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Intelligent Buildings? Ken Collins Jul 12

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Modern buildings have a lot ofmarine-lab-energy-diagram technology that goes into them. From the development of the products they are built from, to the systems that allow us to live, work, and play in them. The rate of technology uptake into our new buildings is surging up every year, especially when it comes to entertainment systems and power control.

However one area where the uptake has been lagging, is automation of the building itself. There are many — mainly commercial buildings — that have computers to control heat and ventilation, opening or closing louvers automatically, not to mention air conditioning systems with some advanced control systems.

But it was this article on an “Intelligent house” that caught our eye in the office. Extending the technology interface between building and control system where it features a prototype climate control system with sensors in the floor and walls to measure the temperature. The information is sent to a server, which can then open or close windows to keep the temperature comfortable. The system is also connected to a weather station which can predict the weather for several days.

To see these features being built into a house is unusual, and the climate control system is described as being a prototype. But why is this? Why (on the whole) is this sort of technology not being developed and marketed widely as the next step up from passive insulation and energy efficient heaters?

The article doesn’t indicate what the cost of the system is, although I imagine if it is a prototype, it won’t be cheap. All home owners look for the payback on anything more than the minimum, it is possible this system has a very, very, long payback.

Or could it be that the idea of a computer controlling parts of your house, including opening and closing external openings, is at odds with our ideas on security, and our fears of someone being able to hack in? (Both in a digital sense and the good old analogue way with a crowbar).

May be we just don’t like the idea of closing all the windows, leaving the house, walking back in and opening the windows again, every time something goes wrong with the system.

What ever the reasons, there is still along way to go with technology integration into our buildings, and more specifically our houses. And the integration of the various independent systems into a unified system.

Houston — You have a problem….. Ken Collins Jun 25

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It’s nice to know, well actually a little worrying to know, that New Zealand building owners aren’t the only ones to neglect maintenance work on their buildings.

A recent article in New Scientist Magazine (15679px-Aerial_View_of_the_NASA_Ames_Research_Center_-_GPN-2000-001560 May 2010) had a small piece on the problems faced by NASA. Yes, even the best let their major assets deteriorate.

With NASA again expected to develop new technologies for space flight, a report to the US National Research Council identifies that may of their labs, including wind tunnels, need repairs and upgrades. With the exception of a new science building at Goddard, over 80 percent of the research laboratories at these facilities are more than 40 years old and need significant annual maintenance and upgrades. Some apparently don’t even have adequate electricity or heat. Clearing the overall repair and maintenance backlog is estimated at US$ 2.46 billion! Up from US$ 1.77 billion in 2004.

Another posting at Parabolicarc.com discusses the issues here.

Closer to home……

A BRANZ study in 2005 into the condition of New Zealand housing stock showed that in order to repair and maintain significant defects an average of $3700 per house was needing to be spent. With between 1.5 and 1.6 million homes in NZ at that time, the total repair bill would be about NZ$ 5.7 billion.

Leaky Buildings — Part 2 — What we now know Ken Collins Jun 08

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Following on from my blog on Leaky Buildings – Part 1 -and how we got to where we are, this blog covers some of the science and research that has gone into the building industry as aponding water lounge roof result.

At this stage I must point out that there are other people with specialist areas of knowledge and research, in what is now quite a wide topic.  So, as blogs tend to be, this is more of an overview from my experience, rather than a detailed technical paper.

With all buildings that have ’leaking’ issues, the problem is that water gets into an area it shouldn’t be (most commonly the structural timber frame), the water stays there because it can’t drain or evaporate away. When the timber remains wet (typically above 30% moisture) and relatively warm, these conditions allow fungi to grow, which rots the timber.

The ways that water gets into a building falls into 4 broad categories, with many iterations in between where a combination of these forces are at work.

Gravity: generally a hole that water drips into, or where water is flowing down a cladding (or a flashing) that doesn’t adequately direct the water away, out of the building fabric.

Capillary Action: where water in the ground is soaked up by building materials (including DSC01305concrete) and transferred along to structural elements over time. This is commonly what is referred to as rising damp. It also happens where water is allowed to pond and hydroscopic materials are soaking in it (or close enough for rain splash to soak the material).

