26 Feb 2006

Homemade Actis Test Yields Good Results

Are reflective insulation foils all they are cracked up to be? Or are they are con trick?

It’s amazing that we still don’t have a definitive answer to this question, despite them having been around for 20 years or more. Most countries don’t accept the claims made by their manufacturers and refuse to let them be used as thermal insulation. But the UK has taken a more relaxed approach and has said that if the foils can be shown to a reputable independent body that they are as good as the traditional forms of insulation, then they will be acceptable for use on building sites across the land.

The problem for these foils is that when they are subjected to the standard method for testing insulation, known as the guarded hot box test, they don’t perform particularly well. They are not useless, it’s just that they can get to an equivalent to about 80mm of mineral wool and no more (doubling the thickness of these reflective foils has only a marginal effect on their efficacy) and that’s not enough to meet the current U-value standards. But in field trials, the foils can be shown to perform as well as 200mm of mineral wool or 120mm of polyiso board and, if these field trials are to be believed, then the foils are good enough to use as an alternative to mineral wool or the polyiso boards made by the likes of Kingspan and Celotex.

Now, the credibility of the foils in the UK has, to date, hinged on one field trial conducted by the main manufacturer, the French company Actis, and witnessed by Geoff Pitts of TRADA. Actis built two identical roof spaces, insulated one with 200mm of mineral wool, the other with their Tri-Iso Super 9 foil and measured how much energy was used to keep each roof at a constant temperature during a couple of winter months in the French Pyrenees. TRADA, who are an accredited third-party certifier of building products, were satisfied that the Actis product was as good as 200mm of mineral wool and, on this basis, Actis has been able to sell acres of Tri-Iso Super 9 to be laid inside the UK’s roofs. It’s particularly popular for roofs where its simple and quick to fit and it gets over the problem of there not being enough rafter depth to accommodate the traditional insulation boards for the foil-based product is only 20mm thick.

Manufacturers of traditional insulation have seen red and have attempted to rubbish the claims of Actis but to date, as far as I know, they have only ever repeated the guarded hot box test. No one has published the results of another comparison field test.

So it was with great interest that I received a letter last week from Charlie Duke, a house designer who lives in Devon, who was also troubled by the reflective foil debate and wanted to see for himself whether it really worked. He has run a series of tests over the winter measuring how long water will stay warm in a variety of insulated shells. The tests were carried out in his garden shed using very basic materials but shouldn’t be dismissed because of this. He wrote:

The temperature of 350ml of water inside two empty cat food tins was measured in half hour intervals. Each tin was enclosed with insulation with a claimed thermal resistance of 5 (equivalent to a U value of 0.2). As the reflective foil requires a 25mm air gap on the heated side, a 100x100x130mm box of 2mm MDF was made with fins to maintain the air gap. To make things as equal as possible another box (without fins) was set inside the 120mm of polyiso insulation. All joints were taped to prevent air loss. The water filled tins were placed on a layer of 70mm polyurethane foam.

The results were remarkable. The heat loss performance from the two tins showed that whilst 120mm of polyiso board consistently beat one 20mm layer of Actis Tri-Iso Super 9 foil, it was never by more than short head. And that the effect of using a double layer of Actis actually gave a marginally better performance than the 120mm of polyiso. Charlie Duke also tested two layers of Actis, with 25mm air gap between them: in theory this should be better than two layers touching each other but it didn’t show any appreciable difference.

Now just how much credence should be paid to Charlie Duke’s tests I am not sure. He makes no claims to being a hot-shot physicist and the nature of his tests, using Whiskas cat food tins for his water container, is probably a bit too Wallace & Gromit for some. But full marks to him for carrying out these tests and contributing to the debate. I spoke to him on the phone on Friday and was convinced that this is a genuine attempt to understand the complex science of heat loss and to make a reasoned comparison of two different systems: i.e. he is not being set-up by Actis. I hope that others are tempted to follow in Charlie Duke’s footsteps and try similar experiments themselves. Indeed, I am very tempted to try and replicate it here in Weston Colville but I suspect it may have to wait for another winter.

