Building a new timber environment

Materials World magazine
,
7 Apr 2015

Peter Wilson predicts new heights and urban densities of timber constructions in the foreseeable future, as more house builders in England rediscover this traditional building material.

In many ways, the Great Fire of London in 1666 established the decidedly negative perceptions of wood as a construction material in our towns and cities that, for some people, have carried on to this day. Indeed, the London Building Acts were substantially predicated on the need to prevent future conflagration in timber structures, principally by preferencing the use of other, more fire-resistant, materials altogether. 

But while legislation pertaining to the use of wood in the world’s denser built environments has often mitigated its use as a primary structural component, regulations around the world are gradually changing in response to research and greater understanding of fire and reliable methods for its prevention. These developments, together with advances in the manufacture of timber-based building components and in the technology of timber construction, have moved matters on considerably in the almost 350 years since a large part of England’s capital was burned to the ground. 

More recently, a combination of factors has generated a strong resurgence of interest in the use of timber in construction. Environmental and sustainability concerns about materials sourcing and use have been focal to this, but an exponential rise in demand for new housing has also advanced the quest for more effective methods of off-site, mass manufacture approaches. Responses to continually increasing requirements for thermal efficiency and airtightness are deliverable with more speed and precision than is possible with traditional on-site masonry construction. 

Scotland’s example

The use of off-site manufacture is more prevalent in areas such as Scotland, where platform timber frame construction has been the predominant system of choice for more than 40 years – 70% of housing north of the border is constructed in this way. A great deal of technological development and hands-on experience has been gained, with housing and other developments in Scotland’s cities regularly reaching up to seven storeys. Manufactured off-site in controlled factory conditions, framed and closed panel systems can easily be delivered to urban areas and assembled far more quickly than is possible with traditional wet trade construction, a method that is also contingent upon the existence of reasonably good weather conditions. In many ways, the timber frame industry in Scotland can be regarded as first class, with a number of advanced factories able to prefabricate a large variety – and volume – of building solutions.

The same has not been the case in England where, until relatively recently, platform timber frame assembly had largely been avoided, a lasting consequence of a World in Action programme from the early 1980s. Even today, the percentage of house completions in England using this method is relatively low (15–20%). A number of high-profile fires in inadequately protected timber frame buildings on urban sites have hardly advanced the case in a property sector still wedded to brick and block construction. However, the demand for the speedy erection of huge numbers of new homes built to low-carbon standards is inevitably impacting on this. 

A new world

The factors of height and urban density are important, because the restricted availability of land – and consequently its cost – point towards buildings in cities throughout the world growing ever upwards. In turn, this will increase the use of technologies capable of mitigating their overall impact on the environment. This is not to suggest that the use of concrete and steel are somehow on the way out, but rather to posit the thought that more hybrid forms of construction that are designed to reduce the amount of non-renewable raw materials employed will increasingly become the norm. 

These developments, coupled with new and very different approaches to energy reduction that enable new buildings to become net generators rather than consumers of power, are likely to introduce some positive transformation in the global built environment. Current projections indicate that 80% of the world’s population of eight billion will live in cities by 2050. Together with international concerns over rapidly accelerating climate change, and the scale and nature of extraction processes involved in converting the raw materials required for the construction of new urban conglomerations, a shift is needed in the way we conceive and construct new buildings and cities. 

Attention is now being directed towards far more extensive use of renewable materials, reused or remanufactured products and innovative approaches to energy supply and use. The aim is no longer simply to move towards the creation of low- or zero-carbon buildings and infrastructure, but to heighten ambitions towards the regular delivery of negative carbon (autarkic) environments. As such, workspaces and homes will be able to generate the heat and electrical energy required to meet our needs, and to store or sell any excess produced. 

Changing the storey

In response to these environmental challenges, recent developments in engineered timber products and in timber engineering have resulted in a new generation of individual vertical wood-based building structures emerging around the globe in the past few years, which offer considerable potential for upscaling to form larger urban conglomerations. This process began with the Stadthaus, in East London’s Murray Grove, an eight-storey apartment building of solid wood construction sitting above a masonry ground floor and concrete foundations. Since then, ever taller timber structures have been built in various countries. These include the Forte Building (Melbourne, 10 storeys) and the Wood Innovation and Design Centre (British Columbia, nine storeys), with others under construction (Bergen, 14 storeys) and even taller projects in advanced planning (Västerbro, Stockholm, 34 storeys). Other studies have shown the potential to construct 20-plus storey commercial buildings from timber, as well as 46-storey equivalents to traditional steel frame construction. 

But it is not only individual or tall buildings that are the subject of these technological advances. In Oslo and its surrounding municipalities, a 10-year programme entitled FutureBuilt began in 2010, with a vision to create carbon-neutral areas combined with high-quality architecture. These developments are taking place within a very specific context. The Oslo region is expected to expand in population by almost 50% by 2050 and the planning of new infrastructure, housing and other facilities capable of meeting this demand has already begun. The aim of the programme is to complete 50 pilot projects – urban areas as well as individual buildings – with the lowest possible greenhouse gas emissions from transport, energy and material consumption. The concept is based on an acceptance that man-made climate change is one of the biggest challenges we face today and that emissions of climate-affecting gases need to be dramatically reduced. Achieving this will undoubtedly have a significant impact on the nature of urban development and architecture. With its programme now halfway to completion, the FutureBuilt initiative already has some 26 projects completed, of which 17 new buildings, six renovation projects and three area developments provide exemplars from which other cities can learn and benefit. 

One of these new projects is Tallhall, the Norwegian Meteorological Institute that, as a supplier of climate research data, was an obvious candidate for demonstrating how emission reduction might be achieved. Constructed above ground from untreated cross-laminated timber plates clad externally with perforated recycled aluminium, the building’s renewable short-travelled wood sequesters considerably more atmospheric carbon dioxide than equivalent volumes of steel or concrete (one cubic metre of wood can hold one tonne of carbon). These open public areas of the building sit over a concrete basement made using a newly developed low-carbon formula and are filled with massed ranks of weather-forecasting computer servers. The energy concept is based on reuse of leftover heat from these machines. The servers are cooled directly within the actual ranks, facilitating water-cooling at temperatures suitable for reuse in low-temperature heating systems. The water also travels through the project’s outside paving, allowing the servers to cool as the paving heats up, for free, melting the snow from the entrance during winter. Conceptually simple, perhaps, but an approach that, applied more widely, would see each new building erected in our towns and cities as a positive contributor to a more habitable built environment. 

So, to return to the Great Fire – it is possible to do a great deal more with wood, the one genuinely renewable construction material available to us, than just burning it. In its new technologically developed forms, it offers a wholly modern and environmentally responsible way to build, compatible with new approaches to energy generation that dispense with the need for wood as a heat source. Burning wood is the last thing we should think of doing with this amazing material.