Condensation: the interior of your house is full of water vapour. From cooking, showering, laundering, un-vented gas heaters, and your own hot breath. If this vapour isn’t extracted or vented out of the house then it can condense on cold surfaces. Such as you see on your windows in winter. This also can happen inside your wall if the conditions are right.

Air Pressure: or more specifically a pressure differential. When it is windy there is a higher air pressure on the outside of the building than the inside. This in effect sucks air through any holes, cracks or openings. If it is raining then the water is taken in along with the air flow.

If you think about all the things that can happen in and around our buildings, the number of ways water can get into our buildings are too numerous to mention. It also follows that just because water has got into a building doesn’t mean it is a ’leaky building’ as such, which commonly implies a cladding failure.

The action (or in-action) of owners has always been an issue. All buildings require regular maintenance, and sometimes a bit of good old fashioned TLC is all that is needed to keep the building water tight. A recent article on the Beehive roof leaking is a perfect example of this.

Another classic is for gardens to be built up around the house. If the sub-floor vents are covered this significantly reduces the sub-floor ventilation and the water coming out of the ground under your floor isn’t removed, allowing sub-floor framing to remain wet. If the bottom of the cladding is buried in the soil (or even too close to the ground) then this will allow water to easily wick up into the framing.

There are a number of variables and reasons for condensation to form inside a wall cavity. Relative humidity, air pressures, vapour pressures, and temperature differentials all contribute to where the Dew Point is. This means that in certain circumstances water vapour could be condensing on the timber framing, inside the insulation, on the back of the cladding, or even on the building paper. This is a known cause of some so-called leak problems and rotten timbers.

When people talk about ’Leaky Buildings’ the most common image that comes to mind is of water getting into the timber framing, through a hole in the exterior cladding, and that timber remaining wet. In the early days of the current leaky buildings problem, existing brick veneer and cavity stucco designs were simply adapted to a wider range of claddings. It was recognised that if (when) water gets through a cladding, a cavity between the cladding and the building paper which is attached to the timber framing allows it to either evaporate or to drain away.

Further research has also shown that the reason for this is that cavity helps to equalise the Window-detailsair pressure behind the cladding, and the lack of air flow allows water to drop out and drain away. But of equal importance, it has shown just how effective a cavity is at allowing any moisture to dry out. BRANZ released initial results of it’s research in Build Magazine in June/July 2007.

They found that water dries 100 times faster from the back of the cladding than from inside timber framing, mainly due to how fast water diffuses through timber. When you add in that we are demanding higher levels of insulation and air tightness in our buildings, the ability for wall framing to dry out is further reduced. This unwanted water then tends to evaporate and condense repeatedly until it soaks into the wall materials or migrates inside the building.

The dilemma we now face is now how to allow for air movement and moisture drainage in a wall while still maintaining a high level of insulation. A cavity behind the cladding allows for ventilation and a drainage path, but it also decreases the insulation value of the wall. So more insulation is shoved in the wall, reducing the ability of the wall to breath even further.

The BRANZ research also highlighted what a significant part air pressure has to play in leaks. The Acceptable Solutions to the Building Code requires that all window and door frames be fully sealed to the structural timber frame to eliminate the air leakage path around these openings. Testing showed that even a small gap in the sealant had a big impact on air flow, and the water it carries. So the important thing is for the cavity behind the cladding to remain at an equal air pressure to the outside. In effect the cladding is now acting as a rain screen, rather than trying to achieve a waterproof membrane.

The truth is that we have ‘thought-built’ buildings. We always have had this, and it is even more so now. To build houses the way we do (in New Zealand) requires knowledge, skill and understanding. Construction clearly requires the designer, inspector, and builder to work from the neck up. They need to think as they draw, observe, and install the building components, like flashings, building paper and claddings. Thinking about where water will be coming from, and where it’s going to go. Miss something and the whole stack of cards can come down.

This is even more so with the rise of ’cladding systems’ where the one manufacturer provides all of the flashings, fixings, and finishings. Even good old fashioned things like weatherboards and bricks are starting to fall into this category. You now need detailed knowledge of how to install a particular system to make it work. Specialist installers, trained by the manufacturers are growing in number. On a recent project there was even a company who specialised in installing just the sealant between the windows and the timber framing. Almost gone are the days of generic claddings where you could use what ever individual components you liked and the whole thing still worked.

