When T·H·A partnered up with Gray Purcell a model and plan had already been developed for the building. The model was well received by T·H·A and corresponded well with the team’s intention to preserve the historic integrity of the building while integrating sustainability into the project. Only modest modifications to the core and shell were deemed necessary by the design team but those modifications had to filter through LEED for New Construction and the requirements of the National Historic Registry.
The building was designed and constructed in 1913 in the 20th Century Italian Renaissance style. The structure is reinforced, poured-in-place concrete and was known at the time as a "fireproof" building. A string of building fires inspired the use of concrete and the building is one of the first non-industrial structures in Portland to use the material. The architect, Morris Whitehouse, duplicated this strategy on the grandstands at the Multnomah Athletic Club. The concrete frame is dressed with a grouping of cut sandstone masonry units that currently characterizes the building’s façade. Large windows dominate the north, west, and south street frontages.
The Portland Rubber Stamp Company occupied the building since 1978 and was the building’s most recent tenant prior to T·H·A. The Rubber Stamp Company used the basement to store mechanical and electrical equipment, the first floor for production, and the second floor for office space. T·H·A now occupies the basement and the first floor of the building.
T·H·A responded creatively to the potential limitations presented by the existing building and objectives for historic preservation and sustainability by coupling simple design strategies with innovative technologies. As designer, part owner, and tenant, LEED objectives led the rehabilitation of the core and shell as well as T·H·A’s improvement of the basement and first floor.
The exterior of the building appears largely as it did in its original form. T·H·A removed many layers of paint from the façade and was "delighted" to reveal the underlying Tenino Sandstone that now softly distinguishes the building from its neighbors. Gray Purcell identified an environmentally friendly spray on sealer, called Prosoco sealer, that will require re-spraying roughly every five years. This strategy will reduce material and maintenance expenses over time when compared to a paint application.
The highlight of the project is the rehabilitation of the T·H·A tenant space, which is rooted in the practice’s focus as a design studio, with an open floor plan and individual controls. The original floor plan had no significant interior rooms and this was noted as the most important feature to recover in the renovation of the space. T·H·A went a step further by extending the benefits of the first floor’s daylight to the basement. The flooring that separates the first floor from the basement is reinforced concrete slab and T·H·A cut out a large section of this slab to build an open stairway to the basement. LEED consultant Ralph DiNola refers to this as "the most ingenious move made in the design". Drafting and other workspaces fill the perimeter of the basement and daylight pours in from the substantial opening formed by the stairwell. Thin cable guardrails were specified to reduce their potential inhibition of daylight penetration into the lower level.
The first floor employs both passive and active strategies to take advantage of daylight access. Storm windows with a low-e coating were installed over the historic double hung sash windows and fill each of the structural bays. During the summer months these storm windows can be removed which allows the original windows to be opened for natural ventilation. The north façade offers the most daylight and faces a neighboring park with trees. Manually operable perforated shades provide occupant control of daylight intrusion. Interior active lighting is provided by T-8 fluorescent lamps with electronic dimmable ballasts and zonal controls and individual task lighting supplements personal needs. The lighting was designed by an independent source and consists of two independent systems that provide light sweeps every two hours after 6:00 PM. A light sensor on the first floor dims lights in two zones if light levels reach a predetermined point and each room is equipped with occupancy sensors and timer switches.
Three enclosed meeting spaces along the east side of the space also receive daylight by virtue of floor-to-ceiling glass partitions. These design strategies, coupled with energy efficient building systems, are primarily responsible for the building’s 24% energy savings beyond ASHRAE 90.1-1999.
A locally controlled 11-zone heating and cooling system reduces superfluous energy consumption and allows occupants more control of their thermal comfort. Seven gas furnaces are housed in two separate mechanical rooms on the lower floor that supply individual zones throughout the office. Four additional heat pumps are situated in the first floor soffits and three of these units (the ones that supply the basement and first floor conference rooms) have economizers attached to them to supply colder outside air if available and required. This reduces the need to draw from the 11 roof-mounted condensing units. Each unit has outside air vents going to it that have fans that are individually regulated.
Tracking the Cost of LEED
The team adopted LEED three months into the design and made a conscious effort to isolate the projected costs and savings of going LEED. T·H·A Principal Jonah Cohen notes that, "On paper, the costs were minimal…but there are hidden costs." Purcell affirms, "There were hidden costs due to our lack of experience with LEED. LEED was fairly new and we didn’t really know how the point system worked…we sort of made up rules as we went along." The team looked at the cost of LEED in terms of systems and materials, but not administrative costs. Navigating LEED for the first time proved to be a time-consuming task. "We spent too much time with energy and environmental strategies. We went down hundreds of dead end paths and this extended the construction time by about two months" notes Purcell.
The team retrospectively recognizes the value of up front planning when aspiring for LEED certification. "Most importantly, I would assemble the team immediately," says Purcell. Construction project manager Alan Fong agrees, "You must gather all of the people up front and know that you’re doing LEED going into it."
Green building consulting firm Green Building Services (GBS) was hired at the beginning of the construction phase to assist with LEED certification. Most design decisions had already been made but T·H·A welcomed LEED savvy that extended beyond their range of expertise. Senior consultant Ralph DiNola notes, "their design inherently met a lot of the LEED criteria…it (our services) was more of a LEED-based evaluation of what they were doing". Few deviations were required from the original design for LEED compliance. "If we had come in earlier it would not have made a drastic difference. That is a testament to the quality of T·H·A’s design," notes DiNola. In general, DiNola adds that the building is comfortably at the LEED silver level and they never got to the point where they felt that they were "buying points" to achieve that level.
The standards of the National Historic Registry and those of LEED were for the most part compatible. To preserve the historic integrity of the façade, the insulation had to be done on the interior of the building. Although the existing windows could not be re-glazed with an insulated glazing system, a storm window system with low-e glazing was found that blended well with the now stripped original windows. In addition to maintaining the original look of the windows, the occupants are now also able to remove the storm windows during the summer months and raise the lower sashes for fresh air. Both of these moves yielded additional costs. From a design standpoint however, both LEED and the Historic Registry share reinforcing goals of historic preservation and environmental conservation that heighten the value of the building to the community.
Keys to Success - Design:
- Use a highly durable and environmentally-sensitive sealant to protect the facade
- Design an open interior to promote deep daylight penetration
- Expose the basement to further daylight benefits
- Install removable high performance windows inside of existing historic windows
- Design a zoned heating system to reduce wasteful heating
- Use economizers to take advantage of outside temperate air
- Hire a green building consultant to evaluate LEED compliance