Ready for Takeoff
How does one get from a "green" building that merely looks environmentally friendly to an intelligent, high-performance building? The answer is already before us—traditional building automation. BAS may not be the first thing that comes to mind when contemplating green products, but its importance has clearly been recognized by one of the leading agencies on sustainable design, the U.
How does one get from a "green" building that merely looks environmentally friendly to an intelligent, high-performance building? The answer is already before us—traditional building automation.
BAS may not be the first thing that comes to mind when contemplating green products, but its importance has clearly been recognized by one of the leading agencies on sustainable design, the U.S. Green Building Council and its Leadership in Energy and Environmental Design program. In fact, USGBC is very specific on the matter, allowing LEED credits in several different areas through the creative use of building automation. The following is a primer on those credits, as well as a look at how building automation can better be optimized in general.
BAS, ASHRAE 90.1 and LEED
Before getting into specifics, it is useful to step back and examine ASHRAE 90.1-1999, "Energy Standard for Buildings Except Low-Rise Residential," which is actually a LEED prerequisite.
Since the release of the 1999 version, BAS and controls systems have become the major focus for what ASHRAE feels are the keys to achieving significant energy savings. With the release of the 2002 edition, building envelope and lighting requirements did not change substantially, but the controls-related requirements within the HVAC section expanded significantly. In fact, most of the mandatory and prescriptive HVAC provisions are controls-related. For example, energy code features include: zone thermostatic controls; automatic shutdown; setback controls; optimum start/stop controls; zone isolation; demand-controlled ventilation; air and water economizers; humidification; VAV fan-speed controls; and VAV static pressure reset from terminal box positions. None of these operations could be performed efficiently today without the use of networked digital BAS controllers.
More specific BAS examples in 90.1 include sections 18.104.22.168 Off-Hour Control and 22.214.171.124 Ventilation Controls for High-Occupancy Areas . In order to meet the requirements of 126.96.36.199, a BAS must include automatic start/stop of systems under different time schedules or for different occupancies; automatic heating setback and cooling setup during unoccupied hours; and optimum start controls. As the 90.1 user's manual recommends, the best way to determine optimum start times and set-point temperatures is by trial and error once the building is occupied. Ideally, optimum start controls will start the system to provide just enough warm-up or cool-down time to bring spaces to occupied set point at just the right time. Because of the complex ways energy is transferred in and out, and stored within a building's mass, it is very hard to predict ahead of time these "optimum" schedules and set points. BAS allows a building operator a simple way to make changes and adjustments to tune the controls closer to the ideal setting for this "off-hour" control. The hope is that BAS will soon be able to take advantage of available and proven optimum start-stop algorithms, as well as real-time and historical operational and weather data, to make these adjustments themselves with the confidence of operators.
188.8.131.52, on the other hand, requires that outside air quantities be automatically reduced below design rates when spaces are partially occupied. The systems normally provided to meet this requirement are called demand-controlled ventilation (DCV) systems and they typically utilize CO 2 sensors as the indicator of bioeffluent concentration, which indicates occupancy, in order to control outside air quantities. This approach is easy to accomplish utilizing CO 2 sensors and control components integrated with a standard BAS. Integrating these sensors into a BAS provides the additional benefit of being able to trend these space occupancies utilizing the CO 2 sensors for other purposes.
The BAS requirements and opportunities listed above all apply to meeting the LEED energy and atmosphere prerequisite 2, but BAS plays an even larger role in achieving other LEED credits.
Moving on, the next significant opportunity is the Energy & Atmosphere Prerequisite Credit 3— Additional Building Systems Commissioning . This credit highlights the importance of building systems commissioning through the life of the building by requiring the development of a recommissioning management manual to be used for near-warranty-end or post-occupancy reviews. BAS has the tools necessary for collection, storage/retrieval, analysis and visualization of equipment and systems operating performance. BAS diagnostics and data visualization tools are available but must be specified to be able to support continuous commissioning plans.
Next is the Energy & Atmosphere Credit 5— Measurement & Verification Utilizing BAS . This credit requires an owner to provide metering equipment for major end users within the building in order to provide ongoing accountability and optimization of building energy consumption over time.
In addition, an owner is required to develop a measurement and verification (M&V) plan that incorporates the monitoring measurement and control parameters from the sensors and metering equipment, with the M&V plan required to follow the International Performance Measurement & Verification Protocol (IPMVP) Volume 1: Concepts and Options for Determining Energy and Water Savings . The IPMVP provides a methodology to accurately catalogue baseline conditions, verify proper operation and confirm the quantity of energy savings.