This obviously isn’t the be all and end all of this problem. There is a lot more to be learnt about how our buildings work in our environment. We are already seeing that some supposedly remediated buildings, aren’t, and they are leaking again. The story still has some way to go — unfortunately.

Earmuffs in Pre-school? Ken Collins Jun 01

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I had promised the next blog would be my second part to the Leaky Homes blog, and it is on its way. However, this article in the Dominion Post caught the eyes of the team in our office.

Do we really need to put earmuffs on our pre-schoolers when they are at Playcentre or other Pre-school facilities?

While the intentions are admirable, to minimise any hearing damage to our wee youngsters in noisy environments.  The people in our office thought earmuffs in pre-schools was going a bit far.

We have recently been involved in refurbishing some pre-schools and assessed the issue of noise as a part of the design solution. As a result we had sound absorbing materials installed on the ceiling and on walls. Sound absorbing vinyl flooring is also now widely available, not to mention that carpet is also a good sound absorber. The location of activities was also considered.

Once the work had been completed there was a significant difference to the sound levels in the kindy, although we weren’t able quantify the difference without the use of a sound meter.

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So, while we agree that everyone (including the little ones) should wear hearing protection when engaged in noisy activity, like using power tools, watching motor racing, etc, we also see that good building design and selection of materials can create an environment that reduces potential problems.

Surely children wearing earmuffs in a pre-school would severely affect the way the teachers could interact with them, and in turn create a host of other problems? We see that it is far better to create an environment that is fit for people rather than the other way round.

Leaky Buildings — Part 1 — How did we get here. Ken Collins May 20

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With the government announcing it’s IMG_7549-web(our) package to help solve the leaky homes crisis this week, it has brought the spotlight back onto what is now a highly emotive subject. While the emphasis is rightly on getting peoples homes safe and fit to live in, it should be remembered that the leaky buildings problem is wider spread than just domestic buildings. Recent reports have shown that it includes schools, commercial and community buildings.

The politics of it is complex and controversial with blame-storming rampant. The reality is that there are so many aspects to obtaining a completed building, from design to move in, that you can’t just point your finger a one person or organisation.  Additionally the physical causes, effects and remedies are only now becoming well known and well understood.

So how did we get here?  In effect it was a combination of a number of issues, coming together all at once.

Ever since humans have built structures and shelters on this land, they have leaked, for one reason or another. In the early 20th Century buildings leaked, however the timber that was used was good strong native timber, which could withstand being wet and then drying out again. The gaps and construction technologies of the day meant that there was airflow through and inside the building structure, which allowed it to dry out. These days everything is sealed up like a chilly bin and any water that does get inside the structure can’t get out again. The timber stays wet, fungus grows and timber rots.

The use of un-treated timber was approved when the kiln drying of timber had become commercially available. Up until then all timber was naturally air dried and would normally be stood up as framing while it was still well above 20% moisture. It would then dry out as the house was completed.  The testing of the day showed that ‘dry’ timber (at it’s moisture equilibrium of about 12-15%) didn’t need treating, assuming it stayed dry. It also meant significantly less energy, chemicals and heavy metals were used in the building industry.

However history has proved that some of this timber didn’t stay dry.Imported-Photos-00026-web

What people also didn’t realise was that the old Boric treatment applied to timber being used internally (to stop borer attack) actually provided some protection against fungal attack when it did get wet.

At the same time the design fashion of the day changed to the use of parapets and low pitch roofs, monolithic plaster wall systems, and the mixing of different cladding materials on the one building.

New cladding materials and cladding systems relied to heavily on thin top coats where the base materials are not inherently water proof, or where jointing systems have proven over time to be ineffective or to be difficult to install and maintain.

The use of sealants to provide flashing and waterproofing barriers increased exponentially, at the expense of mechanical flashing systems. People relied on these chemicals to stop water getting into all sorts of little (an not so little) openings. So while sealants work very well when they are installed properly, they do need maintenance and replacement, especially where they are exposed to UV light.  However all to often they weren’t used or applied in ideal conditions and they failed prematurely as a result.

Added to this there was a lack of continuity across all the disciplines in the building industry, where traditional roles and responsibilities were fragmented.

Despite all of this, it must be pointed out that at the time the majority of people involved in the building industry thought they were doing the right things. Products were researched and tested, assessments and decisions made on the information available. Yes there were (and still are) some dodgy developers, builders and designers out there, but in no way can they account for all of the problems we are now observing.

