Notes From the Log of a LEED Navigator: Pt. 2

The pursuit of a gold or platinum LEED-certified building often requires the implementation of cutting-edge systems. This certainly was the case with Pittsburgh’s David L. Lawrence Convention Center. Again, in our role as the project’s LEED navigator—the agent on a LEED project responsible for continually protecting green elements in the midst of budget shortfalls, value engineering and construction uncertainties—the Green Building Alliance (GBA), in the earliest stages of the project, proposed a number of innovative features, one of which was a green roof on the third-floor deck. We also had a solar energy consultant investigate the possibility of placing building-integrated photovoltaics into the flat portion of the roof structure. Alas, not everything is possible. The green roof was not approved, due to tight timelines, its initial expense and maintenance concerns. When it came to the PV system, analysis revealed that there was too much shading from adjacent buildings to make the technology practical on a large scale.

On the other hand, many “green” technologies were successfully implemented, notably the building’s on-site water reclamation system. This idea was proposed by Burt Hill Kosar Rittelmann Assocs. (BHKR), the project’s M/E/P engineer, during the design competition. But it was later at risk due to its cost and the team’s unfamiliarity with the technology. Still, the commitment to LEED had a significant impact on the final decision. As the navigator, we informed the team that without the system, four to five LEED credits would be lost, along with the opportunity to earn gold certification.

Trail markers:

• Fully investigate any proposed technology and talk to building owners who can attest to its performance. Ideally, such project examples can be found in your region.

• Take responsibility for checking references on at least three existing installations of the proposed system.

• Carefully evaluate the strength of the business behind the technology, including its capitalization, sales volume and level of professionalism.

• Find out if the company selling the system has strong representation in your area.

• Use bundled services provided by the same company whenever possible.

• Ensure that warranty services on the system cover elements to which it’s affixed, such as the roof membrane in the case of a green roof installation.

Hire computer modelers

Hand in glove with the use of sustainable technologies came the need to employ computer modeling. For instance, accurate modeling of unique building types, such as the dramatically curved roof designed by Rafael Viñoly, requires strong skills and experience in the field of building simulation that the majority of design firms do not possess in-house. On this project, BHKR first used a heating and cooling load-calculation program that was developed by an HVAC equipment manufacturer. While this software wouldbe appropriate for the majority of load calculation applications, in this case there were too many energy efficiency features for it to work efficiently. Furthermore, many traditional load-calculation programs do not account for daylighting controls very well. Additional computer modeling, for whichGBA wrote a grant proposal, and to which the U.S. Dept. of Energy gave support, was used to estimate the building’s energy use and amount and quality of daylight. Bill Browning, principal and founder of Green Development Services at the Rocky Mountain Institute, assisted with this proposal, and DOElent one of its top energy-modeling experts: Vladimir Bazjanac from Lawrence Berkeley National Laboratory. CTG Energetics was later hired by GBA to continue energy modeling work, while the design team hired Cambridge, Mass.-based Lam Partners to complete the daylighting study.

Although the building’s large, curved roof presented challenges, the combination of the DOE-2 software, Bazjanac and CTG proved more than proficient in modeling the roof with even greater accuracy. To assist with this challenge, CTG opted to use a newer version of DOE-2 that had stronger capabilities for modeling unusual shapes. When the complete analysis was finished, it indicated a peak-cooling load of just 2,700 tons—46% less than BHKR’s 5,000-ton estimate. The difference in professional analyses, which roughly equated to $1,000/ton or $2.3 million, led to a spirited debate. In the end, 6,000 tons of cooling capacity was specified to provide chilled water for the convention center and an adjacent hotel. If the hotel had been designed at the same time as the convention center, optimizing the system’s size would have been far easier. It is GBA’s hope that if additional chilled water capacity is available later that it can be used for other developments adjacent to the convention center, such as a nearby intermodal transportation center. Over time, the actual cooling load requirements for the convention center and hotel will become known and this critical feedback will enable building owners and developers to provide comfortable building environments in the future without super-sizing HVAC systems.

Trail markers:

• Properly utilize building simulation software programs, such as DOE-2, that are capable of modeling advanced energy-efficiency measures, as this allows for more accurate cooling and heating equipment sizing calculations.

• Right-size chillers, boilers, air handlers and pumps, as such action can save on initial construction, as well as operation costs.

Commissioning

Like some of the new technology installed within the building, the value of building commissioning was hotly debated among members of the design team and the building owner, the Pittsburgh Sports and Exhibition Authority. While perhaps not new to consulting engineers, this service is fairly new to many other people in the A/E/C business. Not only does it require an increased budget, it presents the challenge of an additional set of consultants to manage.

After much prodding, the owner agreed to move forward with commissioning as long as GBA wrote the request for proposal, selected candidates and raised necessary funding. CH2M Hill was selected to work with BHKR at a total cost of $217,000. Of that amount, SEA provided $50,000; the Dept. of Energy of Pennsylvania contributed $100,000; and a local foundation, Citizen Power, donated $25,000.

This undertaking, however, has already proven its worth. For example, a 33% failure rate was found in the variable-air-volume fan boxes. Many of these fans’ motors were incorrectly wired at the factory and the resulting natural resonance caused so much vibration that some of fan blades actually fell off.

Trail markers:

• Start early to educate building owners about the value of commissioning.

• Fully specify commissioning so that all subcontractors can anticipate their responsibilities.

• Use commissioning agents with LEED-certified projects in their portfolio.

• LEED Energy & Atmosphere Credit 3 (additional commissioning) is frequently audited by USGBC. Therefore, it is important that in the selecting a commissioning agent, the agent be experienced in responding to requests for additional information.

The job site

One of the final, but major, components of a successful LEED project is waste management. On-site quality assurance is a fairly simple matter when the green agent is from a construction company; it is another matter entirely when that person is a third-party consultant.

Trail markers:

• Make necessary arrangements with a construction manager to walk the job site, using OSHA-approved equipment, of course.

• Since unauthorized substitution of green materials, especially adhesives and paints, is prevalent, constant vigilance by the green agent is critical.

• Most installers welcome the use of green materials.

• Implement a demolition and construction waste management program. This component is key and warrants further description in and of itself.

What’s next?

Now that LEED certification has grown in market value and building professionals desire to have LEED projects in their portfolios, the motivation is quite high to overcome the challenges described here. Throughout the project, green agents frequently and stridently assured other project team members, “This may be your first LEED project, but it is not your last.” Even the skeptics among the team members now agree.

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