On Everest Double Glazing

There was an interesting thread over on the selfbuild list last week about someone getting Everest in for a quotation for new glazing.

Had Everest round to quote on windows for our upcoming project. I 
thought they would be expensive, but was in for a shock when he came up 
with £45k for 12 windows, 3 double doors, 2 standard doors and a front 
door with side light! The quote is for UPVC with a lifetime guarantee 
for double glazing, U-value 1.2 and light oak finish. The front door 
is hardwood, all the windows look very good quality and it includes 
fitting. 2 garage doors added another £8600 to the price.

I pointed out that was 1/3 of our budget for the whole house build and 
he seamed to forget all about the sales pitch! I also showed him the 
prices in the self build bible for a similar number of doors and 
windows for £7k, again he was stuck for words.

Before I pushed him out the door he had knocked off 28% for bulk order, 
10% for ordering straight away and after a phonecall to the boss 
another 20% if they can use the house for advertising purposes. 
Knocking off the front and garage doors that we didn’t like much anyway 
left a best price of £20k for 12 windows and 5 doors (inc fitting). I 
was budgeting to get all of them (including oak front door and garage 
doors) for £15k max. Am I in the wrong ball park?

Must say my heart always goes into my mouth when I read that someone is using my book for pricing purposes, especially when there is a huge discrepancy between quoted prices and what I’ve suggested that the going rate actually is. I needn’t have worried. Two replies came back thus:

Your instinct is right. Everest is a very expensive way to go and not really
suited to a new build. As an example, we got 15 assorted (softwood) windows,
with glazing (all double, toughened, Pilkington K and Argo-filled) from
Travis Perkins for £2000. Had to fit the glass into the frames ourselves
which added a few hundred pounds. OK, that was a cheap 'n cheerful answer
(which suits me well enough) but a VERY far cry from - what did you say? -
£45,000!!!


and

'get three quotes for anything significant, and six for windows ... 
unless you know what a good price is !

'we paid roughly £10k for six French windows, one very large 
window, one corner window, another window, and two small windows ... 
a few years ago ... toughened & silvered, double glazed, with 
internal glazing bars, fitted ...


Joinery is one of the more complex parts of a build to quote for but what I have been trying to do over the past few years is to reduce the price down to a square metre rate. It’s not perfect because some elements, particularly the smaller pieces, are much more expensive on a metre basis than larger ones. But given that most houses consist of a mix of small windows, large windows and largeish doors, it tends to work out
 reasonably well over a whole house. What people don’t do, of course, which would be very helpful, is to state how much joinery they are buying in square metres. Instead you get long lists — effectively unmeasured joinery schedules — which you can merely hazard a guess at. As a very rough guide, you can guess that the area of joinery is going to be around 20% of your internal floor area, so if you don’t have a joinery schedule to hand, this is a good place to start.

The costs of joinery are also very variable depending partly on the quality but also on how they are finished and fitted. Is the glazing being purchased separately? Is fitting included in the cost? What I found on my last trawl through joinery costs is that prices varied from as little as £80/m2 for unglazed, unpainted softwood frames through to as much as £400/m2 for pre-finished upmarket glazing from the likes of Rationel and Velfac. A basic uPVC system, of the kind that Everest turn out, should be costing no more than £150- £200/m2. My guess is that the house in question has around 40m2 of joinery (not atypical on a selfbuild these days) and that the Everest rep was pitching initially at over £1,000/m2 and ended up down at around £400-£500/m2 mark, still way more than the prices of far better alternatives.

OFT Invesigation into Housebuilding

News that the Office of Fair Trading is launching an investigation into the housebuilding industry had me exclaiming “OK, but why now?” Nothing has really changed that much in the past ten or even twenty years; certainly not the nature of the cozy cartel that exists between the housebuilders, the planners and the amenity groups such as the Council of Preservation for Rural England (CPRE). Both the low rates of new housebuilding and the poor standards of that housebuilding are symptomatic of a general market failure, but then this is no ordinary market.

