The current state of play in terms of Construction Environmental Impact Accounting and Reporting is that there are two main methods that are somewhat clashing:

• Greenhouse Gas Inventory Reporting born from the Kyoto Protocols
  (mainly carbon emissions from operational energy, Scope 1 and 2)
• Life Cycle Assessment (EN 15978, all of carbon, and other impact indicators).

Most of the carbon accounting industry has been established due to the Kyoto Protocols so there’s a lot of knowledge and expertise aligned with those standards.  The challenge of applying the Kyoto style accounting methods to buildings is they were developed for determining national GHG inventories, are really focused on “tail pipe” emissions and ensuring no double-counting at the national level (sum of all reported scope 1 emissions).  The brick manufacturer’s scope 1 emissions are the building owner’s extended scope 3 emissions and hence to account for national emissions the scope 1 emissions are only of interest. As such, scope 3 emissions don’t get a lot of scrutiny. The GHG inventory reporting method needs to be significantly adapted to be useful for optimising the real carbon footprint of an individual building (i.e. needs a really large expansion of scope 2 and 3 emissions accounting which falls in the LCA realm).  We have found that for high performing buildings, it’s often the scope 3 emissions that are the largest contributors.  

EN15978 is a calculation method norm based on Life Cycle Assessment and there is a strong reliance on ISO 14040, 14044 and 14025 which eToolLCD also heavily draws on. ISO 14601 and GHG Protocol are Standards for quantifying, monitoring and reporting GHG emissions at organisation or project-specific level.

LCA covers greenhouse gas emissions for the Construction and Operation phases of the project. These life cycle modules cover the whole of life, whole of project GHG emissions. This includes coverage of what are known more generally as Scope 1 (Manufacturing and burning fossil fuels) and Scope 2 (Indirect consumption of energy – transmitted electricity), as well Scope 3 emissions (extraction, production and transportation of purchased materials, demolition, waste and disposal).

Figure 1 – Relationship between life cycle stages and scope emissions.

Life Cycle Design methodology described in the EN 15978 will allow isolating materials, construction related impacts, actual use, and maintenance, and expand the scope to include the end of life and beyond life cycle impacts (reuse, energy export). Emissions scope is classified as direct (1), indirect (2) and other indirect (3). eToolLCD reports emissions according to project life cycle stages (A, B, C, D). Using a building as an example, Scope 1 Direct emissions from gas hot water system is reported in stage B6 Integrated Operational Energy, Scope 2 Indirect emissions from grid electricity consumption is also reported in B6, therefore both scope emissions will be combined in the same life cycle stage.

Figure 2 – Building Life Cycle modules and different Zero Carbon scope

The use of Life Cycle Design methodology is increasing rapidly as a result of the development of international standards, improved inventory data and tools and a wider recognition and adoption in sustainable design and urban planning policies. Following on from the Paris Agreement, GHG emissions are expected to be regulated at the international level and the life cycle approach will assist in quantifying, reducing and reporting our impacts and how we are performing against our environmental targets. 

Related articles:
eToolLCD and RICS Whole of Life Carbon Assessment for the built environment
LCA and UK GBC Net-Zero Framework