The building sector needs to modernise the communications infrastructure to meet net zero CO2 emission goals, urges Meghan Kaiserman.

 

A fundamental factor in reaching net zero is the reduction of CO2 emissions across all industries. According to the International Energy Association (IEA), the building sector is not on track to meet global 2050 net zero CO2 emission goals, specifically the 2030 target of 35% less energy consumption per square metre compared to 2021.

Buildings account for 30% of global energy consumption today, and there is concern that emission goals will not be met unless the industry takes specific action to digitise systems and implement automation. To implement effective automation more real-time data capture is needed at a level that exceeds the current throughput capacity and responsiveness of legacy RS-485-based infrastructure. In addition, connecting devices and building systems to the network exposes them to cyberattacks, requiring advanced security beyond the current capabilities of these legacy networks.

Single-pair Ethernet can help the building industry meet net zero goals while supporting AI-based automation securely and cost-effectively. Single-pair Ethernet enables long-reach connectivity to the edge for both greenfield and retrofit installations, making it a critical tool for seamless data transfer between IT and OT domains.

Digitisation for energy savings
While teaching people how to conserve energy can be effective, IEA case studies point to automation rather than behaviour change as having the most potential for energy reduction.

Increasing digitalisation of commercial buildings will enable operators to not only measure operational improvements, but also to provide the foundation for operational automation.

With access to the right sensor data and control capabilities, it is possible to optimise the operation of buildings to reduce energy consumption while best serving the people within.

For example, the need to improve indoor air quality places additional demands on building operations. New regulations such as ANSI/ASHRAE 62.1 require the intake of more outdoor air and additional amounts may be required to ensure best practices for health and hygiene. These ventilation standards will result in increased energy consumption, meaning energy demand will need to be further reduced. To achieve optimal operation, the heating, ventilation and air conditioning (HVAC) systems within a building need to be able to work.

Converging operations of HVAC, lighting, fire and access control systems require access to the right data and controls. These allow AI and machine learning optimisation to determine the ideal use of light, heating or cooling based on people’s current and planned activity. They allow control of airflow to help ensure proper indoor air quality while balancing energy consumption.

It is hard, however, to converge data from multiple systems as separate vendors maintain separate databases, leading to data silos. The challenge is to bring diverse data sources together in a single pane of glass, so that trends can be compared and analytics applied to yield new insights, as shown in Figure 1.

Modernising the infrastructure
Key to merging the many different data sources within a building is the measurement and connectivity infrastructure. Traditionally, sensors and controls in commercial buildings have been connected through wired serial communication links using RS-485 transceivers and protocols such as BACnet, Modbus and LonWorks.

RS-485 is a legacy interface that is limited in both throughput and security. For example, the maximum baud rate for BACnet MS/TP, a common building automation protocol running on an RS-485 physical layer, is 115.2kbps. Legacy communication protocols such as BACnet and Modbus were designed for closed networks and lack built-in encryption and authentication capabilities. This creates a cybersecurity threat as these devices are connected to the internet through gateways to IT infrastructure.

 

Single-pair Ethernet, specifically 10BASE-T1L, is a new communication method ratified in November 2019, IEEE 802.3cg, which is now being deployed in buildings. Wired serial link cable used for RS-485 runs can be reused with 10BASE-T1L Ethernet data running over it to adapt existing infrastructure to single-pair Ethernet.

This has many benefits. Nodes can now support higher bandwidths of up to 10Mbps. Nodes are also IP addressable, simplifying the management of devices. Another benefit is that reach increases to 1km, which is enough to support the maximum lengths used for existing RS-485 cabling runs. This is a marked improvement over standard 10Mbps/100Mbps Ethernet’s limit of just 100m.

IEEE 802.3cg specifies Class 15 and allows up to 52W of power to be sent over single twisted pair cable along with 10BASE-T1L data. Power over Ethernet controllers enable systems to deliver power to a range of end devices. Variations in cable quality mean that power delivery is recommended only for new installations.