The OFT obviously wants someone to blame for this state of affairs. Housebuilders point to intransigent planners, planners point at huge landbanks being held back to artificially inflate prices. According to the BBC website, the OFT have appointed an eight-strong team to take representations, but I expect them to get pushed from pillar to post and back, and to end up more or less back where they started.

To my mind, the problem really starts with 1947 Town & Country Planning Act, which effectively nationalised land use. Instead of land being freely brought forward for building by whoever fancied their chances, the new planning authorities started ring-fencing areas suitable for development. As these areas were often large, the small players were effectively cut out from the market. Over the years, this policy of concentration and densification has grown more and more pronounced and the whole development process has been professionalised. The current consolidation going on in the housebuilding industry is merely the latest phase of a process that dates back to 1947.

What the OFT should be looking at is how development took place in the 1920s and 30s, when there were very few controls and no massive national building concerns. There was genuine competition back then and also a high rate of housebuilding. Also they should look closely at what has been happening in Ireland. And France. And Germany. And Scandinavia. And North America. And Australia. They will quickly find out that what goes on in the UK is unique. Other countries build more houses and they generally have far fewer quality issues. Land is often set aside by rural communities for small developers and selfbuilders to create homes and thereby organically grow communities. New development isn’t restricted to all but a few mega-sites, as it is in the UK. Mega-sites may be regarded as sustainable, but they do nothing to enhance competition. The land supply in the UK is now so restricted that the whole process is managed by a small number of very large businesses, who carve up the cake between themselves. The fact that there is little competition is because there is often only one new housing site for miles around.

But rather than blaming everybody or indeed anybody for letting this state of affairs come about, the OFT should come to realise pretty quickly that it’s a creation of our restrictive planning policies. If you really want to reform the housebuilding industry, that is where to start. I don’t think it’ll even be on the agenda.

Bob Matthews on Ventilation

Good series of articles recently on home ventilation in Selfbuild & Design by Bob Matthews, the oldest surviving selfbuild writer in the business. In June, he summarised his findings. In July, he peered into the future. There simply aren’t that many writers out there who would even know where to begin in handling such an assignment. I hope his readers appreciated it.

What did Bob conclude?

• SAP 2005 presumes a ventilation rate of 4 litres/second/occupant, that’s 14.4m3/hr each. I didn’t know that: it seems quite low. For four people living in a 350m3 house, that’s one air change every four hours. Conventionaly, we’ve worked on around one air change every two hours, but I don’t think there is much evidence that this ventilation rate is actually required.

• That 4lts/sec/person requires 100watts of heat to keep at 20°C above outside temps. So for four people, that’s 400 w. And for double the amount of air changes, that would be 800w. Generally, ventilation systems are set up to move much larger amounts of air than this 4lts/sec/person would indicate, so there is a design inefficiency built into most systems.

• Part F of the building regs suggests that you have a 10mm gap undercut on every door, to facilitate air movement around the house. A lot of people won’t like that because it increases noise transfer.

• The default system of home ventilation is trickle vents for supply air extract fans in the wet rooms. Trickle vents must be 5000mm2 in dry rooms (inlets) and 2500mm2 in wet rooms (outlets).

• Passive Stack Ventilation is one of the main alternatives. Trickle vents stay but the extract fans are replaced by air ducts rising from wet rooms to ridge. Kitchen extract requires 125mm tube, utility room, bathroom – 100mm, WC – 80mm or opening window. It doesn’t work in every configuration – bungalows are not tall enough and room-in-the-roof designs have nowhere to run the ducts, and some critics suggest that it only ever works intermittently anyway.

• Assisted Passive Stack is where a fan is added to the system, to ensure it works at all times.

• Central Extract: very similar to assisted passive stack. One fan in the loft pulls air from all the wet rooms. Works with smaller trickle vents than default, and lower extract rates, but designed for continuous operation.

