Plan For A Better BAS
In a campus environment over time, it’s not hard to lose control of the controls. When you tackle the situation for the long-term good, take time to create a master plan. Get a few tips on that here
August 5, 2013
"What a mess!”
That is the sentiment I frequently hear when many owners and managers of multiple building portfolios begin to respond to my query, “Tell me about your building automation systems and controls.”
Whether it is a college or university campus, an airport, or a collection of federal, state or municipal government buildings, this seems to be a recurring theme, regardless of size and complexity. Without a firm long-term plan in place, multiple building environments evolve organically, and their building automation and controls portfolio can be examples of the principle of ever-increasing entropy. After many years of evolution, the result is often a BAS mix of hardware and software — open and proprietary, ancient to state-of-the-art, ranging from stand-alone thermostats to commercial BAS/controls to industrial controls.
CITY OF HOPKINS: A MICROCOSM OF THE USUAL SUSPECTS
It is this very scenario under which I recently conducted the BAS and controls planning process for the City of Hopkins, MN. The City of Hopkins is a small town of about 20,000 people residing in the western suburbs of Minneapolis/St. Paul. Like any small town, the city has an assortment of public buildings. Those within the scope of planning include the Activity Center, Center for the Arts, City Hall, the fire station, Ice Pavilion, and Public Works Building. While not a major airport or a university campus, the City of Hopkins is a multi-building microcosm that presents all the usual suspects encountered in BAS and controls assessment and planning. An overview of the facilities will help us get started. All of the buildings have relatively modern fluorescent lighting systems; however, mechanical HVAC systems and BAS and controls vary considerably, and are summarized in the table on the next page.
The usual suspects comprising various challenges include:
- Buildings of different ages, with the years of construction ranging from 1954 to 2004
- In some cases, buildings underwent retrofits or renovations
- Buildings with no existing BAS or network infrastructure
- Buildings with legacy proprietary systems
- A variety of equipment and communication protocols
MASTER PLAN PROCESS
The process of BAS and controls planning is best explained in the larger context of a BAS and controls retrofit or upgrade program.
The deliverable of this process is the master plan, comprised of the outcomes of each stage. The plan establishes a documented foundation and rationale for the implementations that may follow. In the case of the City of Hopkins, the master plan will serve as guidance for an initial upgrade to City Hall, the fire station, the Activity Center, and the Center for the Arts. But the devil resides in the details, and for each of the requirements categories, the previous questions and many more need to be addressed. While the planning stages are fairly self-explanatory, the three central stages deserve further discussion.
STAGE 2: REQUIREMENTS
Establishment of a set of high-level requirements pertaining to building automation and controls is a key element of the master plan. Combined with a thorough understanding of the building’s systems, these requirements are intended to serve as guidance for development of more detailed engineering design and specifications. It helps to group the requirements by category from the building owner’s perspective. Common categories may include the following:
- Infrastructure and technology. Focused on the underpinnings of BAS and controls, these requirements set direction for foundational elements such as network infrastructure, open standard communication protocols, and user interface platforms.
- Energy and sustainability. Requirements pertaining to functionality necessary to maximize efficiency and/or sustainability.
- Operations and maintenance. Operational requirements are process-focused with intent to establish the basis for and enable continuous improvement of building operations, maintenance, and energy management.
- Financial. Parameters for cost/budget and return on investment.
Selected City of Hopkins’ requirements are listed in Table 3
STAGE 3: EVALUATION
The evaluation stage considers the various options for the BAS architecture and technologies with the requirements as a backdrop. Issues such as feasibility of integration of existing systems and support for required control sequences are evaluated. If required, a cost-benefit analysis may also be part of this stage, including incorporation of potential utility or other incentives.
STAGE 4: CONCEPT
We’ve all seen them: The tiered architecture diagrams that seem to look very much the same from one BAS and controls offering to the next. What is truly important is the adaptation of such an architecture diagram to the city, campus, or portfolio of facilities. While it may be conceptual in planning, laying out the system architecture provides a vision for how systems will connect, and where and how users will interact. Refinement of the architecture comes through iteration by testing the architecture against the requirements. Let’s examine a few aspects of the City of Hopkins’ proposed system architecture with respect to the selected requirements.
Perhaps one of the most critical aspects of the system architecture is the network infrastructure. The network infrastructure is a critical part of any distributed computing system, and for building automation and controls, this holds true. The primary question when it comes to setting the direction for the network infrastructure for building automation is: Will the network be dedicated or shared?
• Dedicated network. A dedicated network offers some advantages in that its sole purpose is to serve the BAS and controls. It can be administered and maintained independently. However, external and remote access requires a dedicated Internet connection.
• Shared network. Utilizing the existing business network as infrastructure may be considered as the necessary structured cabling may already be in place. Also, this network may be maintained by a dedicated IT staff. Use of a VLAN with MAC address binding is recommended to segregate building systems from other network traffic and to further ensure secure communication. This option also paves the way for connection to other facilities and branches, and typically offers existing paths for secure remote access.
