being easier pickings further up the road. 
A 2 m fence and a stout gate – even without a bolt – will provide a considerable measure of defence against unwanted prowling. A tip from my 2010 Milton Keynes benchmark house is to use a 2 m fence but to have the top 300 mm made up of a see-through trellis which is just as difficult to get over but allows you to see who is walking along behind it. Back gardens can be protected, to a lesser extent, by walling or hedging them in. Plan in any obstructions that will at least slow down the progress of a potential burglar. However, bear in mind that a fully enclosed garden, once breached, makes an ideal spot for our burglar to force an unseen rear entry so if your garden is going to be enclosed for security reasons, you need to do it well.
Robust locks 
It is an NHBC standard to have five-lever locks on all external doors and to have window locks as well. The relevant standard here for door locks is BS 3621: you may even get a small discount from your insurers if your locks meet this standard. At least one exit – usually the front door – must be protected by a night latch (Yale-type locks), which can be opened from the inside without a key; this is to aid escape in case of fire. The idea is to lock the door on the night latch when the house is occupied and to use the five-lever mortise lock when the house is empty. Window locks used to be fitted as standard on volume joinery, but a change to the fire regs in 2002, calling for all first floor windows to be openable internally, has thrown this all into a state of confusion. Ideally, you want downstairs windows to be key-lockable and upstairs windows to be openable easily without having to find a key, but the chances of your joinery supplier getting all right are not high! 

French and patio doors
It is marginally easier to force a door inwards than to prise it out but it is likely to be rather noisy. Most front doors open inwards. However, note that double-doors (French doors) are particularly easy to force in or prise outwards; most French doors open outwards and if you fit them be sure to fit decent sliding bolts to the top and bottom of both doors. For extra security, make these lockable bolts. Sliding patio doors are generally a much more secure (and draughtproof) alternative (though not half as elegant); however, many break-ins have occurred where the patio door frame has been levered out of its seating, having only ever been held in by six short screws or, sometimes, nothing more than mastic sealant.
Glass 
The current building regulations will ensure that you have to fit double-glazed sealed units, and the safety standards on glazing insist that safety glass is fitted to all doors, windows next to doors and all glazing less than 800 mm above the internal floor level. Safety glass is expensive, costing nearly twice as much as ordinary float glass. It comes in two varieties, toughened or laminated, and they perform slightly differently. 
Toughened is harder to break but when it breaks it collapses into small nodules, whereas laminated glass has a sheet of plastic sandwiched between two layers of ordinary glass; this makes it harder to break through (from the burglar’s point of view) and is therefore slightly more secure. The police are big fans of laminated glass, and suggest that it should be fitted wherever there is glass next to an accessible lock, but as this includes virtually every ground floor opening window it would be an expensive option.

New security standards
Factory-glazed windows are available which meet a new British security standard, BS 7950, also known as Secured by Design. Rather than just testing the individual locks or the glass, BS 7950 tests the whole window assembly in situ. Typically such a window will have laminated glass on the external face and shootbolt espagnolette locking mechanisms. To get windows to this standard, they really need to have been factory glazed but this doesn’t mean they have to be plastic – most of the big timber joinery manufacturers now produce BS 7950 windows. 

Burglar alarms
There is a huge variety of different alarm systems out there and it’s not easy deciding what to fit. It is usually cheaper to install a wired system, which is particularly well suited to new housing as the wiring can be concealed during first-fix stage. Installation quotes for a four-bedroom house are likely to vary from £500 for a basic system based on a mixture of internal infrared detectors and contact points to over £1,000 for external vibration detectors which are triggered by interference with doors and windows. Should you not want to go to the expense of installing an alarm, as an alternative, the wiring can be first-fixed in a day for between £100 and £200, so that the intruder detectors can be fitted at a later date without disruption to the decorations. Burglar alarms are eligible for zero-rating of VAT when building a new home. 
Fixing a burglar alarm should not be beyond the capabilities of a competent DIYer and there are a number of systems designed for just this. DIY alarms usually consist of a control panel, the detectors and an external siren. The wired systems are the most reliable and are probably best suited to new builds. However, wireless alarms have their advocates and are easily fitted as an afterthought. The standard wireless systems still need mains connections for both the control panel and the siren but the latest generation work entirely on radio signalling: the siren and the control panels are solar powered and you activate the alarm by using a remote control.  
More features tend to add to the cost but it is still possible to get a well-featured wireless system for under £200. Zones are the areas covered by individual detectors and most burglar alarms allow you to arm or disarm any of your zones individually. This is useful if you have pets or if you want only the downstairs armed when you are upstairs at night. Better systems have a capability of checking that all component parts are working – a feature sometimes referred to as a 24 hour zone.

