The WordPress.com stats helper monkeys prepared a 2011 annual report for this blog.
Here’s an excerpt:
A San Francisco cable car holds 60 people. This blog was viewed about 2,900 times in 2011. If it were a cable car, it would take about 48 trips to carry that many people.
With the recent introduction of the Eskom rebates installing a solar water heater as apposed to a conventional electrical geyser has become a no-brainer, and that’s besides the obvious environmental benefits.
Never mind the usual blurb from the solar suppliers about how long (or soon) it takes to pay off your new solar geyser, given the current interest rate environment, the Eskom rebates and looming further hikes in the cost of electricity, installing a solar water geyser when building a new house can in fact give you a positive cash flow from the outset.
Using the example of a 200litre geyser (suitable for a 3-4 person household) the numbers look like this:
Expect to pay around R21 000 for an Integrated Solar Geyser. That’s the type where the geyser is attached to the panel and is visible on your roof. If you don’t fancy the look of having a geyser on your roof add around R2000 for a split system – where the geyser is fitted inside your roof and only the panel is visible. The Eskom rebate will be in the region of R6000, so once you have duly filled in and submitted the requisite forms (with the solar supplier) and received your rebate within 8 weeks ( see http://www.eskomidm.co.za/residential/residential-technologies/steps-to-claiming-your-rebate for more info) you will have effectively paid around R15 000 ( or R17 000 for a split system). Make sure the sytem you are buying qualifies for a rebate as not all systems do. If building a new house factor in the cost of a typical 200litre electrical geyser, which would of set you back around R5200. So for a new build the additional cost of going solar would be R 9 800 or R 11 800 respectively.
The solar suppliers estimate that monthly savings in electricity by heating your water with solar can save up to 40% of your electricity usage. Lets be conservative with that figure and assume an average minimum saving of 30%. Assuming a monthly household current electricity cost of R500 that would represent a saving on electricity bills of R150 per month.
The guarantees on solar heating systems vary from 5 to 10 years, and suppliers claim that their systems will last for as long as 20 years. For the purposes of this costing I will assume that a solar heating system will remain operable for 10 years. If one finances the additional cost of the solar heating system over the conventional geyser, over a period of 10 years at the current prime rate of 9% (using your existing bond for instance to do this) the monthly payback will be R149,47 per month for the split system (R11 800 borrowed at 9% over 10 years), or R124.14 for the integrated system – effectively the same or less than your immediate saving in electricity costs. And that is before Eskom gives us their next 25% increase! Sure interest rates are lower than ever and will start increasing again but that is a cyclical price movement. Electricity costs will only move upwards.
What about your existing house? For replacing your existing geyser with a solar water heating system you of course can’t deduct the cost of your current old geyser. In this case the monthly repayment, calculated on a 10 year loan on the same basis, for the total cost of the solar heating system (less the Eskom rebate), would be R 215,34 for the split system and R190.01 for the integrated system. So while the cash flow wouldn’t be immediately positive (unless you can get that saving up to 40%) it will only take 2 years at the current estimated Eskom price hikes before it is.
In addition going solar will help the environment and reduce your carbon footprint. The reason for this is that the production of electricity from coal is a direct cause of global warming due to the emissions of CO2 during the coal burning process. Furthermore, at 93%, South Africa uses the highest percentage of coal as a means of production of electricity globally ( see http://www.worldcoal.org/coal/uses-of-coal/coal-electricity/ ) – so any reductions in your electricity use will largely offset your carbon footprint and benefit the environment.
The stats helper monkeys at WordPress.com mulled over how this blog did in 2010, and here’s a high level summary of its overall blog health:
The Blog-Health-o-Meter™ reads Minty-Fresh™.
The Leaning Tower of Pisa has 296 steps to reach the top. This blog was viewed about 1,200 times in 2010. If those were steps, it would have climbed the Leaning Tower of Pisa 4 times
In 2010, there were 9 new posts, not bad for the first year! There were 33 pictures uploaded, taking up a total of 68mb. That’s about 3 pictures per month.
The busiest day of the year was May 10th with 33 views. The most popular post that day was PASSIVE SOLAR DESIGN for TIMBER BUILDINGS 23 June 2008.
The top referring sites in 2010 were timberdesign.co.za, healthfitnesstherapy.com, facebook.com, alhome-finance-guide.com, and yabadaba-doo.com.
Some visitors came searching, mostly for archicad non residential buildings, timber homes, green building materials, south africa timber homes, and sustainability of timber as a building material.
These are the posts and pages that got the most views in 2010.
PASSIVE SOLAR DESIGN for TIMBER BUILDINGS 23 June 2008 May 2010
‘Green’ timber homes November 2010
1 comment and 1 Like on WordPress.com,
TIMBER: A Sustainable Building Material 14 October 2008 May 2010
Custom architectural design vs pre-design May 2010
The design of the Interbuild House November 2010
Presentation delivered at the Institute of Timber Frame Builders 2010 General Meeting, on 28th October 2010
The need for ‘Green’
We are all aware that our planet is basically in a mess:
So why should this effect what and how we build? The reason quite simply, is because the construction industry and the built environment consume:
So the built environment can be considered the ‘low hanging fruit’ with regards improving our situation, as any improvements in the way we construct can have a real positive effect on our environment.
It is this awakening that is leading to:
Carbon Neutral Buildings
In order for a building to achieve net zero operating emissions, it must, once built not require any more energy than it produces. In order for a building to be truly carbon neutral they need to have net zero emissions in their construction, operation and the embodied energy of materials – so while perhaps possible by 2020 with new technologies, we are still a long way off.
So, how do we go about getting closer to achieving carbon neutrality?
