Posts Tagged ‘Timber frame’

Green, green grass of home: Norwegian turf roofs

26/09/2012

For a moment, let’s leave aside the technical benefits (or otherwise) of green roofs, and just enjoy how they look in the landscape.

In an article for the forthcoming ESI.info Expert Guide on facades, roof finishes and rainwater management, director of the Future Cities project Austin Williams writes:

Green roofs are now lauded for their biodiversity, carbon neutrality, pollution-busting, happiness-inducing, rainfall attenuating, energy-saving goodness. Putting grass on a roof has evolved into a moral agenda that almost brooks no challenge … Specifiers need to be aware that green roofs are not a miracle cure.

This turf roof blends almost seamlessly into its hillside surroundings. Spot the chimney and small skylight on the left!

Needless to say, green roofs alone won’t meet all the challenges involved in creating a built environment that really works… Sometimes it’s good to view them from a purely aesthetic angle.

That is just what I did last August in Norway. On many of our walks during those two weeks, there were turf-roofed cabins round every corner – although because of their camouflage tops, we often did not spot them until we were right up close.

Most of the pictures in this blog post were taken at or around Herdalssetra, an isolated hill-farm that has been in continuous operation for over 300 years. The 30-odd buildings here are generally small, old timber shacks. Their turf roofs are simply a part of that vernacular and a reflection of which materials were most readily to hand at the time. However, we often saw green roofs in new-build housing developments in major cities like Oslo and Trondheim.

This post, then, is intended as a low-tech visual feast and nothing more. I hope it conveys some of the beauty of the Herdalen valley. Look at these pictures and imagine the bleating of goats, the crunching sound of fjord horses grazing in juicy pastures, the smell of sun-warmed juniper and dwarf birch, all to a backdrop rush of snow-melt waterfalls – and you’re half-way there!

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Norwegian stave churches: 1000 years old and still standing

11/09/2012

A stave church, or stavkirke, is a timber church with a structural framework of timber staves (beams) resting on timber sleepers and carrying timber wall plates. The wall frames are infilled with vertical planks.

Borgund stave church

The exterior varies from simple and rough-hewn to painstakingly ornate, and in size the churches range from small, shed-like structures – such as Haltdalen stavkirke – to the more imposing Heddal stavkirke, which is the largest of its kind still standing. (At the end of this post, you will find the legend of how the latter was built in only three days.*)

In medieval Norway, the stave frame was the prevalent construction method for churches. There were at least a thousand of them – some sources say as many as two thousand – the length and breadth of the country, built in the 12th and 13th centuries. But by 1650, most of them had disappeared. Following the devastation wrought by the Black Death, many churches fell into disrepair, whilst the Reformation brought a change in the construction, style and use of churches.

Tarred pine shingles clad the steep roof sections

Today, only 28 of the original stave churches remain. Set on stone foundations, the rest of the buildings are entirely made from wood; from the dowels to the roof shingles. It is amazing to see how well some of them have lasted.

The best preserved is Borgund stavkirke in the county of  Sogn og Fjordane, in which most of the existing structure consists of original timbers.

Built from pinewood between 1180 and 1200, it is a striking, darkly ornate structure at the heart of a lush valley. I took the pictures in this post when I visited Borgund last August.

From the interior. In places, rune inscriptions can still be seen.

The intricate carvings, small-format shingles, and black dragons’ heads craning their necks from projecting gable apexes, are miles away from the simple, neutral style we tend to associate with Scandinavian architecture.

Through the centuries, stave churches were preserved by covering the timber in tar. When I visited this summer, the church had just been freshly tarred, making the external wood even darker than normal and lending it a rich, warm scent in the sun.

The external gallery, freshly tarred

The magnificent detailing and impressive longevity of it all made me think of the immense contrast between the church itself and the bleak, sparse living conditions of the people who built it. For farmers and craftsmen eking out a living in a remote Norwegian valley, building such a structure must have been an immense undertaking.

