The design professional’s obligation has always been defined by the standard of care — the level of skill and diligence another reasonably prudent architect or engineer would bring under similar circumstances in a similar locale. It is a standard of conduct, not a promise of outcome. Sustainability quietly changes the temptation. When an owner asks a firm to design a building that will achieve net-zero energy, reach LEED certification, hit a measured energy use intensity target, or deliver a defined utility payback, the request invites the firm to promise a result rather than a process. That shift — from performing competently to guaranteeing performance — is where uninsured exposure begins.
The distinction is not academic, because professional liability policies are built around the standard of care and, almost universally, exclude liability a firm assumes by contract that exceeds it. Carriers write the exclusion plainly; a representative policy bars “actual or alleged liability under any oral or written contract or agreement, including but not limited to express warranties or guarantees.” The logic is not punitive. A professional cannot control every variable that determines whether a building performs — occupant behavior, weather, utility rates, commissioning by others, and code officials who read the same drawings differently. Negligence must be proven through expert testimony that a firm fell below its peers; a guarantee needs no such proof. Miss the number and you have breached, regardless of how skillfully you designed. The insurer never agreed to underwrite a promise of perfection, so it does not.
The pressure to make those promises is intensifying, because the performance bar itself keeps rising. Energy-code adoption gained real ground heading into 2026. Illinois adopted the 2024 IECC as its base energy code in November 2025; Rhode Island became the first Northeast state to adopt it, including electric-ready provisions; and seven more Northeast states — Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, and New York — are actively pursuing the same code. Colorado’s Model Low Energy and Carbon code, a modified 2024 IECC, takes effect in July 2026, and stretch codes — voluntary advanced-performance tiers — are proliferating alongside the base codes. As the code floor climbs toward the outcomes green certifications reward, owners increasingly expect the two to converge, and they draft contracts that ask the designer to warrant the result the code and the certification both imply.
There is a further trap in how performance is judged. A building’s designed energy model and its measured operation rarely match in the first year of occupancy, and the gap breeds disputes. Programs such as LEED Zero certify buildings on measured net-zero energy or carbon over a full year of operation, not on modeled intent. Once a contract ties liability to a measured target, the firm inherits a measurement-and-verification argument it cannot fully control — baselines, adjustment factors, and operating assumptions that the federal M&V protocols spell out precisely because reasonable parties disagree about them. Embodied-carbon commitments and green-lease clauses extend the same exposure: a landlord who has promised a tenant a carbon or energy outcome may push that promise upstream to the designer, converting a marketing aspiration into a contractual warranty the firm’s policy will not answer.
The discipline that protects a firm lives in the language it agrees to. The intentional posture is to design to the standard of care and to the applicable code and rating system — and to say exactly that — rather than to guarantee that the completed building will achieve a certification or a measured figure. Design professionals should reserve the right to disclaim express warranties and guarantees, and the profession supports the position. ASCE’s Policy Statement 388 urges engineers to resist warranty and guarantee clauses in service contracts because they assume liability beyond the standard of care and outside the reach of insurance. The AIA’s sustainable-projects guidance frames sustainability obligations as reasonable efforts consistent with the standard of care, not as a guaranteed result. EJCDC and AIA agreements can be edited to define the green scope as design services measured against that standard — the difference between “the design will comply with” and “the building will achieve” is the difference between a covered claim and an uncovered one.
Aligning contract language with coverage is not a one-time edit; it is an ongoing discipline, and it is the work our four-step Strategic Process is built to do. Strategic Discovery surfaces where a firm’s sustainability commitments live — in proposals, certifications, and lease-driven owner demands. Risk Assessment illuminates which of those commitments read as guarantees a policy would exclude. Solution Design coordinates contract language, scope definitions, and E&O structure so the firm designs to a standard it can defend rather than an outcome it cannot control. Ongoing Optimization keeps the program current as codes tighten and rating systems evolve. A performance guarantee can feel like a competitive gesture; uncovered, it is a liability the firm has quietly taken ownership of alone. The firm that designs to the standard of care keeps its exposure where its insurance can still reach it.
— Ryan Mefford, President & Risk Advisor