The Presidio of San Francisco Installs Energy Monitoring and Control System
August 1, 2002
Nestled between San Francisco Bay and the Pacific Ocean, the Presidio of San Francisco is situated at the south end of the Golden Gate Bridge, just west of the city. For nearly 220 years, the Presidio was used as a military garrison successively by three powers—first Spain, then Mexico, and finally, the United States. This rich past is reflected in the site's incomparable collection of historic architecture and its stunning forest and landscaped features. A showcase of military architectural styles dating from before the Civil War, the Presidio is home to nearly 800 buildings, 470 of which are considered historic. The Presidio was declared a National Historic Landmark in 1962.
The Presidio was slated for closure as a military base in 1989 and its jurisdiction transferred from the U.S. Army to the National Park Service in 1994. With 1,480 acres of parklands, distinctive historic features, rare ecological characteristics, and spectacular vistas, the Presidio is a unique national park site. Given its legacy as a military post, the Presidio's infrastructure systems can be likened to those of a small city. The park has its own police and fire services, and an extensive infrastructure including a telecommunications system, 25 miles of roadways, a water treatment plant and water distribution system, a high voltage distribution system, a sanitary sewer system, and a storm sewer system.
Because of the complexities of maintaining the Presidio's buildings and infrastructure, in 1996 Congress established The Presidio Trust ("Trust"), a Federal government corporation charged with managing the interior 80 percent of the Presidio's lands, including nearly all of its buildings. The National Park Service manages the Presidio's coastal areas. The Trust's mission is to preserve and enhance the cultural, natural, scenic, and recreational resources of the Presidio for the American public. In 2013, taxpayer support for the Presidio will end, and the park's operation and continued preservation must be funded by revenues generated by the Trust, principally by leasing the Presidio's rehabilitated historic and non-historic buildings as homes and workplaces. Given both the Trust's preservation and financial self-sufficiency objectives, responsible energy use and energy-efficient technologies are important to the Trust's daily maintenance and operations of the Presidio.
Description of the Energy Monitoring and Control System
As Utilities and Engineering Manager for the Presidio Trust, Jim Kelly tracks the utility usage (electricity, gas, and water) in more than 1,100 residential units and 100 non-residential buildings. With the help of the Trust's staff Energy Monitoring and Control System's (EMCS's) administrator, Minh Pham, and the invaluable assistance of John Wunderlich of DOE's Lawrence Berkeley National Laboratory and Andy Walker of DOE's National Renewable Energy Laboratory, the Trust has installed the backbone of an EMCS provided by Johnson Controls Inc. to make the job easier.
After advertising for a comprehensive EMCS in 1999, the Trust selected Johnson Controls to design and install an EMCS that would be compatible with the historic resources and landscape of the Presidio. Because many of the buildings at the Presidio are separated by more than a mile, and the Presidio has several archeologically sensitive sites' installation of a new high-speed communication infrastructure was infeasible. Instead, the Trust opted to integrate these buildings by connecting the existing copper-wire phone system to a central operator workstation. To date, the EMCS is connected to more than 80 non-residential units, and performs real-time metering of the Presidio's three incoming 12 kilovolt feeds.
The core of the EMCS is a Johnson Controls Metasys®, which connects to various application specific control (ASC) devices including DX-9100s, variable-air-volume controllers, air handling unit controllers, Veris metering modules, and Onicon Btu metering modules. These disparate devices are linked using hard wire, telephone circuits, and modem arrangements, and they are all connected through the Trust's integrated communications network using TCP/IP protocols.
Each ASC is programmed to perform its particular building control function and operate regardless of its connection to the central monitoring and programming workstations. The individual devices monitor and control building processes and energy uses. At the Presidio, the controls are typically based on time of use as well as client and process requirements.
