Assessment and Quantification of the carbon impact of Geotechnical Assets and Underground Construction are at an early stage of development. However, the road to achieving Net Zero is very much upon us and a path on which we all must quickly travel. Unfortunately, a lack of guidance on the suitability of existing carbon accounting tools is apparent in many sectors, not least geotechnical Engineering, moreover the role that Underground Space and Geotechnical Engineering can play in net zero is very much understated. This paper seeks to open-up discussion in this area, helping bridge a gap in knowledge to help practitioners and engineers make informed choices when it comes to carbon savings, not least in application to new (and existing) Geotechnical Applications and Underground Space.