Chapter 6
Measurement and Data Are Improving, But Transparency and Verification Are Needed 
Existing Tools for Assessing Carbon Impact
Recommendations for Future Carbon Assessment Tools
Tools for Greenhouse Gas Assessment Are Needed for District-Scale Planning
Global Standards and Labels for Emission Transparency Can Galvanize the Market
Challenges and Next Steps

Recommendations for Future Carbon Assessment Tools

Emerging tools can provide non-experts such as designers and developers with snapshots on data associated with different decisions; however, they are still at an early stage and require more development. The key to supporting productive use of these tools is for them to provide more transparency and third-party analysis and qualifications to the data.

Disseminating Data and Low-Carbon Methods in Semi-formal and Informal Construction

Adding data on the effects of materials on operational energy costs could be a key incentive towards shifting consumer patterns.

Access to carbon assessment tools is deeply uneven across sectors and regions, necessitating alternative ways to communicate the carbon impacts of material choices to more stakeholders. Although most of the construction boom in developing countries is taking place without the regulation of building energy codes, in a world of smartphones, many inhabitants across the spectrum of housing types (formal, semi-formal, informal) are keeping a close eye on their energy and water bills. Therefore, adding data detailing the effects of materials on operational energy costs such as heating, cooling and air-conditioning could be a key incentive towards shifting consumer patterns, as building occupants begin to understand how to lower their energy bills by simply choosing the right roofing or cladding materials.

For example, conventional building materials – including the concrete and asphalt often used in roofing – absorb solar radiation and emit heat, causing temperatures to increase and cooling loads to soar (Doulos, Santamouris and Livada 2004; Prado and Fereira 2005; Bozdogan Sert et al. 2021; Stache et al. 2022). As informal housing rapidly increases in density, with do-it-yourself additions and upgrades, adding simple data to utility bills supports building occupants to make decisions on additions and renovations using low-cost bio-based materials that lower their energy bills while improving thermal comfort.

Figure 6.2 The Clark’s Crow “at a glance” data tool

The tool shows the environmental and socio-economic impacts of material choices across the entire life cycle.

Source: Keena, Aly Etman and Dyson 2020.

Creating Data and Knowledge-Sharing Networks Among Stakeholders

Future tools need to be interoperable and to communicate impacts across the life cycle.

Perhaps the biggest impediment facing building professionals who do have full access to the latest software is that there are so many different tools available, and experts need to be speaking to each other (Aly Etman et al. 2016; Aly Etman, Keena and Dyson 2017; Keena 2017; Keena and Dyson 2017; Keena, Aly Etman and Dyson 2020). The compartmentalisation and lack of communication among building professionals in each sector results in sub-optimal material designs that contribute to environmental impacts across the life cycle (U.S. Department of Energy 2008; Du Plessis and Cole 2011).

A McKinsey report reinforces the stagnant productivity numbers in the construction sector and predicts that, faced with sustainability demands, the sector will need to reassess digital methods to reduce waste and abate carbon emissions (Barbosa, Woetzel and Mischke 2017). The report highlights the role that “big data” can play in helping to establish collaborative networks, with efficient construction practices that track material, energy and information flows across the building life cycle. In the construction phase alone, on-site productivity could increase by 50 per cent based on the implementation of data techniques and accurate data flows through stakeholder systems that are both backward-looking (tracing back to production phase) and predictive (modelling future use patterns) (Barbosa, Woetzel and Mischke 2017).  

Big data on carbon, energy and material flows can be harnessed to provide stakeholders with an at-a-glance interactive look at the causes and effects of material choices and decisions (Keena 2017; Keena and Dyson 2017; Keena and Dyson 2020). Figure 6.2 shows an example of a dashboard that allows stakeholders to view multiple windows to track, communicate, and assess material flows and environmental impacts across the life cycle. Importantly, it harnesses artificial intelligence and big data to enable users to question the provenance and reliability of the data and to compare different sources.

Future intelligent data frameworks such as this will increase the transparency and reliability of assessment tools as they become more interoperable and accessible to air quality sensors and software that help track the emissions of material processes at different phases of the life cycle, from extraction to demolition. They will also allow for better real-time monitoring of the labour and environmental conditions of construction sites. In Canada, the new Data Homebase application enables stakeholders to access the estimated energy use, carbon emissions and affordability indexes of residential buildings across cities (see Box 6.1).

