1. San Francisco Library

Anthony Bernheim, AIA, associate principle at Simon Martin-Vegue Winkelstein Moris (SMWM), likes to tell an anecdote about the opening of the San Francisco Main Library in April of 1996. During the opening reception, he explained, the mayor cut the ceremonial ribbon and people packed into the building. There were many attendees, more than the building was designed for, and Bernheim, who had served as project manager for SMWM for the new facility, was anxious about the system maintaining the high quality indoor air it was designed for. “I was standing in the main atrium when one of the librarians came up from downstairs,” explained Bernheim. “She said, ‘I just have to tell you, we’re in a lower level, and we still have wonderful air quality in our space.’ It was proof that we had done our job right. ”

It was fitting that a librarian was one of the first to congratulate him on the quality of the library’s air. When the building was first being designed from April of 1990 to August of 1992 by Pei Cobb Freed & Partners and Simon Martin-Vegue Winkelstein Moris, Associated Architects, the formulation of a strategy for good Indoor Air Quality (IAQ) was proposed. According to Bernheim, it was only after the library staff supported and reinforced the proposal that the client agreed to incorporate the IAQ concerns into the project.

Four main strategies were developed for the IAQ portion of the $87 million, 381,000-square-foot project: control of source pollutants, ventilation control, building commissioning, and a maintenance plan. The measures, however, only accounted for approximately 1.1% of the construction costs. As Bernheim describes in a paper on the building entitled San Francisco Main Library: A Healthy Building, the IAQ team’s primary goal was “to provide a safe and healthy environment for patrons and staff ” by developing a “committed” team, establishing IAQ priorities, and developing and implementing effective strategies to uphold those priorities. The team included such experts as noted IAQ specialist Hal Levin of Hal Levin Associates, Flack + Kurtz Consulting Engineers, cost consultant Oppenheim Lewis Inc. and specifications writer John Raeber, FAIA, FCSI.

The HVAC system was an important part of the effort to keep indoor air clean and comfortable. Ground intakes were located far from ground level pollution sources, air flow monitoring devices were installed in the two air handling systems to keep track of and adjust the relative amounts of outdoor and recirculated air, and pre-filters and final filters (at 30% and 85% efficiency, respectively) were installed to remove airborne particulates. Also, an outside air economizer was linked digitally to the Building Automation System, which allows for large quantities of outdoor air to be taken in when temperatures are between 55°F and 72°F. The system now provides an average minimum ventilation rate of 25 cubic feet per minute (CFM) of outdoor air per occupant.

Materials selection and installation was another important part of the IAQ effort. A six-tiered ranking system was used to categorize materials from acceptable (Class 1) to acceptable with preconditioning (Class 3) to unacceptable (Class 6). To categorize each material, the team worked with materials suppliers to gather information on a product’s specifications including chemical composition, Material Safety Data Sheets (MSDSs), and Environmental Chamber Test reports. Bernheim is quick to point out, however, that product specifications and MSDSs may lack important IAQ data. The Medium Density Fiberboard, for instance, did not provide sufficient information for selection, and was only accepted after the manufacturer performed an Environmental Chamber Test report.

Other precautions included: removing damp or mold-infected products from the site; fabricating casework off-site to avoid contamination from drying adhesives and finishes; preconditioning furniture in a ventilated warehouse; sealing fabric-wrapped acoustic fiberglass ceiling panels with polyester and polyvinylflour ide film; and installing cementitious flooring in an auditorium where sheet floor material was deemed unacceptable.

Because the designers could not eliminate all harmful emissions, a flush-out period was scheduled to rid the building of odors and potential contaminants before occupancy commenced. For over two months prior to occupancy, the buildings HVAC system was run day and night with 100% outside air.

Building Commissioning

An important part of the IAQ process was the inclusion of building commissioning. Simply put, building commissioning is an extension of traditional testing, adjusting, and balancing inspections. “Buildings are getting more complicated. We as architects don’t understand all the cabling and wiring,” said Bernheim. “So we’re seeing IAQ problems, energy efficiency problems, and system control problems because, for example, we can’t tell from observation whether cables and wires are connected correctly.” He referred to a story about a building owner who couldn’t control an air handling unit, a problem that was eventually traced back to a contractor who had simply installed a wire incorrectly. “Commissioning is really the way of the future to control these issues. If someone is checking each piece of equipment, verifying its installation on site, testing each piece, and testing the system, you’ll get a building that operates smoothly, despite it’s complexity.”

According to the Portland Energy Conservation Inc. (PECI), a nonprofit corporation that has done substantial research building in energy efficiency, “Commissioning seeks to determine whether equipment meets a facility’s operational goals or whether it needs to be adjusted to improve efficiency and overall performance.” In a recent study of 175 commissioning case studies, PECI found that those projects that used commissioning procedures cited benefits such as energy savings, improved thermal comfort, improved indoor air quality, improved system function, and improved operation and maintenance.