LEED Credit 5 requires a building owner to follow M&V Options B, C or D within the IPMVP, which requires some sort of submetering to be utilized to confirm energy savings. Permanently installed metering tied to the BAS provides the best opportunity to fully integrate the M&V plan.
Incidentally, M&V will play a key role in an engineer being able to optimize the BAS. It's simply a precursor to what is ultimately needed for BAS: reliable predictive control functions. The M&V data gained by the LEED requirement provides the much-needed information on how systems are utilized and performing so that the BAS can be programmed to react to real-time operational histories.
This data can be utilized by a BAS to know when to shed non-critical loads, diagnose system/equipment inefficiencies and improve overall system performance.
Next up is the Indoor Environmental Quality—Prerequisite 1 and Credit 1— BAS and Indoor Air Quality . The IAQ prerequisite calls for meeting the minimum requirements of ASHRAE 62-1999 & 2001 Appendix H, Ventilation for Acceptable Indoor Air Quality . BAS has played a pivotal role in measuring and maintaining the required minimum ventilation rates since the inception of this standard.
Also, LEED for New Construction Indoor Environmental Quality Credit 1— Carbon Dioxide (CO 2 ) Monitoring requires permanent monitoring with feedback for operational adjustments of space ventilation performance per ASHRAE 62-2001 Appendix C. BAS is, without a doubt, imperative to perform this function.
Another achievable LEED BAS credit is Indoor Environmental Quality Credit 6.1— BAS and User Controllability of Systems . To earn this credit, a user is required to have operable windows and lighting controls. BAS, specifically, can be used to allow building occupants manual control of operable motorized windows. BAS can also be used to warn occupants of impending weather conditions or non-optimal outdoor conditions by allowing manual control overrides that can react to data generated from weather stations or remote warning systems.
Another important occupant control LEED BAS credit opportunity is Indoor Environmental Quality Credit 7.2— BAS and Thermal Comfort . The stipulations of this credit are that a permanent temperature and humidity monitoring system be provided and configured to allow building operators to control thermal comfort performance and effectiveness of humidification and dehumidification systems. Strategically located temperature and humidity sensors, integrated with BAS to control the HVAC systems, is the most commonly utilized approach to meet this requirement. The intent is to allow building users greater control of their working environment in order to improve overall worker productivity, as well as the health and well-being of building occupants.
As an additional point, LEED for Existing Buildings has utilized the U.S. Environmental Protection Agency's Energy Star label benchmarking tool as the Energy & Atmosphere Prerequisite 2 standard. To qualify for this prerequisite, a building must achieve a score of 60 or better utilizing the Energy Star benchmarking tool. Many BAS functions, including those listed above to meet ASHRAE 90.1, can be utilized to improve the energy performance of a building to meet this prerequisite.
Building sustainability requirements, as defined by LEED, could prove to be the catalyst for integration and the ultimate application-driven environment for user interactive connectivity of the various packaged building control subsystems that will maximize the potential of BAS. In fact, the promise of multi-system interoperability is getting closer to reality in the controls market due to advances in network connectivity and the availability of standard communication protocols.
Specifically, continuous advancement in microprocessor and distributed open network technologies, as well as the application of software concepts migrating from industrial environments, is allowing BAS to quickly move from simply controlling and monitoring a building's renewable and non-renewable energy and water resources to truly optimizing the allocation and consumption of these resources. For example, one potential application is to learn from actual operations and weather histories. This data can then become operational and seasonal trend information that the BAS automatically uses to adjust control parameters and schedules.
The potential for this strategy has been available for years, but the user friendliness of the new generation BAS human-machine interface (HMI) products, as well as the emerging data-harvesting and analysis software, have truly driven this optimization to the foreground. Moreover, the long-desired ability to interactively aid building operators in the detection and diagnosis of operational problems for large HVAC systems is also on the horizon. It all comes down to meeting the expectations (as shown in Figure 1, on p. 32) that the operation of systems and equipment does not violate the rules of normal operation. The basis for these expectations can be confirmed from periodic historical averages determined by BAS-run mathematical models or data gleaned from expert knowledge that is, in turn, compared with actual BAS measurements and calculations. These expected-vs.-actual results are the foundation on which commissioning activities are planned and executed.
BAS is also being used to provide a larger range of individual user control options over all environmental conditions—temperature, airflow, lighting, ventilation and the like. These changes are expected to yield significant improvements in worker productivity. Some BAS suppliers have even developed personal environment products that allow users to regulate airflow and temperature at their workspaces.
