Open and Shut Case

Location is everything for commercial real estate, but it’s not usually something one says about a forensic laboratory. But then, the San Mateo County Sheriff’s Forensic Laboratory and Coroner’s Office in California breaks the mold in many ways. The facility is a highly secure and technologically innovative laboratory. But it is also an open and inviting workplace that provides its users the tools and long-term flexibility they’ll need to move forward with evolving research methods.

The impressive structure was the result of a kind of “high noon” scenario. San Mateo County authorities threw a challenge before the A/E design team—Hellmuth, Obata + Kassabaum, San Francisco. They wanted to create a new facility for a new millenium. And as the first building the county would construct in the 21st century, it would have to provide a model for the entire county.

HOK not only met the challenge, but by working as a cohesive team, its designers were able to integrate all building elements—both aesthetically and functionally—to the point that the facility’s occupants were champing at the bit to move in. “Once we finished, we had a hard time keeping them out,” jokes Dick Powers, P.E., HOK’s lead mechanical engineer.

Powers attributes the success of the integrated design effort in part to the manageable size of the project. In his experience, he explains, on mega-projects, it’s more difficult to have a good integrated effort. But the San Mateo County project was different. “It’s not a project you get lost in,” he says. “Half a dozen people worked on it, and you could get your arms around it. And also, the project manager [Lynn Filar] had us constantly working together and functioning as a team.”

However, to create a building that is so open, yet meets the security requirements of a forensic laboratory and coroner’s office, it took more than a cooperative effort among the designers. The design team as a whole was committed to working closely with county authorities and other project personnel.

In fact, from the first day of programming, the county asked the team to collaborate as a true alliance to plan, design, build and manage the new facility. The owner, architect, engineer, construction manager and trade contractors came together as one integrated team throughout design and construction.

Commissioned for success

Such a partnering spirit was necessary because San Mateo County requested that the design team consider the following:

• Cost-effective sustainable strategies.

• Orienting the building for passive energy.

• Alternative energy systems.

• Using passive energy practices in the mechanical system design.

• Engaging the structural system as an intrinsic element of the design.

• Using recycled, recyclable materials.

• Finding alternative funding sources.

In committing to the county’s desire for a sustainable facility that would also reduce its operating costs, the team developed a template based on the U.S. Green Building Council’s LEED rating system.

LEED prerequisites proved invaluable to the design team, but one in particular—commissioning—is especially worth mentioning. The engineering design entity—the HOK Engineering Group—acted as commissioning agent by assigning this function to a separate engineering team that had not been involved in the design process. The commissioning team wrote the plan, monitored installation, testing and systems demonstrations and authored the LEED commissioning documentation.

The actual decision to certify the building with the USGBC was not made until the project design was nearly complete. As the project progressed, designers realized that the decisions made in the interest of meeting program requirements had, in fact, yielded a design that could be certified at a silver level.

Confluence of disciplines

As far as the design itself, it was developed using an integrated multi-disciplinary process. Decisions regarding building orientation and massing were based on passive solar design principles, and energy analysis was used to optimize the design. (For more on the solar power system, see “Making the Case for Photovoltaics,” p. 37.)

But the PV system and its inclusion in the overall design points to something greater than itself: the complete integration of the architectural and engineering effort for the entire project. Each element in the building, whether structural, electrical or mechanical, was produced through a careful consideration of how these components could function together.

And the beginning of this successful integrated engineering story takes us back to the first-mentioned design element: location. The construction itself took 15 months. But, says Alan Bright, P.E., HOK’s lead architectural engineer on the project, “We worked with the county for a year prior to the site selection. We did some master plan studies and finally decided on the site. We looked at a number of design options. The [county] wanted to stack a two-story building into the hillside. But after we looked at the models and talked to the eventual facility users, one story seemed to be the right configuration.”

