Greenhouse-gas (GHG) emissions are agreed to be the culprit that shifts global weather patterns, threatens climate systems and endangers human health. Longterm effects of GHGs only can be reversed by global proactive actions focused on emission reduction. The Paris Climate Agreement is one such solution, wherein 200 countries worldwide signed an initiative to keep rising temperatures below 1.5°C. Net zero is the first goal to reduce and reverse climate change.
The definition of net zero varies based on boundaries, timeframes, mitigation strategies, etc. The Intergovernmental Panel on Climate Change states net zero occurs “when anthropogenic emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals over a specified period.”
Today, buildings are responsible for nearly 40 percent of annual global GHG emissions. Therefore, reducing carbon emissions in buildings is one of the most-urgent objectives in combating global climate change and a major goal for the infrastructure industry. GHG’s impact in this sector is driven by building materials and operating energy consumption—essentially embodied and operational carbon.
A variety of tools and strategies exist for each building lifecycle phase that can potentially facilitate buildings’ net zero journeys. The following sections introduce roadmaps with various toolsets, including standards and workflows to enable carbon and performance tracking for sequences in each stage.
Predesign Phase: Preparation
At this point, the design and construction team should implement specific roles and responsibilities as well as reach consensus on project data governance to facilitate verification and validation. Similarly, contractors and manufacturers should set up effective digital information exchange processes to reduce risk and cost, and boost productivity.
The first step—identifying sustainability goals and key performance indicators (KPIs)—ensures essential information is captured from the early stage of design throughout the building lifecycle. Next is development of a set of documents and standards as well as identification of required details to measure and monitor throughout the lifecycle. For example, ISO 19650 is a series of international standards that define the collaborative processes for effective information management.
Incorporating required information into implementation standards can facilitate its collection and exchange as well as provide the data needed for performance analyses, while saving time and reducing inconsistency. The team then advances to classification mapping to identify and specify valuable sustainability attributes for each building element as well as facilitate information tracking, especially performance-related.
Next, they set up intelligent digital documentation templates and establish implementation workflows to streamline data collection and assist in design while colleagues develop object libraries and material databases to store CO2- friendly materials and their physical properties. These resources serve as the single source of truth for design analysis, avoiding redundant work and efforts. The last step is to establish performance thresholds to provide design guidance and facilitate informed decision-making.
Design Phase: Predictive Analysis
After establishing the groundwork and understanding what’s valuable in the predesign phase, the project team can move to the design phase—also known as “cradle to grate” carbon tracking—to optimize the building system via informed design decisions and predictive analysis.
Step one identifies the strategies and design scenarios applicable to the project, including passive and active design, operational considerations, potential onsite renewable energy, transformed and reusable materials, and building methods with higher efficiency and less construction waste. These ideas can be narrowed with set exploration ranges, performance criteria, and analyses to evaluate pros and cons.
By utilizing design-authoring tools with parameterization functionality and automatic performance-analyses feedback, the team can generate varied designs and feedback for decision-making. Typically, setting up parametric and performance-analysis models for design automation and generative design is a lengthy and tedious process; but it can be streamlined with proper workflows using templates and material libraries from the predesign phase.
Predictive analyses and optimization workflows provide tradeoff studies for informed decision-making to support higher-performing designs. After the design exploration and trade-off studies, the BIM authoring tool can be used to capture data through design documentation based on the predetermined standards carried through design, construction, and, ultimately, operation and maintenance use.
Construction Phase: Real-Time Tracking and Monitoring
The construction phase focuses on augmenting procurement and construction processes via simulation as well as real-time tracking and monitoring. Carbon tracking extends “cradle to grate” to “cradle to gate.” This approach reduces the construction carbon footprint and ensures workers’ health and safety through low-emission transportation, 4D/5D simulation, augmented reality (AR) and virtual reality (VR) coordination, smart sensors, wearable technologies and blockchain material tracking.
Step one explores applicable strategies to reduce carbon emissions and enhance a green and healthy construction site. Next, logistic planning ensures efficient material transportation to reduce time, cost and carbon emissions. These results are compared to the carbon estimation developed during predictive analysis. Advanced 4D/5D modeling can be used to simulate the construction sequence for identifying the most efficient and cost-effective means for site logistics, and AR/VR can facilitate coordination to spot potential conflicts and hazards.
Onsite tracking technologies—including RFID tags and wearables to track material logistics, real-time construction sequence, workers’ health and safety, and onsite carbon emission—can support construction management, leading to a green construction site.
Adoption of 4D/5D construction sequencing and cost estimation to save time and costs and reduce waste has become standard regardless of net zero goals. VR, sensor and drone applications to support remote monitoring, operations and safety are trends that further promote green construction sites.
Blockchain also has become a key enabler for carbon tracking. By reporting carbon emissions across a blockchain network, AEC professionals create a single platform for carbon measurement and facilitate connections among participants on a trusted platform that guarantees privacy, security and traceability.
Handover and Operational Phase: Real-Time Monitoring
Ultimately these efforts lead to a better position for the operational phase, which is focused on streamlining data transition, enabling business intelligence, and enhancing maintenance and operation. This phase aims to incorporate various activities to maintain and operate the building efficiently regarding energy consumption, comfort and occupants’ well-being.
The initial step is to identify the monitoring targets and applicable strategies to smooth data transition, increase building intelligence, and optimize operation and maintenance. These activities should be initiated and prepared in the predesign phase and incorporated into BIM implementation standards to facilitate data collection of the required information during the design process as well as assist with specifying related sensors and Building Automation Systems accordingly.
Next is data collection and handover. During handover, the collected data allow development of a facilities-management model, which is the foundation of a digital twin model and can be integrated with the computerized maintenance management system (CMMS) to configure business intelligence. As-built data collection is followed by sensor data and KPIs monitoring configuration, so collected sensor data are correlated to the KPIs of interest. This is essential to transforming data into useful information to support operational strategies by giving data meaning and logic.
After establishing the data correlation and performance thresholds, various CMMS or Enterprise Asset Management (EAM) platforms set up rules and logic for efficient building operation and preventive maintenance. For example, a system can turn down the intake of outdoor air when there’s no occupant within a certain space, reducing operational energy.
Data from prior phases re leveraged to develop a digital twin that enables real-time monitoring and incorporates machine and deep learning to provide preventive maintenance, asset-condition forecasting, and problem-cause remedies throughout the net zero journey.