The conventional Design-Bid-Build method offers clean lines of responsibility and works best for straightforward projects with prescriptive specifications.
 

In today’s construction landscape, where ambitious performance goals, compressed schedules, and complex designs have become the norm, traditional project delivery methods often struggle to keep pace. Architects, contractors, subcontractors, and manufacturers are tasked with managing the selection and installation of more and more sophisticated systems while navigating design intent, constructability, budget constraints, changing codes, and a constant flow of technological advances.
 

Increasing responsibilities and pressures necessitate new approaches to the design and construction processes. For many building enclosure projects, allowances must be made to identify, thoroughly assess, and brainstorm better options to address anticipated and unforeseen challenges. While multiple project delivery methods exist, two of the most popular approaches in use today are Design-Bid-Build and Design-Assist. 
 

Over the past decade, the Design-Assist model has gained momentum for its unique ability to handle complexity with maximum efficiency, consistently leading to improved results. The Design-Assist process is built upon collaboration, bringing project partners together early and often. Rather than moving through a linear process with little early stakeholder input and hoping everyone aligns later, teams collaborate iteratively from the start. They explore options and concepts sooner, leading to better-performing solutions that often cost less and cause fewer schedule delays.
 

“Architects face the challenging task of designing projects that incorporate multiple systems and must know a little bit about everything on the project,” explains Troy Hein, pre-construction manager for Oldcastle BuildingEnvelope. “Having all parties, including CGs, subcontractors, and manufacturers, involved from the design phase on, provides real-time answers to application details and spurs the process for developing novel solutions to potential problems, meeting aggressive schedules, and keeping projects on budget.”

Design-Bid-Build: A Linear Approach

The conventional Design-Bid-Build method offers clean lines of responsibility and works best for straightforward projects with prescriptive specifications. The architect completes drawings, contractors compete on price, and the project team constructs what was designed. For simple jobs, the clarity of sequence can be advantageous.
 

However, its linear approach is also a limitation. When systems become more complex or require modification, or when timelines are exceedingly strict, Design-Bid-Build restricts early manufacturer input, when their knowledge and ability to adapt is most valuable. Opportunities to conduct modeling, thorough system reviews, or exploration of innovative solutions and schedules often surface too late to influence the design without costly revisions, limiting product options to a standard book of parts.
 

Design-Assist: Bringing Expertise to the Table from the Start

Design-Assist maintains the architect’s and owner’s control over design vision but enhances the process by incorporating input from manufacturers, CGs, specialty subcontractors, and others before the drawings are locked in. This delivery model relies upon early, ongoing collaboration of project participants. 
 

The Design-Assist approach begins with the drawing up of contracts. Unlike Design-Bid-Build contracts that focus on annotating the specific liabilities for which each project team is responsible, Design-Assist contracts emphasize a robust communication process, requiring early-stage collaboration among all parties. A well-designed Design-Assist contract should include:
 

• The owner’s responsibilities to provide accurate and timely information to the design professionals and contractors.
• The scope of work for contractors, glaziers, and subs, 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 contractors’ compensation.
• Any other specific responsibilities associated with 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 empowers all parties to participate in the collaborative Design-Assist process from the project’s initial phases.
 

This highly collaborative approach is particularly well-suited to medium and large projects that lack prescriptive specifications or may require exploration of new solutions to problems unique to the project. There are numerous advantages:
 

• Enhanced risk mitigation
• Improved constructability
• Multiple opportunities for innovation
• Regular opportunities for real-time feedback
• Better cost evaluation
• More predictable performance outcomes
• Truncated product schedules
   

Hein emphasizes that success in Design-Assist comes down to choosing partners wisely. “This project delivery method requires a high level of trust, so choosing qualified partners with a strong track record and experience in Design-Assist projects is essential.”
 

A Real-Life Example: Gund Hall’s Façade Overhaul

The power of Design-Assist becomes very evident in complex, high-stakes enclosure projects. One such project was the recent renovation of Gund Hall at the Harvard Graduate School of Design in Cambridge, Massachusetts.
 

A broad team of experts was tasked with designing and executing the renovation, including Bruner/Cott Architects, Shawmut Design and Construction, Harvard GSD, A&A Window Products, Simpson Gumpertz & Heger, RDH Building Science, manufacturer Vitro Architectural Glass, and fabricator Oldcastle BuildingEnvelope. It was imperative for all stakeholders to work together to deliver a fast-paced solution, something simply not possible with Design-Bid-Build.
 

The project team convened twice weekly for approximately 11 weeks to assess issues, brainstorm options, and evaluate potential solutions. The frequent cadence allowed rapid iteration across:
 

• Design
• Modeling
• Constructability analysis
• Structural evaluations
• Thermal simulations
• In situ performance mockups 
• Manufacturing feasibility reviews
   

A Project Defined by Constraints

Built in 1972, Gund Hall required renovations to improve its thermal performance to meet current standards, and to resolve persistent interior water leaks that impacted students, staff, and equipment.
 

In addition, it was critical that any renovations maintain the original architectural intent of the iconic structure. The project also needed to be completed in a limited summer window when the facility experienced its lowest usage volume.
 

