More and more developers want to cut down the life cycle and embodied carbon of their projects – the greenhouse gas emissions caused by producing and delivering materials and construction at the site, and by their in-use and end-of-life phases.
The Fifth Estate‘s UK correspondent, David Thorpe, looked at a few tools in the European region to help developers seize this under-appreciated opportunity to minimise carbon emissions, and even go carbon positive.
Tools like Athena can give architects and developers an inventory of greenhouse gas emissions that account for embodied carbon from material installation.
Athena is a set of comprehensive life cycle inventory databases for building materials and products contained in a series of reports. There are various tools.
The Athena EcoCalculator for Assemblies spreadsheet tool is very fast but limited in design options: developers should use this tool for a quick rough estimate of building design footprint.
It has pre-defined assembly and envelope configurations: the user needs only to input the square footage of any particular assembly to receive instantaneous embodied life cycle impact assessment results (operating energy is not included).
The Athena Impact Estimator for Buildings is more flexible, and gives a more detailed and accurate footprint estimate of a building. It’s a stand-alone program that allows users to model their own custom assembly and envelope configurations, and is for proposed designs and existing buildings.
Pavement is an life cycle assessment-based software tool that measures environmental impact of roadway designs. Although designed for American roads, it is generally applicable.
Often overlooked is the impact of the surrounding site, the landscape around the buildings.
Materials used in landscaping can have caused the emission of greenhouse gases, but equally the amount and type of vegetation can capture carbon dioxide from the atmosphere, to let your project become carbon positive over time.
The right species can also improve biodiversity and attract pollinators. The i-Tree Planting Calculator should be used to calculate precise sequestration by plant species, although you have to pretend you live in the USA to use it!
A new online tool available anywhere is Pathfinder, a very easy to use app for estimating the embodied carbon, operational carbon, and sequestered carbon of a given landscape design.
You can draw the outline of your site using a Google map and then specify how much of it is green space and how much of it is hardstanding, refining the contents and materials used in each.
It will then tell you how much carbon is sequestered, over what period it will become climate positive, and what is the carbon cost of construction. This allows you to experiment with different design considerations in order to achieve the best possible result.
For example, it can account for the carbon footprint of paving, walls, curbs, fences, gates, site features, drainage, irrigation, subsurface features, mulch and soil. For sequestration, it covers wetlands, trees, lawn and shrubs. Equally, the impact of using gas or electric-powered equipment and fertiliser.
It uses datasets from the Indiana Impact Estimator and the U.S. Forest Service but is usable around the world.
Embodied carbon tools
The first incorporates embodied average energy/carbon coefficients from the Inventory of Carbon and Energy created by the University of Bath, enabling engineers to calculate the total embodied carbon and energy of the overall structural design. This data is unfortunately out of date now, however.
Tally quantifies embodied energy along with other environmental impacts and emissions to land, air and water. It can be used for whole-building analysis or for comparative analyses of various design options, and can account for the diverse range of material classes defined in a BIM model.
This tool, like Pathfinder, can produce data graphics that are comprehensible, transparent and customisable. Much better than a spreadsheet, especially for persuading clients to take your advice.
The data gap
Embodied energy modelling can help to reduce the carbon footprint of a built project, and encourage a shift to low embodied energy materials. But unfortunately the typical design and construction schedule often does not permit lengthy modelling and assessment.
However, the above modelling tools are reasonably accurate and easy to use, and so shouldn’t slow down a design team’s work.
The only challenge remaining is the good provision of accurate data by manufacturers and suppliers of the products.
Designers should therefore favour products which are transparent and upfront about their lifecycle impacts.