Although commissioning may involve an up front cost, it is a small price to pay compared to the alternative. “Why not go through a commissioning process instead of paying everyone at the end to go through battles,” said Bernheim. “If you don’t use it, sometimes some of the systems aren’t working correctly, and nobody can figure out why. Then disputes arise, fingers start pointing, and everyone goes to the project to resolve the problems. You can just hear the dollars ticking away as all these people are standing there.”

According to Bernheim’s paper, commissioning construction cost for the San Francisco Main Library was approximately $65,000. The PECI study also sheds some light on the funds needed for such a project: the median cost of 11 commissioning projects in a category that included libraries, museums, a prison, a theater and a sports arena was $16,000, with an average cost of $.19 per square foot. Two thirds of these projects achieved an average savings of $90-92,000 per year for electric costs and $2,250-11,200 per year for gas costs.

2. THE ALCOA HEADQUARTERS

According to Martin Powell, principal at the Pittsburgh-based architecture firm The Design Alliance, designing a new headquarters for the Aluminum Company of America (Alcoa) meant following very specific principles the client had outlined: a flexible workspace and a healthy environment.

The client was moving out of a building in downtown Pittsburgh it had occupied since 1953. There, it had been conducting experiments with project teams and non-hierarchical, mobile office layouts – gaining attention in the process from publications like BusinessWeek and the Wall Street Journal – but had been constrained by the building’s rigid interior structure. Alcoa now wanted a new headquarters that would allow it to fully realize its growing emphasis on open, flexible workspaces and a healthy environment. It hired The Design Alliance to design a building that would help it meet those two main requirements. “They wanted the office space to be open and ergonomically and environmentally appropriate,” said Powell. “So springing from these requests, we looked at systems that would provide high levels of comfort and IAQ.”

One important part of the solution was a new technique for air delivery: underfloor ventilation. A relative newcomer to the U.S., underfloor delivery of ventilation air has been used successfully in Europe and Japan for years. Basically, the system entails an access floor (the raised floor traditionally used in computer rooms for cable management) whose volume is used as a plenum through which ventilation air is channeled into the office above. When this set-up is combined with the distribution technique called displacement ventilation, the benefits are manifold.

Benefits of Displacement Ventilation via Access Flooring

Displacement ventilation works by capitalizing on natural air flow and minimizing the mixing of supply air with room air. Unlike traditional ventilation techniques where supply air is mixed with room air in an attempt to achieve homogeneous temperature and air quality, displacement works by supplying fresh air directly to occupants through diffusers in or near the floor. Great care is taken to fashion the floor-mounted diffusers such that air is dispersed slowly into the air, lava-lamp style. Occupants then experience undiluted supply air that is distributed at this low velocity. Heat gains from people and machines carry air via “thermal plumes” to higher areas near the ceiling, where it is exhausted. The whole space, then, is stratified such that temperature differences between the occupied areas and higher areas are much greater than in a mixed system.

“Displacement ventilation can be thought of as cooling and ventilating the occupants as opposed to cooling and ventilating the space to cool and ventilate the occupants,” said engineer Daniel Nall, P.E., of Flack + Kurtz Consulting Engineers, who was hired by the design team due to his knowledge of displacement ventilation. Because this type of ventilation allows for a high level of temperature stratification, cooling loads were effectively decreased, allowing for chillers to be downsized. According to Nall, the first cost for Alcoa’s HVAC system was significantly reduced, as were the energy costs for conditioning the space.

The Alcoa building’s HVAC system however, was not designed to use 100% outside air for supply air as some displacement systems do (see next example), and instead filters and mixes return air at mixing boxes located on each floor. But it still achieves the main goal of delivering cool air directly to occupants and allowing for heat loads and pollutants to drift naturally upward and out through the ceiling return.

Using a raised floor also had numerous benefits. Not only did the system allow the designers to go with an 11’ 6” ceiling for improved daylighting (and a reduction of lighting costs and heat load), but it also reduced ductwork, and, most importantly for Powell, reduced the amount of money spent on office reorganization. “We’re realizing that the moves and changes and general ‘churn’ experienced by the office is really almost a three month cycle,” said Powell. “And in many open plan offices the air conditioning system can’t keep up with evolving change – taking the ceiling down and reworking ductwork just never happens. So we realized the need to be able to make changes in 24 hours that used to take three months.”

According to Powell, the team was able to contain first cost by looking at the overall system. “Yes, raised floors are more expensive than putting carpets on concrete floors,” said Powell. “But when the raised floor is considered in combination with lower mechanical building plant and lower light levels due to daylight and easily changed offices, it saves money. Using it forced us to be more rigorous in our analysis of cost – we couldn’t just reduce cost on a line by line basis. Everything works together.” Powell wouldn’t comment on the exact amount saved. According to a study by Flack & Kurtz, however, a raised floor HVAC system was estimated to cost $29.81 per square foot for a 50,000 square foot office building, while a standard overhead HVAC system would have cost $31.94 per square foot.