We start by aiming to achieve net zero operating emissions, and to do this we look at a range of initiatives and technologies such as:
To get closer to Carbon Neutrality, we also need to consider;
Timber: a ‘Green’ building material
Why is timber considered to be a ‘Green’ building material?
Source: www.woodforgood.com
‘Greener’ design for Timber
While selecting the correct materials is a step in the right direction, much of what is required to achieve a ‘green’ home goes beyond just material choice. It also requires the correct design strategies.
The key aim of these is to maximise the utilisation of timber (remembering that 70% of all timber consumed is used in construction); by smart design, making the best use of properties unique to the material, reducing waste and enhancing durability.
Making the best use of the unique properties of Timber
Timber has a high strength to weight ratio, with its highest strength running parallel to the grain. While as a material it provides considerable flexibility in design, in terms of efficiency, it performs best with clearly defined and logical load paths. The process of rational construction calls for, for example, trusses to be seated directly above first floor wall studs which in turn fit directly above floor joists which are directly lined up above ground floor wall studs.. These principles can reduce excessive lintels and heavy beams and if applied correctly, can lead to a logical clarity in the design of a timber building, particularly where the structural and loadbearing elements are exposed to view.
When designing for energy efficiency, materials need to be evaluated in terms of their thermal properties, namely insulation and thermal mass retention properties. An important factor in favouring properties of either insulation or mass retention is the diurnal fluctuation (day night temperature variation) of a particular region – generally the further inland, away from the temperature-moderating effect of the ocean, the greater the diurnal fluctuation. Lightweight materials such as timber have high insulation values and low thermal mass retention properties while the reverse applies for high mass materials such as masonry. In coastal and other areas of low diurnal fluctuation, timber is the ideal material due to its insulation properties, as well as the opportunities afforded for insulation in the space within a timber frame wall. It’s easier to heat a timber house than a masonry house as the timber walls provide more insulation while absorbing less of the heat. In dry inland areas with high diurnal fluctuation, energy efficiency would best be achieved by including elements of high mass, such as a masonry fireplace, or concrete floors, within a timber building, which would absorb heat during the day and emit this at night, so doing moderating the temperatures and reducing energy required for artificial heating and cooling. In summer these elements of high mass act as a heat sink at night, which help to keep the building cooler during the day. This principles need to be applied in conjunction with passive solar design, by designing to shade elements of high mass in summer, and allowing them to collect heat from the low angled winter sun.
Reduce Wastage
Specification of the grade and type of timber product, and particularly the avoidance of over specification, can have a large impact on efficiencies and wastage. Timber is a natural product, each piece is unique, and more acceptance of variations in colour, texture and pattern, and acceptance of the occasional knot, will go a long way in reducing wastage. In other words more appreciation is required of the material as a natural product.
Resource efficient design is the practice of designing to maximise the utilisation of a material. As timber, for example, comes in standard lengths in increments of 300mm, it makes sense to rather design a deck say, of 3m wide, than 3.2m; which would result in a 200mm off-cut of each piece of decking. Similarly the practice of placing studs at 400 or 600mm centres is ‘resource efficient’, as this coincides with typical internal partition board widths of 1200mm.
Enhancing Durability
Correct detailing of externally exposed timber serves to enhance durability. Timber and should always when wet shed water, for example by bevelled edges. Moisture traps should be avoided and natural ventilation provided, particularly below suspended floor structures. End grain should not be exposed to weather in such a way that water lingers.
Design a building which will be enduring in terms of aesthetics
Sustainability, as a concept, is all about what we leave behind for future generations. The main aim, above all, in terms of sustainable design, should therefore be to create buildings with a timeless architectural quality, an enduring aesthetic appeal, adaptable or easily modifiable over time, and beautiful within their environment, so that future generations, rather than wanting to remove and replace them, will to want preserve and live in them.
The current state of the building industry and the trend towards Green
We have been through one of the worst downturns in the construction industry for some time and all indicators point to the fact that recovery is going to be slow. In fact it has been said that the new ‘normal’ once the market has recovered, will be nowhere close to where the old ‘normal’ was.
There is a change occurring though.
As we slowly emerge from the recession, and the number of enquiries I receive certainly is’nt increasing dramatically, it is the change in the nature of the typical enquiry that is more relevant.
In the past if someone enquired wanting to find out about getting a timber house designed, it was more than likely because they simply liked the idea of living in a timber home. Today, I am just as likely to get an enquiry from someone wanting a ‘green’ home, and as a result of that they are considering building a timber home.
So while the market for new construction is still trying to pick itself up, there has been a growing trend in interest in ‘green’ buildings. Consumers have been made aware, thanks largely to the media, (just about every décor magazine has had a special ‘green’ issue) that by making the right choices they can make the world a better place – and timber homes tick all of the right boxes.
On a brief search online, on websites such as ‘trendhunter’ and others, reveals that the current trend towards eco-homes includes consumer concerns over issues such as:
(note timber homes still ticking all the boxes)
…and other issues more related to design and technology such as:
The downside
The downside is that every supplier of every type of product and service is claiming to be green. All it takes is for a environment unfriendly product to be made slightly less unfriendly …”eco” cement being a case in point.
Consumers are therefore hard pressed to distinguish between real ‘green’ choices and ‘greenwash’
To counter this, information needs to be accurate and backed by credentials. With so many offerings to choose from, consumers will, as they are doing overseas, start looking towards certification to distinguish between the ‘talkers’ and the ‘do-ers’. For example asking for FSC certified timber and wanting buildings the are rated by the South African Green Building council’s Green Star rating system – although it may still be some time before there is a category for single residential buildings. Expect also in future an increasing demand for eco friendly timber treatment such as tan-e.
