Enhancing integration of electric and HVAC design

Know the factors to consider when working to maximize integration of electrical and HVAC system design to achieve economic and operational benefits.

07/31/2018


Learning objectives

  • Understand the benefits of integrating electrical and HVAC design.
  • Become familiar with the codes and standards that affect electrical and HVAC integration.
  • Learn about several technologies and tools that can maximize electrical and HVAC design integration.

The integration of electrical design with HVAC systems continues to gain importance and potential as building systems become increasingly complex—and more capable of sharing information.

Building systems' growing complexity, functionality, and flexibility—and their ability to integrate at higher levels—is being rapidly driven by applications made possible by the Internet of Things (IoT), which enables operational systems and subsystems to "talk" to each other and deliver more accurate and useful information to the operations staff (and improve the occupant experience). This enhanced communication and integration results in smarter buildings and enables operators to make the best-informed decisions in running and maintaining their buildings in a safe, secure, and energy-efficient manner.

Figure 1: This shows an example of a room data sheet, which may be used to communicate the project requirements in the design-development phase and construction specifications. Courtesy: IMEG Corp.The electrical and HVAC designers need to work together from the schematic design stage forward to coordinate and optimize their design integration. Taking advantage of the opportunities to maximize integration begins with a dedication to communication and a mutual understanding of each discipline's terminology and systems. They also need to compare apples to apples—if one is saying "horsepower" and one is saying "kilowatts," there is an increased chance for miscommunication and error.

The designers also need to effectively communicate with the building owner/users-a critical action for understanding the expected results of the project's overall integrated automation (IA) system and to specify the correct input points, sequences, systems, and analytical reports. An air handler, for example, will have multiple sensors with analog inputs, analog outputs, digital inputs, and digital outputs that need to be coordinated.

The designers should be knowledgeable about the benefits and liabilities of all systems being considered, provide a lifecycle cost-benefit analysis for all options, and then guide the owner/user in selections. The owner's desired results should be included in the owner's project requirements (OPR) for use during the design phase and commissioning. A multidiscipline, coordinated room data sheet or matrix of input points and building systems may be used to communicate the requirements in the design-development phase and construction specifications (see Figure 1).

Proper integration of electrical and HVAC systems also includes the rightsizing of the systems and equipment. Oversized chillers, generators, boilers, and transformers are not operating at their highest efficiency, which adds operating costs, extra space requirements, and additional installed cost.

Small steps toward integration

Who remembers pneumatic controls? Historically, electrical designers specified equipment and controls in Construction Specifications Institute (CSI) Division 16 or 26, and mechanical designers specified equipment and controls in CSI Division 15 or 23. Integration was done mainly on a hard-wired contact level between the electrical and mechanical systems.

The fire alarm system duct detector could be wired to shut down the air handling unit's starter, but it would take an additional two wires to the temperature controls to signal that the fan had been shut down and the dampers should close. This made it difficult to integrate controls.

In response, ASHRAE developed a data-communication protocol for building automation and control networks (BACnet) to allow building systems from different manufacturers to interoperate. The version BACnet/IP allows for IP subnetworks and internetworks of multiple BACnet networks. As a result, the fire alarm's BACnet interface could have bidirectional supervisory communications with the building's temperature controls over a LAN (local area network) pair of wires.

Figure 2: Integrated automation breaks down the silos of all systems. Courtesy: IMEG Corp.As building technology advances, having separate control networks for each system becomes more expensive and complex. Owners are asking for more features and integration to reduce operating costs and simplify operations. We have come a long way from pneumatic controls, and the pace of change is accelerating. The next step is to knock down the silos of disciplines that still are doing their own thing, and instead start thinking holistically (see Figure 2).

Standards for integration

Electrical and HVAC design integration is guided by standards such as those developed by Construction Specifications Institute (CSI), the Electronic Components Industry Association (ECIA), and the Consumer Electronics Association (CEA).

CSI Division 25, Integrated Automation, covers systems including building automation, energy-management optimization, lighting, room scheduling, fire detection and suppression, security, information technology (IT)/telecommunications, elevators, audio/video systems, and others. According to CSI, IA systems should be able to include renewable energy monitoring and control and be designed for single or multiple buildings.

CSI Division 25 also specifies that a building's IA system integrate the subsystems represented by the CSI Master Format Facilities Subgroup, which includes:

  • Division 11—Equipment.
  • Division 14—Conveying Systems.
  • Division 21—Fire Suppression.
  • Division 22—Plumbing.
  • Division 23—HVAC.
  • Division 26—Electrical.
  • Division 27—Communications.
  • Division 28—Electronic Safety & Security.

The CSI Division 25 specification includes common work for operation and maintenance, cabling, commissioning, network devices, instrumentation and terminal devices, control of equipment, and control sequences. Field devices, such as sensors, transmitters, and control valves, are typically connected to their respective local control panels, which communicate with the monitoring and control hardware.

In the future, an IoT device may connect to the backbone and communicate with the integrated building systems. There are wireless remote sensors and switches that make it easy to retrofit existing buildings or add a control point. The IA servers and switches could be co-located with the IT servers. An operator workstation that could monitor all the integrated systems would save space and time spent training operators on multiple systems.

For building controls integration, the ECIA and CEA have jointly adopted EIA/CEA 709.1-B-2002: Control Network Protocol Specification as an open-architecture building controls standard. This standard is approved by ANSI and was originally developed by Echelon Corp. (Echelon's LonTalk, the communications protocol that allows LonWorks-compatible control devices to communicate with one another, is based on this standard.)

Open-architecture control systems have hardware and software specifications that are public information, and available to third parties to develop equipment and software for the open system. Other communication standards are Modbus, BACnet, and proprietary standards. The norm is proprietary building automation, fire alarm, security, and other systems, which restricts the amount of practical integration. Regardless of the building controls standard used, cybersecurity must be addressed in the IA system design, specifications, and operations.

The electrical, HVAC, communication, and security designers should discuss the IA and network standards with each other and building owners-and agree on which ones to use on the project. This enables them to select and schedule equipment and reduce IA communication problems and the need for network gateways. The different systems need to be able to communicate to synergize the gathered information.

As an example, a radio-frequency identification (RFID)-tagged employee badge could initiate the access-control system to communicate with three other building systems provided by different contractors, sending the signals that could turn on the designated lights, activate the occupied setpoints, call the elevator to the entry level, and log the employee number.

The integrated automation system could be provided by the building management/automation system (BMS/BAS), the electrical contractor, or an independent integration contractor. Many of the large electrical equipment suppliers have vertically integrated BAS into the services and built communications and metering into their equipment. This is a trend in the global integrated automation field, with a growing market.


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