The concept was to achieve a marriage between the building’s highly technical interior program and the external influences of the sloped site and to integrate solar influences by exploring building orientation, roof design and opportunities for natural light. A single-story configuration with south sloping roof surfaces lent itself to natural daylight through north-facing clerestories. On the sides facing north and west, high glazed walls and clerestory windows enhance the amount of natural lighting. “One goal in this single-level project was to get labs 30 ft. deep,” explains Bright. “On the northern side, shorter overhangs and clerestories allow more natural light into the facility.”

Designers claim that very few artificial lights are necessary during the day. But they do exist, paired with occupancy sensors and photocells that dim the fixtures. “Lights give both downlight and uplight. And all light fixtures on the perimeters have individual dimming,” says Lynn Filar, HOK San Francisco’s project manager and project architect.

And once again, the use of a sustainable design element—daylighting—is integrated and linked to another significant design feature in the facility.

All parts work together

To make maximum use of natural light, the laboratories were designed without ceilings. To successfully accomplish this, architects and engineers laid out the envelope and systems using a three-dimensional approach from the initial concept layouts. A grid was established at what would have been the ceiling height. This 5-ft. x 5-ft. physical grid was used to support the direct/indirect lights, communication cables and lab piping services.

It was an integrated effort to design and use the ceiling-level grid for multiple purposes, says Filar, noting its seismic structural function, in addition to pipe and wire distribution. “It was designed by the electrical engineer, though in the end we didn’t use it for electrical distribution,” she says.

Above the grid, lab supply and exhaust ducts are located high in the space, carefully placed to avoid shadowing from the clerestories. Supply diffusers were dropped to the grid plane while the exhaust grilles were kept high to remove warmer air. The result was an organized, light and open feeling to the lab spaces. “[HVAC designer] Jan [Santos] worked carefully with Alan [Bright] in designing the ducts for aesthetic appeal,” says Filar. “Jan was very thorough and careful in the layout of the ductwork.”

The design also integrates operable windows in office areas, with the HVAC system shutting down mechanically supplied air when the windows are open, to minimize air conditioning. “We interlocked the VAV boxes with the operable windows, with the BAS handling these functions,” explains Filar.

External conditions greatly influenced HVAC choices: “San Mateo is a mild climate,” says Powers. “Not very cold, not very hot.”

As a result, air-cooled direct-expansion air handlers were selected, with each room featuring individual airflow tracking. But regarding airflow, one particular challenge was getting a handle on a pressure-controlled DNA suite. “Migration of evidence is definitely a concern in these facilities. Particulate matter and DNA can’t be allowed to escape,” says Filar.

“This was the last to get functioning,” adds Powers. To finally get it on line, he says, a separate HVAC system had to be installed in the office portion of the suite.

Other security provisions take a number of forms—both inside and outside the facility. “Forensic labs have a higher security level than other labs,” says Filar. “In terms of a security system, we worked closely with the sheriff’s office to get a building that was this ‘open.’ For example, it’s built up on a concrete plinth to keep cars from driving through.”

But there is also the issue of safeguarding evidence that is stored and tested within the facility. “Forensic labs are becoming more competitive,” says Filar. “Integrity of evidence has become very important. They all want to achieve accreditation, because otherwise, they can be picked on by defense attorneys.”

Other features in the building include natural ventilation in non-lab spaces, energy-efficient fume hoods, variable-volume lab supply and exhaust and waterless urinals. Also, during construction, there was an aggressive waste recycling plan that diverted more than 78% of construction waste from landfills. Sustainable materials included lab casework made of certified wood with epoxy resin tops. Floors are a combination of linoleum and sheet vinyl. The flooring in office areas includes a renewable, natural bamboo plank system—a hot trend in most LEED-certified buildings.

Among the tangible evidence of the project’s success are the following:

• The 22,000 sq. ft. of rooftop-mounted photovoltaic panels produce enough power to accommodate all the building’s non-HVAC electrical. With energy cost savings estimated at $66,000 per year, the installation has a simple payback period of about 10 years and requires minimal maintenance. Rebates and incentives will offset 30% to 40% of the initial costs required to build the system.

