Platinum on a Budget - Consulting

A long the Willamette River just south of downtown Portland lies a former shipyard that is undergoing an extreme makeover. In a pioneering public-private partnership, the city teamed with its largest employer, Oregon Health & Science University, and two of the city’s progressive development companies to build a dense urban neighborhood with housing, green spaces and retail—and also an expansion of the OHSU campus.

One of the first new buildings to rise in the neighborhood is River Campus One, a mixed-use facility for office space, wellness, medical research, clinics, surgery, classrooms and ground-floor retail. Part of a $140 million project, the 400,000-sq.-ft., 16-story building will be situated next to a new aerial tram—only the second such system of its kind in the United States—connecting South Waterfront with the main campus atop Marquam Hill about a mile away.

The building team expects to apply for a USGBC LEED platinum rating. That’s nothing new. What’s unprecedented, however, is that we hope to achieve it at a reasonable cost. Upon completion in summer 2006, designers expect the facility to achieve energy savings 61% greater than what Oregon and ASHRAE 90.1-1999—the current LEED standard—require.

Despite boasting a plethora of green technologies—solar panels, radiant cooling systems, rainwater harvesting and even its own microturbine-based energy-generation plant—the building’s mechanical and electrical systems are actually expected to cost less than our original forecasts.

Goals and approaches

The project kicked off in August of 2003 with a two-day charrette to identify integrated design goals, with final core and shell designs due approximately a year later. But successful green buildings require a willingness to tackle projects from many angles. For us, the first step involves analyzing daily, seasonal and annual use patterns for lighting, heating, cooling, ventilation, plug loads, pumps and motors. Step two is to analyze opportunities to reduce demand through more efficient building envelopes, chillers, boilers and lighting. Whenever possible, we try to harvest natural resources, including wind and water. Energy storage systems are another means to utilize cheaper off-peak electricity.

Third, we favor a “right-sizing” approach. In other words, we specify mechanical systems after detailed analysis, as opposed to oversizing systems to meet peak loads. Some designers worry that such an approach might yield a system that’s not powerful enough. On the surface that might be true, but our philosophy is that it’s better to build in expansion than try to accomplish everything at the beginning.

Next on the slate is code analysis. We regularly challenge restrictive codes that add cost without benefit. In this project, we succeeded in securing 12 successful code appeals.

Solar singularity

All told, savings on initial investments in energy-efficiency and HVAC measures—including incentives—should amount to approximately $3.8 million and the project is expected to secure all 10 energy-efficiency points on the LEED scorecard. Only 15 of the first 195 LEED-certified projects have done so to date. Engineering analyses, including LEED documentation, were generally built into the initial fee, since LEED was an objective from the beginning. As goals ratcheted up—in shooting from silver to platinum—there were additional, albeit small, engineering fees. Building commissioning, required by LEED and performed by Interface, was extra, at a cost of about $120,000, or $0.30 per sq. ft. Smoke control system testing added another $25,000, or about $0.06 per sq. ft.

OK, that’s enough numbers and philosophy—on to the main event. A notable characteristic of the project is its commitment to solar energy. Not only does it include a set of integrated photovoltaic modules, it also boasts a 6,000-sq.-ft., site-built, solar collector. Located in front of the south-facing wall of the 15th and 16th stories, which are recessed from the lower portions of the building, the collector is an envelope composite constituted of low-iron glass. But its function is to serve HVAC more than power.

This additional construct essentially transforms the facade into a giant solar air heater. Air rises as it heats, moves through handling units across a heat exchanger and is used to pre-heat domestic hot water. A spacing bar in the middle of the glass, placed horizontally, forces air to make a loop through the collector, which increases its temperature upon exiting. The unit offsets about 1% of building energy use, requires almost no maintenance and involves no replacement costs over time. Additionally, it provides daylighting for offices and labs on the top two floors and operates as a “double envelope,” saving on heat loss since radiated heat from the building is recovered by the collector.

But the building’s PV modules also play a role in heating and cooling. Rather than simply blocking undesirable summer sunshine with shades on the south facade, our engineers discovered they could reduce glare and heat gain—simultaneously lowering the building’s HVAC requirements for cooling—by using the free surface on the awnings to mount building-integrated solar electric panels. This building-integrated system will produce about 60 kW of electricity at peak output—about 66,000 kW-hr. annually.

Besides demonstrating the value of solar, available state and federal tax credits, as well as accelerated depreciation incentives from the Oregon Energy Trust, made the effort more than worthwhile. More so, the system is a great example of integrated engineering and architecture at work. Indeed, many of the building’s significant energy-efficiency measures came from choices regarding envelope, insulation and glazing. But for purposes of this article, we’ll focus on engineered building systems.

Powerhouse

When one considers the amount of energy lost in the traditional process of electrical generation and transmission—about two-thirds thermal loss—the value of on-site energy production measures is clear. Besides the photovoltaics, River Campus One features its own 300-kW central utility plant, which is serviced by five 60-kW microturbines with built-in capacity for expansion. The microturbines, in fact, account for about a third of the building’s electrical energy needs, eliminating the thermal losses from purchased power.

From an environmental perspective, calculations show the building’s on-site generation will result in an annual reduction of 630 tons or 12% of carbon dioxide emissions from a similar project without microturbines. That’s about 20,000 tons over 30 years, considering the usual period for figuring such reductions. Sulfur dioxide and nitrogen oxide emissions would be reduced by about 38%. Of course, the main source of CO ₂ emission reductions is the high level of energy efficiency, which would add another 100,000 tons of emission reductions over 30 years.