How Design is responding to the Green movement
From CAD to BIM
Where we went from drawing boards to CAD in the 90’s, there has been rapidly increasing development in new type of design software called Building Information Modelling.
Whereas CAD is simply drawing on a drawing board enhanced to essentially doing the same thing on a computer, ie still essentially drawing lines and pictures, with BIM one actually constructs a virtual model of your building as you design, using entities such as walls, columns and slabs. As these entities can be given attributes, for example a timber frame wall with fibre cement cladding on 9mm OSB with 100mm Isotherm between the studs and 15mm gypsum board internally, it can also calculate R-values and heat retention and therefore can model overall thermal and environmental performance using add on packages specifically developed for this purpose.
A report released last month by McGraw-Hill Construction, titled “ “Green BIM: How Building Information Modeling is Contributing to Green Design and Construction,” states that the growth of the green building and the development of BIM are currently two of the most dynamic trends in the construction industry.
“Green building is already transforming design and construction in the U.S., and BIM has the potential to increase innovation—and design and construction efficiency,”
“Although they have been growing independently, it was inevitable that they would converge because the analysis and simulation capabilities of modeling are such a natural fit with the objectives of green building.”
Green Design with BIM
BIM can aid green design by:
Analytical sun studies
Conducting a sun study helps the designer to evaluate and refine his project to effectively use daylight sources.
Continuous control of usage of resources
Quantities and detailed data about building components can be generated, providing the architect and the owner with valuable information about the materials used.
What-if scenarios for design optimization
The ability to run different scenarios supports the green design process.
Computer energy simulations
An example is EcoDesigner which is a plug in for ArchiCAD, which is what I am using. As soon as a design takes shape, comparative energy reports can be generated with a click. The resulting reports give feedback about the buildings energy usage, yearly running costs, and carbon footprint.
See http://www.graphisoft.com/products/ecodesigner/
Conclusion
Timber frame is used in buildings around the world. Despite statistics such as 70% of the developed world’s population live in timber frame homes; 90% in Canada and the US, and 20% in the UK, it has a relatively miniscule share of the local market and figures are hard to find. Between my own ‘guestimate’ of half a percent, and the Wood Foundation’s 2%, lets for arguments sake say timber homes make up 1% of the residential market in SA.
Why so many people in SA still choose to build in brick, something that is still done the same as it was a 100 years ago, when everything else around us is changing so rapidly, think cellphones, internet, advances in medicine, and of course the environment and the state of the world, is a mystery. My bet is that, as the pressure on resources increase and the efforts to slow down global warming escalate, and the message from the media to make the right choices gets ever louder, there will be a shift. And possibly a large one.
At our, for arguments sake, 1% of the market, even a 1% shift from brick to timber frame represents a 100% increase in demand for timber homes. A 2% shift represents a 200% increase and so on. I think our industry may soon get very busy.
The Interbuild House
Published in Wood SA & Timber Times October 2010
The Interbuild House was designed and built for The Wood Foundation and The Institute of Timber Frame Builders’ exhibition stand for the Interbuild Africa 2010 Expo in Johannesburg.
While everyone has seen the beauty of timber homes in magazines and movies, in South Africa, where timber homes currently make up a miniscule percentage of the total number of residential homes, one can readily assume that the majority of visitors to the expo had never actually been inside one. With this in mind the Interbuild House was conceived to showcase the versatility and warmth of timber used in construction.
Typically the architectural design of a home is informed by contextual issues stemming from the site combined with the specific requirements of the client. Contextual issues to consider usually include topography, orientation, access, views and local weather conditions. Client requirements to consider include accommodation requirements as well as lifestyle preferences. In the case of the Interbuild House, however, being built inside the MTN Expo Centre at NASREC, with the ‘occupants’ of the home being visitors passing through, an additional set of design criteria – that of designing for an expo – had to be considered. In terms of exhibition stand design theory, an exhibit should have a central, primary message; be easy to navigate; provide for an interactive experience; allow visitors to learn and come away with useful information and be specific to the audience. As with the general layout of any exhibition, which is a series of interconnected passages without dead-ends to allow easy ‘wandering about’ by visitors, so should a large ‘walk- through’ exhibit have many points of access to encourage the flow through of visitors. With this in mind the Interbuild House, though only 60 sq.m in area, had 4 access doors. Also with visitors approaching from any direction, all sides had to be equally appealing.
A total of 22 sponsors provided the various materials and fittings, and a variety of different internal and external claddings were used to showcase the numerous finishes available when building a timber home. The main ‘living’ area, with predominantly wooden finishes internally, had a high vaulted ceiling with exposed trusses, both to showcase the attractiveness of the structural elements as well as to increase the sense of space by using large volumes in a relatively small area. The bedroom with smooth plastered walls – dispelling the idea that timber frame homes are all wooden – was so inviting that several visitors, weary after a long day, were tempted to have a quick nap.
None of this would have been possible without the builder, Werner Slabbert, of Eco Log Homes, who completed the project in what must be a record time. The components were manufactured and the house pre-assembled off site. With careful attention to detail it was then taken apart and re-assembled inside the exhibition centre in just two and a half days.
In terms of achieving its goals, by all accounts the Interbuild House was a success. It was a popular exhibit and over 4500 sets of brochures were handed out. Visitors got to experience the warmth and beauty of a timber home first hand, and with the number of high profile volunteers from various organisations related to the timber industry manning the exhibit, they would certainly have come away with useful information.
The future of the house? …The Interbuild House will become a permanent show house at the Waterstone Lifestyle Centre, North Riding, Gauteng.
Custom architectural design involves the process of engaging the services of an architectural professional to design home specific to your site and requirements. Pre-design refers to a ready made ‘stock plan’ that one can purchase.
