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Can BIM Enable Successful Green Retrofits of Existing Buildings?

Shivani Soni on November 28, 2022 - in Articles, Feature, Featured

A graphic shows the “digital glue” toward net-zero.

By Shivani S. Soni and Geoffrey A. Tears


BIM! Sustainability! Net-zero! Lifecycle Carbon! Green Retrofit! All previously thought to just be buzzwords, these terms are gaining more traction in the AECO industry as it starts to update older buildings and build more-efficient ones. In 2008, the UK passed “The Climate Change Act” establishing emission-reduction goals that now are law. The UK is the first nation to set a binding mitigation goal for climate change.

In a 2019 report (10 years later), the Climate Change Committee suggested the UK could minimize its contribution to global warming by setting a target to have all greenhouse gas emissions reduced by the year 2050. The target is known as “net-zero” since it can be achieved by removing CO2 from the atmosphere to offset some sources of emissions by planting trees, building more efficiently and locally sourcing building materials. This, in turn, led to a “push and pull strategy,” encouraging industries and businesses to creatively find solutions already identified in their sector. It spearheaded the development of numerous frameworks and policies by many other countries and cities worldwide following its lead.

For example, in 2019 the city of New York introduced “Local Law 97,” setting the stage for U.S. adoption of sustainable/net-zero requirements. It became one of the first major U.S. cities to begin mandating greenhouse gas emissions tracking throughout the built environment. With certain exemptions, this law requires that existing and new buildings more than 25,000 square feet must meet and track specific sustainability and net-zero goals by 2030 with the objective to be completely net-zero by 2050. All these new regulations come with hefty consequences for noncompliance.

Enter BIM

The process of meeting these requirements for new buildings and sites is much more streamlined and attainable. For existing owners, there hasn’t been a clear-cut path to follow for the green retrofitting of their buildings to meet these fast-approaching goals. Ultimately, this puts them at risk for massive fines and other potentially worse scenarios. Many owners have no clue where to begin.

Owners of existing buildings, who may feel overwhelmed by all the requirements for tracking and optimizing their building’s sustainability and lifecycle carbon footprint, need assistance to guide them in the right direction. One solution is using building information modeling (BIM) and building analysis technology to benchmark and then optimize their buildings in an accurate and effective way, leading to a successful green retrofit.

In recent years, the increased adoption of BIM and other technologies has given the AECO industry an exponentially more-significant level of insight compared to traditional methods in the development, design and construction of building projects utilized worldwide. Initially, BIM was used as a process to model in 3D and support clash detection, visualization, etc. Now, with the industry more adept at using technology and BIM, increased numbers of project stakeholders of existing and new buildings are effectively using those tools. They support collaboration with the help of the cloud to quantify project data through the asset lifecycle of a project, leading to more-informed decisions and better coordination among all stakeholders.

As awareness of global climate change and its impact increases, so does the understanding that buildings are the biggest offenders in emitting greenhouse gasses. According to the 2021 “UN Global Alliance for Building and Construction: Global Status Report,” in 2019 and pre-COVID-19, the building sector was responsible for almost 37 percent of the total CO2 emissions and energy usage worldwide.

Although this amount was reduced slightly during the global pandemic, the building sector is expected to return to higher levels. This means the need for existing buildings to perform more sustainably is recognized as one of the highest priorities for the world to lessen and reverse the current climate crisis. By 2040, nearly two-thirds of the built environment will be existing buildings that stand today, according to IEA’s “Energy Technology Perspectives” report of 2020. These existing buildings will require a massive intervention—or a “green retrofit”—to optimize them for a net-zero future and help drive down global C02 emissions.


Graphics show the textual and building aspects of as-built and retrofit alignment toward net-zero.


Lifecycle Modeling

Digital database development of the environmental impacts of building materials and components has evolved alongside the advancements in cloud storage technologies. This development led to increased BIM integration, enabling whole-life modeling. It opens the door for designers to collect and analyze data across multiple buildings, lowering risk, lifecycle costs and whole-life carbon footprint.