Visualisation frameworks that trace a material’s lineage and characteristics, as well as predict its future impacts on operational energy and end-of-life, are especially critical for the design architects and engineers who have an outsized impact on the decision-making process and typically have very little time to justify material specifications. This is crucial to ensure confidence in the shift towards locally sourced circular, bio-based, and earth-based materials, since species quality and structural characteristics vary extensively. Huge strides have been made in developing accessible design standards for bamboo (Harries et al. 2022), but frameworks for other species are lacking, with guidelines almost non-existent for forest detritus and agricultural by-products.

Box 6.1

Data Homebase: A web application visualising Canada’s housing characteristics to foster a circular economy

Like many countries worldwide, Canada is facing a housing crisis. One approach to tackling housing supply is through the circular economy, by keeping materials and buildings in use for as long as possible to reduce waste and promote sustainability, and by re-using building materials rather than turning them into waste. However, effective circular economy decision-making requires robust data on buildings, and in most cases these data are widely scattered and lack standardisation.  

To overcome this barrier, an interdisciplinary team led by researchers at McGill University has developed “housing passports,” or standardised digital descriptions of residential building characteristics. Each housing passport represents different residential typologies based on analysis of the existing building stock. Through a new web-based, data visualisation application called Data Homebase, housing passport information is organised, linked and visualised in a manner that makes it easily accessible to a wide variety of housing stakeholders, from the building sector to finance and policy making. For example, housing passports can help banks complete property assessments and help cities manage government housing assets.  

Data Homebase integrates and annotates data, displaying calculations of estimated energy use, carbon emissions and affordability indexes of residential buildings across Canadian cities. It does this at multiple scales: the city scale, the neighbourhood scale and the building materials scale. By providing a comprehensive display of a building’s degree of circularity across these scales, the app allows stakeholders to detect which buildings at the city and neighbourhood level, and what aspects of an individual building, are primed for improvement, from retrofit to material recovery. Stakeholders can use these data as a resource for implementing new circular building design strategies towards mitigating housing-related greenhouse gas emissions.

Source: Keena and Friedman 2022.

Assessment Tools Need to Consider the Full Ecosystemic Impacts of Bio-based Materials

It is critical that future tools assess the local impacts on regional ecosystems for different practices of extracting materials.

In scaling up the global shift towards bio-based materials, it is critical that future tools assess the local impacts on regional ecosystems for different practices of extracting materials, especially primary timber and bamboo. Life-cycle assessments for bio-based construction materials have rarely considered the impacts of land use and land-use changes (Hoxha et al. 2020). Besides carbon and climate change, land use for biomass supply also impacts biodiversity and ecosystem services (Verkerk et al. 2014; Gaudreault et al. 2016; Ferrarini et al. 2017). Given the huge regional variations of ecosystems, suitable biomass sources and production scales need to be assessed and identified at the regional level to ensure that the use of biomass supports healthy ecosystems.

Current life-cycle assessment methods can support holistic assessment of some environmental impacts but not all. For example, assessing the impacts on biodiversity and ecosystem services will need other complementary tools and data for regional assessment (Winter et al. 2017; VanderWilde and Newell 2021). Different life-cycle assessment methods (for example, attributional and consequential life-cycle assessments) and carbon accounting frameworks exist. The suitability and practicality of these methods to support policymaking for bio-based building materials will need to be assessed.

At the global scale, there is an urgent need to support the development of predictive models to anticipate the impacts on global ecosystems of scaling up bio-based material processes. The use of biomass affects diverse ecosystems that remove CO2 from the atmosphere, which should be considered when assessing the impacts of bio-based materials. For example, one study linked a life-cycle assessment model of cross-laminated timber with a forest dynamic simulation for a pine forest in the southeastern United States to understand the carbon fluxes associated with the life cycle of both cross-laminated timber and forest lands supplying wood across 100 years (Lan et al. 2020).

Further predictive models and assessment studies are urgently needed for all regions, especially in emerging economies, to set the policy for sustainable management of both forest-based and agricultural-based biomaterial stocks.