Best practices for building integration and interoperability

Many benefits to building integration include efficiency and reduced maintenance, when best practices are followed during the design process.


This article has been peer-reviewed.Learning objectives:

  • Understand the basics of building system integration.
  • Learn about the drivers behind designing integrated systems, such as system performance.
  • Assess examples of integrating building systems.

Today, it seems that almost any daily task can be done with the click of a mouse or swipe of a finger. This convenience has led to some assumptions that a modern building automation system (BAS) will be able to deliver this same functionality. With sufficient upfront thought and planning, system functionality of unprecedented versatility and impact is possible using integration and interoperability. Projects must be designed with an understanding of how different systems can work together and what is possible to provide the features that the user and owner are expecting. However, the user and the owner must first be made aware of the opportunities to gain additional functionality for little to no added cost.

Defining interoperability and integration

Figure 1: The owner’s goal for this office building was to create an exceptional occupancy experience using minimal resources. All graphics courtesy: Affiliated Engineers Inc.From a controls perspective, interoperability is the ability of different systems to communicate using a common communication protocol. For building automation systems, interoperability typically involves BACnet, Modbus, and local operating networks (LonWorks) communication protocols, which allow different manufacturers’ equipment a way to communicate and share data. Traditional analog and digital hardwired signals are still used for simple interoperable interfaces including permissives and safety locks. Permissives are several process conditions that must be met before a piece of equipment is allowed to start.

In the building controls world, integration is the process of connecting multiple systems that control or monitor separate equipment by using interoperable parts to provide a single functioning system. Systems may be interoperable, but integration is required to make them function together.

Why do we integrate?

A building consists of a combination of many different systems and equipment that are built by different manufacturers and installed/commissioned by different contractors. An integrated building provides visibility in several ways: visibility of data analysis tools, visibility of building status to operations, and visibility of performance to building owners. When and how to coordinate the integration is a key consideration. Coordination can begin during schematic design, especially if the project is structured as design-build or design-assist, by leveraging the presence of the construction team. This allows contractors and construction managers to start understanding the level of systems involved. Understanding the payback on an investment of integrating many systems is multifaceted and complicated. Cabling costs, system-integration labor, design labor, and distributors are all things to consider as added costs. The key question concerns how quickly those costs can be offset and whether that is measurable. According to the Continental Automated Building Association, a cable-reduction savings of 56% can be realized by integrating systems and sharing cable and pathways.

 Figure 2:  The rewards for integration and interoperability are high and provide a means to increase efficiency, comfort, and reliability, and to reduce maintenance for the life of a building. What once was optional is becoming standard practice.Energy efficiency and system performance are important reasons to integrate systems. Electricity, natural gas, hot water, chilled water, and steam are common utilities in a building. For energy purposes, real-time energy demand and consumption can be trended and exported for analysis to find opportunities to improve system performance. Natural gas and electricity are usually metered by the utility provider at a building entry point for billing purposes, but for many buildings, these meters are not integrated despite the low cost—even no cost—of doing so. If energy efficiency and conservation are the main goals, then an integrated design can easily accommodate the addition of pulse output signals from the natural gas and electrical meter. Most electrical meters come standard with Modbus remote terminal unit (RTU) or Modbus transmission control protocol/internet protocol (TCP/IP) communications for additional integration opportunities that provide a more granular understanding of energy consumption and demand. The information garnered from such an interface ranges from power usage and quality to system health. Chilled-water and hot-water systems are typically designed with temperature and flow measurements that can easily be upgraded to an energy-consumption meter.

Integration can save energy through increased system performance. When packaged air handling units (AHUs) can communicate with air terminal devices, opportunities are available to reset AHU discharge temperature and pressure based on actual conditions. If lighting and HVAC occupancy times are automatically coordinated, energy savings are maximized. Integrating occupancy signals from the access-control system provides additional advanced opportunities for the BAS to determine the actual occupancy of the building and update ventilation setpoints and lighting levels based on this information.

Figure 3: Integration is connecting multiple systems that control or monitor separate pieces of equipment by using interoperable parts to provide a single functioning system. Integration is required to make interoperable systems function together.Another important reason to integrate is maintenance. Many maintenance personnel are expected to retire within the next 5 years. The facility manager for a Midwestern health care client recently determined 54% of their maintenance staff is expected to retire in the next 5 years. Staff counts are decreasing, yet the complexity in systems is increasing, usually to meet energy goals. If these advanced mechanical systems cannot be maintained, they will in some cases decrease system efficiency. For example, a heat-recovery system operating with a faulty temperature sensor may be running when it is not advantageous to save energy, resulting in wasting pumping energy, which adds to operational costs. This gap can be filled using technology and running reports to verify system health. Islanded subsystems, or systems installed without any connection to the overall network, make maintaining systems very difficult and will impact building performance for the life of the systems.

Another example of increasing staff efficiency is integrating the building automation system with a computerized maintenance management system (CMMS). This gives the maintenance staff the added efficiency of automatically generating work orders.  

Increased occupant comfort is a byproduct of integration. System data that’s introduced into the building network can be analyzed and alarmed by the BAS or interfaced with third-party fault-detection and diagnostics applications. Having all the data in one historical database is a crucial tool for troubleshooting. Visibility of systems helps increase overall reliability and resiliency by exposing data that can be used to adjust parameters, calibration, and maintenance schedules. Equipment status and operational deviations allow for proactive maintenance instead of emergency reactions.

The phases of a successful integration

Figure 4: The payback on an investment of integrating many systems is multifaceted and complicated. A key concern is how quickly additional costs can be offset and whether the savings is measurable.Standards focusing on interoperability exist (like BACnet), yet guiding standards focusing on building-integration best practices are limited. It is often left up to the controls contractor or system integrator to provide their off-the-shelf solution. In this article, we are going to refer to controls contractors that integrate multiple systems as “systems integrators” because of the added expectations of integration. Most system integrators and controls contractors have their own equipment or controllers for similar applications. A typical controls contractor is not necessarily concerned about whether the integration is successful or not, where a system integrator is concerned. This is where it is important to understand what system is being provided and what limitations may be present. For example, some controls contractors lock points available to BACnet if not specified to be exposed. Additional integration challenges include the constant evolution of software and hardware, low-bid integrator selection, time constraints, training, legacy systems, and poorly defined requirements.

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