One of the biggest realisations has been that despite the knowledge obtained from testing IMG_5557-webconstruction and cladding systems to assess their suitability for New Zealand conditions, the true test has been their actual performance in the real world over 5, 10, 20, 40 years. It is particularly hard to assess likely in-use performance by doing accelerated weathering experiments and the like. Often people relied on overseas testing and research, which wasn’t always totally applicable to NZ conditions.

The result is that in the last 10 years many methods that were thought to be ok, have proven to not be. Manufacturers have changed their installation, fixing and jointing instructions. A number of products that were tested as being suitable for NZ buildings have been withdrawn after they were found to fail. This includes products that were assessed by the Building Research Association of New Zealand (BRANZ) and given a BRANZ Appraisal Certificate, only for that certificate to be withdrawn later when problems arose.

What was thought to be best practise 10 years ago, now isn’t and so things have changed, and will continue to do so.

The fact is that you can never know with 100% accuracy how a material or a system will perform until it has actually been in use, in the environment, for a period of time. There are so many variables of, exposure, wind loads, quality of workmanship, movement inherent to timber framed buildings, not to mention maintenance (or the lack of it). After all, how many people wash their houses down every six months as is recommended by paint and roofing manufacturers.

Lessons have been learnt and things are now done differently. Will they prove to be successful over the medium to long term, the industry won’t know until we get there.

In the second part of this blog, I will look at some of the science behind the issues and what is currently thought to be the best solutions.

Timber treatment: what are the best options? Ken Collins May 11

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timber treatment 2Some time ago there was a lot of media coverage on the use of CCA (Copper Chrome Arsenic) timber preservative. This caused a number of our clients to ask for alternatives, so we did a little research into what the implications are.

Pine needs to have large amounts of preservative to stop it rotting when in contact with water, and especially in ground.

There are two alternatives to CCA commercially available: Copper Azole based (CuAz) and Alkaline Copper Quaternary (ACQ). Both rely on very high concentrations of copper to act as an agent against fungal and insect attack, and as such both are strongly alkaline.

Unfortunately this also means that these products are very aggressive to mild steel and even galvanised steel. The Building Research Association of New Zealand (BRANZ) did some testing and found that in comparison to CCA treated timber:

  • In timber treated to H3.2 (the treatment level for timber in occasional water contact, often used in exterior wall framing, in wet areas, and outdoors above ground contact like decks), mild steel corrodes at rates of up to 5 times in CuAz and ACQ preservative.
  • In timber treated to H5 (the treatment for timber in contact with the ground, eg floor piles, structural posts, and fence posts), mild steel corrodes at rates of up to 12 times in ACQ preservative. (you can’t get H5 treatment in CuAz).
  • Galvanised steel corroded at a slower rate than mild steel, however the corrosion rate of galv steel in CuAz and especially in ACQ was still significantly higher than in CCA treated timber.
  • 316 Stainless Steel performed well in all the preservatives with minimal differences in corrosion rates.

A copy of their Conference Paper is available here and the more in depth Study Report can be found here.

timber treatmentIn short this means that if you use the alternatives to CCA then all the fixings (nails and screws), bolts and brackets (in-fact anything metal) that touches the timber must be 316 stainless steel or powdercoated. Consideration also needs to be given to the use of stainless steel flashings as well, because even water runoff from ACQ and CuAz treated timber will corrode mild steel, aluminium, and galvanised steel..

What ever you do, there is no current solution to preserving timber without using large amounts of heavy metals and toxic chemicals. But in saying this, you would have to suck on a lot of logs (or wood chips) to leach enough of the chemicals out of the timber for it to have a measureable effect on you. This includes CCA treatment.

So, unless you are building a children’s play area and have particular concerns about children eating the wood, CCA treated timber is still the best to use for the construction of buildings in NZ, especially where you need to treat to H3.2 or above. Not only for cost, but also because of serious durability concerns raised by the BRANZ testing.

Energy creep…more energy efficient homes don’t necessarily mean people use less energy Ken Collins Apr 23

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New Scientist magazine ran a brief report on research into energy use in houses after they were made more energy efficient. Conducted in the UK, it highlights that after insulation, double glazing and energy efficient heating is installed the amount of energy used is still close to the old levels, prior to the improvements.