25 Feb 2006

Should we build next to main roads?

If you want to build a new road in Britain today, you have to go to inordinate lengths to avoid upsetting the existing inhabitants. Urban motorways, which in the 60s and 70s were seen as futuristic and progressive, have long since been consigned to the dustbin, brought down mostly over concerns to the health and well-being of those who are forced to live close by heavy traffic. Even if you want to build a by-pass, there has to be public enquiries carried out to assess the damage likely to be caused to the environment and to the would-be neighbours.

Logically, you would think that having gone to a lot of trouble and expense to avoid routing new roads close to existing houses, you would continue to give the new road a wide berth when it came to allocating land for new housing development.

However, there is little evidence that this is the case. Concerns for the public welfare seem to vanish into thin air once the road is completed and often the new road ends up forming a convenient development boundary for the settlement it was built to relieve.

This process is apparent in many of the small towns around where I live and I am sure it is a development pattern replicated across the country. There is currently a particularly gross example of this sort of development taking place on the northern fringe of Cambridge, to be known in the future as Arbury Park. The site is right next to an elevated section of the A14, which at this point forms the Cambridge Northern by-pass which carries 50-odd thousand vehicle movements every day.

You’d think any regional master planner would have identified this spot as being one to leave well alone. There will be a continual roar of traffic noise and diesel particulates will be present in high number whenever the wind blows from the north or east. But alas no; it was granted planning permission in 2001 for 900 new homes and a primary school. There was no public outcry because no one lives there. And when the time comes for the 2000 or so residents to move in, they will not be able to complain because they can see, hear and smell the place they have chosen to live.

I suppose it’s one way of making private housing more affordable.

11 Feb 2006

Sandra Bullock screwed by her builders

In the great tradition of tabloid-style headlines, not to mention an excuse to place a picture of a beautiful woman on the blog, here is the story of Sandra Bullock’s abortive attempts at building a house. It was featured in the Sunday Times on Feb 5th but, of course, I missed it and had to rely on The Week to point it out to me a week later.

Being Hollywood reportage, one really has no idea how much of this story is true, but it makes a welcome change to my usual diet of screed costs, heat pumps and me bleating-off, grumpy-old-man style, about the state of contemporary Britain.

John Harlow is the journalist. This was his piece taken from Times Online

IN an explosive ending worthy of Hollywood, Sandra Bullock, the star of Miss Congeniality, is preparing to demolish her £4m “dream home” in Texas in the culmination of a long wrangle with the builders.
Bullock spent years designing the lakeside mansion in Austin, complete with towers and spires, a spa, library and cinema. But two nights after moving in she moved out again, claiming that the house was a potential deathtrap with a leaking roof, toxic mould, unsafe fireplaces, faulty wiring and crumbling walls.

Bullock sued her builders, winning £3.9m in damages and penalties. She has not yet been able to collect the money to carry out repairs and has opted instead for a cheaper solution: tearing the house down and starting again.

“She’s going to blow it up, demolish it,” said a spokesman for the actress. “She will be pressing the button, or whatever you do to make the wrecking ball go — probably this coming week.”

The saga has already had one dramatic result: following last spring’s trial, the Texan authorities introduced a new law which has become known as the “Bullock Warranty”, obliging builders to guarantee the quality of their work.

Critics say the cost of litigation is such that victims will have to be as rich as Bullock, who earns up to £10m a film, to enforce such an agreement. They nevertheless acknowledge it as a victory in the never-ending struggle between home-owners and shoddy workers.

Bullock has not been left homeless during the eight-year dispute. The 41-year-old actress has another home in Austin as well as flats in Los Angeles and New York and, despite an intense allergy to horses, a property in the “urban cowboy” town of Jackson Hole, Wyoming.

