BRANZ carbon foot-printing tools

This Issue This is a part of the BRANZ tools feature

By - , Build 185

Carbon-footprinting tools developed by BRANZ will help designers and architects – and ultimately New Zealand – meet net-zero carbon targets.

Figure 2: Stand-alone house design compared to carbon budget.
Figure 1: Stand-alone house design compared to reference building.

THE GOALS OF the Climate Change Response (Zero Carbon) Amendment Act 2019 are to reduce emissions to net zero by 2050 and limit global warming to no more than 1.5°C above pre-industrial levels.

Meeting the challenge ahead

To achieve this, we require a fundamental change in how we design buildings. Simply put, we need buildings to reduce their carbon footprint. This will be a real challenge for industry – currently, we do not even understand the carbon footprint of most buildings we design.

The Ministry of Business, Innovation and Employment’s Building for climate change programme consulted recently on a proposal for a building’s carbon footprint to be calculated as a requirement for obtaining a consent. This would help us understand the range of carbon footprints for different building typologies and how design and materials choices contribute to these.

Based on consultation feedback received, most of those in our industry are generally supportive of this because it will help to achieve climate change goals (see the submissions report). They understand that we need to change the way we design and build, specifically by considering carbon as an integral part of the design process in the future.

BRANZ developed the whole-building whole-of-life framework and released LCAQuick in 2016 – resources and tools to help upskill the industry’s ability to assess the environmental impact of building designs. Under this framework, BRANZ has continued to develop a suite of carbon-footprinting tools to help project teams calculate and reduce the carbon footprint of their building designs.

What is carbon footprinting?

Carbon footprinting is a calculation method that provides an understanding of the potential climate change impact of building design. It is powerful when it is used to inform decisions during the design process. It is also part of a more holistic calculation method called life cycle assessment, which considers multiple environmental issues. More details on this can be found in LCA to inform concepts in Build 147.

When we apply this to buildings, it means calculating emissions that occur during construction, use and end of life of a building. A building’s life cycle is split into various stages (see Table 1) that identify when emissions are occurring and through what processes.

Table 1 When emissions occur and by what processes

Tools make it easier

BRANZ’s tools can help design teams become more familiar with carbon footprinting so this can be carried out early in the design process – before final decisions are made. Knowing the climate change impacts of alternative options helps to make informed decisions on how to lessen climate change impact.

Carbon-footprinting tools enable designers to iteratively assess the carbon implications of their designs. That means they can assess several design options to see which one has the lowest climate change impact.

Carbon footprinting can be complicated and is sometimes an overwhelming technique to learn, even when assisted by a tool. Usually, a user would need to enter the resources (materials, energy and water) that a potential design may use, have appropriate environmental data for those resources and make assumptions about how those resources are used.

BRANZ’s whole-building whole-of-life framework provides a set of resources – for example, databases and assumptions – that can help make carbon footprinting of buildings more consistent. See more on this framework. All BRANZ’s carbon tools have been developed under this framework.

Table 2 summarises the tools BRANZ has available and what is in development. All these tools will be Excel based and freely available on BRANZ’s website.

Table 2 BRANZ carbon-footprinting tools

LCAQuick

LCAQuick is the main tool featured in Table 2. It is a whole-building whole-of-life assessment tool and can calculate the impacts for an entire building throughout its entire life for a variety of environmental issues. It is meant to educate industry professionals about life cycle assessment.

BRANZ provides training sessions on LCAQuick to help architecture and design firms incorporate life cycle assessment into their workflow.

Ultimately, this is a tool that will calculate the total carbon footprint of a building, but it can also be used to compare different construction types if desired. It also compares the building design to a similar reference building and carbon budget (see examples in Figures 1 and 2).

LCAQuick can be downloaded for free at www.branz.co.nz/lcaquick, and training can be booked by emailing [email protected]

Figure 1: Stand-alone house design compared to reference building.
Figure 2: Stand-alone house design compared to carbon budget.

Tools for early design decisions

It’s important for designers to consider the carbon footprint in design decisions as early as possible. Decisions during concept and preliminary design, such as structure and enclosure, have a significant impact on a building’s carbon footprint. They are time-consuming and costly to change if carbon footprinting is introduced later in a project.

BRANZ has developed three tools focused on allowing users to explore and compare common design decisions (the last two are due for release later in 2021 after feedback from consultation has been incorporated). The tools require no project-specific information, making them easy to use when early design decisions are being made.

The goal is for users to play around and develop their understanding of the impacts different design options have. These tools are:

  • CO2NSTRUCT – used to see the impact of common building materials
  • CO2RE – compares the impact and R-values of common residential constructions
  • LCAPlay – compares the impact of different building forms, structural systems, façade and HVAC systems in commercial buildings.

Tools to compare carbon footprints

If you haven’t had any experience carbon footprinting buildings, it can be difficult to know whether the footprint of your building is good and what targets you should be aiming for. LCAQuick helps with this by comparing the assessed building to a similar reference building and carbon budgets, but this information isn’t readily available.

BRANZ has developed CO2MPARE, which provides building carbon benchmarks and carbon budgets based on BRANZ’s research that can be useful for setting targets at the start of a project. This will be released later this year.

For more

These tools are available from www.branz.co.nz/sustainable-building/.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.

Figure 2: Stand-alone house design compared to carbon budget.
Figure 1: Stand-alone house design compared to reference building.

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