Because raised floor systems are so new in the U.S., during the initial design stage the team gathered information from the few buildings in the U.S. and abroad that had employed the system, including the Hong Kong and Shanghai Bank designed by Norman Foster and the S.C. Johnson Worldwide Professional Headquarters building in Racine, WI designed by HOK Inc.

In implementing their own system, the team relied on Nall’s expertise in a mathematical technique called computational fluid dynamics, or CFD. CFD is a mathematical tool used by engineers to study the movement of fluids around and through objects. Although CFD was initially developed for the aerospace industry and run on supercomputers, engineers like Nall are beginning to use the technique to analyze how air flows through a building, thanks to the new generations of high-speed and low-cost desktop computers.

In this case, CFD was used to design the displacement ventilation system and analyze everything from diffuser placement to possible condensation problems in windows to perimeter heating and cooling systems. CFD, for example, showed the importance of details like locating return air inlets at the head of the window to capture rising hot plumes generated by sunlight and reduce heat gain in the space. CFD also helped select face velocities of diffusers in the perimeter system to overcome thermal effects of the window wall (such as cold downdrafts in winter), and demonstrated that in many areas diffuser placement was not as important as the design of the diffuser itself.

According to Powell, Nall’s use of CFD was “instrumental in giving us confidence that we were going to deliver optimum comfort. It really demonstrates one system’s interaction with another. It’s an incredibly useful tool.”

Problems

Interestingly enough, Powell noted that the most difficult problem of building an underfloor delivery system did not appear in the installation, but in the design stage before even the first square meter of flooring was installed. “When you have an integrated solution where all systems are working collaboratively, all the engineers and architects have to work collaboratively,” said Powell. “And that’s extremely hard to accomplish when many architects and engineers come to a project with 18 or 20 years of experience in fields where individual contribution, not teamwork, is rewarded.” Many times, explained Powell, the average senior professional wants to make individual contributions and avoid the difficulties of teamwork.

To help them meet the challenge of such integration between separate fields, the architects developed strategies to help them in the design process. Co-located teams were used to keep members in touch with each other and the evolving design. “We’ve found that if we work side by side in the same space with professionals of other backgrounds, we get better group efforts,” explained Powell. To keep meeting time productive, “Group work products” were required after each session, whether they were sketches, action items, or detailed minutes. “Something we could walk away with,” said Powell . The firm even avoided working with engineering companies that responded negatively to the idea of working in the team-based approach.

3. GREEN ON THE GRAND

The Green on the Grand is an office building in Kitchener, Ontario, Canada, that was built to “set the standard for environmental responsibility in new construction,” according to Enermodal Engineering Inc. and Ian Cook Construction, the two companies that partnered to complete the project. The building was designed to meet the challenges of the Canadian C-2000 program, a program run by CANMET (the research arm of Natural Resources Canada) that provides guidelines for building environmentally sensitive buildings. In becoming the first C-2000 project, the building incorporated everything from passive solar heating and daylighting to highly insulated, air-tight walls to resource-conserving and low-VOC emitting materials. And at CAN$67 per square foot, the building cost no more to build than a typical office building in the same region.

One of the team’s main goals was to provide superior indoor air quality. Part of the solution was to separate the heating and cooling system from that of the ventilation system so that displacement ventilation could be used to bring in 100% outside air delivered directly to inhabitants. (Traditional forced-air systems usually require some amount of mixing of supply air with return air.)

The ventilation system’s main component is an air-handling unit that contains two heat exchangers, two fans, and a heating/cooling coil. Outside air is moved through a rotary-wheel heat exchanger to recover heat. A hydronic heating/cooling coil then heats or cools the air and, in the cooling season, dehumidifies it as well. Another heat exchanger, this one a plate-type unit, further conditions incoming air. Displacement ventilation is then used by introducing the air at low velocities into the room at floor level and exhausting it at grills located high on the walls. According to Stephen Carpenter, P. Eng., president of Enermodal, tests have shown 450 ppm of CO2 at occupant levels, only half of the standard limit required in a workspace and only 100 ppm above outside air. “You are never breathing anyone else’s air or pollutants,” he explained.

The heating and cooling system was designed to be as efficient as possible and to utilize environmentally benign technology. A CFC/HCFC-free, gas fired adsorption chiller/heater supplies hot or cold water to radiant heating/cooling panels. The benefits of radiant heat distributed by water included less energy needed to transfer the water to radiators and more zone control of temperature through control valves rather than air-based registers. According to Carpenter, the building was designed to use only 50% of the energy of a building constructed to ASHRAE 90.1. It ended up at only 20% less, a discrepancy Carpenter attributes to two factors: “The adsorption unit did not perform as we expected, due to seasonal inefficiencies,” he explained. Secondly, the building is being occupied longer per day than what is assumed in 90.1. “ASHRAE assumes that the building will be occupied 53 hours a week. The reality is that the building is running 16 hours a day because of the mix of tenants that we have. Actually there is very little opportunity to shut systems down. So we estimate our savings should have been about 35%,” he said.