She nevertheless considers Austin her “little piece of blue heaven” where she feels free to go out “dressed like a pig”.
The city is known for alternative lifestyles reflected in a popular T-shirt slogan, “Keep Austin weird”. Her estate on River Hills Road is on Lake Austin, opposite a park where an annual music festival is held.

Bullock moved to Austin after she first tasted fame in the 1994 thriller Speed. Advised by John Bullock, her father and manager, she planned a £1m, 5,000 sq ft house on the shore. But Benny Daneshjou, then the most fashionable builder in Austin, said he could double the size for an extra £300,000.

She accepted Daneshjou’s offer but, as she later told the court, the bills starting flowing in and soon reached £4m — at one point she was sinking £500,000 a month into the “money pit”. She ordered a halt to the construction in 2000, when she realised that she was losing control of the project.

A year later Daneshjou sued her over unpaid bills, so she counter-sued for fraud. The dispute ended in court last spring. During the eight-week trial Bullock cried and cracked jokes at her lawyers’ expense — “You guys are pricey. It’s going to be a good Christmas for you, isn’t it?”— but maintained that she was suing the builder out of principle.

Her lawyers described the mansion as the “house of broken dreams”. The damages that Bullock won were the largest awarded in a private housing dispute in Texas. But she is still pursuing the builder through the courts, claiming that he has “hidden” many assets by signing them over to his wife.

Despite having told newspapers that she was bored with acting, Bullock has returned to work, partly to pay for a new house. She has just finished shooting her comeback film, a supernatural romance with Keanu Reeves, her co-star in Speed.
Bullock is said to be amused by the film’s title: it is called The Lake House.

10 Feb 2006

Why is floor screeding so expensive?

Jonathan asks

Why do people charge so much for floor screeding? I've got about 90m2 of 65mm screed over 60m Kingspan insulation — I am not fitting underfloor heating —and I thought the only quote I've got of £1350 seems quite high if, in theory 2 men can do the job in a day, then they are getting £800+ in labour!? I've had a couple of local plasterers come and look at the job and they didn't fancy it when they saw the big expanse and recounted various tales of problems with cracking and settling of levels! They said could you not just concrete it and then put on a finish with self-leveling screed!?

Mark reckons

My "time taken" tables suggest that 65mm screed takes around 25 mins per m2. This, in turn, suggests a labour rate of around £8-£10 per m2, on top of a materials price of £4.50 per m2. This would suggest your quote is close to the market rate.

Normally screeders work in a 2 and 1 gang so this 25 minutes figure includes a labourer to mix the screed on site. My latest benchmark house has a ground floor area of 55m2 and the screeding was done in 3 man-days, which is spot on 25mins per m2.

However, you do see people getting screeding done at apparently much faster rates. How come? Well one obvious issue is quality. A good screeder doesn't hurry - it's an art that not many people do well. Also, supplying readymixed screed can make savings - you would loose the labouring costs and get those 25 mins down to around 18 mins per m2 - but you would of course be adding to the materials cost.

The overall time taken is also affected by whether it is a large space or lots of small rooms. Large spaces are quicker to lay but, as your plasterers point out, they are not without their problems, esp. if you are laying underfloor heating in the screed. BS EN 1264 recommends that you limit the area to be screeded to 40m2, or 8m lengths in any one direction. If you exceed this, you should separate the floor into bays divided by some flexible expansion material. You can generally stop cracking by using mesh or adding fibres to the mix but on very large areas you may find that the screed has a tendency to lift up due to expansion.

9 Feb 2006

Homebuilding & Renovating Show, NEC, March 2-5

Matt asks

I'm new to this game, just starting out with the long process of research and I'm planning on going to the NEC show next month.

Would you recommend me going for 1 or 2 days?

I thought it might be worth 1 day for the seminars and 1 day forgetting round all the exhibitors, including the Smart Home show.

Any advice is welcome

Mark reckons

It's a big show, which has been running for around 15 years now, and each year it seems to be a little bigger than the one before. You could easily spend all four days there and not see everything but whether you'd want to do that is another matter.

