Last edited 18 Sep 2020

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How much carbon are your buildings responsible for?

Contents

[edit] Introduction

Carbon emissions must be reduced drastically if we are to limit global warming to safe levels. Construction is responsible for around 40% of global emissions.

[edit] Reducing embodied and whole-life carbon in buildings

Architectural Technologists are in a position to act positively on this issue by considering the whole life carbon footprint of the designs they develop and how the materials they specify perform in carbon terms.

[edit] Terminology

CarbonFigure1.jpg
Figure 1: Stages considered in a life cycle carbon assessment.

[edit] Guidance and legislation

A lot of changes have evolved in this area, including requirements around embodied carbon appearing in the New London Plan and many cities, regions and businesses adopting net-zero carbon targets. Here are some of the key updates.

Firstly, the RICS professional statement on whole life carbon calculation was released in 2017, standardising how carbon footprinting is carried out in the industry. This was much needed to allow safe and reliable comparisons to be made between buildings and for benchmarks to be developed and agreed upon across industry. Before this point, there was no agreed scope for life cycle assessments, leading to disparate and incomparable results.

Secondly, the 2018 version of BREEAM New Construction revised extensively how credits under the ‘Materials’ category are scored. For buildings aiming for high levels of attainment under BREEAM, carrying out LCA is now strongly encouraged.

References to the green guide to specification were removed and the scoring process heavily weighted towards carrying out life cycle analysis of design options, beginning at conceptual design stage. This has encouraged consideration of carbon impacts early in the design process when there is the best chance of making the design both carbon- and material-efficient.

[edit] Software tools

There are a range of tools available to aid in calculation and analysis of the whole life carbon impacts of buildings, including EC3, eTool, OneClick LCA and HBERT. OneClick and eTool are two commercially available tools approved by the BRE for use as part of BREEAM assessments (ref. BREEAM Mat01 tool v1.9).

A process for measuring and reducing whole building life cycle carbon footprints:

  1. Baseline calculation.
  2. Carbon hotspot analysis.
  3. Identify carbon reduction opportunities.
  4. Establish project reduction target.
  5. Refine opportunities.
  6. Incorporate opportunities into the design.

[edit] Carbon hotspots

Carbon hotspots are where the highest proportion of a buildingscarbon footprint are found. These could be defined either by life cycle stage, building element or by material. The results of a recent carbon baselining exercise are presented in the following pie charts.

Figure 2: Carbon baseline figures by life cycle module.
CarbonFigure2.jpg

Figure 3: Carbon baseline materials hotspots.
CarbonFigure3.jpg

In this example, modules A1–A3 (Figure 2) were found to be the biggest life cycle stage carbon hotspot, and cement (Figure 3) was the biggest materials carbon hotspot. With this information, the design team could focus their carbon reduction efforts on their materials specification, developing low carbon opportunities and specifications, particularly for concrete elements.

[edit] Taking action

In summary, it is easier than ever to determine and act on the carbon footprint of designs. This is possibly the biggest opportunity for Architectural Technologists to make a positive contribution towards global decarbonisation efforts.

[edit] Rules of thumb


This article originally appeared in the Architectural Technology Journal (at) issue 133 published by CIAT in Spring 2020. It was written by James Robb BSc (Hons) MCIAT

--CIAT

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