Lighting

Along a similar vein, lighting, which represents nearly 25% of total energy used in a building of this size, provided another opportunity for energy reduction. In fact, it was the team’s goal to reduce lighting consumption by 40% over ASHRAE 90.1-1999 standards. This was carried out in many ways. For example, in the building’s many exam rooms, single multi-lamp 48-in.-dia. lensed “skydomes” that better mimic natural light are used instead of standard 1-ft. × 4-ft. lensed fluorescent luminaires. Furthermore, only half of the lamps in the room are activated by sensors when the room is occupied. Doctors, however, have an override switch to turn on all lights if necessary for exam purposes.

Designers also specified reduced lighting levels for lobbies and other pass-through spaces. Hallway occupancy sensors and local daylighting sensors switch off normal and emergency lighting in areas that have sufficient natural light or are unoccupied. Significantly reduced outdoor lighting with cutoff fixtures further reduces energy consumption, easily meeting the LEED requirements for eliminating light trespass.

Water conservation

Finally, but not the least significant, are the building’s water conservation measures. Contrary to its image as a rainy city, Portland receives less cumulative annual rainfall—36 in.—than cities like New York with almost 50 in. per year. Rainwater captured on the roof of a building this size can provide about 500,000 gals. per year—about 10% of the building’s requirements. That said, Portland’s high local water and sewer fees and system development charges created enough economic incentive for OHSU to move forward with a rainwater reclamation system. Additionally, because the South Waterfront district lies along the banks of the Willamette, high groundwater levels require continuous pumping to de-water the building site. This provided another incentive to reuse water.

Furthermore, River Campus One’s ambitious conservation scheme mandated that cooling tower and landscape irrigation systems use non-potable water. But providing enough water for all non-potable flows required some way to recycle the estimated 5 million gals. per year of wastewater.

The team was emboldened by a visit to New York City to tour a LEED gold-rated high-rise residential project that used an on-site bioreactor plant for sewage treatment.

Designed by Albany, Ore.-based Vision Engineering, the on-site membrane bioreactor requires very little operator attention. With the exception of sludge handling—a biweekly discharge of about 3,000 gals.—and annual membrane cleanout, the plant will operate virtually unattended.

Landscape irrigation was accomplished through a combination of rainwater, a small amount of pumped groundwater and a large volume of treated sewage water courtesy of the bioreactor.

Finally, our research showed primary water usage came from sinks, toilets and urinals. The team selected lower-water-consuming fixtures, which, while slightly more expensive, will collectively use about 36% water than code stipulates.

But reusing so much water required on-site storage and treatment. Luckily, the 22,000-gal. fire-suppression storage tank, which code requires anyway, could simply be made bigger—with 16,000 gals. of water still reserved for a fire. The inherent coolness of the water also meant it could be circulated through the building’s radiant floor cooling system.

Best in the West

Although no building can be analyzed completely before its construction is complete and the first year of occupancy occurs, OHSU’s River Campus One is well on its way to becoming one of the most resource-efficient buildings in the West.

With the project likely to secure all 10 LEED energy-efficiency points—only 15 of the first 195 LEED-certified projects have done so to date—and platinum status, it’s befitting of the university’s mission of promoting good health that its building will maintain optimal air quality and natural light.

But this project is also ultimately about saving developers’ and owners’ money through innovative engineering and integrated design. About $3.2 million will be saved on easily measured reductions in M/E and related systems, with an incremental investment of about $1 million—and that before taking into account financial and tax incentives of $600,000. These investments don’t include the bioreactor, which is financed by third-party investors and was outside the scope of Interface’s design efforts. In total, the project saved about 10% of the initial $30 million M/E/P equipment and systems budget.

But whether the project goes LEED platinum or not, the real winner remains OHSU, whose occupants will enjoy greater interior comfort at vastly reduced operating costs.

Project at a Glance

Designers of Oregon Heath & Science University’s new River Campus One building in Portland are gunning for 60% energy savings over state code and the USGBC LEED requirement—which conforms with ASHRAE 90.1-1999. This means taking advantage of all feasible high-performance measures, with key strategies such as:

Chilled-beam cooling systems

Microturbine heat recovery

Solar collectors for both electricity and water heating

Outside air economizers, where possible, taking advantage of Portland’s generally temperate year-round daytime temperatures and moderate humidity

High-efficiency (95%) boilers and chillers

Variable-air-volume air handlers and variable frequency drives on most pumps and motors to match supply and demand more carefully

Demand-controlled ventilation using carbon dioxide sensors and occupancy sensors, so spaces are fully conditioned only when in use

Heat recovery from laboratories, general exhausts and locker rooms

Displacement ventilation approach in core exam/office areas, reducing air contaminant levels caused by traditional air diffusers and eliminating the need for reheating building air at the room level

Radiant heating and cooling for the atrium and lobby, using reclaimed rain and ground water (for cooling) and waste heat from the microturbines (for heating)

Load shifting using a system of hot-, warm- and chilled-water storage to reduce costly peak demands

Passive heating and cooling and natural ventilation of stair enclosures

Energy-efficient lighting fixtures and controls that incorporate daylighting wherever feasible

Night-flush ventilation with outside air up to one hour before daily occupancy

Process water heat recovery, with reuse for pre-heating hot water for the building

Occupancy sensors on lab hood/exhaust systems to avoid dumping conditioned air outside when labs are not in use.

Measurement and verification of energy-using systems that is incorporated into the building automation system and allows troubleshooting of future energy use anomalies

Building commissioning, including field verification of all energy-using equipment—ensuring operation according to design intent, as well as peer review of design intent during design development and the construction documents phase