• By avoiding the purchase of fossil-fuel generated electricity, the solar-powered PV system spares the environment from thousands of tons of emission of nitrogen oxides, sulfur dioxide and carbon dioxide—all contributors to smog, acid rain and global warming. Over the 25-year life of the PV system—the largest in the country—the solar-generated electricity should reduce CO2emissions by 6,841 tons. These emission reductions are equivalent to planting 320,000 trees or removing 1,600 cars from California’s highways.

• The Forensic Laboratory is the first of the 19 local labs to meet state-established forensic facility standards.

• The lab has generated new income by charging a fee for providing services to 22 cities and jurisdictions.

• The county has established a new partnership with the local community college district to establish a crime lab technician and education program.

• The single level linear design improves communication for the scientists. It also allows for large, open labs that provide flexibility for inexpensive and fast reconfigurations. The exposed overhead lab utilities and services enhance the flexibility.

• The design allowed the lab to achieve American Society of Crime Lab Directors (ASCLD) accreditation.

• The county reports that the facility has boosted employee morale and helped it recruit talented new people.

But perhaps most important, based on the building’s success, the county board has mandated that all future county facilities incorporate sustainable design: It has become a model for the entire county.

Project recap

At the onset of schematic design, the county challenged the team to design and deliver a sustainable building. The facility offers a bright and airy work environment that meets stringent security requirements and reduces energy usage more than 20% relative to stringent California Title 24 requirements. This project demonstrates that integrated high-performance design can produce a better workplace while also substantially reducing operating costs and reliance on the grid.

A Model of Sustainability and Efficiency

With energy conservation at the forefront of people’s concerns—especially in California—it was important that the San Mateo County Sheriff’s Forensic Laboratory and Coroner’s Office be designed with systems that consumed the least amount of energy and with building materials produced using minimum amounts of energy. Making this building as sustainable as possible would serve the needs of the county and make strong business sense. They also expected it to act as a prototype for future county buildings.

In recognition of Earth Day 2003, the American Institute of Architects and its Committee on the Environment selected 10 top examples of sustainable design for the year. The San Mateo Forensic Lab was one of these projects. And given California’s concern for energy conservation, it’s no wonder that of the 10 projects, six of them are in California.

Making the Case for Photovoltaics

A major design goal for the new San Mateo County Sheriff’s Forensic Laboratory and Coroner’s Office was to marry the building’s highly technical interior program with the external impact of its sloped site in the San Mateo Hills. The design team sought to integrate solar influences by exploring building orientation, roof design and opportunities for natural light.

“We eventually recognized that a southwest orientation and a sloping roof would allow us to use a large array of photovoltaic panels,” says Lynn Filar, HOK San Francisco’s project manager and project architect.

Designers ended up creating a PV system that covers virtually all roof areas of the facility. “When the sun hits these panels, they create DC voltage,” says David Chow, P.E., project electrical engineer. “We gather them together, wire them in a series, and then connect them back to an inverter that converts energy from DC to AC power that we can connect to the utility grid.”

Northern California has perfect weather for photovoltaics, notes Chow. “If the panels get too hot or too cold, they don’t perform well. The mild weather here provides optimum conditions. There is enough sun to power the system but it’s also cool enough to keep the panels from overheating.”

Energy modeling and life-cycle cost studies determined that the PV installation would yield significant energy savings while requiring minimal maintenance because of the lack of moving parts and simple mounting system. Utility rebates would pay for almost half the system’s initial cost.

In the first four months of operation—from January to April 2003—the PV system supplied more power than the building needed. “Of course this was during the mild season in the Bay Area, and it was very temperate,” says Filar. “And energy conservation measures like daylighting, occupancy sensors and a sophisticated mechanical system help reduce the load.”

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