Another exciting BAS frontier involves web services. Several open communication protocols and technologies have been developed over the past 10 years, such as OPC, LON and BACnet, with the intent of allowing BAS from different manufacturers to interact effectively. Recent changes to the BACnet standard include the use of web services to provide a means of integrating building automation and control systems with other computing applications. I/P gateways will still be required between different protocols, but the development of these gateways is getting easier and less expensive. Therefore, connectivity should not be seen as a limiting factor.
The development of applications, however, is another story. Potential uses of web-based technology will open the floodgates to the newer programming talent in the HTML- and XML-based web-programming world. Web-based BAS, which enhances real-time data acquisition and performs continuous building diagnostics and commissioning, is not yet common practice. However, the enhanced data visualization capabilities of web-based BAS will allow this detailed data to be utilized from the global-system-level to the subsystem-equipment-level diagnostics. Web-based BAS can provide enhanced graphics to analyze time-series data to help facility operators analyze their building systems. Most web-based BAS that have actually been installed have these enhanced analysis and reporting capabilities. Unfortunately, they are not being utilized to diagnose or to make operating decisions. However, it is just a matter of time until the tide turns through training and experience. And with the lessons learned, interactions will be made possible by the Internet.
The intended result of all this technology is to simplify access to building energy and performance data—defined in the M&V plan—for inclusion in BAS databases that would:
Generate comprehensive building systems-performance verification reports.
Access equipment run-time data for use by maintenance management systems.
Allow tenants partial control of space temperature set points.
Couple room scheduling with ventilation and comfort control.
Implement specified BAS applications to support the verification of the LEED sustainability goals.
There is always a tendency by building owners and operators to require the building controls and BAS to be simplified to match the competency level of the maintenance staff working for them, relying on the KISS—Keep It Simple...and Straightforward—principle. However, if the right approach were always to keep things simple, we would still be hand-cranking our automobiles and adjusting the choke from the steering column just as Henry Ford did nearly 100 years ago. Ever-improving technology has revolutionized the automobile in less than a century; it's now time for the buildings we live and work in to become as intelligent and high-performance as the cars we drive, by continuously exploring ways to maximize the use of BAS in light of new products and applications.
Additional BAS Resources
"An Overview of Building Diagnostics," John M. House and George E. Kelly, National Institute of Standards and Technology, Diagnostics for Commercial Buildings: Research to Practice, June 16%%MDASSML%%17,1999, Pacific Energy Center, San Francisco.
Document LBNL-5251, "Web-based Energy Information Systems for Energy Management and Demand Response in Commercial Buildings," Naoya Motegi, Mary Ann Piette, Sat-kartar Kinney and Karen Herter, Ernest Orlando, Lawrence Berkley National Laboratory, April 18, 2003, California Energy Commission.
Public Interest Energy Research Program, High Performance Commercial Building Systems.
LEED Green Building Rating System for New Construction and Major Renovations (LEED-NC) Version 2.1, Nov. 2002, Revised March 14, 2003, USGBC.
ANSI/ASHRAE/IESNA Standard 90.1-2001, ISSN 1041-2336 Energy Standard for Buildings Except Low-Rise Residential Buildings.
Professional Engineer's Guide to the ENERGY STAR Label for Buildings, United States Environmental Protection Agency, Office of Air and Radiation (6202J) EPA 430-F-01-XX, June 2003.
ANSI/ASHRAE Standard 135-2001 and 135.1-2003, BACnet—A Data Communication Protocol for Building Automation and Control Networks.
•The International Energy Conservation Code, formerly known as the MEC. The IECC was published in 1998 and 2000. The 2000 IECC with supplements was published in 2001.
San Francisco Announces Green Building Ordinance
The city of San Francisco has announced the adoption of a green building ordinance that requires all new projects, including city-owned facilities and leaseholds, to achieve a LEED Silver certification from the U.S. Green Building Council.
San Francisco's green building ordinance will apply to all new city construction projects, renovations and building additions. San Francisco joins nine other cities that have adopted green building ordinances requiring LEED.
"The city's adoption of LEED Silver standards in their ordinance demonstrates San Francisco's exemplary commitment to green building," said USGBC President, CEO & Founding Chair, Rick Fedrizzi. "We look forward to more cities following their leadership."
Under this ordinance, municipal buildings will need to follow green building design principles, which will help to create healthy workplaces and increase energy productivity. According to Jared Blumenfeld, director of the San Francisco Dept. of the Environment, the ordinance will also literally translate into millions of dollars in savings on future operational costs for new city buildings. "The ordinance is good for the city and will help improve the health of our environment and the well-being of the thousands of employees that continue to provide services for this community," he explained.