NBS Releases New Guide on Embodied Carbon Calculations for BIM Objects

NBS (part of Hubexo), a specification and product information platform for the construction industry, has partnered with Circular Ecology, environmental sustainability specialists and authors of the ICE database, to launch a comprehensive guide. The ‘NBS Guide: Embodied Carbon Calculations – How to apply carbon values to BIM objects’ provides practical guidance for construction professionals. 

This collaboration tackles the persistent fragmentation of embodied carbon data, a critical challenge preventing designers from making choices that could significantly reduce a project’s carbon footprint. The new guide directly addresses this gap by providing a practical framework for embedding upfront carbon data (Modules A1-A5 as per BS EN 15804) directly into BIM objects.

Authored by Dr Craig Jones, Managing Director at Circular Ecology, Joe Rouse, Senior Sustainability Consultant at Circular Ecology, and Dr Lee Jones, Head of Sustainability at Hubexo, the guide focuses specifically on upfront embodied carbon emissions. It provides expert guidance on how to calculate and assign embodied carbon data directly at the BIM object level using a geometry-led approach. 

As part of the guide, four distinct BIM object types are mentioned:

• Layered Items – Single layered materials or systems
• Layered Assemblies – Assemblies made up of layered items
• Items – Single or multi-material items that are not used in layered assemblies
• Composite Assemblies – Multi-material items that are composite (not layered)

For each type, it details the methodology for calculating embodied carbon by multiplying quantity by emission factors, and important factors such as material densities. The guide aims to translate and simplify existing principles into the practical realities of implementation to BIM object information, enabling designers to make better carbon decisions during the design process. 

By standardising how embodied carbon emissions are recorded in BIM objects, the guide looks to ensure consistency and clarity across projects.

Dr Lee Jones said: ‘Every design decision made without embodied carbon data is a missed opportunity to reduce our industry’s environmental impact. This guide gives designers the tools to make informed carbon choices from day one. We’ve translated complex standards into practical methodology that works within existing BIM workflows. The result? Transparent, consistent carbon data that enables comparisons and supports the construction sector’s transition to net zero.’

To find out more and to access the guide, click here.