• Positive Input: in many ways the opposite to Central Extract. Instead of drawing air out of the house, it blows it in, putting the house as a whole under a slight positive pressure. The chief exponents of this system are Nuaire. I’ve been rude about Positive Input Ventilation before, but Bob is much more generous.

• Mechanical Ventilation with Heat Recovery (MVHR): discussed in some detail in recent post. Bob reckons that air leakage should be below 4 q50 (don’t ask – it’s a measurement of air leakage under pressure), which is much lower than we are currently achieving on non-manufactured houses. The current building reg standard is 10 q50, whilst the Passivhaus standard calls for 0.6 q50. Quite a difference. MVHR is the only system here that requires both input and output to be balanced, as they are both controlled by the fan or fans. Everything else is either entirely passive (i.e. no fans) or has fan controlled output or input (only one here). This balancing requirement is a crucial and little discussed feature of MVHR. I suspect it needs adjusting quite frequently but is rarely done.

• Individual Room Ventilators with Heat Recovery: rather than whole house solution, you have a individual room ventilators with a heat recovery capability. Designed for continuous operation.


And what did Bob speculate about in the later article?

• He cast doubt the accepted mantra of the current generation of energy wonks: Build Tight, Ventilate Right. Systems like dynamic insulation (see recent post) mean that airtightness may not be quite the holy grail that it is held up to be.

• Intelligent trickle vents, which self-adjust according to wind speed, air pressure and humidity levels.

• Intelligent controls for mechanical ventilation: at the moment, it’s off/on/boost. In the future, systems may begin to emulate the sophistication now seen with space heating controls.

• Supply Air Windows: Howarth are now making these windows which work by drawing air in between the two panes and pre-heating it on its way into the house. In effect, it’s a sort of heat recovery trickle vent, designed to work with the house under negative pressure, so usually installed with passive stack ventilation, or continuous central extract fan.

• Earth tubes: these draw supply air through underground pipes in order to pre-heat or cool the air before it gets to the house. Much experimented with over the years, but nowhere widely adopted. There are fears about contamination and mould growth within the underground tubes and this seems to hold back more widespread adoption of the technique.

• Dynamic Insulation: the capacity of walls and roofs to draw air in through their structure and to pre-heat it on its travels. A topic covered in a recent blog post here.

In fact, supply air windows, earth tubes and dynamic insulation are all ways of passively pre-heating the supply air. All have great potential but they are all also a long way from becoming mainstream.

I particularly like Bob’s concluding remarks. In the future, we will probably reach more understanding about ventilation processes, and we will be able to design systems more accurately. Then there will be less need to over-ventilate in order to be on the safe side, as at present. There is a need for greater knowledge about the complex issues involved in domestic ventilation. A lot more research is required so that we can create healthy environment in our homes while at the same time minimising the damage we do to the environment as a whole.

There are indeed lots of issues still to be resolved:
• Our understanding of house ventilation seems to be being driven by cold climate countries like Canada and Sweden, where ventilation is more critical. Does their take on it really transfer across to our lukewarm, maritime climate?
• Specifically, is airtightness quite as important as we are being led to believe?
• Are fully passive ventilation systems reliable? Or do we require fans to drive at least part of the system?
• Should we be driving towards more sophisticated controls and sensors in order to balance running costs with air quality? Or is dumb good?
• Are the health concerns about drawing supply air through ducting legitimate, or just a fear of the unknown?

The trouble with sedum roofs

The trouble with sedum roofs is that they only get you so far. Eventually, you'll want to break out from under the grass ceiling.

That’s enough of that.

Mechanical Ventilation with Heat Recovery

One of the little discussed details surrounding the Passive House debate is the use and abuse of mechanical ventilation. The Passivhaus standard insists on it: other low energy standards are not so prescriptive. I believe that the way the new Code for Sustainable Homes standards have been drafted, the top levels more or less ape the Passivhaus standard and therefore mechanical ventilation with heat recovery will become de rigeur.

