From concept to constructability: How Design-Assist turns challenges into innovation

Bruner/Cott Architects faced several challenges while working on the Harvard Graduate School of Design’s Gund Hall envelope project, located in Cambridge, Mass. The project involved a highly complex façade renovation, a fast-tracked timeline, and high thermal efficiency requirements. Bruner/Cott likely could not have relied on a traditional Design-Bid-Build approach to design and implement the technology needed for the project. Instead, the team delivered a successful project by using a Design-Assist approach in which contractors, subcontractors, manufacturers, fabricators, and architects huddled early on to brainstorm solutions.

Design-Assist vs. Design-Bid-Build

With a typical Design-Bid-Build project, the design and construction proceed in a linear fashion. The architect designs the project, competitive bidding takes place, the winning contractor hires subcontractors, and the team completes the project. The contract clearly specifies liabilities for each project team member, thereby reducing ambiguity. Simple, straightforward projects typically utilize the Design-Bid-Build approach.

When the timeline is short and/or the design and construction are more complex, design teams often instead look to Design-Build or Design-Assist. The Design-Build approach has the designers and contractors under a single contract. The design and construction proceed simultaneously, featuring a high level of collaboration and valuable input from key manufacturers. With Design-Assist, manufacturers are just as involved as the designers and contractors, if not more, providing information and guidance in a project’s early phases.

“Architects face the challenging task of designing projects that incorporate various systems and must know a little bit about everything on the project,” explains Troy Hein, pre-construction manager for Oldcastle BuildingEnvelope. “Having the fenestration system manufacturer involved during the design phase provides real-time answers to application detailing, specification consulting, structural and thermal analysis, value engineering, and code compliance.”

Enhancing risk mitigation, constructability, and innovation, Design-Assist is particularly suited for medium and larger projects that don’t have prescriptive specifications. To successfully execute these projects, Hein recommends that requests for proposals clearly outline the expectations for glazing trade partners who join early in the project. “This project delivery method requires a high level of trust, so choosing qualified partners with a strong track record and experience in Design-Assist or Design-Build projects is essential.”

In a typical framework, the contractor or construction manager acts as the team captain during Design-Assist meetings. Unlike Design-Build, separate design and construction contracts establish a fixed price or guaranteed maximum price once the scope of work has been clearly defined.

A written Design-Assist contract should include:

• The owner’s responsibilities to provide accurate and timely information to the design professionals and contractors.
• The contractor’s scope of work and the extent of any guarantee or warranty of information provided.
• The timing for when such information will be exchanged and any special requirements for how the information is to be communicated.
• The contractor’s compensation.
• Any other specific responsibilities associated with the Design-Assist services and assumed by various project participants.

By clearly defining roles and responsibilities and establishing proper lines of communication, a well-written contract helps eliminate confusion and supports a more seamless process.
 
Harvard’s Gund Hall

Originally built in 1972, Gund Hall was challenged with poor thermal performance and significant water leakage. To meet Harvard’s aesthetic, waterproofing, and energy performance goals, the team had to look beyond off-the-shelf offerings and design its own bespoke solution.

To adhere to Massachusetts’ requirements for energy efficiency, the designers considered triple glazing for the expansive glass on the north and south elevations, but the glazing’s thickness would have disrupted the façade’s original aesthetic. The team then determined that vacuum-insulated glazing (VIG) could meet the U-factor goals for thermal performance, but the technology couldn’t deliver enough condensation resistance.

Through the Design-Assist process, the project team closely collaborated on the development of a hybrid VIG solution. Meeting twice a week for approximately 11 weeks, the group worked together on the design, modeling, testing, and development of 32 customized extrusions for the curtain wall. 

The resulting sightline went from 2 ½ inches to 2 inches with a decreased profile depth, meaning the team made the system sleeker. At the same time, they maintained structural integrity and boosted performance. To address the condensation issue, thermal modeling and Design-Assist collaboration led the team to experiment with flipping the VIG orientation, and it worked.

Regarding performance, a standard insulated glazing unit would have offered a center-of-glass U-factor of 0.24. Instead, the hybrid VIG solution drove that value all the way down to 0.06, delivering an overall U-factor of 0.19 for the system. (Lower U-factors correspond to more effective insulation.)

Another challenge arose with the sloped glazing aspect of the project. The team had to figure out how to create visual continuity at the points where the vertical curtain wall and glazing came together.

“We spent a lot of time in [Design-Assist] meetings focusing on the joint between the two,” recalls Bruner/Cott Associate Architect George H. Gard, AIA. “We worked with the team to develop the bespoke elements [in the curtain wall and sloped glazing] to make them as close to identical as possible.”

Had a classic Design-Build approach been used, Gard says the complexity of the glazing solutions would have pushed a lot of decisions very late in the process and reduced the amount of collaboration that the design team and client could have had with the fabricator. “By opting for Design-Assist, this shortened the feedback loops, less documentation was needed, and the system was largely vetted,” he reports.

“The final design resulted from many hours of Design-Assist meetings, collaborating with the design team on aesthetics and performance,” adds Hein. “Each design iteration involved close examination and approval of details by the design team, running thermal models to ensure performance requirements were met, and monitoring constructability and manufacturability. Having all stakeholders and experts in one room was beneficial in keeping the project moving forward.”

While Design-Bid-Build might have delivered a façade solution capable of meeting thermal requirements, it would have required a longer project schedule and likely a higher price tag with lower performance values.

With a small summer window for construction plus the challenges of maintaining the historic structure’s aesthetics, addressing the water leakage and condensation issues, and meeting aggressive energy performance goals, Gund Hall required all hands on deck. “Someone was thinking about how [the curtain wall] goes on the building, someone was thinking about how it comes out of an extruder, and we were all thinking about how it drains water and insulates the building,” says Gard.

Leveraging manufacturers’ expertise

While Design-Bid-Build works for smaller, simplified projects, when a complex solution is required, architects have much to gain from the insights that experienced manufacturers have to offer. By bringing experts in their field of technology on to the design team, Design-Assist is an ideal way to collaborate and produce an optimized solution for a challenging project.

Explore the full Harvard Gund Hall case study to see how Design-Assist collaboration delivered breakthrough façade solutions on Oldcastle BuildingEnvelope's project page.

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