Striking a Balance: Sustainability and Performance

One organization's lessons learned regarding building-envelope design and maintainability

By Tim G. Pennigar  

It’s nearly impossible to have gone through a workday in the last two years without having a conversation that deals with the green upheaval in the construction and building management world. Many maintenance and engineering managers no doubt have become fluent in the new language of sustainability.

Of course, the profession still has its cynics, and in this pragmatic climate, healthy cynicism is actually a useful trait. It keeps managers from burning the company money on the latest development.

The goal here is not attempt to dissuade green cynicism or champion the views of green proponents. Instead, the goal is to convince operational types the green, sustainability movement is creating a rare opportunity to enhance the performance and maintainability of facilities.

Combining Zeal and Practicality
The green movement is following the predictable path of every young movement. Early romantic zeal is clearing a path for good science and good business. This union of good zeal and practicality is indispensable. Together, they are driving green innovations, such as storm water reclamation, vegetative roofing, photovoltaic technology, and other advances becoming familiar to facilities.

This pursuit of good practice motivated the Engineering & Operations group at Duke University Health Systems in 2007 to begin writing a series called Lessons Learned on building design and construction. The intended audience was designers and constructors of future buildings on the campus, but the lessons also might help other managers tap into sustainability to benefit their facilities.

Building Envelope Lessons
During the past four decades, architectural firms, engineers, and contractors from every region of the country have helped shape the Duke medical campus. In this time of rapid expansion, Duke has occupied and maintained millions of square feet of new construction representing many individual buildings of various form and function.

Witnessing the life-cycle performance of such a diversity of buildings, design, and materials is an experience reserved for few but large institutional owners. This context forms the institutional knowledge on the construction of the building envelope.

Some lessons have been hard won at the cost of significant labor and financial resources diverted to chronically leaking buildings. All of them reflect a belief that high-performance, durable buildings are the product of thoughtful and deliberate intent.

Roofing-system design. Few building components possess the power of a roofing system to impact facility operations. Installed and maintained properly, a roofing system is a reliable ally, protecting both the property and the mission. Done poorly, it becomes a deep and continual draw on an institution’s resources, which are best used to support patient care or cancer research, not to fund a premature roof failure.

Exterior building skin. Duke Medicine began taking greater interest in exterior wall design upon realizing many chronic roof leaks actually resulted from wall defects. A manager can have a bad roof removed and replaced by a more durable roof, but a poorly designed or poorly constructed building facade cannot simply be replaced. Workers will patch and repair it repeatedly, with limited short-term success for the remainder of the building’s life.

More building owners would take an active role in skin review if they realized how much of their annual maintenance budget and labor are consumed by less-than-exemplary original design and construction.

Construction drawings. A general decline has occurred in the quality of architectural drawings and specifications for the building envelope during the past two decades.

In some cases, skin-construction drawings are too generic, incomplete, often unrealistic, and provide little or no help integrating critical elements on the building skin. This condition results in the construction manager and contractor fixing the design in the field, often under a tight construction schedule. The final product is seldom as durable as it should be, and the manager receives a new building that is prone to a lifetime of chronic moisture and leak problems.

In other cases, barrier-wall or face-sealed designs rely entirely on sealants as the barrier to moisture intrusion. This design approach is extremely unwise for facilities with no tolerance for moisture intrusion, such as hospitals. Designs must emphasize redundancy and provide a secondary drainage plane to effectively redirect water intrusion back to the outside of the wall cavity and away from the patient-care environment.

Also, building facades are overly complex. Designers should be aware of the operational impact produced by the overly creative use of horizontal setbacks and reveal elements on building facades. These features become collection points for airborne dirt and bird debris. Maintaining an acceptable building appearance might require regular cleaning with fresh water and possibly harsh chemicals — hardly environmentally friendly practices.

Of even greater concern is the likelihood of building leaks along these setbacks and ledges, which workers can access and repair only at significant hazard and cost. Buildings should be architecturally engaging, but designers should invest at least as much energy in making buildings as reliable and durable as they do in making them engaging and beautiful.

Construction Coordination
Some reasonably competent skin designs have been completely doomed by poor execution in the field. Sometimes, a critical detail is very attractive in plan but cannot be constructed as envisioned, due to phasing conflicts not considered during design. At other times, weak coordination of building trades undermines a critical detail.

As a matter of process, constructing a high-performance building skin requires people to communicate well and often. A great deal is at stake here. For example, if responsibility for a critical window flashing detail is missed and poorly executed, the result is a leakage path multiplied hundreds of times on the building facade.

Durable by Design
These institutional stories are set in different times and spaces, but they share one theme — durability, and its presence or lack. Managers understand the concept of durability because they see its immense value when it is present in structures and facilities, as well as the substantial costs when it is missing.

Advancing the concept of durability within the green building movement should be the highest priority for building and operations professionals. Durability might be the most elegant expression of green design — elegant because durability suggests refinement and thoughtful intent, and green because it reflects an understanding of stewardship and service.

The language of durability can lift the green movement to a new level and with it the quality and performance of the building industry.

Sustainability logic begs an important question: Can organizations achieve their stated goals of greenness and sustainable building if executives and managers also do not demand the highest quality and technical competence in construction specifications and detailed drawings?

Even with the best intentions, durable, high-performance green buildings cannot result from boilerplate drawings. Sustainable buildings and built assemblies that leak or fail because of half-hearted design or construction will not look very sustainable buried in a landfill.

Tim G. Pennigar — — is project manager for structural systems with Duke University Health Systems.

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  posted on 2/1/2008   Article Use Policy

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