Detectors
The detectors on which burglar alarms are based come in a number of guises. The two commonest are the passive infrared (PIR) detector, which is triggered by movement across its path, and the door or window-opening detector that is set off when a magnetic contact is broken. You can also get detectors based on pressure pads – typically these would be under a doormat and would be triggered when someone unexpected treads on it. You can give great thought to just which detector to put where and still get it all wrong. 
Many a break-in now occurs via an upstairs window: the thieves never go downstairs because they reckon it will be alarmed, so they just ransack the bedrooms before leaving the same way they came in. So maybe it pays to have lots of detection zones but possibly only if you are very confident in your ability to operate the system.
If you’ve never lived with a burglar alarm, you might be forgiven for thinking that they are the last word in home security. However, the consequences of fitting an alarm can be fairly tortuous for the householder and their neighbours. All systems are set to make a loud noise for a few minutes; false alarms will make you very unpopular and false alarms do happen, so a burglar alarm is not without its problems. A recent police estimate reckoned that no less than nine out of ten ringing alarms are actually false alarms and the police now have a policy, in effect in most areas from 2006, of withdrawing their response after more than three false alarms. 

Monitored alarms
If you have a very remote site or are not entirely happy about a 105-decibel alarm ringing when a mouse crosses the floor, the next step up the security ladder is to get a monitored alarm. These link your house via the phone lines either to the local police or to a security firm. If you want the police to monitor your alarm, then the system must be installed by a company approved by one of two bodies; NACOSS (National Approval Council of Security Systems) or SSAIB (Security Systems and Alarm Inspection Board). Needless to say NACOSS or SSAIB approved systems cost rather more than unapproved ones. Or as one wag put it to me, it’s daylight robbery what these guys get away with. Monitored systems also carry an annual charge which is likely to be in excess of £150; they are only available if two key holders besides the occupants live close by and are prepared to be called out in the middle of the night. 

Movement sensors
Alarm systems don’t have to just concern themselves with making loud noises or sending messages off to police stations. You can also rig up detector beams running across the front and the back of your house which set off a buzzer inside when they are crossed. They vary in sophistication from simple passive infrared beams like the ones used to trip lights, to multi-height beams running between two concealed posts which aim to be cat and fox proof. The well designed systems will give you fairly reliable intruder alerts: a poor system, tripping out every time a bird flies by, will just make you paranoid. 

Car parking
Both integral and detached garages can be included in whole house intruder alarm systems, but this tends to be very inconvenient; the car has to be left outside whilst the alarm is deactivated (usually inside the house). It rather defeats the purpose of these remote control devices for garage doors. 

Other measures
Door chains (from £3) and viewers (from £4) are becoming more common, and are recommended by the police. Surely the most cheeky is the fake ‘Protected by Burglar Alarm’ bell casing which you screw on to your outside wall. Available at around £8 from DIY sheds.

Security lighting
Passive Infrared (PIR) detectors, similar to the ones used on internal movement sensors in burglar alarms, are also used on external lighting. These can be very useful around dark entrances although the halogen bulbs (sometimes 500W) can be so bright that you dazzle passers-by and tend to make them think you live in a high-security prison.  There are some very cheap versions on the market (at around £10-£15) which are best avoided; at around £30 you start to get ones where it is possible to change the bulb. Better forms of external lighting exist that can be wired to PIR switches, as well as manual override switches, which give pleasant external illumination as well as some form of security .
There are also a number of products that can be used to give the effect of occupation when the house is empty. For around £20, you can buy a gizmo which fits in between a lightbulb and its lamp holder that acts as a light-sensitive switch, useful for simulating occupation when you are away. 

Shutter protection
To fit security roll-down shutters to every opening on a detached house would cost over £6,000 so no way is this a cheap and cheerful option. Indeed it looks pretty severe as well, but if you are away a lot and have particular reason to fear intruders, then shutters are very secure. They don’t work well with outward opening windows (think about it) and are best designed around either sliding sash style or tilt and turn windows. On the Continent, shutter protection is often taken as a given, but then on the Continent windows only ever seem to open inwards. Strange to reflect how different something as basic as a window can be.

Safes

Home safes are available from £150 for a wall fitting one and from £200 for one bolted to the floor. Placing a safe in an existing house can be awkward but in a new house it’s a doddle – if you’ve planned ahead for it.

30 Dec 2014

What it takes to buy a city centre building plot

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.


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.