By digitizing the existing built environment into a BIM environment, owners have an amazing opportunity to potentially understand how their building currently performs against industry benchmarks. They can use those analyses to better guide them in designing strategies to maintain, enhance and reuse methods to provide more-sustainable and energy-efficient buildings with a smaller carbon footprint than before.

With BIM, stakeholders can create point clouds using reality capture and 3D scanning technology to take a snapshot of their building’s as-built conditions. The building or site can be integrated into the digital environment as a BIM model, becoming an asset that can be shared, analyzed and updated as needed. To provide the most-accurate and detailed analysis results, the representation of materials, building systems and mechanical systems should be included in the BIM model. After a building or site’s as-built conditions have been digitized into a BIM platform, the next step will be to perform several detailed analyses to gain more insight into the baseline performance of the project. This step often is called “benchmarking” and involves using computers to perform analyses on the model, including the following:

• Form/Spatial Analysis

• Solar/Daylight Analysis

• Wind/CFD Analysis

• Thermal Comfort Analysis

• Material Thermal Properties

• Building Energy Modeling (BEM)

• Mechanical Systems Analysis

• Electrical Systems Analysis

• Photovoltaic Potential

• Embodied Carbon Analysis

• Material Quantification

• Material Carbon Footprint

• Whole-Building Carbon Footprint

The Full Digital Twin

Since BIM uses processing power, it’s faster and more efficient at handling design, construction, maintenance and demolition data than ever before. Implementing BIM will greatly benefit the green retrofit of existing structures and can aid sustainability performance studies at the early design stage. It provides a centralized digital model to monitor a building’s environmental performance continually throughout its lifecycle to assist green retrofit decisions. Getting the proper green retrofit requires the optimal combination of numerous design strategies and BIM tools. These should be verified and validated with building energy modeling tools during design decision making to support the sustainability team or consultants involved in the project.

This model—commonly known as a digital twin—can be integrated into the asset- and facilities-management strategy after the as-builts are digitized and benchmarking is finished. Owners can start using digital twins for their buildings, campuses, portfolios, businesses and related building services. With the help of a digital twin, strategic objectives such as sustainability, health and well-being, and decarbonization may be achieved—with their progress tracked in real-time.

Increasing Sustainability and Profitability

Although some historical buildings may be protected from making too many physical alterations, there are many opportunities to leverage operational data through an Internet of Things (IoT) platform to decrease their carbon emissions and track sustainability goals. According to recent statistics, 84 percent of IoT deployments now in place meet or have the capacity to address the UN’s Sustainable Development Goals. During the last two decades, the cost of IoT sensors has decreased and are more widely available. Consequently, businesses can adopt IoT applications that will increase their building or site’s sustainability and profitability.

The Future Ahead

Many opportunities are emerging on the horizon to achieve net-zero. The AECO industry must look to innovative technology methods in every phase of a building’s lifetime to create a sustainable and net-zero future. BIM is a key first step in a very complicated puzzle for the future of sustainable development with the ability to cover a structure’s planning, design and construction as well as lifespan, renovation and demolition.


City of New York, “Greenhouse Gas Emission Reporting,” Nov. 15, 2019.

City of New York, “Local Law 97,” Nov. 15, 2020.

GBC, UK, “Climate Change,” 2021.

IEA, “Energy Technology Perspectives 2020,” September 2020.

IEA, “Tracking Buildings 2021,” April 2021.

Lim, Yaik-Wah, et al., “Review of BIM for existing building sustainability performance and green retrofit.” International Journal of Sustainable Building Technology and Urban Development, 2021, 110-125.

The Climate Change Committee, “Phase Out Greenhouse Gas Emissions by 2050 to End UK Contribution to Global Warming,” May 2, 2019.

United Nations Environment Programme, “2021 Global Status Report for Buildings and Construction: Towards a Zero-emission, Efficient, and Resilient Buildings and Construction Sector,” Nairobi, 14-15.

Yaung, D., and Merritt, J., “World Economic Forum,” July 22, 2022. 

Shivani S. Soni is global head of co-innovation, Symetri; email: [email protected].

Geoffrey A. Tears is senior AECO solution specialist, Microdesk; email: [email protected].

About Shivani Soni

Shivani S. Soni is global head of co-innovation, Symetri; email: [email protected].

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