The issue underlying all this is the ever-present contradiction between saving energy and maintaining good indoor air quality. You have to have fresh air inside a home and this fresh air has to be heated (or sometimes cooled) in order for it to remain comfortable indoors. However well you insulate the fabric of the structure, you still have this energy demand to deal with. The energy load naturally varies according to the outside conditions, but it can often be more than 1kW, sometimes even 2kW. That represents around half the overall heat load for the house.

Now the Passive House approach is to first reduce the air leakage of the structure to an absolute minimum. This ensures that you don’t have to heat more air than you actually require. Then you run inlet and outlet ducts around the house and you draw in the fresh air via a heat exchanger, which pulls as much heat as possible out of the exhaust air. This is what is known as a Mechanical Ventilation System with Heat Recovery. The acronym we use in the UK is MVHR.

These air-to-air heat exchangers have been getting more and more efficient over the years and some claim to recapture as much as 90% of the heat from the exhaust air. Also the electric fans that drive them have also been getting more efficient, thus further increasing the CoP (Coefficient of Performance).

Even with a 90% recovery rate, you still need an additional heat source to keep the house warm, but not much. You have reduced the overall heat loss to a minimum. The structure doesn’t transmit much heat, the air leakage is all but eliminated and the supply air is pre-heated by the exhaust air. It’s technically very difficult to do much more than this and this is essentially why the Passivhaus standard is regarded so highly by our energy wonks.

But there are health concerns that have yet to be fully addressed here. Whilst much of the world lives fairly happily with ducted air heating systems, they are not without their problems and issues. And the typical North American home, where this form of heating and air conditioning is the norm, is not built to anything like the airtightness specifications demanded by the Passivhaus standard. What will happen if you a) force people to build to really demanding air tightness levels and then b) force them to use mechanical systems to manage their air supply? We’ve seen a few thousand homes built to these exacting standards in Europe and as yet no one has reported any major problems with air quality. But the UK is proposing to roll out such standards on an unprecedented scale, albeit after 2016. Is this really practicable? Or even sensible?

Take a look at this guidance, emanating from the Canada Mortgage and Housing Corporation recently, on what you need to do to keep your MVHR (which they refer to as HRV) systems tickety-boo. There is a surprisingly long list of maintenance issues to be attended to. Do you really think all UK homeowners will do this? And what will happen if (and when) they don’t?

MAINTAINING YOUR HEAT RECOVERY VENTILATOR (HRV)

Your heat recovery ventilator (HRV) can help make your house a clean, healthy living environment, while keeping fuel bills down. But your HRV can't do all this without your help.
It only takes seven simple steps to keep your HRV happy…

The Seven Steps to a Happy HRV

First turn off the HRV and unplug it.

• Step 1: Clean or Replace Air Filters
Dirty or clogged filters can lower ventilation efficiency. Try to clean your filters at least every two months. Filters in most new HRVs can be easily removed, cleaned with a vacuum cleaner, then washed with mild soap and water before being replaced. Older units have replaceable filters. If your HRV is easily accessible, this is a 5 minute job.

• Step 2: Check Outdoor Intake and Exhaust Hoods
Remove leaves, waste paper or other obstructions that may be blocking the outside vents of your HRV. Without this vital airflow, your HRV won't function properly. During winter, clear any snow or frost buildup blocking outside vents.

• Step 3: Inspect the Condensate Drain
Check to see if your HRV has a condensate drain, a pipe or plastic tube coming out of the bottom. If it does, slowly pour about two litres of warm, clean water in the drain inside the HRV to make sure it's flowing freely. If there's a backup, clean the drain.

• Step 4: Clean the Heat Exchange Core
Check your HRV owner's manual for instructions on cleaning the heat exchange core. Vacuuming the core and washing it with soap and water will reduce dust which can build up inside the core.

• Step 5: Clean Grilles and Inspect the Ductwork
Once a year, check the ductwork leading to and from your HRV. Remove and inspect the grilles covering the duct ends, then vacuum inside the ducts. If a more thorough cleaning is required, call your service technician.

