Non-Domestic Construction Sector: Historical and Current Use of Timber Frames in the UK

The non-domestic construction industry in the U.K. entails the development of buildings for various non-domestic uses, including offices, schools, hotels, visitor centrers, libraries, community centres, and supermarkets (Palmer, Terry, & Armitage, 2016). Timber frame technique of construction uses standardized prefabricated timber wall panels and floors and is commonly used in the developed nations (Palmer, Terry, & Armitage, 2016). According to Reynolds and Enjily (2005), this current technology uses advanced insulation and vapour control layers, as well as breathable membranes that ensure increased durability. In adoption, as the authors posit, regulations for building, including acoustic, thermal, and fire performance are all incorporated in the timber frame design. Timber frames are well proven and provide a versatile construction methodology with a variety of the main benefits. These include fast erection, offsite construction technique, reduction of the imminent risk of delays, reduction in site waste, ease of project planning, reduction in site storage requirements, utilization of sustainable building materials, achievement of a high Eco Homes Rating, and reduction in overall building program (Reynolds and Enjily, 2005). Using timber frames is a positive strategy as it helps combat climate change. The UK government has established numerous directives and policies that encourage the reduction of carbon dioxide emissions and energy consumption within the non-domestic sector, including the Climate Change Act of 2008 (Lockwood, 2013).

Historical and Current Perspective of Timber Systems in the U.K.

Timber frame construction in the U.K. is dated back to the medieval times, and until the 15th century, it was the most widely used building material (Philliopson, 2003). System-built timber frame dwellings were introduced in the U.K. as early as in the 1920s, which was a response to the shortage of labour after the First World War. As Phillipson (2003) highlights, since the timber frame systems were introduced in the aftermath of the war, external walls were typically made of heavy-framed panels or virtual solid timber planks, which were clad mainly with timber boards. Phillipson (2003) highlighted that systems incorporated timber stud frame external walls from 1927 to 1941. Essentially, the timber frames consisted single-storey height panels, but in London County, they extended to two storeys (Phillipson, 2003). The frames were usually overlaid using breather membranes, or bitumen felt, coupled with timber boards that were nailed to the frame. Frames were lined with either plasterboard or fibreboard and insulation was not used.

In 1942, the Secretary of State of Scotland, the Ministry of Health, and the minister of works did appoint an Interdepartmental Committee that focused on house construction, which became the Burt Committee because it was presided over by Sir George Burt (Phillipson, 2003). Its purpose was considering the methods and materials that were suitable for building while taking the economy, the speed of erection, and efficiency into consideration. The work of the Burt Committee resulted in an increase in the number of non-traditional properties that were built in the U.K., including timber frame buildings (Phillipson, 2003). However, the shortage of timber resulted to the rationing of standards, thereby limiting section sizes where timber was used for construction purposes. It meant that the timber sections that were used for construction after 1945 were often smaller than those used before. Besides, innovations were introduced, such as the use of stressed skin panels, and separate claddings, where they were fabricated in the factory and subsequently assembled on site.

However, dramatic growth in market share for the use of timber frames came in the 1960s and 1970s, when industrialized housing boom occurred through to the year 2002 (Phillipson, 2003). For instance, in 2002, the use of timber was rarely used for the structural construction of buildings that were above two to three storeys (Moore, 2015). However, it is important to note that only one out of every six homes that were built in the U.K. used timber frames. There are many successful implementations of timber frames currently, including iCon Daventry building, College Lake Visitor Centre, Bessemer Grange Primary School, Angmering Community Centre, Oakham Centre of Education Primary School, Pool Innovation Centre, and Premier Inn and Beefeater Restaurant.

The Premium Inn and Beefeater Restaurant is located in mid-Sussex and was originally intended to reduce energy consumption by 70% with its 140mm timber frame that has triple glazing. The Pool Innovation Centre is mainly a timber-clad, three-storey building that rents offices in Redruth that has natural ventilation (Palmer, Terry, & Armitage, 2016). Oakham Centre of Education Primary School located in Rutland is a 2,600m2 school that can accommodate 210 pupils with a separate hydrotherapy pool, community room, and nursery (Palmer, Terry, & Armitage, 2016). It uses a well-insulated prefabricated timber walls and is eco-friendly, being equipped with solar thermal panels. Icon Daventry is highly insulated with timber frames, making it eco-friendly (Palmer, Terry, & Armitage, 2016). The college Lake Visitor Centre located in Tring Hertfordshire has a single storey section that entails the use of grass roof, as well as a two-storey timber section. Bessemer Grange Primary School was constructed in the 1950s but had an extension built in 2010 using glulam timber frames (Palmer, Terry, & Armitage, 2016). Angmering Community Centre, on the other hand, located in West Sussex, is a single-storey building that uses timber frames (Palmer, Terry, & Armitage, 2016). These are some of the successful non-domestic timber frame construction projects that have been implemented successfully in the U.K. According to Lewis (2005), currently, timber frames can be used in multi-storey buildings.

