San Diego Building Gets Smart

The all-electric, 22-story, 600,000-sq.-ft. 550 Corporate Center building in San Diego was anything but energy-efficient when it was constructed in the 1980s. But thanks to phased retrofits to the building automation system (BAS), it has received two consecutive annual awards for energy efficiency by the Building Owners and Managers Association (BOMA).

The system overhaul was initiated to meet Y2K compliance. The building's engineering staff did not want another proprietary BAS system. "The goal was to have a system that was open, flexible and expandable," says John Gibson, the chief engineer at 550 Corporate Center. "A system that could truly be managed in-house without having to pay someone to come out and tweak or fine-tune it."

A LonWorks-based system was specified. In assessing the new BAS strategy, designers first had to gain control over the physical plant, as well as the air handling units on all floors and most of the lighting within the building. To better manage the AHUs, 13 panels that each controlled two floors were replaced with rooftop controllers. Schedulers, lighting panels and other devices were also tied to the new BAS network.

Because of the non-hierarchical architecture of the network, new devices can be added easily. This simplified subsequent additions to the network, including parking garage fans and lighting system improvements. It also allows for easy future additions. For example, each year, the building manager has plans to refit variable air volume (VAV) valves on two floors.

One of the key energy savers is the ACS (automated control system), which allows tenants to turn on lights and air conditioning after hours. The building's lights and air conditioning are on from 8 a.m. to 6 p.m. Monday through Friday. After hours, tenants can call into the ACS and turn on lights and air conditioning in their area for two, three or four hours at a time. Lighting is provided at no cost, but tenants are billed for after-hours use of air conditioning. Each tenant has a four-digit ID code, and each user from each tenant has a four-digit PIN code.

As part of its contract with tenants, the building used to run lights and air conditioning on Saturday from 8 a.m. until 1 p.m., whether anyone was in the building or not. "We'd cool 343,000 sq. ft. of space and five people would show up to work in the whole building," Gibson said. "Now, individuals can turn it on in their areas when they come in. Even though we don't charge for Saturday usage, that feature has paid for the system a couple of times over."

After-hours energy consumption is also reduced by a two-stage air conditioning system. Two 400-ton chillers cool the building during the day, and at night, a 100-ton reciprocating chiller is left running to cool computer rooms for various tenants.

Future HVAC system enhancements include the refitting of the remaining VAVs. Eventually, Gibson would like to connect the security and parking garage systems into the LonWorks network, as this could mean less reliance on outside suppliers. Connecting the parking system to the LonWorks network could also enable tenants to automatically turn on the lights or air conditioning in their offices as they swipe their card entering the garage.

Every year since 1999, the building's energy usage has decreased. As a result, it was honored by BOMA for its energy conservation efforts in both 2001 and 2002.