I will be there all four days but then I am paid by the organsers to deliver some of the seminars. At this show, and also at the London one in September, there are two theatres running seminars concurrently, so you have to choose which topic you want to check out. If there is a clash, then you have to go on two days. The timings don't alter and the topics are clearly marked up outside the theatres: seminars start every hour on the half hour from 10.30 through to 3.30. You used to have to queue to get tickets but in the past year they have relaxed this requirement so that you can come and go as you please.

Some people come specifically for a day of free seminars and plonk themselves down in a prominent seat for the duration. Others treat them more as a quiet spot to have a sit down and a snooze. But overall they are reasonably informative, especially if you are starting out. Old hands would find them a bit basic, methinks.

The exhibition is probably most useful to people with live projects to get comparison quotes on and to get a feel for the businesses plying for their custom. It can be a bit overwhelming just wandering about from stand to stand if you have nothing specific in mind. There is a satelite exhibition called Smart Homes, which has grown out of the original exhibition: it has its own seminars running throughout the day. And last year there was an attempt to create a green zone in the main exhibition, but it wasn't very clearly marked so I don't think many people realised when they were in it. This year this idea is being taken a stage further with a Period House zone as well as a green one..

If you come, do look me up. When I am not doing seminars (12.30, 1.30 and 3.30, each one for an hour), I am usually hanging around the Ask the Experts stand, which is always located close to the seminar theatres.

7 Feb 2006

From Poundbury to Sherfield Park: another utopian dream bites the dust

Last week I drove up the A33 between Basingstoke and Reading and ran into a nightmare vision of the future. There I was, driving along a country A road, minding my own business and I pitched up at a new roundabout. Could it be a supermarket? Or a science park? No, it was a new housing estate called Sherfield Park and it has to be the most pretentious, most pointless development I have ever seen. Frankly, an enormous Tesco with fake plastic columns would look a lot more authentic than Sherfield Park.

The picture shows the three-storey terraced scheme straddling the spine road into the development. It looks like it should be in London, but it’s not, it’s right in the heart of the Hampshire countryside. Why on earth are they building Georgian townhouse terraces here?

The answer lies with the current planning obsession with density, known by the acronym PPG3, which is seen as the best way of developing new homes without upsetting the natives. It all started with Prince Charles’ Poundbury development in Dorset. Poundbury was reactionary. Reactionary in style; it was a throw back to old vernacular forms of English housebuilding. But also reactionary in its layout, in that it cocked a snook at the car-led, cul-de-sac designs which have, until recently, characterized our new housing estates. Poundbury sought to create much more than a dormitory: it aimed at building a functioning community, with shops, pubs and halls where people could meet and socialise.

There is a little magic about Poundbury. It works. People like it, it looks good, and influential people go and visit it to see what all the fuss is about. Even avowed modernists who loathe Prince Charles’ olde-worlde designs have to admit that Poundbury is a damn good development. It was started in 1993 — it is yet to be finished — and, during the 12 years of its existence, its influence has spread far and wide. It became the model for PPG3, which came into force six years ago. No more cul-de-sacs, no more detached houses surrounded by decent sized gardens, no more wasteful two-storey homes. And only one and a half parking spaces per house.

But just as the New Towns movement turned into a lame excuse to build some really crap towns, so Poundbury and PPG3 have become diktats used to inspire some really shocking new developments. Such is the obsession with density and sustainability that the houses are cramped, the gardens miniscule and there is nowhere to park the car. The theory being that, of course, being communities, not mere housing estates, people will be walking to work or maybe popping off on their bikes. Or catching the bus that comes past once every ten minutes. A likely story.

PPG3 seems to have replaced one sterile form of development with another. What we are now getting is these strange looking urban extensions like Sherfield Park. Except that this one is five miles out of Basingstoke, and is surrounded by green fields. There is nothing remotely urban about this site and making it look like a town looks like some sick architectural joke. Sherfield Park, like dozens of similar examples dotted around the country, is a just a very ordinary housing estate that just happens to look like a dumbed-down version of Poundbury.