Pre-designed home plans have up until recent times, with the exception of ‘SA Home Plans’ and a couple of similar sounding books (typically with plans arranged in chapters named Tuscan, Bali Style, Cape Cod, etc), been the sole preserve of residential developments. These typically have a selection of plans to choose from when buying ‘plot & plan’. In the timber home industry a couple of the larger firms in South Africa have, for many years, also offered clients a choice of pre-designed plans to choose from. The massive growth of the internet has, however, resulted in an almost endless choice of inexpensive (relative to custom design anyway) pre-designed plans one can simply buy online. One can assume, by the sheer volume of websites offering this, that many people are choosing this route.
While the typical architectural professional’s response may be that people are being short-changed by buying off-the-shelf plans, and that any design which doesn’t take it’s cues from the contextual issues of a particular site and requirements of a client is not and simply cannot be good architecture, many have joined in and are adding to the ever growing stock of available plans.
For builders:
An advantage is time. From being approached by a prospective new homeowner to the time when you actually get going and start earning money, the turnaround time on a pre-design plan would be significantly quicker than having to wait an extra sixth months or so for a design specific to the site and client’s requirements. You could simply refer an interested client to a pre-design website, once they’ve chosen a plan get it priced, use a registered draughtsperson to position the house on and add a site plan, submit the plans for approval and get started on site.
The flipside to this, if you are building from pre-design plans, is how do you differentiate yourself from every other builder? And given there will eventually be several builders building the same design, assuming pre-design grows in popularity here as it is doing overseas, how do you market yourself for the next job other than with good quality workmanship? All you are left with is price and if everyone is building a similar product the builder with the best price gets the job. Prospective clients, however, regardless of who designed the house, often decide on which builder to talk to based on what their homes look like. It then stands to reason that, assuming you want less tendered and more negotiated contracts, you work closely and build a relationship with a good designer, which in turn sets the look of your work apart.
For those of us in the design profession:
In what we as designers do for a living, my best work is often my next work – and that’s not to say I don’t enjoy the challenges and satisfaction in seeing and attending to a work in progress until its final completion. But the new project always provides a new opportunity to do some good, challenging, exciting architectural work. Contextual issues to consider include views, microclimate, access, topography, orientation, security and privacy requirements. Clients requirements informing the design include lifestyle, personalities, spaces to relax, cook, dine, entertain, work & play, future expansion needs and retirement. Add to this the ever increasing need for energy efficiency and sustainability, as well as the designers own aesthetic input. One considers all of these and solves, as one would a complex puzzle, for the best solution to achieve a result clients would consider ‘home’ as apposed to a house. An extension of themselves and their personalities – it’s not by chance you sometimes walk into someone’s well designed home and say “this is so you!” – as well as meeting all their practical requirements in their day to day living. And this does take time, a lot of time. The longest part of the design process is often the first part – figuring out, with the clients, exactly what their needs and requirements are.
For the prospective new homeowner:
Pre-design plans are significantly cheaper as you are not paying for the countless hours spent drawing up and re-working a custom plan. You are paying a reduced fee for the re-use of a standard plan that many other people will also be using. These are not designed with specific requirements in mind, but rather are broad interpretations of what people want. Plans are often categorised on a basis of common stylistic themes such as the previously mentioned Tuscan, etc, and I would recommend that aspirant pre-designers evolve this into more regionally relevant categories, taking at least broader local climatic regions into account, for example Karoo homes, Cape Coastal, etc.
The advantages of a custom plan done by a professional however, if you have the budget for it, are many. Besides the design being unique to your specific requirements and site, there are also advantages to having an architectural professional involved throughout the project. These include assistance with contract administration, selecting and appointing a contractor, monitoring progress on site and valuations for monthly payments. And it follows that the best person for the job would be one that was involved with the design from its inception.
Future scenario:
With conventional brick homes, pre-design has always had a place with larger ‘plot & plan’ residential developments. As timber frame becomes more of an accepted norm for residential housing developments so will, presumably, the demand for pre-designed plans for timber frame homes in that market.
For the client on the upper end of the spectrum, my guess is that it is unlikely that they would ever choose to go any other route than a unique custom designed home done for their specific site and requirements.
It is at the middle of the market (a typical three bedroom, one en-suite bathroom and one shared bathroom open plan living etc.) where we may see the emergence of this new trend. A potential new homeowner, who may have scribbled their own plan on a piece of paper, with the intention of giving this to a draughtsperson to draw up as is, may well be better off with a well designed stock plan – if at least basic adaptations are made to ensure correct orientation for the site.
A win-win situation in the lower to mid-budget market may well be a client who first browses a lot of online plans and then chooses something, as close to what they want, for adaptation – it’s often easier to decide whether you like something or not when looking at it than trying to articulate what you would like from scratch. This would cut a significant amount of time, and therefore cost, from the custom design process. Just Google ‘home plans’ and take it from there. Prices range from around R2000 to R4000 (there are also some offering plans for as little as R10 but, as with most things, you get what you pay for).
On finding a plan that closest matches your particular requirements purchase a well designed home plan and have that adapted to suit your requirements and site. This service is often offered by the designer selling the stock plans, which could be suitable if in your area, or could be done by any architectural professional you choose to work with. The end result may well be a house suited to your needs, with a significantly reduced design time and cost (even with adaptations), and a happy contractor who can get on with the building work sooner.
For many people though, your home, large or small, will remain as much an expression of who you are, and an extension of your personal space and attitudes, than just a mere house. Unless you are very fortunate to find a pre-design home that suits or is adaptable to your every need, myself and many others will be in the business of custom residential design for a long time to come. Your home, besides being your largest and most expensive asset, is also where you will spend most of your time, and it makes sense to put a relatively appropriate amount of thought, time and money well spent, into its design.
