Aggressive water-efficiency strategies are also being implemented to reduce consumption up to 70% compared with a typical building. About two-thirds of the building's water use will be supplied by rainwater.
The roof gardens mitigate building temperature and stormwater runoff volume and incorporate low-water-use native landscaping. As much as 90,000 gallons of rainwater will be collected and stored in two cisterns, then filtered and reused for nonpotable applications, such as irrigation, toilet flushing, cooling-tower make-up and cleaning photovoltaic panels.
McCarthy is on time and within budget for substantial completion by early October, says Craig Swenson, project director. Since McCarthy was involved in preconstruction services, the project team was empowered to maintain the project's sustainability goals in addition to focusing on budget and schedule, he says.
The approximately 50% to 70% reduction in energy usage will stem primarily from the 23,000 sq ft of rooftop integrated solar arrays sized at a peak capacity of almost 500 kW. Savings calculations are based on energy data from similar labs in similar climates.
ZGF organized the building's program to reduce energy loads. "Locating the computational laboratories and other non-laboratory spaces in one wing and wet laboratories in the other optimized the mechanical system," says Ted Hyman, a ZGF partner.
He says two independent HVAC solutions were used: single-pass air with heat recovery in the wet laboratories and more-passive heating and cooling in the dry spaces, taking advantage of the mild coastal climate. John McDonald, principal of MEP design consultant Integral Group out of the firms' Oakland office, says the project "separates ventilation air from other building loads. We only supply the air needed for ventilation—thereby saving the energy needed to condition this outside air compared to a conventional building."
The high-efficiency system includes two 25,000-gallon thermal energy storage tanks that use water instead of air to move heat in and out of the building. That cuts HVAC energy consumption by 87% compared with similar laboratory buildings. "We then use a hydronic system to heat or cool the building's other loads," McDonald says. "The thermal energy that water can transfer is orders of magnitude larger than that of air, so we use less energy to move this heating and cooling media around the building."
Active induction diffusers will reduce air changes in the labs to four during occupied times—compared with 12 or more for a typical building—and just two per hour during unoccupied times, says Lily Chiu, a ZGF associate partner.
Other energy-efficient elements include orientation and massing, such as a deep overhang on the south facade and placing the wings east-west—to minimize solar exposures—and locating the wet laboratory spaces to the south. Strategic glass placement helps filter direct sunlight in public spaces.
In non-laboratory spaces, operable windows provide natural ventilation. Further energy reductions are expected through the use of chilled beams, an exhaust-heat recovery coil and water-cooled freezers.
Electrical outlets will automatically turn off during specified times. Occupancy and daylight sensors will control the high-efficiency lighting. Occupant engagement strategies will further the net-zero goal. "A building control and management system will display real-time building performance in public areas and allow individual laboratory and office communities to monitor their energy and water consumption against historical use patterns," Palmore says.
With completion nearing, the project team is fine-tuning the net-zero systems, which will be monitored regularly and audited after one year for certification. "Balancing the final expected electrical load and consumption from the building to the electrical power generated by the PVs has been a challenge," Swenson says. "The design engineers have been continuously running the calculations and making adjustments to the quantity of the panels to ensure that net zero is maintained."