Medieval carvings, beautifully preserved

* There is an old legend about the building of Heddal stave church.

A local farmer, Raud Rygi, wanted to have a new church built. A mysterious stranger came along and offered to do the impossible: to build the church in only three days. His fee for this task was one of three things: either the farmer would have to fetch him the sun and the moon out of the sky, hand him his own heart on a plate, or guess the stranger’s name. Unsurprisingly, Raud chose the third option. He thought he would have plenty of time for name-guessing, as surely nobody could build a church in three days…

However, on the first night, the materials were already in place. On the second night, the steeple was raised. Despairing, and with only one day left before the church would be complete, Raud wandered round the building site at dusk. Suddenly, he heard a haunting voice rising out of the mountain, singing a lullaby: “Hush now, little one, tomorrow Finn will bring you the moon, the sun, and Raud’s heart for you to play with…”

Riddle solved: the builder was Finn, the troll. Raud Rygi’s life was saved, and Heddal had its new stave church.

Runic inscriptions on a church wall

The Old King’s Road, leading up to Borgund stave church

A burning issue: should we really be subsidising the biomass industry?

25/05/2012

Is the extensive burning of biomass for electricity generation a good use of (arguably) renewable resources and an important contribution to the low-carbon economy? Or is it in fact a threat to our environment and the timber industry, and an inefficient use of a very valuable resource?

In this guest post, Stirling-based building product manufacturer Norbord argues the latter.

What is the most responsible use of timber?

The background
Wood is a valuable resource, which, unlike other sources of renewable energy, is limited due to available land area and the length of the growing cycle. In the UK, current sustainable harvest is fully utilised by Norbord and other manufacturers through a lifecycle of grow –> use –> re-use –> recycle – and then, and only then, –> recover for energy.

This responsible and environmentally efficient lifecycle ensures carbon is stored for many years before being released back into the atmosphere when it is finally burned to produce energy.

As part of its commitment to a low carbon economy, the Government has introduced subsidies to electricity generators under the Renewables Obligation (RO). These subsidies incentivise the burning of wood for electricity-only generation, at efficiency levels of less than 30%.

The issue
The wood panel industry relies entirely on UK wood (virgin and recovered), which is now under huge pressure from the large-scale biomass energy sector. In simple terms, our industry is under threat because the Government subsidies allow the energy generators to pay more than double the price currently paid by the UK wood panel industry for its primary raw material. As a result, this has driven up average wood prices by 60% in the last five years.

And the problem looks set to grow. There has been a huge increase in the number of planning applications for biomass power stations that generate electricity by burning wood. These plants have the capacity to consume many times the entire UK’s timber harvest. Additionally, the Government is introducing subsidies with respect to the Renewable Heat Incentive (RHI) scheme, which will further distort the market.

Biomass protest (image by faul on Flickr)

The impact
The threat to the wood panel industry is clear, however the current legislation has wider-reaching consequences too:

• The loss of the wood panel industry would cost tens of thousands of jobs across the UK, many of them in manufacturing, damaging already fragile economies.
• The environmental impact – the inefficient burning of wood will in fact generate a net increase in UK CO2 emissions, to the order of hundreds of millions of tonnes.
• UK bill-payers, already struggling with rising costs for household energy, are actually paying £810 million a year for these so-called ‘green’ subsidies through hidden charges in their bills.
• Consumers will experience significant price increases on wood panel products and other manufactured items, driven by the rising cost of raw materials.
• Large negative impact on the UK’s balance of trade, as we would need to import wood from overseas to meet demand.
• Distortion of the ‘Hierarchy of Use’ for wood, to which the UK Government is committed.

What’s being done?
The Wood Panel Industries Federation’s Make Wood Work and Stop Burning our Trees campaigns are backed by Norbord and the other UK panel producers, and supported by other forest product industry organisations. They are national campaigns aimed at persuading the Government to encourage the best possible use of this valuable and limited material.