By Jacques Cronje, published in the Timber Frame Talk magazine, January 2010.
I’d like to start by saying I can’t predict the future better than anyone else. We live in interesting times, so here are some of my personal thoughts on trends we may see emerge this year.
As when trying to predict the movement of a share price, there are two aspects to consider in attempting to plot any future scenario: the fundamentals and the market sentiment.
The fundamentals:
The market for new houses was brought to its knees last year as a result of the global economic crises. After several interest cuts (rates have dropped by 5% since Dec 2008), the full effects of which have not yet been felt, the economists tell us house prices have turned the corner and are on the way up – albeit very marginally. And we need house prices to go up! Several of us in the business of new builds would have lost out in the last year to a potential client or two who opted to pick up an existing old house for a song rather than having to fork out for architectural fees and then the relatively expensive cost of building new. Whether we will see another rate cut is yet to be seen (according to January 14’s FINWEEK, Standard Banks economist Johan Botha says yes, and Nedbank’s Dennis Dykes says no – so go figure).
We all know that when America sneezes, the world catches a cold – but how about getting on the road to good health again? The demand for new homes in America has not yet recovered. That said, they’ve invented a whole new industry, which it seems will be keeping the homebuilders busy for some time thanks to the energy crisis. It’s called ‘weatherization’, a fancy ‘Americanization’ for ‘make waterproof, airtight and install more insulation’. It comes with instruction manuals, books, specialist assessors, specialist contractors, training courses – the works. Just Google ‘weatherization’ and you will see what I mean.
Another energy-related fundamental. In addition to the global drive for energy efficiency to reduce greenhouse gas emissions, we have our own homegrown economic energy crisis of massive proportions heading our way – it seems there is no way around the fact that Eskom needs to hike tariffs by 35%. So ‘weatherization’ may soon become popular here too, along with various forms of alternative energy! Wind and photovoltaic energy, which currently seem very expensive when looking at the cost per watt hour, won’t be looking half as bad when compared to Eskom’s new pricing. And, off course, when that increased demand for newly built homes eventually filters through, it won’t be difficult to see the obvious benefits of going with a more energy-efficient timber frame home.
The FIFA World Cup. The eyes of the world will be on us in five months’ time, and the possibility exists that many visitors and TV spectators, both from further north on our continent, and overseas, having never seen our magnificent country before, will become interested in settling here. The latter group will hopefully bring their tastes and preferences in houses with them: energy efficient, acceptance of timber frame as a norm, and of course the demand for good design. The former: a general increase in economic activity and skills, and hopefully our local population get used to more multiculturalism so that we don’t see a resurgence of xenophobia.
Crime levels. The FIFA World Cup, when the final whistle has blown, and ………………….( fill your prediction in here) leaves with the cup, will besides having left us with better roads, stadiums and airports, also no doubt leave us with a better trained and equipped police force. That’s the upside. The downside is that the expectations (thanks also to unfulfilled promises by government of the creation of thousands of new jobs) of the burgeoning marginalised and unemployed will in all likelihood not be met and, unless the ever increasing divide between rich and poor is not addressed, we can expect more pressure from the ‘have-nots’ to want the stuff of the ‘haves’.
Water, the new oil. Or blue is the new black. The world is potentially facing a water crisis. On top of that, South Africa is a water-scarce country (with an annual rainfall of less than half the world average at 450mm/yr, and with 80% of the rain falling in five months of the year across various unevenly distributed catchments). The water crises won’t happen in 2010, but the time to start taking cognisance of it is now. If it happens it will make the energy crisis look like a minor glitch – by the time oil runs out we should have other alternatives, and even if we have to walk more for awhile and grow our own vegetables we will survive. Water, however, is the source of all life as we know it. According to the Dept. of Water Affairs and Forestry, 40% of all water consumption globally occurs within the built environment. Water-efficient building design, construction and use by occupants of buildings therefore represent a massive opportunity to reduce our use of water. In January 2000, I was quoted in the Sunday Argus (in an article ‘Building with Nature in Mind’) as saying “we flush drinking water down our toilets…I’m sure we’ll look back in disbelief one day” – it is now 10 years later and we still flush drinking water down the toilet. Time for a wake up. Think water-saving fixtures, greywater recycling, rainwater collection, indigenous gardens.
Sentiment:
As slow as the economic recovery may be, people seem tired of putting things on hold and want to get on with it. If you wanted to build that house, you in all likelihood still want to build it at some stage. I’ve seen this in enquiries for new homes – several of last year’s enquiries that petered out have re-emerged, and there is also a definite increase in new enquiries. The flipside is that the demand for open residential land is still low – the procurement of which is obviously the first stage in the process of building a new home (and I know this from personal experience – I’ve had a plot on the market in Knysna with lagoon views, Heads views, everything views, and not one offer in the last six months – contact me if you are interested!). If one flips the coin over yet again there are, however, plenty of people who bought vacant land in developments in the boom times who are now sitting with them – and having to decide whether or not to build now and take advantage of a quieter construction market before the next upsurge, or try and sell the plot amid the low demand for land. The construction market is, as with any other economic market, cyclical. It has always been and, unless there is a major upheaval (see the bit on water above), it will always be – advise them to build now.
The age of opulence is over (or at least frowned upon). Think about the large banks in the UK that had to plead their case to the public over their need to pay high year-end bonuses. Did the man in the street even care about this a couple of years ago? Granted, a small percentage of some of the taxpayers’ money probably found its way into bonuses via the governments bailout of banks. There is a trend emerging of people wanting to do the right thing. To be seen as overly stinking rich will one day be uncool (not to mention the associated ‘haves/have-nots’ crime related problems which accompany that). Think smaller houses, better design, more efficient use of space and materials – and better security. Consider the latter integrated into the aesthetic and design of the house – sliding timber shutters, shading above a window that can fold down to secure it when you are away, etc.