The article says that some people who have made their houses more energy efficient are more likely to indulge in small excesses — turning up the heating or keeping it on for longer. Kevin Lomas of Loughborough University, UK — who was part of the research team that carried out the surveys — is quoted as saying:

’…..often they are more concerned about comfort than saving energy.’

Or, perhaps they think that because their house is more energy efficient they can indulge in being more comfortable and still save energy.

Whatever the reasons, is this the law of unintended consequences at work? Is it human nature to use as much energy as it takes to be comfortable, to the point that it hurts the wallet? Does having more energy efficient homes actually reduce energy use significantly, or does it just allow us to be more comfortable?

Certainly there have been media reports of people installing energy efficient heat pumps and then getting power bills twice what they were before. That is because they ran these things all day and all night thinking there were cheap to run. Yes, heat pumps are cheap to run, but they still cost a lot when you run them all day every day.

By way of example, one of the guys in the office was talking about how the nights are getting colder. It wasn’t cold enough for him to be bothered to light his wood burner, so he put on a jumper. Later in the night he heard the neighbours heat pump going. So, was the use of heating based on a heat pump being too easy to turn on, for instant reward?

The point is that the highly publicised and popular schemes to insulate older homes in NZ may backfire a little, in that not nearly as much energy will be saved as anticipated, or worse still even more energy is used because of an efficiency perception.

The relative merits of various energy sources to heat homes was provided graphically by Right House recently. Their business is to provide advice on energy efficient home design and performance, as well as individual products.

They show comparisons on various types of energy and their costs for NZ conditions. Interestingly enough, fire wood is the cheapest fuel per kWh of heat by far and the cheapest cost to run per year, despite it being the least efficient.

Electricity on the other hand is the third highest cost per unit, but is the most efficient at turning energy into warmth. The result is that a heat pump is also has the cheapest yearly running cost, making it the same as firewood.

heating-cost-comparison Fuel-Prices

occupants-influence

Therefore the amount of energy required to heat a home comfortably is a combination of selecting the right heating method for the size and style of the house, as well as how the occupants use the house, and how ’comfortable’ they want to be.

However, a noticeable trend is the significant shift to using electricity as the energy source. In NZ it is perceived as being clean and green with our significant use of  hydro and geothermal generation.

NZ is already under pressure with the need for more generation and no-one wants new wind turbines or hydro power stations in their back yard, let alone nuclear. But with the ever increasing move away from burning things to provide heat, to switching things on, the pressure to provide more generation may force our hand.

We may end up needing to burn things to allow us to switch things on. It’s all a matter or perception really.

Should we be reducing building insulation to improve energy efficiency? Ken Collins Apr 22

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energy efficiencyI recently read an article on the cost of reducing our carbon footprint to pre-1990 levels. It suggested that the actual cost to consumers would be minimal, adding only a few percent to daily consumables. That is except for air travel, which would jump 150%. In effect they tried to debunk the myth that taxing the use of carbon and reducing the amount of carbon used is highly costly.

Reading towards the end, their assumptions were based on two significant developments. First that all vehicles would be electric powered. And second that almost all power worldwide is generated by renewable or nuclear sources. i.e. no gas or coal fire stations.

This got me thinking about assumptions we all make when it comes other things, like the energy use in buildings.

Conventional wisdom suggests that we put stacks of insulation into buildings so they cost less to heat. However, on a recent office building project the services engineer identified that the greatest energy use, and therefore cost, was not in heating the office, but in cooling it!

With large areas of glass, and a lot of electrical equipment, the heat load the building was absorbing meant that it needs a lot of cooling to keep it comfortable.

Their recommendation was to actually reduce the amount of insulation to let heat escape!

It came down to a smarter approach where the correct glass was needed to limit the heating value of the sun, and putting the insulation in the right places, with the right amount, so as not to loose too much heat, but not retain too much either.

This was contrary to the standard models used to determine insulation in NZ buildings, which takes a simplistic blanket approach.

The only thing now is for the cost of the technical calculations to come down to be within reach of the average budget. Thermal modelling of individual buildings from services engineers is still an expensive business, where the cost often outweighs the benefits, even if this more intelligent and detailed approach can save on both building cost and operating cost.

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