GLUMAC - Engineers for a sustainable future

by Bob Schroeder, P.E., LEED^®AP, Portland Associate Principal

The past and future meet at the Portland Armory, a 19th century landmark in the heart of Portland's Pearl District, which has been transformed into a performing arts center, a community space and shining example of sustainable design.

The team of Gerding Edlen Development, GBD Architects, their consultants and the client, Portland Center Stage, developed the Armory as the first historic building on the National Register of Historic Places to achieve Platinum status under the U.S. Green Building Council's (USGBC) LEED^® Rating System.

Built in 1891, the Portland Armory is one of the Northwest's most significant 19th century buildings. Its arched doorways and distinctive architectural style make it a magnet for visitors. To create new chapters in its rich history, it recently opened as a permanent home for Portland Center Stage. A sizable portion of the interior space was designed for the community to gather, learn, work and be entertained.

One primary challenge was to install modern mechanical, electrical, plumbing and telecommunications systems in a historical renovation project where visibility to architecture was paramount. Chilled water was extended from the district cooling plant that serves all of the Brewery Blocks. This eliminated the need for unsightly equipment on the visible barrel roof of the building.

Air handlers utilize fan wall technology which provides multiple smaller fans, providing not only improved acoustical performance but added redundancy for the owner. Eliminating sound traps and providing electronic filtration minimized pressure drops and reduced motor loads. Electronic filtration minimized pressure drops and provided high levels of air filtration to meet LEED^® standards.

The entry lobby has a radiant floor with displacement ventilation, which delivers air at approximately 63€F and at 20 ft per minute. Computational Fluid Dynamics (CFD) was performed on the building to confirm ventilation effectiveness for the systems.

To achieve the individual temperature control credit for the administrative offices, an underfloor access system was installed to provide not only ventilation air but also distribution of electrical and telecommunications systems. Raised floors typically have 12-24 inches of space, however, only 9 inches was available to the project due to the barrel dome configuration at the perimeter. To supplement cooling and provide heating needs, we utilized chilled beams which are essentially a horizontal fan coil unit. They also integrate space lighting and provide an attractive ceiling element.

A sophisticated energy management system with a full measurement and verification plan to sub-meter the building was installed, and allows for fine-tuning components over time.

Plumbing systems for the building utilize low flow fixtures throughout, and dual flush technology water closets. A rainwater harvesting system was installed on the site to collect rainwater through the drain system and store it in a large concrete tank. Water is filtered and sterilized before being distributed to water closets, urinals and for irrigation use. The tank was sized to accommodate drought contentions in the summer.

The lighting system was designed to evoke a theatrical experience upon entering the space, while highlighting the architectural character of the historic building and working within the structure of the LEED^® program. Lobby spaces were treated as extensions of the theatres. Many of the luminaires were specified with colored theatrical gels, creating interesting contrast to the exposed, raw finishes of the space. Track lighting was provided to enable the spaces to be used for a variety of programs, with the intent that the project would be viewed as a community space in addition to a theatre. To ensure energy efficiency and increase lamp life, the lobby spaces were designed with an architectural dimming system that would allow for pre-programmed scene controls and time controls for the non-emergency lighting. The approach to the office lighting and functional theatre workspaces, was to use high efficiency luminaires and efficacious lamps. As mentioned, lighting was integrated with the mechanical chilled beams to minimize ceiling systems. With the aggressive approach to daylighting through the use of skylights, many of the office level luminaires, in open public and workspaces, integrate daylight dimming through photocell input. Individual offices are provided with user controlled dimming, to ensure a productive working environment.

Integrating technology systems such as telecommunications cabling and security systems into the project provided some unique challenges. In addition to the routing of conduits and cables being difficult due to the historic structure of the building, there is a widely varying use for the Armory Theater. There are offices, work areas, rehearsal spaces, stages, event lobbies and function spaces spread across multiple floors, with all of these spaces requiring different types of cabling and equipment needs. With daily business operations on the top floor and the main public entry on the ground floor, security access zones and time-of-day use issues were discussed in detail, as was the video surveillance methodology.

Of particular interest is the video surveillance system that consists of IP-enabled cameras that attach to the Armory's data network in the same manner as a PC. A single network cable transports video streams to a central network-attached server and delivers the power for the cameras. This reduced the overall amount of raw materials, such as copper and polymers for cabling, by 50%. This approach also allows for access to the video system by the administration staff from any computer with access to their network, such as a home PC or even a handheld PDA.

The security access control system can be used not only to limit access to secure areas, but to provide the building systems controls with information as to what areas of the building are occupied, allowing the lighting and HVAC systems to be controlled accordingly.