With 26 hospitals throughout Northern California, Sutter Healthcare is continuously updating and modernizing their facilities in order to optimize patient comfort while also reducing energy costs. A big part of this effort involves upgrading their BAS to take advantage of the latest functionality and efficiencies available.

Frequently, upgrading BAS requires the replacement of vast amounts of network cabling, which in any facility can present numerous challenges and issues. However, the nature of a health care facility magnifies these challenges.

Such was the case with the upgrade of the BAS installed at the Sutter Davis Hospital in Davis, CA. This two-story, 94,000-sq-ft, 48-bed hospital houses approximately 380 employees and supports more than 250 physicians. With a mix of office space, patient rooms, and operating rooms, Sutter wanted to upgrade the existing BAS with the newest technology.

All New - Sensors to Stations

Because the existing system was originally installed in 1994 when the facility opened, this meant that everything from sensors to workstations needed to be replaced. The new system installed was Siemens Building Technologies’ APOGEE® BAS.

New supervisory controllers and workstations used were Ethernet-based and, thus, able to utilize the existing Ethernet infrastructure. However, all of the approximately 220 terminal box controllers and a number of differential pressure monitors, zone humidifiers, and fire/smoke damper monitors required a new network infrastructure in order to communicate on the BAS.

The existing network cabling was incompatible with the new BAS. In order to avoid running vast amounts of new cabling throughout the facility, Sutter decided to use a wireless network to connect all of these devices to their BAS instead of a traditional hard-wired network, which would have been the only option just a few years ago.

In order to implement the wireless network, a radio transceiver was mounted next to each new terminal box controller and other new field devices installed. Additionally, a radio transceiver was mounted at the supervisory controller to support each wireless network. Communications between the radio transceivers at the controllers and field devices, and the supervisory controllers were routed via a wireless mesh network based on the emerging ZigBee® wireless standard.

In a wireless mesh network, devices communicate with more then one other device and route message traffic for not only themselves but also their neighbors. As a result, multiple redundant paths of communications are formed and messages are able to route around obstructions as required.

Additionally, the network has embedded intelligence so that if a message path is disrupted because of a change in the environment, the network is smart enough to find the next optimal path. The redundancy and self-healing nature of the technology ensures reliable network communications even in a hospital where large metal obstructions like lead shielding exist and are moved around. For Sutter, the benefits of using wireless were numerous, but the major advantage was minimizing the disruption the upgrade would create.

Other Benefits

The wireless approach provided additional benefits. The amount of ceilings opened up was minimized and, thus, the amount of airborne contamination and efforts required to contain airborne contamination were greatly reduced. Also, terminal boxes could be transferred from the older controllers and hard-wired network to the new controllers and wireless network one at a time. This enabled a seamless migration system without the need to take entire terminal box controller networks down for periods of time. Thus, the retrofit of the BAS could be completed in a fraction of the time that would have been required if hard-wired controller networks were used.

As John Peete, director of plant operations at the hospital, stated: “We decided to use Siemens’ new wireless technology for many reasons. However, first and foremost, it eliminated the need to rewire the entire facility, which is a big plus and a lot less disruptive to our patients, staff, and visitors.” ES