Discover how we integrated our approach to Net Zero Masterplanning solutions in our Cheshire, UK Pilot Project case study.
Net zero carbon has become a strategic aim of many developments, however, true net zero carbon is a confused term, which lacks certification and is hard to achieve. The low impact approach requires a more radical way of thinking when considering building on a large scale.
In doing this, we need to think about Whole-life Carbon (carbon impact of a building through-out its life). There are two types of Carbon use:
1. Embodied Carbon – The carbon used to construct the building.
2. Operational Carbon – The carbon used in the running of the building.
We begin by strategically looking at Embodied Carbon - In principle we want to utilise materials that either have carbon locked in them already or have a very low carbon footprint (including transport).
Working with the land owner of a large strategic site in Cheshire, UK, we have had the opportunity to propose how to implement three principle Low Carbon approaches with the aim of reducing the overall embodied carbon footprint of the development.
Creative Re-use - Waste as a Resource
This is the principle of re-using or repurposing building materials that have already been used.
To achieve this on a larger site we would seek to source a reliable local supplier or establish a store/‘Material Emporium’ on site to start to catalogue, stockpile and sort reclaimed materials from the surrounding area ready for construction.
This approach could help reflect local distinctiveness. For example, an established stock of reclaimed bricks might help produce buildings that reflect historical context or vernacular style.
To maximise efficiency in reuse, materials should be profiled from largest to smallest to ensure the capacity of material is retained where possible. i.e. large beams not cut to create smaller elements without first assessing them for use as larger elements.
Building as a material bank
This approach seeks to specify and detail materials that are designed for dismantling and reuse at the end of the building’s life. Items are catalogued and a record is kept of what the building is made of.
Standardised component sizes and mechanical fixings allow for an ease of deconstruction and re-appropriation.
As the build reaches the end of its life, there is a recorded catalogue of its ‘material bank’ that can be reclaimed and reused.
This whole life cycle approach will be critical for meeting the targets for schemes such as LETI and RIBA Climate Change
Utilising Natural Materials - Ultra-local ‘Biogenic’ material use.
Biogenic building materials are low carbon materials derived from natural sources like plants, animals, or microorganisms - Think of wood, bamboo, earth and straw. They are renewable, reduce environmental impact, and promote sustainability by utilizing what nature already offers instead of relying on synthetic or non-renewable resources.
Utilising available, local Biogenic materials would hugely reduce ‘Carbon miles’, and helps create a design quite literally of its place. Through implementation at a large scale, there is an added opportunity to upskill a local workforce for green building technologies.
To start, the site and its surroundings need to be assessed for opportunities to source Biogenic materials. For example, high clay content soils are good for adobe bricks.
Constructing from materials such as straw bale or hemp offers a low embodied carbon material source, which may be available locally in order to further reduce the potential carbon negative footprint of the development.
The insulating properties of many Biogenic materials are often good, so with the correct application, there is the potential to achieve Passivhaus standards, while creating buildings with a unique character and aesthetic that adds to rich and meaningful place-making.
Case study:
As part of our initial work, a thorough assessment of the location was undertaken to understand the local resources available and the historic build typology. It was apparent that this particular Site’s clayey Mudstone bedrock offers a fantastic opportunity to utilise the ground’s properties for either making bricks or creating cob walls. This strategic project was however going to take a number of years to be brought forward through planning and this presented an opportunity to use the lead in time to establish a ‘mean while’ use on site.
The location has been historically farmed and had a low baseline Biodiversity level. During the consultation period we wanted to establish planned enhancement to on-site habitat and implement landscape features that would form part of the completed scheme. Enhancement to the site’s borders was a way to initially start to do this.
To utilise the large agricultural area, Hemp was put forward as a plant that sequesters 9 to 15 tonnes of CO2 per hectare, similar to the amount sequestered by a young forest, however each crop cycle only takes five months to grow. (Source European Commission) Once harvested the plant can be processed into a number of building products. During the process of allocation, and planning permission over the next 2-3 years, the 32.8 hectare area could yield 2 crops annually, sequestering approximately 545 tonnes of carbon a year. A total of 1635 tonnes of carbon over the 3 year period. As a rough guide, the same as 16 new build 4 bed houses (@500kgCO2/m2 - Source LETI Design Guide).
To utilise this captured carbon, the hemp crop can be dried and processed on site to form cast hempcrete or hemp blocks, locking in the sequestered carbon into the buildings.
A strategic commercial area neighbouring the site will be utilised to stockpile materials as they are processed in readiness for the build. This could also offer a location to store materials for re-use as they become available locally.
As construction commences development will be spit in 2 main phases allowing further hemp harvests on the land yet to be developed. Initial ‘pilot’ projects across the site, showcasing the reuse, biogenic and building as material library approaches will enable upskilling of a local labour pool and provide an opportunity for the local community to engage and interact with the build process.
Utilising a local material supply chain presents an opportunity for the resultant buildings to show unique details “of their place”, adding an architectural quality and distinctiveness while driving down their Carbon impact.
We are aspiring for more developments to be brought forward holistically in this way to manage and combat the Carbon contributed by the construction industry. The low carbon approaches will also however dictate a particular architectural language that speaks of its time and provide a rationale to the new building design.
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