Legislation, Policies, and Standards

The building regulations are mainly statutory instruments that aim at ensuring that building policies are set out (Wang, Chang, & Dauber, 2010). Most building are approved using the regulations. The regulations that apply in England and Wales are encapsulated in the Building Act 1984 while the Building (Scotland) Act 2003 is applied in Scotland. However, under the Climate Change Act of 2008, the government of the U.K. commits itself to legally binding greenhouse gas (GHC) emission reduction targets of at least 34% by the year 2020, and at least 80% by the year 2050 in relativity to the 1990 levels of GHC emissions (Phillipson, 2003; Lockwood, 2013). According to Phillipson (2003), around 45% of carbon dioxide emission in the UK are mainly from buildings, and of that, 18% come from the non-domestic sector. As the author articulates, this comes cooling and space heating, lighting and water heating, and thus, it is not surprising that the government has pledged to take steps towards reducing the emissions in the sector. For new buildings, and mainly via the Buildings Regulations Act, the government has made various changes designed for amassing the thermal efficiency of buildings, which include those that entail the use of timber frames, and thus, be able to reduce the emissions and pave the way for the establishment of Code for Sustainable Homes. In essence, as Valikangas (2002) notes that the aim of the government is to ensure that all new houses have a zero carbon footprint by the year 2019, and the target ensures that Code 6 in the code for Sustainable homes is met.

Within the controls of Building Regulations, there are two measures that relate to the carbon dioxide emissions from the buildings, the target emissions rates (TER) as the dwellings Emission rates (DER). While TER refers to the level of emissions that have been set do for each of the domestic building types, DER deals with non-domestic property. DER is based on SAP calculations, building codes that need to be observed while constructing non-domestic buildings. Since the Building Regulations have been observed successive regulation have subsequently lowered TER, meaning that buildings are currently constructed with fewer emissions. For instance, according to Wang, Chang, and Dauber (2010), the 2010 TER Building Regulations was about 25% lower than that in the 2006 Regulations, while that of 2013 was significantly lower. For this reason, TER continues to reduce, meaning that more sustainable and green buildings are being constructed in the non-domestic sector of the U.K.

However, it is important to note that the basic principle of the move towards zero carbon regulations and standards has essentially been a fabric first approach, characterized by energy efficient services and fabric being prioritized over the renewable energy generation technologies which are cheaper and easier to achieve the targets through the improvement of the buildings fabric than by the use of renewable resources to light and heat the buildings.

It is vital to note that the move towards zero carbon housing, use of timber frames for construction was the first choice for anyone seeking to achieve sustainable construction. As Vukotic, Fenner, and Symons (2010) asserts, the fabrication of construction materials demands the use of energy, which results in carbon dioxide emissions that are referred to as the embodied carbon and approximately covers 20% of the whole life carbon cost for any building. However, timber frames are advantageous because they have a negative embodied carbon dioxide value (Vukotic, Fenner, & Symons, 2010; Soulti & Moncaster, 2014). Even though there is a need for the timber frames to be transported, which significantly raises carbon emissions due to transportation, the more timber frames that a building uses, the lower its carbon footprint will be. Importantly, forests act as a carbon sink, where carbon dioxide is absorbed from the air and stored. The old trees are less efficient than the younger ones in carbon capture, and thus, felling trees for timber frames and replanting younger saplings helps remove carbon from the atmosphere.

Code Compliance

The move towards emission of zero carbon means that timber frames are the natural methods for every construction company to undertake as it helps move towards the code compliance, which is divided into nine categories, energy, surface water run-off, water, management, materials, waste, health and well-being, pollution, and ecology. Timber frames are governed by the codes of practice, including BS EN 1995-1-1 Eurocode 5 and the UK National Annex to Eurocode 5: BS EN 1995-1-1, which dictate the rules for timber frame buildings, including safety (British Standards Institution, 2012).

Regarding energy, timber frames are more advantageous. It is significantly cheaper to obtain a U value mainly by insulating wall panels externally by the use of timber frames compared to masonry construction. Besides, it is easier to obtain lower U values needed for the achievement of Code 6 with the use of timber frames, meaning that they are more thermally efficient when employed in buildings (The Institution of Structural Engineers, 2013). It means that less energy is required for space heating, and thus, lower carbon dioxide emissions, meaning more points will be scored. According to Soulti and Moncaster (2014) and Weight (2011), considering materials, timber frames are expected to earn more points as it has very low embodied carbon dioxide, and has better sourcing credits in comparison to the products used for masonry. Considering waste code category, timber frames can be fabricated off-site with m...