More on wanting to do the right thing. Sustainability and green is in, thanks to the media, movies like An Inconvenient Truth and an increase in global awareness raised by campaigns around conferences such as Copenhagen. A couple of years ago if someone asked me for solar panels incorporated into the design of their house, they in all likelihood worked in conservation and drove a Toyota Prius. We had to hard-sell the case for energy efficiency, passive solar design, the use of rainwater tanks and solar water panels. Today, almost without exception, every client asks how they can do their bit to have a ‘greener’, more sustainable house. Clients are well informed, so beware of ‘greenwash’ – the unfortunately also growing trend of calling everything ‘eco’ (like the latest offering from cement manufacturers, an ‘eco-friendly concrete’, which in itself is an oxymoron) without producing a product with real ‘eco’ credentials. The general interest and awareness of all things green should translate into an increase in the share of the market for sustainably designed timber homes as the general demand for new homes picks up again.
pre-fab cabin
As with the effects of economic sentiment on us from the US and Europe, so do their emerging trends and fashions filter through to us (though admittedly this is largely skewed towards fashion and music). In terms of architecture abroad, sustainability is fast becoming mainstream. There is also a general increase in the interest in prefab, for different reasons in different places. In the UK, where the term ‘offsite construction’ is used, it is seen as a ‘modern method of construction’, streamlining processes for larger buildings such as hospitals and schools. Bathrooms, for example, are supplied as completed factory-built ‘Pods’ along with sanitary fittings and tiling complete, just requiring to be connected up. Another factor there is the drive to reduce the amount of labour on site where stringent Health and Safety regulations apply (try and take one step onto any building site in the UK without a day-glow vest and a hard hat) and produce more in a controlled factory environment. In the US, ‘modern’ prefab is all the rage, popularised by magazines like Dwell, mostly for small residential homes and cabins (small is the new big). Europe is seeing a growing popularity of brands such as Huf Haus, who are setting the trend in contemporary timber post and beam prefab construction, both locally and as an export.
I see signs of a growing interest in pre-fab here too, by an increase in enquiries regarding the pre-fab systems development side of my practice, though I suspect that it may still be awhile yet before that takes off here – lets allow more of the public to first get used to the idea of timber homes.
By Jacques Cronje, published in Wood SA & Timber Times Sept 2008.
Over the past couple of thousand years the development of civilisations have been inextricably linked with the development of mans use of timber – from early dwellings, when timber was used along with stone, clay and earth, to the building of the first ships and carts. Even the Ancient Greek temples, whose stone ruins we still study today, were designed to follow the forms of their timber predecessors. Some of the oldest timber frame structures still in use today are the 7th Century ‘Golden Hall’, and the five storey pagoda, ‘Goju-no-to’, in the ancient village of Ikaruga in Japan, built over one thousand four hundred years ago, as well as the 11th /12th Century Stave Church at Greenstead in Essex, United Kindgom.
With the exception of all but a few parts of the world the timber building tradition has largely been replaced over the last century as designers and builders moved towards masonry, concrete and steel. In today’s increasingly high paced and high-tech world some people, however, prefer a home that is more than just a place of shelter from the elements – they want a sanctuary, a place of rejuvenation and relaxation and a place that reflects their aesthetic ideals. It should therefore come as no surprise that there has been a worldwide rediscovery of the most natural of all building products, timber, as people again gravitate towards building homes that best express the beauty and tranquillity of nature. In South Africa, timber homes were re-introduced as an alternative to conventional brick and mortar homes in the sixties, and have seen a growing resurgence, as in other parts of the world, over the last decade.
‘Timber Frame’ has many forms, and in South Africa, the term refers to what some countries call ‘conventional framing’. In the U.S.A, ‘Timber Frame’, is what we refer to as ‘Post and Beam’ construction and the British call ‘Heavy Framing’. American ‘Timber Framing’, which uses fewer and larger timber members, is based on a traditional method of building dating back to ancient Japan, Europe and medieval England. The traditional ‘Heavy Framing’ timber building style of the U.K and Europe, also referred to as ‘Half-Timbered’ construction, is characterised by the visible dark framing with white panels distinctive of the Tudor style. Conventional Timber Framing, as is predominant in South Africa, is also referred to as ‘Platform Framing’. The walls are manufactured on site or pre-manufactured in panels, and then raised and fitted onto the floor platform of the building, with the next floor platform, in the case of a double storey building, resting on the frames. External cladding can be timber in various options, a manufactured fibre-cement building plank which can be painted to any colour, or a smooth plastered cementitious finish. Internal cladding can be smooth skimmed dry walling, or timber panelling in various profiles, textures and styles. Solid Log homes have also maintained popularity and there are several firms in South Africa who produce high quality log homes.
Buildings are collectively one of the largest consumers of world energy resources and in present times of global warming and changing weather patterns, sustainability, and more specifically, sustainable building, is fast progressing from a buzzword to a necessity and we are increasingly called upon to make carefully considered environmentally friendly choices in terms of what we consume. Of the various raw materials to choose from for building, timber has by far the lowest embodied energy and is the only truly renewable resource. Global debate over sustainable managements of forests and the dangers of deforestation has led to the development of forest management certification, ensuring that timber from plantations is a harvested sustainably.
