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SUSTAINABLE BUILDING


Using timber to achieve net-zero buildings


enhance a learning environment. Timber classrooms have been proven to reduce


stress among students versus traditional classrooms, as evidenced by a 2007 study, Schools without Stress, by Weitzer Parkett and proHolz of Austria. As well as reducing stress, biophilic design can enhance sensory and motor development by using elements from the living, natural environment which can help inspire curiosity, imagination and discovery in students. Furthermore, the use of natural materials can reduce fatigue, while cognitive ability and emotional wellbeing can be increased by the inclusion of nature in learning environments.


Net-zero in use or construction? T


he term net-zero is becoming familiar to many but it can mean different things to different


people. In the context of the built environment, it is used to describe both buildings that are net- zero carbon in operation and those that are net- zero carbon in their construction. The starting point for a net-zero construction


definition is: “when the amount of carbon emissions


associated with a building’s product and construction stages up to practical completion is zero or negative, through the use of offsets or the net export of onsite renewable energy.” Likewise, the current definition for a building’s


in use energy is: “when the amount of carbon emissions


associated with the building’s operational energy on an annual basis is zero or negative.” Operational energy includes heating and


cooling systems, cooking, lighting and plug loads. Construction energy considers the total carbon emissions created throughout the construction process. Only when both elements satisfy a net- zero ideal can a building be deemed to fully comply with the aims of the Climate Change Act and fit within the Government set targets of 2030 for operational net-zero and the 2050 embodied target.


Net-zero carbon construction: Natural, sustainable materials should be considered first, avoiding high embodied carbon materials wherever possible and still ensuring longevity. Efforts should be made to use fewer materials generally and to reduce the weight of dead loads, thus minimising structural weight and reducing foundation load and size. Transportation to the build site and onsite construction should be


July/August 2022


reduced by utilising offsite, modular construction. Waste and site works should be minimised and the construction materials and methods used should allow for future demounting, replacement or reuse of the structure or its elements.


Operational energy: Glazing should have high U values and, where possible, have a low surface area, whilst balancing the need for natural daylight and thermal comfort. All windows should be openable to allow cross ventilation. All systems for heating, lighting, cooling and fans should include demand controls. Fossil fuelled heating and hot water systems must be avoided and renewable energy sources should be maximised. The installation of onsite renewable energy sources, and battery storage, should be considered.


Using timber for schools As timber is a natural product that sequesters carbon as it grows, it is a highly suitable material for reducing carbon during the product stage. Each square metre of timber frame removes and stores over 12Kg of CO2 during the construction phases. While it is unlikely that the whole build could become negative in terms of carbon just by using a timber frame, it is an essential factor in achieving a calculated net-zero build. The government’s Net Zero Strategy, published


in autumn 2021, acknowledges that wood “has the lowest embodied carbon of any mainstream building material” and promises to “promote the safe use of timber in construction”. However, timber has some considerable


secondary benefits. It is a truly sustainable product when sourced from forests certified by the Forest Stewardship Council or the Programme for the Endorsement of Forest Certification. It also has well-known biophilic properties which help


TG Escapes u0800 917 7726 uinfo@tgescapes.co.uk uwww.tgescapes.co.uk


www.education-today.co.uk 47


Conclusion Overall a timber construction will always be more carbon efficient than a traditional masonry build. At the moment, there is some small benefit from a cost perspective. However, as the cost of offsetting rises, the economic case for construction methods that require less offsetting improves. The use of a timber structure makes achieving


net-zero easier and more economical, which is often the critical factor in the educational market.


Mark Brown is a Consultant at TG Escapes Modular Eco-Buildings who provide timber frame offsite building solutions to the education sector.


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