Ministry of Business, Innovation & Employment
Whole-of-Life Embodied Carbon Assessment: Technical Methodology
New Zealand has committed to achieving zero greenhouse gas (GHG) emissions, excluding biogenic methane, by 2050. This requires significant change in the building industry, due to its significant proportion of New Zealand's total GHG emissions. This will be outlined in the Government's Emissions Reduction Plan due to be released next month.
MBIE have therefore outlined a methodology in order to consistently assess the embodied carbon emissions of buildings in New Zealand, with the aim to significantly reduce these emissions. There are four key principles for this methodology - consistent, transparent, accessible & understandable and outcome-driven.
The methodology is intended to be used prior to the building consent process, and be submitted along side this documentation. In saying this, the methodology is still applicable to operational and end-of-life stages as well as calculating embodied carbon of existing buildings.
In defining embodied carbon, the document outlines that the embodied carbon of an entity is the sum of all greenhouse gas emissions that occur at each stage of its life cycle. measured in kg CO2-e2. In LCA studies, they are reported as 'Global Warming Potential' (GWP).
The scope of the embodied carbon assessment process currently outlines two sections. One is mandatory, the other is optional. All significant elements of a new build that perform the primary functions of the building are required, while things like interior fittings, ceilings or temporary works are not. The non-mandatory elements are reported separately to ensure fair comparisons be made.
Mandatory reporting requirements:
- life cycle stage
- carbon emissions and benefits
The reports will also be split between non-technical and technical outputs, to encourage carbon literacy.
There is additional complexity and effort required to assess emissions across all LCA modules and to mitigate potential reductions in accessiblity to the assessments. To do so, the results will differentiate between the pre-operational stage and estimated future life cycle stages.
Assumptions, again for consistancy, include a building design life of 50 years, however longer lifetimes are encouraged.
While requiring post construction life cycle emissions creates complexities in the assessment of buildings, it encourages a more holistic embodied carbon. Helping to avoid perverse incentives, such as low embodied carbon products which need frequent replacement.
Previously, there has been little demand for a high quality embodied carbon database for the construction sector. This is why a data hierarchy providesa a pragmatic method of recognising potential gaps. The Building for Climate Change programme is investigating options for establishing robust, transparent and publicly available databases to support embodied carbon calculations.
To concluded, once embodied carbon assessments become part of the building regulartory system, further detail will be supplied to ensure the regulations can be consistently enforced, including template formats and information requirements for the technical and non-technical outputs.
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