Timber as a building material further serves to reduce carbon in the atmosphere. The carbon cycle in the life cycle of a tree is such that during the growth and life of a tree carbon is absorbed out of the atmosphere, and when a tree burnt as fuel or left to decay the same amount of carbon is again released into the atmosphere. In this cycle a tree can be said to be carbon neutral, or a temporary store of carbon. If, however, the tree is harvested for use as a building material, the timber utilised remains a store of carbon for the duration of the life of the building, therefore reducing the amount returned to the atmosphere.
While it is perhaps the increase in technology and pace of development that increase our inner yearning to re-connect with nature, timber as a material has not been left behind by technological advances, the most significant of which was undoubtedly the advent of the glue-laminated beam. This was followed by the development of plywood, composite boards, engineered beams – allowing lighter timbers to span longer distances and various developments of using metal fixings and steel in combination with timber to create more efficient structural systems. The ability to span longer distances have in terms of design, elevated the timber home from the humble shelter it used to be, to light and spacious open plan structures, which has certainly aided the increase in popularity of timber homes.
With Timber Homes the building process is quick and efficient, utilising easily transportable lightweight materials which greatly reduces disturbance to the surrounding environment during the construction process. It is the ideal building type for inaccessible or remote sites, as well as steep sites and when building in environmentally sensitive areas. From a design point of view timber is an ideal material to work with providing unlimited scope, weather it be to blend in with the natural surroundings, achieve clean lines, intricate detail or impressive beams and structure. The timber frame building system in South Africa is included in the National Building Regulations (NBR), specified in SANS 10082 – Code of Practice for Timber Frame Buildings, and is recognized by the NHBRC, lending institutions, insurers and local authorities. Given continued sustainable forest management, an increasing desire to make the correct environmental choices, and the re-discovery of the comfort of living in a timber home and the natural beauty of timber as a material, the growing trend of building timber homes could be just the start…
There has been a lot of debate recently around energy efficiency and product choice. It started with SASFA, the Southern African Light Steel Frame Building Association’s claim that that light steel-frame houses are more energy-efficient than conventional clay-brick houses.
Corobrik responded aggressively and are taking on SASFA about their claims. They are claiming, as a result of recently undertaken thermal studies commissioned by themselves, that “The findings on the influence of insulation (R-value) in different wall types on the thermal characteristics of houses leave no doubt that conventional clay-brick homes, in South Africa’s climate, demand less electricity for heating and cooling over their life cycle than a comparable light steel-frame, lightweight walled alternative”[1]
This debate may in all likelihood soon spill into the general public domain, as the parties fight for their market share in market with a still depressed demand for new houses. In one way or the other, the image of timber frame may be affected, and we may need to add our voice to the debate. Another of Corobriks’ statements is that “The real world is far from a ‘steady state’ with factors such as air movement, reflectivity, thermal mass, constantly changing temperatures, day and night, and various degrees of thermal bridging across the insulation layer of lightweight walls all playing their part.” Luckily for us timber frame enthusiasts, ‘thermal bridging’ is a not serious issue as timber itself has a high thermal resistance (R-value), whereas as steel is highly conductive and therefore transfers heat at across the wall right past any amount of insulation at each stud.
My opinion (which I have already added to the debate – Urban Green File # 76, 26 Oct 2009), is that to say that either brick or lightweight frame houses are more energy efficient is a bold claim, as lot depends on factors such as orientation, glazing and shading, and more importantly on the climatic zone in which you are building – which the design strategy called Passive Solar Design seeks to address (more about that in another article).
The fact is, there is actually no debate to be had around insulation when comparing a conventional brick wall to a lightweight frame wall packed with insulation material – the lightweight frame wall will win hands down. Where brick walls have an advantage is in terms of their thermal mass, which is very different to insulation. Purely in terms of energy efficiency, when building in an area experiencing high diurnal (day/night) temperature fluctuations (drier inland regions, generally), you are better off with a building which includes some elements of brickwork or concrete, for example a timber frame building on a conventional concrete foundation, with high thermal mass to absorb and let off heat, so doing moderating internal temperatures. If you are building in an area of low diurnall temperature fluctuation, coastal, moderate areas generally (as the sea does the job of moderating day/night temperatures), you’d be better off building a lightweight structure with lightweight highly insulated walls, as you don’t require thermal mass retention but rather insulation. And insulated lightweight wall homes area easier and less costly to heat up than homes built of brick. Think of a brick house as a cast iron bath, which firstly absorbs the heat from the water untill the bath itself is warm – requiring a lot more hot water to have a warm bath; and a timber frame house like a fibreglass bath ( lower mass – does’nt absorb much heat from the water) – a lot less hot water, and therefore energy, is required to have a warm bath.
The debate around Energy Efficiency will also soon be more than just another green building strategy and marketing angle, as it currently is for some. The South African National Standard, SANS 204 – Energy Efficiency in Buildings, has been published in draft form, and while the plan is to have it as a voluntary standard initially, it will at some point in the future become part of the National Building Regulations.
With regards Corobriks claims, Urban Green File “plans to investigate Corobrik’s findings thoroughly and to publish an article on this topic in an upcoming edition.”
We have in recent times become increasingly aware of the fact that our human activities are having a large environmental impact on our planet and directly contributing to global warming. Energy supply shortages have further awakened our realisation that we need to pay attention to how much energy we consume. As 30 – 40% of global energy, and up 40% of all materials consumed, is done so by the construction of our built environment, particular attention needs to be focused on the sustainability of the building materials we use.
When evaluating the sustainability of a building material, it needs to be considered in terms of its energy use, its impact on the carbon cycle, and its environmental impact.