How Design-Assist Produced a Breakthrough Glazing System

To meet the thermal requirements, the design team initially explored triple glazing for the north and south faces of Gund Hall. While able to meet energy-performance goals, the collective team identified a problem: the thickness and profile of triple glazing would have disrupted Gund Hall’s iconic façade lines.
 

Through Design-Assist, the collection of project teams evaluated Vacuum-Insulated Glazing (VIG) as an alternative. While this solution was able to decrease the system profile, it failed to meet condensation-resistance requirements.
 

Together, the project teams identified a hybrid model. Using a standard VIG as manufactured by Vitro Architectural Glass as the foundation, Oldcastle BuildingEnvelope fabricated a hybrid VIG unit by adding an additional ¼” glass layer and a ½” airspace. By modifying an existing system and incorporating the hybrid VIG to enhance thermal performance, the team successfully met all performance objectives while preserving the building’s architectural character. Through the Design-Assist model, the results of the Gund Hall renovation team included:
 

• A sightline reduction from 2½ inches to 2 inches 
• A decreased profile depth that closely matched the original design
• A fully vetted assembly before construction
• A unique solution to condensation by reversing the hybrid VIG orientation

The performance gains were dramatic. By utilizing the hybrid VIG, the renovation achieved an overall system U-factor of 0.19 versus that of a conventional triple-glazed system U-factor of 0.26. Without the iterative process will all stakeholders, this solution may never have been identified or taken significant re-work and change requests down the line, causing schedule delays.
 

Solving the Riddle of Gund Hall’s Unique Trays 

A primary design component of Gund Hall is its stepped trays. While distinctive, time and the elements caused numerous seals to fail, resulting in significant water intrusion throughout the structure. Some students even resorted to using umbrellas while at their workstations during storms. The single-pane glass common at the time of construction was also a major source of energy loss within the structure.
 

A further complication was the extensive network of interior trusses. This eye-catching, inspiring web of glazing made installation of new high-performance windows systems from the inside of Gund Hall impossible. 
 

The collaborative, real-time nature of the Design-Assist approach eliminated the time-consuming back-and-forth between owners, designers, and vendors that cost money and caused delays. While triple-glass units were used on the trays, the thermal modeling conducted as part of the collaborative process revealed hybrid VIG units were not necessary to meet the project’s thermal performance goals, saving the owners significant money. 
 

Real-time discussion of glazing options also resulted in a solution to the installation quandary. Modification of an existing window wall system allowed for a pre-glazed, exterior installation. This innovation also enabled use of a system that addressed the waterproofing issue.  

Achieving Sloped Glazing Continuity 

Another major challenge of the Gund Hall project was the visual transition between vertical and sloped glazing. Maintaining aesthetic harmony required careful coordination among all project parties. Through a series of Design-Assist meetings with all stakeholders, a solution of bespoke elements was developed to make the vertical and sloped features as close to identical as possible. 
 

The necessary precision would not have been possible had these issues been discovered only during fabrication under a traditional Design-Bid-Build approach. The collaboration of the Design-Assist model enabled the team to shorten feedback loops, reduce the amount of documentation, and more efficiently vet the system.
 

The result? A façade solution that delivered improved performance, met the aesthetic goals, and held construction to the tight 11-week summer schedule.

Hein explains, “Each design iteration involved close examination and approval of details by the design team, running thermal models to ensure performance requirements were met, monitoring constructability and manufacturability, and the creation of 32 separate modified extrusions over the course of the project. Having all stakeholders and experts in one room was essential in keeping the project moving forward.” 
 

Why Design-Assist Outperforms Other Methods for Complex Building Enclosures

The Gund Hall project highlights several advantages of the Design-Assist approach:
 

Faster Schedules and Reduced Delays
Key decisions are made earlier and with more complete information, and stakeholders can plan for and adjust to manufacturing, delivery, and installation schedules to meet project timelines.
 

Thorough Assessments
Real-time evaluation through thermal modeling, structural analysis, and code compliance reviews.
 

Preservation of Architectural Intent
Because manufacturers are engaged while design is still flexible, performance improvements are prevented from compromising form.
 

Shortened Feedback Loops
Communications happen in real time, not through slow, document-heavy exchanges.
 

Lower Costs
Potential problems are resolved before bidding or fabrication, reducing change orders and rework fees.
 

Best Practices for Successful Design-Assist Projects

Design-Assist works best when the process is clear and collaborative. Key best practices include:
 

Engage Experts Early
Projects without prescriptive specifications, those seeking innovative solutions, or those with very tight schedules, benefit most from early input.
 

Collaborate with Experienced Partners
Trust is essential, so working with teams comfortable with the Design-Assist approach helps eliminate misunderstandings.
 

Follow an Effective Meeting Structure
Typically, the contractor or construction manager acts as “team captain,” ensuring coordination and accountability.
 

Define Scope, Schedule, and Budget Transparently
Collaboration aligns expectations from the outset.
 

Use a Well Written Design-Assist Contract
A strong contract should clearly outline expectations and eliminate ambiguity, allowing teams to focus on innovation rather than interpretation.