Working with leading organisations within the building trade, we are lobbying the government to review current and proposed legislation. An Early Day Motion has been tabled in Parliament in support of the Make Wood Work campaign. Specifically, we are asking the Government:

1. To respect the obligated “Hierarchy of Use” in the framing of legislation.
2. To review the RO and RHI incentives with respect to their distortion of this Hierarchy.
3. To incentivise the use of wood for energy only after its full lifecycle use, for carbon storage.
4. To better integrate the process across disparate Government Departments.
5. To commit to, and deliver on, an expansion of productive woodlands.
6. To engage fully with the wood processing industry as represented by the Wood Panel Industries Federation (WPIF) and Confor (Confederation of Forest Industries).

How can you help?
The Biomass Issue has consequences for the UK economy, our environment and for the tens of thousands of UK workers whose jobs are at risk as a result of this legislation.

Please support our campaign by signing the petition.

Thank you to Norbord for this guest post. What are your views on biomass and the Government incentives? Whether you are in opposition to the above or in support of it, I would love to hear from you.

In the meantime, here is some more background information:

The relative sustainability of building materials – guides and sources

06/12/2011

The trade associations, enthusiasts and lobbyists for different building materials are busy telling us how sustainable their material of choice is, and how it out-performs all others. Amongst the myriad claims, facts and figures, how can we establish which material is the most environmentally friendly?  And is that even the right question to ask?

Timber is a natural material and absorbs CO2 while it grows, steel is eminently recyclable, concrete is ideal for thermal mass construction, whereas bricks are durable and can be reclaimed.

Even if we discover which has the lowest embodied carbon, for example, we may not agree on what sustainability actually means. Are we talking about cradle-to-grave lifespans, economic viability, wildlife considerations, energy performance, aesthetic impact, recyclability – or even taking a holistic view of the building’s use and social sustainability within a local community?

In the absence of a unified framework of assessment and an agreement on relevant metrics, the debate will continue.

At the end of the day, each project needs its own, tailored assessment. A good designer will select from all options and choose what is fit for purpose, rather than become too attached – by habit or preference – to one material or another.

But in order to make that choice, we need a level-headed view of the facts available for each material, accompanied by real-life case studies. We also need to consult with people who are in the know about the different accreditations and codes, and can give an unbiased overview. Below are some sources that make a good start.

Codes and certifications: consultancy

  • Mel Starrs, Associate Director at PRP Architects, specialises in sustainability and green buildings. Her Elemental blog is full of useful information.
  • The CodeStore.co.uk has a directory of CSH consultants and assessors. Materials is number 3 on the Code’s list of 9 sustainable design criteria.
  • Jennifer Hardi works for the BRE’s Low Carbon Future team and is also part of the technical support team for the Energy Saving Trust’s Best Practice Helpline.
  • Bruno Miglio is a Leader of Global Materials Science at Arup. The team offers advice on the use of materials in engineering and architecture – from design to reuse or demolition.
  • The BRE’s Green Guide to Specification assesses building materials and components in terms of their environmental impact across their entire life cycle.

Concrete

This is Concrete showcases sustainable construction projects and encourages project-based feedback, presenting case study evidence to support the sustainability credentials of concrete.

Sustainable Concrete has information on concrete production, performance and end-use, and provides indicators on materials efficiency.

MPA (Mineral Products Association) runs the Concrete Centre, which contains news, publications, webcasts, online services, advice and design tools.

Steel

The BCSA is the national organisation for the steel construction industry. Its website, SteelConstruction.org, has a section dedicated to sustainability. The BCSA’s Target Zero project “will generate costed solutions for structural steel framed construction that achieves highest BREEAM ratings and changes to Part L of the Building Regulations, meeting emissions reduction targets towards zero carbon by 2019.”

Timber

TRADA has a library of downloads that detail the sustainability of timber. The Association’s Technology Assessed scheme also helps establish whether a company’s literature gives a fair representation of the benefits and characteristics of a product or service – a useful tool against greenwash.

