Why sash windows work

Alan Burgess of Masterframe has taken the trouble to prove what many of us had long suspected. That sash windows work as superb ventilators. The trick is to open them a little at both the top and the bottom and this sets up a circulation of air that will clear the room of stale air, bad smells or excess heat in summer. Alan, together with his technical director Ray Rabbett, have run a series of simulations on software used by the ventilation trade which shows just how effective the traditional sash design is compared to other common window formats, such as top hung casements or tilt and turn. The results of their work will be published shortly.

For Burgess, it’s of more than academic interest. He is, and always has been, passionate about sash windows, and his company makes nothing else. He’s long felt that the powers-that-be have been conspiring against the sash design and pushing us all gently towards a more modern, European style, using energy efficiency arguments to jolly us along. Burgess feels that his contemporary re-working of the traditional sash designs are the equal of casements and tilt and turns in this respect, but now he has some proof that they are actually superior in terms of ventilation. And in a critical passage in Part F, the ventilation regulations, there is a reference that says that, when replacing windows, rapid ventilation should not be made worse. Up until now, no one has challenged the assumption that this simply means that the openings should be of similar size. But it transpires that a single opening casement is far less effective at rapid ventilation than a combination of top and bottom openings.

In common with many people, Burgess has long decried the ripping out of Victorian sashes and their replacement by top hung casements. Up till now, the objections have only ever been aesthetic. If this research is taken on board — and Part F is up for consultation very shortly — then it means that in future existing sashes will either have to be repaired or replaced on a like-for-like basis.

On Icynene

Icynene has arrived in the UK. What is it and why should it raise you from your slumber? It’s a spray-in foam insulation system, hailing from Canada and its makers claim you can get PassivHaus style performance from it without having to build walls and roofs which are 500mm thick. In fact, it gets used in the high Artic where the temperature falls to minus 60°C at only 90mm thickness.

I interviewed Jeff Hood, one of Icynene’s owners and the man responsible for bringing the product into Europe. Since the company’s formation in 1986 in Toronto, it’s achieved spectacular growth in North America and now accounts for around 5% of installations in US new housing. It works equally well in hot climates as in cold. Unlike the more common polyurethane foams, Icynene is blown with water: this was originally done to avoid formaldehyde off gassing but they have stuck with it to produce a unique sponge-like product that remains flexible. This flexibility is one of the keys to its success because it produces a truly airtight barrier and one that will stay airtight indefinitely. Hood tells me that this factor alone makes Icynene much more effective than almost any other insulation system. “We don’t believe boards are really effective because the caulking around them is never going to be done perfectly and in any event it will crack over time.”

So far all well and good. However, Icynene faces one or two problems before it can become widely adopted in Europe. “Europe is U value obsessed,” says Hood. “We believe we can get excellent performance from this product at fairly minimal thicknesses and that, whilst we could apply it at 300mm depth, there is no point because the performance improvement is absolutely minimal. Why waste footprint needlessly?”

Europe however is still feeling the effects of a nasty little tiff with the multifoil industry which, in truth, is still not satisfactorily resolved. The multifoil manufacturers make very similar claims and thus far have not been able to establish them via traditional testing methods. Icynene is a very different product to multifoil but the claims made by Hood and his colleagues have many similarities. Thus far Icynene has won BBA approval for use in walls and roofs, but only as a substitute (in performance terms) with glass fibre and/or polystyrene, which makes it rather poorer than the polyurethane family. But Hood’s contention is that it’s actually much better than all the other available mainstream insulation products and to prove it he has hired the building scientists at Napier University in Edinburgh to run some tests on Icynene in their laboratory in Glenrothes, a facility I visited last year with the UK Timber Frame Association. Results should be available soon. If they confirm Hood’s contentions, it could re-ignite the debate over the effectiveness of the established testing method, the guarded hotbox test.

Many people will think that we’ve been here before. The multifoil debate raged for many years and it was all based around the validity or otherwise of the guarded hot box as being the best (or only) method for measuring the effectiveness of insulation materials. The difference this time is that, in Icynene, we have a manufacturer who can quite happily supply insulation at any thickness. As Hood explained to me: “We can spray at whatever thickness the client wants, we just don’t want to waste their money, or use more material or footprint than is necessary. We think that’s green. And we think the move in Europe towards PassivHaus-style massive insulation is a costly mistake.” With Icynene installed in over 200,000 buildings including several LEED platinum standards, it could be that our future insulation standards could once again be up for debate.

Demand Control Ventilation

There was an interesting product on display at EcoBuild that I hadn’t seen before. It’s a whole house ventilation system from a Dutch outfit called Itho and they call it Demand Control Ventilation. You can read the blurb on their website, but the crucial factors here are that:
• it’s extract only
• there’s no heat recovery
• it only works when CO2 detectors say GO
• it uses much smaller ducting than MVHR systems

Why should it be of interest? It presents a challenge to the orthodoxy of built tight, ventilate right which is enshrined in SAP Appendix Q. This dictates that first you should seal up your house, as if it was an aircraft fuselage, and then introduce an air handling system which should work 24/7, even in the summer months. OK, by adding heat recovery, you minimise the heat loss, but nevertheless it’s an awful faffle to get all the kit in place and it needs to be balanced to ensure that it works as designed. There are bound to be a lot of MVHR systems out there that don’t perform anything like they were intended to.

In contrast, extract only on demand ventilation is a much simpler concept. The idea of using CO2 detectors to turn the system on and off is theoretically sound, as it tends to be CO2 concentration in rooms that makes the atmosphere stuffy. CO2 build up in an enclosed bedroom overnight can be a big issue (background reading at www.veetech.co.uk) and it’s one that MVHR deals with very crudely — by pumping warmed air INTO the bedroom rather than extracting it.