This EMCS arrangement allows the system to adapt to the diverse requirements of the Presidio. Some buildings have minimal EMCS requirements, needing only boiler controls and submetering of electric and water consumption. Others, like the Presidio's Officers' Club, which has been upgraded to host museum-quality exhibitions, require complicated systems that balance inside and outside air temperature and humidity, heating systems, electrical submetering, and a security system.
Benefits of the EMCS
One of the benefits of the EMCS is that energy-consuming equipment can be both monitored and controlled automatically. There are many criteria by which energy-consuming equipment can be controlled, including: time of use, outside air temperature, and user occupancy. When energy-consuming equipment is not needed, the EMCS can turn off or slow down the equipment's operation. This conserves energy, minimizes maintenance requirements, and prolongs the equipment's life.
Another important benefit of the EMCS is the ability to perform submetering of electric, water, and gas usage for the Trust's non-residential tenants. Using an EMCS to provide online energy use and run-time data can be an effective tool for energy billing and for providing feedback to energy users, enabling them to monitor and control their own consumption based on quantifiable data.
The installation of any system as vast and comprehensive as the Presidio's is bound to encounter a few challenges. John Wunderlich, staff engineer at LBNL, has been working with the Presidio staff through a FEMP design assistance grant to overcome these hurdles and bring the system online.
One of the initial challenges came to light after approximately 30 buildings were brought online. Each of these buildings communicated to the operator workstation by processing data through a modem, sending it on to a network control module located at the operator workstation, and then downloading the information to the operator workstation. Since communication via the modem is much slower than a typical modem connection, there was congestion at the network control module, and the Trust would receive nearly 200 off-line messages a day. At Wunderlich's suggestion, this problem is being addressed by developing EMCS "hubs" at three remote buildings, each of which houses individual network control modules that communicate with the central operator workstation via existing fiber optic lines. With these measures, off-line messages have been practically eliminated.
The most interesting aspect of the EMCS submetering project is the unique integration of the standard, off-the-shelf Johnson Controls Metasys® system with the Trust's database and information technology. The database analysis function that will power the Internet interface was completed by a team of engineers from LBNL and the Presidio Trust at minimum expense, using readily-available data analysis software.
Future Possibilities for the EMCS
The Presidio Trust anticipates continuing to develop its EMCS as buildings are rehabilitated or as new technology becomes available. Some new EMCS applications that the Trust and LBNL are currently working on include:
Solar Photovoltaic (PV) Pilot Project—Due to the microclimates within the Presidio, the Trust must determine the most effective location for photovoltaic power generation. To this end, the Trust is currently installing a 5 kilowatt PV system, the output of which will be monitored by the EMCS and analyzed in tandem with solar radiance meters installed at the PV array and at various other buildings. The data will show power output versus solar radiance, and will show which areas in the Presidio would most benefit from PV power.
Micro-Cogeneration—In response to the recent California energy crunch and Presidential directive, the Presidio Trust has initiated a pilot project to evaluate the feasibility of using highly efficient micro-cogeneration as an alternative energy source. The operation of these micro-cogeneration units would be controlled by criteria such as time of use, outside air temperature, heat demand, price of electricity, and price of gas. The Trust is working with LBNL and FEMP to evaluate how best to integrate the Metasys® system with possible micro-cogeneration operation.
Metering of Natural Gas Consumption—The Trust is currently working with PG&E on direct digital monitoring of gas meters at select Presidio buildings. This metering system would tie into the EMCS, and the resulting data would be made available to tenants in the same format as electrical metering. The real-time metering of natural gas would allow the Trust and tenants to monitor, and thereby efficiently control, a building's total energy consumption.
Continue Installation of the EMCS as Planned—A continuing aspect of the Trust's energy management is to design and install additional controls in all online buildings to improve their energy efficiency.
With innovative sustainable technologies, the Presidio remains a well-preserved historical tribute to another era and a model of 21st century ingenuity.
For more information on the energy management system at the Presidio of San Francisco, please contact Jim Kelly of the Presidio Trust at email@example.com.