Proposed mini-conference – A low emissions future for geotechnics

- Ross Roberts

Call for expressions of interest

The NZGS is planning to run a series of short local mini-conferences in June or July this year with the aim of identifying how the geotechnical sector can play its part in meeting our national targets for greenhouse gas emissions.

We are looking for:

  1. Volunteers in each centre to help run the event
  2. Speakers to present on the topic

We expect this to be a relatively low-key series of one-day events, with invited speakers from a range of backgrounds and some discussion sessions. There are big changes coming to the construction sector, driven by central government requirements, which will impact on all our projects. These sessions are intended to work out how ready we are, and define what we need to do to prepare.

Please contact Jen Smith (JSmith@tonkintaylor.co.nz) to find out more.

Background

On 31 January the Climate Change Commission published their draft advice for consultation. In their report, they note:

“In Aotearoa, the Government has committed to reaching net zero emissions of long-lived gases by 2050, and to reducing biogenic methane emissions by between 24-47% by 2050.

The work that He Pou a Rangi, the Climate Change Commission, has carried out over the last year shows that meeting these targets is possible – and can lead to a thriving, climate-resilient and low emissions Aotearoa.

Transformational and lasting change across society and the economy will be needed, but the Commission’s analysis shows the tools to start the work to reach our targets and address climate change in Aotearoa already exist.

To meet the Commission’s proposed emissions budgets, Aotearoa does not need to rely on future technologies. As new technologies develop, this will allow the country to reduce emissions even faster.

However, the Government must pick up the pace. Aotearoa will not meet its targets without strong and decisive action now to drive low emissions technologies and behaviour change across all sectors. 2050 is not far away – particularly if you consider the life span of infrastructure, vehicles, buildings – and people.

Aotearoa must focus on decarbonising and reducing emissions at the source. As a country we can no longer rely on forests to meet our climate change targets.

Current government policies do not put Aotearoa on track to meet our recommended emissions budgets and the 2050 targets. In 2018, gross greenhouse gas emissions in Aotearoa were about 45.5 Mt CO2-e of long-lived gases, and 1.34 Mt CH4 (biogenic methane). Our analysis shows if policy stayed as it is now, Aotearoa would fall short of achieving the 2050 net zero long-lived gas target by 6.3 Mt CO2-e. Biogenic methane would reduce 12% below 2017 levels and fall short of the current target of 24-47%.

The building and construction sector is a large contributor to greenhouse gas emissions from producing materials, constructing buildings and infrastructure, and the energy used in buildings. In New Zealand, about 20% of our emissions are from our built environment. About half of these emissions are operational (for example, heating and cooling buildings), while the rest are embodied emissions.

Chandrakumar et al (2019) attempted to calculate the acceptable whole-of-life carbon emissions for a residential building in New Zealand to be compatible with a global warming limit of 2°C. They found that the climate target of a detached New Zealand house over a 90-year lifetime is 71 tonnes CO2 equivalent, and reported that this would be equivalent to a reduction of 80% relative to current practice. Even in the best-case scenario where operational emissions were eliminated entirely, construction would still need to eliminate 60% of embodied carbon to meet national objectives. This is a very significant challenge, and one we have no current clear pathway to achieve.

Purpose

Significant carbon equivalent reductions are required from our construction practices in order to meet our climate change goals. However, advice on achieving these in the geotechnical realm is rare, and it has been reported that emissions from the construction industry in New Zealand have increased by 66 percent in the decade from 2007 to 2017.

There are few tools to allow a robust comparison between different design alternatives in the geotechnical sphere. The BRANZ “Whole-building whole-of-life framework” provides tools, data and information to support decision making for sustainable building design. It assists calculation of the climate change impacts and other environmental impacts of our buildings (BRANZ, u.d.). This tool does allow a comparison between concrete and other building materials using data valid for New Zealand, but it focusses on structural elements, does not directly consider foundations and has no data for subgrade improvement, earthworks or other geotechnical structures.

Geotechnical professionals have the skills to help their clients adapt to, and to some extent to mitigate, the effects of climate change.  These mini-conferences are intended to identify what the geotechnical sector can do to play our part, and what we need to do to help our clients.

Ross Roberts
Email - ross.c.roberts@gmail.com

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