The energy use of a material occurs during the process of obtaining it in its raw state, such as mining in the case of metals, quarrying in the case of clay, or harvesting in the case of timber, the transport of the raw material, the manufacturing processes, and the transport of the final product to site. This total sum of energy invested into a material is referred to as the embodied energy of the material, and varies largely from one type of material to the next. In South Africa, as the bulk of our electricity generation is derived from the burning of coal, which produces CO2 and therefore causes global warming, the energy use of material becomes even more relevant.
When comparing the embodied energy of timber to that of other building materials one also needs to take into consideration the comparative embodied energy in the differing types of timber product, and assess this along with other environmental impacts. Timber products range from air dried sawn hardwood, with the lowest embodied energy (of around 0.5 MJ/kg), to kiln dried softwood (at around 3.4 MJ/kg), to engineered timber products such as plywood (at around 10.4 MJ/kg) and Glulam (for example laminated beams, at 11 MJ/kg). By way of comparison to other types of building material, clay bricks have an embodied energy of approx. 2.5 MJ/kg, cement 5.6, mild steel 34 and aluminium 170 MJ/kg. A large component of embodied energy is transport, and timber performs favourably when comparing the environmental cost of transport to other materials due to timber products generally being light and easy to handle with high strength to weight ratios.
The Embodied Energy of a material needs to be considered along with factors such as the effect on the carbon cycle and other environmental impacts. In terms of renewability, plantation timber is renewable and can be regrown in a relatively short time (15-25years). Other environmental impacts that need to be considered are those of pollution impacts during the manufacturing process and solid waste generation. The waste produced during the processing of a raw material into a product, while not necessarily having an economic cost, has an environmental cost, and as such must be considered when comparing materials in terms of sustainability. In comparing a timber frame wall to a steel frame wall in terms of total pollutants emitted, it is estimated that the environmental cost of a timber wall is 30% of that of a steel frame wall. While the manufacture of timber products is associated with low levels of emissions, and the forests where the timber is grown act as a store of CO2, the manufacture of cement, for example, involves emissions of sulphur dioxide, carbon dioxide and nitrogen oxides.
In terms of water usage, while trees consume vast amounts of water while growing, the bulk of this returns to the water cycle as clean water. For the production and usage of concrete by comparison, water consumption and alkaline liquid effluents are part of the process. Similarly the production of steel results in the poor quality wastewater.
In addition to the embodied energy of each material used one must, in considering the energy usage of the occupants of the building during its lifecycle, also take into account the thermal properties of the building envelope, by looking at the insulation values as well as heat retention properties of the materials. Timber has a relatively much higher resistance value than masonry and is therefore a much better insulator. The timber frame wall system further affords a cavity allowing for the inclusion of insulation material, which further contributes to energy efficiency. Clay bricks or other high mass materials have an advantage when building in areas of high diurnal fluctuation due to their heat retention properties.
The carbon cycle of timber as a building material is very different to that of other building materials. As part of the process of photosynthesis, trees give off oxygen and absorb carbon from the air, which is stored in the tissue of the tree. When a tree is burnt as fuel or left to decay the same amount of carbon is again released into the atmosphere. In this cycle a tree can be said to be carbon neutral, or a temporary store of carbon. If, however, the tree is harvested for use as a building material, the timber utilised remains a store of carbon for the duration of the life of the building, therefore reducing the amount returned to the atmosphere.
Once the decision is made to use timber as a building material, appropriate design strategies should be incorporated to further enhance the sustainability of a building by maximising the utilisation of timber, reducing waste and enhancing durability. Specification of the grade and type of timber product, and particularly the avoidance of over specification can have a large impact on efficiencies and wastage. For example the specification of large sections of high strength and aesthetic quality grades will result in the creation of more waste. The same applies when specifying timber cladding, flooring or panelling as ‘select’ or ‘clear’. Timber is a natural product, and each piece is unique, and more acceptance of variations in colour, texture and pattern, in other words more appreciation of the material as a natural product will go a long way in reducing wastage. The specification of locally grown plantation timber further reduces energy costs when compared to the environmental impact of transporting important timber.
Resource efficient design is the practice of designing to maximise the utilisation of a material. Timber, for example, comes in standard lengths (in increments of 300mm), and it therefore makes sense to rather design a deck say, of 3m wide, than 3.2m; which would result in a 200mm off-cut of each piece of decking.
Timber has a high strength to weight ratio, with its highest strength running parallel to the grain. While as a material it provides considerable flexibility in design, in terms of efficiency, it performs best with clearly defined and logical load paths. The process of rational construction calls for example, for trusses to be seated directly above first floor wall studs which in turn fit directly above floor joists which are directly lined up above ground floor wall studs. Similarly a post on a suspended floor structure supporting a ridge beam would have a support post to the ground directly below it. These principles can reduce excessive lintels and heavy beams and if applied correctly, can lead to a logical clarity in the design of a timber building, particularly where the structural and loadbearing elements are exposed to view.
Correct detailing of externally exposed timber serves to enhance durability. Timber should be kept dry wherever possible, by providing eaves and protective flashing, and should always when wet shed water, for example by bevelled edges. Moisture traps should be avoided and natural ventilation provided, particularly below suspended floor structures. Where timber is in a very exposed situation it should be fixed in such a way that it could be easily replaced if necessary, for example screwed in place instead of nailed.
Timber is a truly renewable building material, it is easy to work with and provides endless alternatives in design. It is a store of carbon and has a low embodied energy. Timber Frame is a time honoured, energy-efficient, environmentally sound, versatile, structurally safe and above all aesthetically pleasing method of building. Given a increasing global trend of sustainable forest management, an increasing desire to make the correct environmental choices, and the re-discovery of the comfort of living in a timber home and the natural beauty of timber as a material, the growing trend of building timber homes could be just the start…and the right thing to do.