As indicated by the requirements, the City of Hopkins elected to use their existing shared network. Dedicated or shared, most BAS/control networks share a range of attributes that need to be considered, including:
- Network security
- Accommodation of existing systems as well as new systems
- Interconnection of buildings within a portfolio
- Scalability of the system to accommodate future additions
COMMUNICATION PROTOCOLS AND TECHNOLOGIES
One cannot discuss core attributes of a BAS without mentioning communication protocols. The use of open standards such as BACnet, LonTalk, and Modbus are proven (albeit imperfect) solutions for integration of building systems and equipment. At the enterprise level, integration requires use of more IT-centric solutions such as XML, web services, and integration with databases. But for building systems, the most common options for establishing common denominators remain BACnet, LonTalk, and Modbus. Table 4. further describes some of the most prevalent technologies and protocols, as well as some emerging ones.
Beyond the application of open standard communication protocols and technologies, for both BACnet and LonTalk products, there are means to further assure compliance with the respective standards. Both organizations field a testing and certification arm.
For BACnet, BTL, or the BACnet Testing Laboratories tests products. BTL Listed products are categorized by device profiles and are listed at BTL’s website: http://www.bacnetinternational.net/btl/.
Likewise, LonMark International provides testing and certification for LonTalk products. The LonMark International Certified Product Catalog lists certified devices: http://www.lonmark.org/certifications/device_certification/product_catalog/.
In both cases, be cautious of products advertised as “Compatible” or “Compliant.” Products that are not listed or marked may not have been independently tested and/or certified.
Any BAS should allow for configuration of user accounts with five basic levels of privilege at a minimum. Beyond these five basic levels, many systems allow for user access to be configured in more discrete ways. For example, an owner may want users to have access only to appropriate areas within the building(s) or campus, or to limit the types of changes various users can make.
At the City of Hopkins, the BAS users are limited to a small set of people, including the public works supervisor, a couple members of his team, and IT support. However, other people that may use such a system to span a range of roles, including:
- Building engineers/operators
- Commissioning agents
- Facility management
Means of access are as important as user roles and privileges. Most users prefer to have access well beyond the confines of a workstation. In recent years, most if not all systems offer web-based access, opening up accessibility to any device with a Web browser. Note that use on mobile devices needs to be evaluated carefully since web-based systems may not render pages for use on all tablets or smart phones. Systems also offer various options for messaging via email or text.
As noted in the sample requirements for the City of Hopkins, a graphics standard is recommended to provide clear expectations for project delivery of all BAS graphics, and to assure that the resulting graphics are consistent in content, look, and feel. The graphics standard should include the points required for each type of graphic, and what items need to be viewed only or viewed and controlled from a graphic. Typical types of graphics include:
- Floor plans and areas
- Equipment, such as chillers, boilers, air handling units, rooftop units, and terminal units
- Systems, such as chiller plants and boiler plants
Development of templates for each graphic type is a good way to standardize graphical content. The process yields benefits for all parties involved, including clear scope and understanding between the owner and contractor as well as greater ease of use for operators.
What about changing graphics after the initial installation? Almost all BAS require a set of specialized software tools to perform maintenance, service and upgrades, or to make any changes to configuration, programming, or graphics. For example, adding a VAV box or making a change to a boiler plant graphic likely requires software tools. The City of Hopkins requires the capability to make such minor changes; therefore, the necessary tools need to be provided.
TRENDING, HISTORICAL DATA, AND REPORTS
Historical data can be an invaluable tool to monitor and troubleshoot systems, and to evaluate system performance over time. However, the data collection and storage must be:
- Collected reliably, with appropriate buffering and storage media;
- Collected at time intervals and for durations corresponding with the intended use of the data; and
- Stored/archived in an open database format that can be exported for analysis in common spreadsheet tools.
Frequency and duration are key parameters to specify for each point to be trended. Some trends may only require a rolling window for a relatively short duration at short intervals, such as temperatures in an air handling unit to be used for troubleshooting. On the other hand, trends to be used for long-term energy performance, such as equipment efficiency and meter or submeter data, should be trended at longer intervals for durations of a year or more. The City of Hopkins will employ a range of trends for both troubleshooting as well as performance monitoring.
PLANNING FOR A BETTER BAS
While I believe the positive outcomes of planning will be readily apparent for the City of Hopkins, it is easy to imagine that the benefits of planning increase exponentially with the scale and complexity of a given program. As with any endeavor, deliberate forethought and planning up front mitigate risk and will yield better long-term results. Carefully thinking through the attributes of the system with respect to the owner’s requirements yields a concept that provides a strong foundation for design, implementation, and ongoing operations. A more complete list of core attributes with sample questions is provided in Table 5. in checklist form for use in planning your next BAS.