AN E C O L O G I C A L A P P R O A C H
An ecological approach to construction is an attitude toward use of local materials and building which closely relates to the wider environment.
The way we currently relate to our environment has caused an alarming decline in soil, water and air quality and in populations of animals, plants and insects. Adopting more regenerative farming and land management practices, supporting rewilding and tree-planting and understanding how to build and live more interdependently with local wildlife can begin the patient and sustained work required to repair the land and restore precious habitats and ecosystems.
Rural landscapes are often viewed by city-dwellers as a bucolic idyll for rest and recreation. In his ‘Wessex’ novels, Thomas Hardy was deeply aware of this, promoting a vision of an interdependent and dynamic rural landscape where people are deeply in tune with the land and its resources. Rather than preserving a romantic notion of what is ‘natural’ we should celebrate the complexity and variety of rural environments, nurturing greater diversity in the types of landscapes that make it up.
An ecological approach to construction is an attitude toward use of local materials in construction and a way of approaching building which closely relates to the wider environment. Principally, this approach advocates the use of materials in construction that are available locally and that are organic and can be replenished, with low-embodied energy and toxicity. It also emphasises the importance of working with the site from the strategic scale down to specific details to make the act of building a practice that is capable of producing an environment that is locally distinct, enhancing the unique characteristics of a location’s geography, biodiversity and cultural use. Buildings themselves should be constructed with appropriate contemporary technology to enable the buildings to have both low embodied energy and a low energy and water demand, and they should also be safe to build and easy to adapt for future generations.
Traditional timber frame construction accounts for around 1/4 of UK housebuilding – simple, economical and versatile it is increasingly being augemented by off-site pre-fabrication to improve efficiency and quality and reduce costs.
Timber is the most sustainable building material that available locally – its embodied carbon is lower than concrete and steel in raw materials alone and when timber sequestration is incorporated, timber locks up a significant volume of carbon dioxide.
Our design is a development a traditional timber frame but is fabricated off-site in timber cassettes which are made to a high tolerance and brought to site where they can be rapidly assembled. Factory manufactured wall panels, floor and roof panels that can include the wall insulation, doors, windows and service zones pre-fitted for ease and speed of on- site installation of M&E works.
Incraesingly, engineered frame or panel systems are also enabling timber structures to perform in ways conventional timber cannot.
The design could be adjusted to make use of composite timber sections or larger solid timber elements, such as Cross Laminated Timber cores or spine walls.
There are many different types of renewable fibre that can be used in construction, for insulation and for finishing, including flax and hemp. Hemp has become more popular and increasingly explored in recent years and has historically been grown in Bridport, providing the raw materials for the town’s rope and net industry.
Hemp is used as insulation between the timber frame, with an additional layer applied to the exterior surface of the frame to leave the timber framework expressed and producing an unusual and expressive interior within the dwelling.
Cost-efficiency is optimised when assembly and preparation of material happens in a factory environment consistent with other moves toward off-site construction approaches in the industry, which would require additional infrastructure locally but would increase the potential for local pre- fabrication and supply to the housebuilding industry.
More labour and cost intensive, the material can also be compacted on site using formwork – a more costly option but which can provide a more distinctive and special interior finish where self-build or sweat equity models are possible.
Local to Bridport there are a wide variety of hardwoods and softwood timbers available in smaller quantities that are not conventionally used in the construction of new homes because the economies of scale that dictates the procurement of the big housebuilders inhibits more resourceful, locally specific opportunities in design.
Many species – from hardwoods such as poplar, ash, oak and lime to softwoods such as western red cedar, larch and douglas fir are suitable for different aspects of the construction. Local oak, larch, fir and cedar can be used in to make natural, subtly varied cladding for new dwellings.
The construction can be panellised to allow for off-site fabrication. Utilising timber boards which increase in width with each storey, give each building variety and distinctiveness without adding substantial cost. The boards can be coloured with natural pigments and dyes or left to weather naturally, and can be left either rough sawn or planed.
To provide further variety, an alternative exterior treatment involves sheathing the building exterior in a woodfibre board, such as Savolit, which is then finished with a characterful, textured lime render.
Roof: Metal sheeting, either natural zinc or aluminium, is used for the roof. This enables it to be easily replaced in the future for a more ecological material – hemp roof panels are being tested by a number of manufacturers, but are not yet compliant with British Standards.
Joinery: Windows and door frames designs are developed with local businesses and manufactured using locally available timbers. Timber joinery is more expensive to install, but can be repaired and maintained in a way that uPVC windows cannot.
Foundations: The ground conditions on different sites will vary – in some situations, the use of steel ground screws may be possible, reducing the volume of concrete used to found the building. Where concrete is necessary, a low-carbon, high % GGBS mix can reduce carbon embodied in the foundations by as much as 50%.