Understanding the principles of sustainability as it relates to building design is an essential part of an architect's education. The Embodied carbon contained within the structure and fabric of the building is a crucial element of the sustainable city. However, this is sometimes a difficult concept for students to grasp and putting definition into the embodied carbon can involve complex calculations and spreadsheets. The purpose of this project is to provide a simple interactive on-line tool that helps students grasp the basic principles and allows them to make informed decisions early in the design process.
The on-line tool takes the form of a 'flip book' allowing students can choose different materials for the structure and the fabric of the building. Based upon their choices, the program calculates the total embodied carbon.
Nine options for structure and four options for fabric are illustrated in such a way to allow students to mix and match their options so that various combinations of structure can be used with alternative fabric options to show the total embodied carbon.
This initiative was carried out in collaboration with FCBS Architects and the development of the on line toolinvloved collaboration between structural engineer, environmental scientist, computer coding specialist and architect / illustrator.
Buildings account for approximately 40% of all greenhouse gas emissions. Sustainable design has tended to focus on operational issues, but approximately a quarter of the above total is the embodied carbon contained in the building's fabric and structure. These are the emissions arising from extraction, manufacturing, transportation, installation and disposal.
The embodied carbon flip book has been developed as a simple interactive tool to help understand the principles of sustainable design. The Embodied carbon contained within the structure and fabric of the building is a crucial element. The purpose of this flip book is to provide a simple interactive on-line tool that provides comparative data for different options allowing informed decisions early in the design process.
Nine options for structure are shown using a 6m x 6m grid. In some instances, a longer span 12m x 6 m option is shown. In addition, 4 options for building fabric are illustrated. The flip book allows students to mix and match options so that various combinations of structure can be used with alternative fabric options to show the total embodied carbon.
The 'flip book' format allows you to choose different forms of construction at different levels of the building, so it is possible to put a timber frame or SFS upper floor over a reinforced concrete ground floor (as might be the case with a hotel project where big spans are needed to the ground floor areas. Alternative foundations are also provided and care is needed when choosing an appropriate combination, and, as a rule of thumb, lighter forms of construction, such as timber or SFS frame are placed over more substantial structures such as concrete, steel or masonry. Sizes and thicknesses are provided for beams and slabs to give an indication of the structural zones needed.
The flip book was a UoL Beacon funded project and involved collaboration between a number of specialists within the university.
The structural design for elements of construction within the embodied carbon flip book has been calculated for representative purposes, the sizes shown are not intended for construction. The 6m x 6m bay size is typical for various structural systems and might be increased for steel or have to be reduced for timber
It has been assumed that lateral stability is not a critical design condition and therefore the effects of wind loading have been ignored. The first-floor loading assumes light office use (2.5kN/M2) with no partitions. The roof loading (0.6 kN/M2) assumes snow drifting is not a critical design condition. A safe ground bearing pressure of 150kN/m2 has been assumed for pad and strip foundations. Minimum depth to the underside of foundations has been assumed to be 600mm and the foundations have been sized assuming no reinforcement.
The flip book allows the mix and match of different forms of construction, reflecting real life scenarios. General rules are not to impose a point load over a large span (12m) beam. Various types of foundations have been included and bases should be provided at column positions and strip foundations under loadbearing wall.
The Embodied Carbon Flip Book and Carbon Calculator have been developed at Liverpool School of Architecture for use in Higher Education institutions for educational purposes only. Calculations are divided into 'Structure' and 'Envelope', to permit selection of a range of material choices and strategies. Calculations are based on estimations of material quantities and dimensions. Embodied carbon is calculated based on conversion of material mass to CO²e (carbon dioxide equivalent). More information can be found here: https://www.istructe.org/IStructE/media/Public/Resources/istructe-how-to-calculate-embodied-carbon.pdf
Embodied carbon data for selected materials used in the UK construction industry is largely sourced from Version 2.0 (2011) and Version 3.0 (2019) of the Inventory of Carbon & Energy (ICE), published by Circular Ecology. The latest version can be found here: https://circularecology.com/embodied-carbon-footprint-database.html
Additional embodied carbon data has been sourced from individual Environmental Product Declarations.
Embodied carbon lifecycle stages are based on: BS EN 15978:2011: Sustainability of construction works / Assessment of environmental performance of buildings / Calculation method. In the Carbon Flip Book, embodied carbon calculations include Cradle to gate Product (A1-A3) data only. In the Carbon Calculator, embodied carbon due to Transport (A4), Site (A5), and End of life (C1-C4) operations are estimated as a percentage of Cradle to gate Product (A1-A3) data, unless otherwise stated. Embodied carbon due to Transport (A4) by distance (km) is based on Greenhouse gas reporting: conversion factors published by DEFRA.
In the Carbon Flip Book, embodied carbon calculations for timber and other natural products do not include carbon storage. In the Carbon Calculator, carbon storage values are reported separately. More information about carbon storage and sequestration can be found here:
Jay H. Arehart, Jim Hart, Francesco Pomponi, Bernardino D'Amico, 'Carbon Sequestration and Storage in the Built Environment'. February 2021; Sustainable Production and Consumption 27(18). DOI: 10.1016/j.spc.2021.02.028
Target metrics for embodied carbon and operational energy can be found at: https://www.architecture.com/-/media/files/Climate-action/RIBA-2030-Climate-Challenge.pdf
The flip book was produced using a custom HTML framework, incorporating Open-Source animation code to animate the pages and Javascript to calculate the Embodied Carbon. A Cascading Style Sheet was used to style the images and text. This approach presented a significant challenge; however, it is compatible with majority of web browsers. We are currently developing version two, this will have a design further optimised for use on mobile devices and use a PhP/MySQL database to store carbon and building data and allow for easier updating.
There are a number of ways use the flip book, the first being a simple exploration different options, the significance of larger spans, and the implications of timber v steel v concrete v masonry. Having chosen an option, it is then possible to extrapolate from the model (12x18m plan with 3.5m floor heights) to a proposed design. The lower floor of the model, could be multiplied a number of times to replicate a building of more than 2 storeys. For a single-story building, use just the data for the upper floor and roof from the model plus the sub structure. These are fairly crude approximations, and, of course, it is likely that the student's project may not have a simple 6m x 6 grids. Nevertheless, it is a reasonable staring point make strategic design decisions prior to moving on to more sophisticated tools to calculate the embodied carbon.
Peter Farrall (architectural)
Ranald Lawrence (environmental)
Ted Ruffell (structural)
Martin Winchester (coding)