I gather from a nearby resident that the place is already famous for its parking disputes: in the absence of the community hall for years to come, at least this is one way of getting the neighbours together!

6 Feb 2006

Whither gas prices?

Gas prices have been in the news today. Again. They are set to rise. Again.

But when? And by how much? If ever there was a smoke and mirrors story, it’s this. 15%, 20%, some say prices need to rise by 25%. But just this morning, Patrick Heren, an energy analyst, appeared on Wake Up to Money at 5.30 a.m. saying he thought it was just a short-term spike and that prices would fall in 2007.

As someone who makes recommendations about which heating systems to choose for new houses, based on future running costs, it’s all rather confusing. For a start, I like to price my fuel in kilowatt-hours (kWh): it is how it is sold to the consumer by the gas and the electricity companies, so it’s an easy unit for comparison sake. For years, mains gas cost around 1.5p per kWh: it has crept up to near 1.8p recently, but if you want to work out where it will be after the next round of price rises, you are left floundering. Instead the media resort to fuel bills for the average house. Or you get a graph of the wholesale gas price in pence per therm. What is a therm, for chrissake? Wikipedia to the rescue.

A therm is the energy equivalent of burning 100 cubic feet of natural gas at standard temperature and pressure. It’s undeniably imperial. It’s equivalent to 100,000 BTU (British Thermal Units). And somewhere in the dark recesses of the Housebuilder’s Bible, (actually p 390 of the current edition), I can extract the fact that there are 3,410 BTU in every kWh. I can’t remember how I came to know that fact, but it’s been in every edition of my book and that’s now an institution older than Wikipedia so it must be right. So by dividing 100,000 by 3,410, we should arrive at the number of kWh in a therm. The answer is 29.3.

Patrick Heren’s graph shows that, back in 2002, the wholesale price of gas was 20p a therm. That is 0.7p per kWh, when the retail price was 1.5p. So back then, British Gas was making a comfy 100% mark-up.

But today, the wholesale price appears to be 64p a therm. Well, the BBC are saying this is the current price. Patrick’s graph, reproduced from the Independent, shows it at around 56p. Either way, it’s more than the current retail price. On the Continent, the wholesale price is much less, just under 40p a therm or 1.3p per kWh.

In the short term, gas supplies in the UK are being squeezed, hence the imminent price rises. The North Sea still supplies 95% of our gas but getting hold of the extra 5% is beset with problems because our European neighbours don’t want to part with it and we haven’t got the infrastructure to get it direct from Russia. That is why our prices are way higher than anywhere else. At the moment.

But what does the future hold? At some point in the next three months, I have to go to press with a graph showing relative costs of using different forms of heating. At the moment, the market is in a state of flux. Where do I guess gas prices will be over the next two or three years? 2p or 3p per kWh? And what of electricity? Currently hovering around 7p per kWh, they seem set to go higher. But to where? 10p? 12p?

And to an old greenie like me, I can’t help feeling that the increasing price of fuel is actually a good news item because it will, at last, stop us using it so freely. Strange that the Independent, the greenest of our national dailies, chooses to headline its story with the poor and the vulnerable will die if they can no longer afford to heat their homes. They can’t have it both ways! Last summer the same people were dieing because global warming was making them too hot. Best not to be poor or vulnerable. Or to make yourself too scared by reading the Indie.

3 Feb 2006

2 Feb 2006

On teenagers and showers

Our total household water consumption currently stands at 350m3 per annum. That’s just under 1000 litres per day. Bear in mind, if you didn’t already know it, that 1000 litres of water occupies a cubic metre of space and that water companies habitually sell water by the cubic metre rather than the litre, just to save three confusing noughts on the bill.

Now 350m3 per annum is a large figure, even for a family of five. Water company guidelines, used to set prices, suggest that a family of five should be averaging no more than 230m3 per annum and indeed, in our first few years in this house, first occupied in 1993, that’s more or less what we consumed. But as our three boys got older, the consumption level has crept up and up and their current predilection for showers has ratcheted up our water usage to new heights. We are consuming 50% more water than we ought to. Yikes! What is our excuse?