• Step 6: Service the Fans
Remove the dirt that has accumulated on the blades by gently brushing them. Most new HRVs are designed to run continuously without lubrication, but older models require a few drops of proper motor lubricating oil in a designated oil intake. Check your manual for complete instructions.

• Step 7: Arrange for Annual Servicing
Your HRV should be serviced annually. If you are not comfortable doing it yourself, contact a technician accredited by the Heating, Refrigerating and Air Conditioning Institute of Canada. Make sure the technician you call has been trained by the manufacturer of your HRV.

Check Your HRV Balance: the Garbage Bag Test
HRVs need to be balanced, with the fresh air flow matching the exhaust flow. If you do not know if the HRV was balanced when installed or if you have changed or added HRV ducts, you may want to check the balance with the following simple procedure. This rough test will take about 10 minutes.

Use a large plastic leaf collection bag, typically 1.2m (48 in.) long. Untwist a wire coat hanger. Tape the wire to the mouth of the bag to keep it open. You now have a garbage bag flow tester. Go outside to where your HRV ducts exit the foundation.

• Step 1:
Crush the bag flat and hold the opening tightly over the exhaust hood. The air flowing out of the hood will inflate the bag. Time the inflation. If the bag inflates in eight seconds or more, go to Step 2. If the bag inflates in less than eight seconds, turn the HRV to a lower speed, and repeat the test. Then go to Step 2.

• Step 2:
Swing the bag to inflate it and hold the opening against the wall around the HRV supply hood. The air going into the HRV will now deflate the bag. Time the deflation. If your HRV is balanced, air going into the HRV will balance the air coming out of the HRV. The inflation and deflation times should be roughly equal. If you find that the bag inflates twice as fast as it deflates, for instance, your HRV is unbalanced. If you can see no problem with the filters that would cause such an imbalance, you should call a service person to test and adjust your HRV.

Please don't ignore your HRV. Just a little bit of your time is all it takes to keep it running smoothly.

• April or May
— Turn dehumidistat (the adjustable control on many HRVs which activates the HRV according to relative humidity) to HIGH setting or to OFF.

• September or October
— Clean core
— Check fans
— Check condensate drain
— Check grilles and ducts in house
— Reset humidistat (40%–80%)

Photovoltaic glass

“When a journalist talks about PV cells, we know we are dealing with an amateur.” Jerry Stokes, President of Suntech Europe, drops this little admonition on me as he talks me over their installation at the Kingspan (Code Level 6) Lighthouse at Offsite 2007 (see previous post). As I have already used PV cells several times in the conversation so far, he has already pencilled me in as a numbskull. I reflect on the number of times I have casually written about PV cells over the years. Oh well, you live and learn. Apparently the photovoltaic cells are the tiny little bits that make up the modules, arrays or panels (all of which are OK to refer to) but on their own are not very useful. You need thousands of cells to make a module. I will know next time.

Suntech is an interesting company. It was started in China in 2001 by Shi Zhengrong, a solar engineer. It’s seen explosive growth, mainly supplying the German photovoltaic boom, and is now listed on the NYSE with a valuation of around $5.5billion. How many six-year-old companies have done that in Britain? (Don’t know, but expect answer to be none). Shi, who owns 40% of the company, is now one of the richest men in mainland China. All from making photovoltaics.

At the Offsite exhibition last week, Suntech were showing off a Japanese PV system called Photovol Glass which is the first translucent photovoltaic skin I have seen. It can be used as a substitute for glass in applications like glazed facades and roofs. As well as generating electricity, it cuts out heat transfer and UV radiation, but admits around 10% of daylight, thus making it suitable for large glazed facades or roof panels. Money wasn’t mentioned in my conversation with Stokes, so I can only assume that it costs rather more than traditional PV, which is hardly well-known for being cheap in the first place, but if it rolls out as Suntech hope, it could pave the way for one day becoming a replacement for standard glass. Or maybe not. What does an amateur like me really know about this stuff?