The Forestry Commission also provides comprehensive facts and figures on the timber trade.

Stone

All members of the Stone Federation of Great Britain have to comply with this Sustainability Statement. The Federation provides a Technical Advice Service for the commercial and domestic use of natural stone.

Stephen Critchley – a Master Stonemason in Central London – is a font of knowledge on ancient and modern uses of natural stone, giving talks, workshops and demonstrations.

The simplest view of the sustainability of natural stone – there is tonnes of it about and it lasts for a very long time – is outlined here by CED.

Bricks and blocks

Bricks, in the words of the Brick Development Association, are “a versatile and durable building material, with excellent life cycle performance, energy efficiency, high thermal mass and responsible manufacturing.” Its publications on the sustainability issues of bricks and brickwork are listed here.

Sustainable Build details the manufacture and use of bricks as a sustainable building material in this article, and also comments on stone vs brick.

What other sources have you found useful for determining the sustainability of specific building materials? Please leave a comment and let me know!

This post was inspired by an interesting conversation on Twitter with structural engineers David Sharpe and James Thomson.

Compare and select building materials on ESI.info

Wise living: BoKlok, the IKEA house

15/06/2010

The IKEA way of life?

For some people, a weekend trip to IKEA is like a descent into the innermost circles of hell. The success of the outing is measured in how many times you have fallen out with your partner, shouted at your parents, or lost your kids amongst the soft toys and sofa beds. More than five = the norm. Less than five = a miracle.

Strangely (and somewhat pathetically?) I actually love going to IKEA. Perhaps it feels like a temporary dip into my Scandinavian gene-pool. Or maybe it’s the smug satisfaction of actually understanding, and being able to pronounce correctly, the peculiar names of the furniture pieces. Or it might just be the pull of the Swedish meatballs and Kopparberg pear cider…

Either way, did you know you can buy not only flat-pack furniture at IKEA, but an actual house to put your Billy Bookcases in?

Each unit has a balcony or patio

The BoKlok website explains the concept behind what IKEA is aiming for: affordable, comfortable and energy-efficient housing.

BoKlok is a groundbreaking concept to housing that involves providing space-saving, functional and high quality housing at a price that enables as many people as possible to afford a stylish and comfortable home.

As with other products from the Swedish furniture behemoth, the housing is kept at affordable levels through the use of standard, straight-forward designs and large-volume manufacturing. A lot of the production is done off-site, for cost-effectiveness and quality control.

Narrow street frontage for efficient land use

Apartment blocks and terraced houses are available; originally developed for the Swedish market, but now also built in Norway, Finland, Denmark, and Great Britain. The concept is also being launched in Germany (where off-site-manufactured and energy-efficient housing is not exactly a new idea).

Some of the design features are typically Scandinavian: timber construction and cladding, enclosed courtyards, open-plan living spaces, high ceilings and large windows. Perhaps surprisingly, the terraced housing features living areas downstairs and bedrooms upstairs – the opposite of many Nordic homes, where architects make the most of rising heat to keep bedrooms cool on the ground floor and living-rooms warm on the first floor. (Here, ThisIsMoney.co.uk looks at the potential financial benefits of “upside-down” living.)

I want my Werther's Originals back

All BoKlok schemes are sold through special sales events in IKEA stores, but before you rush out to buy one, a note of caution: the BoKlok group is awaiting the recovery of the UK housing market before it invests further over here.

Originally in partnership with the Home Group, IKEA/BoKlok AB has only completed one development in this country so far; the St James Village in Gateshead. The BoKlok/Home Group partnership is no longer active, with the Home Group having relinquished their national licence to use the BoKlok concept.

In a statement from January this year, BoKlok says they have no plans to withdraw from the UK market, though:

We believe that the BoKlok concept has a good market potential in the UK. There is an increasing need for good affordable homes and BoKlok can provide many people with better homes.