Well, m’lud, when they were babies, they made do with one shared bath a day. Now they all shower. This morning I timed Jack, our eldest, in and out of the shower. Discreetly, you understand. I don’t think he even knew I was clocking him but I was keeping an ear out. He took eight minutes. God knows what he does in the shower for eight minutes each day: it’s a long time since I was seventeen and I think we only had crap showers back in 1970 and so we used to soak in baths. Showers were seen as a way of saving water. Not any more.

Jack is the worst for long showers but the other two aren’t far behind. I reckon that, between us, our family of five probably account for around 20 minutes in the shower each day. Maybe even a little more. And each of our showers delivers 20 litres of water per minute and our water bills bear this out in black and white. I think the switch to using showers accounts for almost all this increase in our water consumption. A bath once a day uses maybe 100 litres. 20 minutes of showers at 20 litres per minute uses 400 litres. The difference, 300 litres, times 365 days a year is 109m3. And we’ve gone from 230m3 per annum to 350m3. Hmm.

The additional water cost? Cambridge Water Company are currently billing us £1.75 for each cubic meter of water (inc both supply and sewerage). So the extra 109m3 will be costing us £190 a year.

But what about the effect on our heating bills?

We use an oil-fired boiler and I log its consumption, just as I log the water bills. There isn’t quite such an obvious trend here for domestic hot water heating duties fall some way behind space-heating as far as the boiler is concerned. And, of course, space-heating demand varies from year to year. But nevertheless there is an appreciable upward trend to be observed. In the early days, the 1990s, we used just over 6 litres of heating oil per day, averaged throughout the year. But during the past two years (i.e. 2004 and 2005), our oil burn has crept up to 7 litres per day.

Now a litre of heating oil, costing 35p, contains just over 10kWh of energy. Because the boiler isn’t the most up-to-date condensing model, this only produces around 8kWh of energy in the hot water systems. This additional 8kWh is enough to heat up 140 litres of water from 8°C to 60°C.

Now, if we are using an extra 300 litres of water a day in the showers, around two thirds of this will need to be heated in order to get a nice shower temperature at around 43°C. So this would suggest the extra showers would consume 100 litres of cold water and 200 litres of hot water. 200 litres or 140 litres? The figures are a bit fuzzy, but there can be no doubt that our changing habits are showing through on both water and oil consumption.

The additional heating cost? 200 litres of extra hot water a day equates to an additional 14kWh energy used, after boiler inefficiencies are accounted for. That is 4,900kWh extra per annum, equivalent to 480 litres of heating oil, costing currently 35p per litre, or £168 each year.

Add this £168 to the water costs (£190), and you can see that the boys’ love of power showers is costing us £350 a year.


The most obvious point is that power showers are incredibly resource hungry. Whilst a huge amount of effort seems to have been spent on producing products like washing machines, and fridges which consume less water and less power, these savings pall into insignificance when set against the extra demand we are placing on our showers. There is Part L of the building regs banging on about fitting four compact fluorescent lightbulbs (annual saving around 300kWh) and using argon in double glazed sealed units (annual saving another 300kWh): meanwhile a household growing up and starting to use to power showers adds 4,900kWh to the annual energy consumption, more than the entire lighting load for the same household.

Having said that, this figure of 4,900kWh per annum is itself dwarfed by the energy used to fly a family of five to Spain and back. That’s around 25,000kWh, which is equivalent to the entire space heating and hot water requirements of our household for any given year.

It makes you realise just how anal our energy saving regulations have become. And how incredibly difficult it will be to bring about significant reductions in our energy consumption. Not to mention our water consumption. For every energy and water saving measure we introduce, we seem to find a new device which more than cancels out the benefits.

Having said that, there is obviously great scope to produce both energy savings and water savings from designing clever showers, which give the feel of a power shower from a greatly reduced flow rate.