The design-build project delivery method is gaining momentum as the most popular construction method in the U.S. because the integrated process saves time and money, allows for more innovation and fosters collaboration. Design-build firms have a reputation for outperforming traditional delivery methods, and the same opportunities exist for better implementation of building performance strategies.

Strategies that reduce carbon emissions

When an owner only has one contract with a single point of responsibility through use of the design-build method, it can be easier to align ESG goals and project performance. Having the designer, consultants and contractor working together from the onset of a project provides consistent and aligned total building optimizations and decarbonization recommendations that are within the project budget and schedule.

For example, emphasizing sustainable design strategies and building performance in conceptual design leads to greater reductions in carbon emissions. Early energy modeling helps determine building massing, orientation, window-wall ratios, envelope performance, shading devices and potential for on-site renewable energy generation.

The mechanical, electrical and plumbing engineers and the energy modeler can collaborate on building electrification, right-sizing equipment and life cycle cost assessments of proposed MEP systems while the architect is tackling building programming and structural engineers are determining the efficiency of the structural system.

Case study: RiverSouth in Austin

During the RiverSouth project in Austin, Texas, the integrated project team used Toyota’s A3 thinking that was developed in the 1940s. The A3 process facilitates collaborative problem-solving by simplifying the problem, analysis, proposed solutions and expected results onto a single 11x17 sheet of paper to optimize decisions during design or to solve an issue with constructability.

During design, the A3 process was used to investigate a diaphragm wall and the window mullions. The diaphragm wall study compared the basis of design piers and retention system versus the diaphragm wall for ground water control needed, given the project’s proximity to the floodplain of the Colorado River and the Town Lake.

Though the diaphragm wall prolonged the construction schedule by four months and added cost to the project, it allowed three additional levels of parking below grade, lowered the podium for a more attractive façade, added an additional 40,000 square feet of office space, maximized the floor-area ratio, increased the building’s rentable square footage, increased the leasing efficiencies and decreased the overall cost per square foot of the building.

The window mullion study evaluated several different curtain wall mullion spacings to maximize sight lines from the office levels to outside the building. The horizontal mullion spacing was analyzed for human scale and views. The original design comprised two different panel sizes with horizontal mullions at eye level. The goal was to find mullion layouts that optimized views while maintaining efficient panel sizes, creating an aesthetically pleasing curtain wall layout and maintaining energy efficiency.

A graphic of different window options.

Window mullions options for the RiverSouth project. Graphic credit Beck Group.

During the study, a day-long energy modeling charrette compared four different glazing options, spandrels and mullion configurations to balance energy efficiency, return on investment, and impacts to daylight, glare, views and solar heat gain. The resulting solution provides uninterrupted views using VRE1-43 with argon and thermal spacers and an overall energy cost savings of 24.1% over ASHRAE 90.1-2010.

Additionally, during mid-construction documentation, the developer investigated smart building technology that uses automated processes and technology to control and collect data on the building's operation to improve efficiency, sustainability, and the health and wellness of tenants. The design-build team quickly evaluated design and construction changes, potential rework needed, and budget and schedule impacts to help determine the feasibility of proposed strategies.

Overall, the smart building technology optimizes building operations and efficiency through tenant submetering, collecting space utilization to increased occupant comfort, touchless office technology and smart bathroom amenities. As a result, the building ranks among the most technologically advanced and safest high-rises in Austin, with a low carbon footprint accelerated by its design-build process.

Learn more about decarbonization strategies

How the integrated process can make decarbonization easier