Successfully Leed-ing the Way

Installing the ice storage tanks in the rooftop penthouse was no easy feat.

When the Washington State Department of General Administration was looking for proposals the construction of its new office building, just a promise of high efficiency and comfort would not be nearly enough.

As a result of legislation passed by the state earlier-this year, all public buildings more than 5,000 sq.ft. have to achieve a Silver LEED (Leadership in Energy and Environmental Design) rating, as designated by the U.S. Green Building Council.

This meant that the department had to ensure that the new 210,000 sq.ft. Tumwater Office Properties housing the Washington State Department of Transportation and the Department of Corrections contained a wide variety of high efficiency, sustainable features.

Because having the right mechanical contractor on the project is essential for a successful LEED project, property developers Wright Runstad & Co had no one else in mind than MacDonald-Miller Facility Solutions, Inc. to be on their team.

Contracting Business' Commercial Contractor of the Year in 1991 and a winner of a Design/Build award in 2002, the company has a long history providing top-quality HVAC, plumbing, engineering, and controls services.

Tumwater Office Properties consists of four floors of office space, with nearly 2,400 sq.ft. retail space on the first floor, a 4,000 sq.ft. shared auditorium/conference space, and a 3,500 sq.ft. data center.

"Our team had to come up with a design that ad-hered closely to the state government's stringent specifications, and also took into account the need to control construction costs," says Steve Woolery, P.E., project engineer with MacDonald Miller.

LEED-driven Comfort, Control, & Efficiency
When assessing a building's performance to determine its prospective rating, the LEED committee assigns points based on site sustainability, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality, and innovation and design process.

For the mechanical systems for Tumwater Office Properties, the MacDonald-Miller team looked at how its design could meet these criteria and ensure the comfort of the building's tenants. For example:

1) The team installed a customized direct digital control (DDC) system to monitor the building's mechanical systems. "This system notonly communicates with every DDC terminal controller and plant controller, it also communicates with the variable speed drives serving the pumps and cooling tower via a single pair of wires, using a Lonworks interface," says Woolery.

The DDC system also provides CO2-based demand responsive ventilation in the auditorium and conference room spaces, as well as controls lighting zones through an interface with the lighting control system.

For more precise control, the team went beyond traditional zoning standards. Small conference rooms not treated as separate zones feature an exhaust fan to increase air circulation when the rooms are densely occupied.

2) To improve indoor air quality, MacDonald-Miller designed ventilation systems complying with ASHRAE Standard 62-1999. Air filters with a MERV 13 rating were installed in rooftop air handling units and in fan coil units, and outdoor air intakes were installed above the roof level to help avoid potential contaminants at the ground level.

"Indoor pollutants from the copy rooms and janitor closets were also a concern," says Woolery. "Therefore, there's a minimum of 0.03 in. negative pressure in these rooms, with the contaminants exhausted directly to the outdoors."

Finally, MacDonald-Miller's goals for proper IAQ extended to the installation process itself. Here, the team kept the open ends of the ductwork covered with plastic sheeting during construction to prevent any entry of dust or contaminants.

3) For increased energy efficiency, MacDonald-Miller's design included:

• A high-efficiency chiller, with ice storage to allow the chiller to run when the outdoor temperature, as well as the condenser water, is cool
• High-efficiency natural gas boilers • High-efficiency lighting fixtures, using approximately 30% less energy than mandated by the energy code
• Automatic daylighting controls to reduce lighting energy when sufficient ambient light is available • Variable air volume (VAV) terminal units equipped with ECM motors
• Variable frequency drives (VFDs) for the variable flow hot water and chilled water pumps and cooling tower fan
• Carbon dioxide sensors installed in auditorium spaces and conference rooms to reduce ventilation during periods of little or no occupancy.

4) To limit the building's environmental impact on both local and regional resources, MacDonald-Miller installed waterless urinals, dual-flush toilets, and low-flow auto-shutoff lavatory faucets powered by batteries, which recharge themselves with water flow.

"Using these components, we were able to reduce potable water usage by 45%, as compared to the 1992 Energy Policy Act baseline requirements," says Woolery.

Challenges Along the Way
Throughout the project, the MacDonald-Miller team faced a variety of design and installation challenges, including when one of the tenants withdrew from the building.

"This change required us to reprogram most of the tenant spaces, delaying tenant improvement design by more than six months, with no postponement of the building completion date," Woolery says.

Another challenge the team faced was the installation and integration of the ice storage system. For example, installing the ice storage tanks in a rooftop penthouse room was no easy feat. The tanks are 71/2-ft. in diameter and 81/2-ft. tall, and hold more than 1,650 gal. water. When filled, each tank weighs 17,000 lbs.

"Originally, we thought we would need seismic bracing on both the tops and the bottoms of the tanks to keep them from tipping in the event of an earthquake," says Woolery. "After having our design evaluated by a structural engineer, we found that we only had to brace them on the bottom because the tanks's height/ width ratio makes them relatively stable ."

Woolery adds that a definite challenge was to integrate the operation of the chiller with the ice melting. "This required an in-depth coordination of the various components of the chilled water system in order to develop a comprehensive sequence of operation," he says.

A third challenge involved the building's data center, which is cooled by floormounted chilled water computer room units during normal building operation.

Not only did the building owner require that spare cooling units be provided for redundancy,the team had to come up with way to ensure that the data center would remain conditioned in the event of a power failure.

Thus, MacDonald-Miller installed watercooled DX computer room units for redundant operation, should one or more of the chilled-water units fail. These units are also connected to stand-by power to provide full data center cooling in the event of a utility failure.

"We've also fitted the DX units with waterside economizer coils to reduce energy usage when it's cold outside," adds Woolery. "These units operate much less often than the chilled water units. Therefore, we can maximize energy savings because the primary cooling unit fans don't have to overcome the additional pressure drop of the economizer coil."

High-level Commissioning
"For this project, we used our 'Level Four' commissioning program, a written plan that leaves no room for error and ensures that the building operates per the design intent and the owner's desires," says Woolery.

In addition, an independent commissioning agent was retained by Wright Runstad & Co. to oversee and verify the commissioning process.

With the start-up and commissioning of Tumwater Office Properties complete, it was time to turn the building over to the LEED committee and to the tenants. The result: an anticipated Silver rating from the U.S. Green Building Council and a gold star from the Tumwater's occupants.

According to Woolery, "Despite the challenge of providing a system had to meet the strict requirements of LEED certification and the State of Washingston's standards and still be reasonable in cost, we were able to complete the project earlier than required and below budget. This is definitely a result of great teamwork and the Design/Build process."