In contrast, having a system that turns on only when CO2 levels call for it seems both logical and economical. Also, if people sleep with their windows open (which they do precisely to avoid CO2 build up) then the ventilation system won’t come into play. With an MVHR system, you risk double ventilating.

At the moment, it seems CO2 detection ventilation systems don’t really cut the mustard with Appendix Q and Itho are faced with months if not years of expensive testing to get the system accepted by UK regulators. But I wouldn’t be surprised if, in the long run, ventilation systems like this don’t come to predominate in the UK climate.

POSTSCRIPT: Just spoken with Simon Kaye, one of Itho’s UK sales team, and he confirmed that this system is not Appendix Q compliant, and therefore will not meet the higher levels of the Code for Sustainable Homes. Thus far, only Holland has approved the use of Demand Control Ventilation in low energy housing and they have found that it’s more energy efficient than MVHR, which Itho also market. However, to get accepted into the UK market, this product will have to undergo extensive testing, costing upwards of £40,000. At this point in time, Itho have no plans to do this because it’s not clear that there will be a large enough market to justify testing, so for the time being its likely to remain a curio, rather than a practicality. However, selfbuilders not having to reach Code Level 3 or 4 may be interested in the product.

I also learnt that there is only one CO2 detector but that each outlet valve has a sensor which feeds via Cat 5 cable to the detector. If CO2 is detected as being high in one room (say a bedroom overnight), the fan switches on until CO2 levels are reduced to normal. The other valves dampen while this is happening. There is also a humidity detector built into the unit which is wired to sensors in the wet rooms. The success of the system obviously depends on the detectors continuing to operate correctly. I would think that it would only make sense if there was a service contract in place to check all this out. But then, ideally, an MVHR system should be regularly serviced as well, and I bet very few actually are.

Europe's smallest towers?

I misread the headline. I was sure it said “Foster unveils Western Europe’s smallest towers.” I smiled. I thought, what a lovely story, the guy’s got it at last. Let’s hear it for tiny towers.

But it was, of course, tallest, not smallest. And here they are in all their glory lording it over Paris. No, our tax-exile starchitect doesn’t get it at all, does he?

God, I think I’m turning into Prince Charles.

Builders rates softening

There’s really no definitive way of knowing exactly how much a builder charges because every contract is different and each rate is negotiated on a job-by-job basis. But there is a lot of evidence around that labour rates are softening across the board in response to the recession.

Having said that, recession bites in some funny and unexpected ways. I keep hearing about builders who are rushed off their feet and have order books as long as ever. A plumber I know locally (in Linton, Cambs) told me he’d never known it so slow, but that his brother (a plumber in Swindon, Wilts) was snowed under, so much so that my local plumber was now working three days a week in Swindon. Just why Swindon should be busy, whilst Cambridgeshire is quiet, seems to defy common sense, but that’s often what happens.

Other tit bits. A groundworker I know was getting £160 a day for agency work a year ago. Now the rate is £80 a day. Ouch if you are looking for work but good news if you are paying for it. My bricklaying contact tells me that the rate per thousand bricks laid has softened from around £420/k down to £360/k (though be warned that this rate is subject to a lot of regional variation — many quieter areas of the country never got as high as £360/k in the boom). And at EcoBuild last week, I gleaned that rates for timber frame erection were down from £20/m2 to £15/m2.

On Germaine Greer

Spent much of Wednesday and Thursday at EcoBuild. Overall impression was that it was bigger and busier than last year. How much of the traffic was the semi-employed, filling in another day without meaningful employ, we’ll never know.

But if you do want to fill a day, EcoBuild is a great place to do it. For starters, they had some very interesting speakers — celebs you would not normally expect to see at a building event — and all on view for free. I caught Michael Portillo, Mathew Parrish, Dan Cruickshank, Nigel Lawson and Germaine Greer, and Boris Johnson’s kid brother Leo (just like Boris only a brunette). All of them spoke fluently, some even made sense, but the one I felt like blogging about was Germaine Greer.

QUESTION: What was she doing there in the first place? ANSWER: she seems to be something of a housing pundit these days. I’m not altogether sure why, as she has almost nothing to say on the subject that is remotely coherent. She strides to the podium and delivers a series of knock about, grumpy old woman style thoughts, gets lots of laughs from the audience (because she is funny) and that’s it. But what she actually did was give a long list of things she disliked about modern housing. I didn’t write any of this down but from memory it included:
• wheelie bins (disfiguring)
• fences (naff)
• staircases (too many, and sometimes used as a “feature”)
• bad design (but she didn’t say what good design was)
• too many 2, 3 and 4 bedroomed houses
• too many flats
• gardens not big enough
• too many gardens
• solar panels on rooftops
• wind cowls (pointed, because Bill Dunster was next up – he managed to look really piqued – maybe he was?)

She went on and on, shooting her mouth off, picking off targets like she was on a machine gun on the front line at the Somme. All good stuff, and the audience lapped it up, but afterwards it left a strange taste in the mouth. Was she in favour of anything at all? Or was she just playing the gallery for a laugh? Has Germaine Greer really got anything useful to say about housing, or is her elevation to pundit status merely a commentary on the fact that there is now a vacuum out there?

On English Heritage

Thanks to Old Bollocks to alerting me to some scams going down at English Heritage, as exposed in yesterday’s Sunday Times.

It’s not an area I write about much, but I’ve long felt that the whole conservation scene is verging on the edge of being one big scam. This article is important because it takes the battle to English Heritage in a way that’s not happened before, basically accusing them of abusing their powers. I suspect that the author in question, Richard Girling, is opening up a Pandora’s box.

My one continuing beef about English Heritage and the whole conservation lobby is the sheer size of it. There are, according to the article, 350,000 listed buildings in the England. In my book, that’s about 300,000 too many.