Andrew Carpenter, chief executive of the Structural Timber Association, explains how building in timber can create a high performance building envelope.
Over the past year, both the British economy and the construction sector as a whole have turned a corner, with growth returning and remaining stable. While it is important that we seize the opportunity to secure this recovery, our industry still has a number of issues it needs to tackle with regards to sustainability, such as rising energy prices and the growing drive for zero carbon. Creating a secure, airtight building envelope will go a significant way to meeting these challenges, and timber is the ideal material to achieve this.
When constructing a building’s exterior envelope, the Structural Timber Association (STA) encourages all its members to pursue a fabric first approach, where the energy performance of the building is achieved primarily through the external structure. A secure envelope helps to minimise heat- loss, placing less demand on a building’s heating systems. Not only does this have the desired effect of reducing a building’s carbon footprint, it also helps to keep heating bills under control – an important consideration for both business and residential occupiers, especially as energy bills continue to rise.
Taking a Fabric First approach also negates the need to install renewable technologies, including solar panels, micro wind turbines and ground source heat pumps, which are often inefficient, expensive and notoriously difficult to maintain.
Evidence also suggests that it is easier to manage performance when constructing with structural timber methods, thanks to the higher level of off-site prefabrication inherent in its manufacturing process. This is particularly the case for the junction performance, where the work done in the factory allows for greater control of the elements, and the junctions are considered before it gets to site. It is not only easier to monitor quality in the factory environment, but in addition, the all-critical insulation is positioned such that it is able to work more effectively – thereby reducing the risk of environmental conditions, or work from another trade, negatively impacting on it.
Off-site construction also allows for quality to be monitored at every stage, unlike other methods, which are reliant on a multitude of trades. Factory based activities allow for better and safer working conditions, while also protecting the workers from the changeable British climate, which is likely to lead to better quality work. There is also increasing agreement across the sector that prefabricated systems will go some way to helping reduce the gap between a building’s design intent and its in-built credentials.
Low carbon building
Using structural timber as a way of creating a secure building envelope is an effective way of helping current and potential clients to meet their environmental targets. As an organic, non-toxic and naturally renewable building material, timber is the most sustainable form of construction. In addition, the carbon dioxide produced in both its transportation and manufacture is absorbed by the tree during its lifetime. By comparison, the production of concrete and steel accounts for around eight per cent of the world’s carbon dioxide emissions, due to its carbon intensive production processes.
In the longer term, buildings with secure envelopes are also the perfect fit with the low carbon agenda currently being pursued by national, regional and local governments. This includes the modifications to Part L of the Building Regulations, which require new build homes to be six per cent more efficient than under current regulations, with nine per cent uplift in the efficiency standards of non-domestic buildings. A new fabric energy efficiency target has also been introduced as part of these regulations, which timber is ideally positioned to meet. Although a number of these regulations are currently in flux and will be liable to change, utilising timber at its optimum can ensure that clients are ahead of the curve.
Without a doubt, timber delivers sustainable and energy efficient solutions – low embodied carbon, a choice of insulation performance, minimal waste, speed of construction, solutions without needing renewables, and off-site manufacture in a quality controlled environment. As the price of energy continues to rise, a building’s operational performance will inevitably become something that consumers will focus on more. It is strongly believed that this will lead to a significant increase in the use of timber across all sectors and encompassing hybrid solutions, such as CLT, SIPS and glulam. When consumers start to demand energy efficient homes, the envelope of buildings will come into focus like never before, and that’s something we must all be ready for.