As a first step towards digitisation, building controllers using standard 10Mbps/100Mbps Ethernet have been deployed, communicating with Ethernet-based versions of these legacy protocols, called BACnet/IP and Modbus TCP/IP. BACnet/IP devices use the same data objects as BACnet MS/TP legacy devices, so it is easy to implement a system with both types of devices.

Ethernet-connected installations with IP-based protocols such as BACnet/IP and Modbus TCP/IP that support modern cybersecurity measures are on the rise. BACnet has about a 60% market share worldwide and about 80% of new installs use wired RS-485-based serial communications. The Building Services Research and Information Association estimates that in 2019, 5% of HVAC sensors were wireless with lower connection reliability and the need for batteries limiting where this can be adopted.

Improved communications
Heating and cooling systems have multiple components that need to exchange information to achieve the temperature set point, including thermostats, controllers, air handling units and variable air volume units. Speeding up the frequency of communication from common serial baud rates of 9.6kbps-115.2kbps to an Ethernet bandwidth of 10Mbps is a substantial increase in data throughput.

There are several important benefits that come with such high-speed IP-based communications. The first is that building managers can deal with analytics not samples. The slow data rates of legacy communication means they have to prioritise what data is collected and sample it. With single-pair Ethernet, managers can stop worrying about serial communication sampling rates and focus on developing advanced analytics they can now perform with the additional data that can be collected from the system.

Additional data enables greater energy savings through faster control loops or computationally intensive energy optimisations using models and real-time sensor inputs.
Legacy-wired serial communications require a gateway to convert data from edge devices into Ethernet-based packets before passing it to the cloud. Upgrading wired serial communication links to single-pair Ethernet, 10BASE-T1L, eliminates these gateways while reusing existing cabling. This avoids data silos, reduces failure points, eliminates the cost of gateways and drives down overall latency.

Another benefit is responsiveness. Communication protocols and software running on gateways slow down response time to the order of seconds, while building automation applications such as I/O monitoring may require 100ms or lower latency. The higher throughput of single-pair Ethernet combined with the elimination of gateways means faster throughput so systems can respond in real time.

Security
One of the biggest challenges faced by building digitalisation is converging the IT and OT domains. It is possible to retrofit security into legacy RS-485-based field bus OT networks by upgrading to protocols such as BACnet/SC, but this is costly, time-consuming and can miss vulnerabilities in the existing system. Effective security is critical – building automation systems received the most cyberattacks among all industrial control systems. A 2020 study by Kaspersky found it was higher than oil, gas, energy and automotive manufacturing.

The legacy wired serial communication protocol BACnet has been adapted to BACnet/SC12, which supports secure communications on a wired serial link allowing encryption. All BACnet devices on the network need to be upgraded simultaneously to take full advantage of these new capabilities. Existing equipment using legacy BACnet will need to be redesigned and serviced to add the additional cryptography functions required for BACnet/SC. Single-pair Ethernet, specifically 10BASE-T1L, allows an edge node that had been connected using wired, insecure serial communications such as BACnet to be upgraded and connected using BACnet/IP protocol running Ethernet-based security. Importantly, this is achieved without running new, costly Ethernet cables along existing signal paths.

By upgrading devices on OT networks to run secure Ethernet-based protocols, much of the risk associated with cyberattacks can be mitigated. Single-pair Ethernet, 10BASE-T1L, has the promise of enabling the transition from insecure legacy communication to secure Ethernet-based communications with one generation of hardware upgrades while reusing existing wiring infrastructure.

Single-pair Ethernet, 10BASE-T1L, is an important technology that brings IP connectivity to the edge, improving security, reusing wiring, converging IT and OT networks and even delivering power. With significantly higher throughput, elimination of gateways and advanced security, single-pair Ethernet will help the building industry achieve the IEA’s Net Zero 2030 emissions goal. Modernising the communication infrastructure of buildings will provide access to real-time data within a building while eliminating data silos and enabling a single pane of glass approach to management. In addition to faster control loop closure for conventional control schemes and support for AI and ML optimisations, managers will be able to generate actionable insights that result in substantial energy savings.