Modern chillers have sophisticated control systems and highly advanced load management programs. The chiller controls are integrated with the Building Management Systems (BMS) which have control and monitoring capability, depending upon the complexity and requirements of the HVAC system. Typically, the BMS system would cover AHUs, temperature sensor in the workplace, air quality sensors etc. and allow the operator to monitor and control the entire HVAC system operations from one location. The BMS is connected to the sensor or equipment through wiring laid out throughout the building at the construction state.
However, BMS systems rarely work at the level of sophistication and complexity that they were designed for. The reasons are many – the BMS system not commissioned or not commissioned properly due to cost or time constraints, faulty sensors that don’t get replaced, poor support from OEMs for the software upgrades etc. The problem gets more acute in older buildings where the BMS system is a legacy one and spare parts are not easily available. Changing a BMS system is also not an option as the wiring is not easily accessible in older constructions.
A new wireless technology is now helping designers and operators to get free from the “wires” literally and use low frequency radio waves to communicate between sensor and the control systems wirelessly. LPWAN (Low Power Wide Area Network) systems integrated with IoT devices can cover wider distances, use less power and the radio waves can pass through building walls. This article describes in brief what is LoRaWAN and how the HVAC and Building industry will benefit from this technology soon.
What is LPWAN
The Low Power Wide Area Network is an alternate to the cellular and Wi-Fi networks that are currently used to connect sensors and devices. The LPWAN system uses LoRa technology (owned by SEMTECH) based devices that use the LoRaWAN protocol which has been developed by the LoRa Alliance, a non-profit industry organisation that oversees the development of the protocol. There are over 100 countries where LoRaWAN applications are in use across various industries.
LoRa technology uses the unlicensed radio spectrum and the LoRaWAN protocol lays down the standards for data packet transmission and sharing. The key advantages of a LoRa are
1. Low power: The technology uses very minimal power compared to current technologies and hence, allows batteries of remote IoT devices to last longer, even up to multiple years.
2. Range: This is one of the key features of the technology as the range is as far as 5 km in urban settings and 15 km in open rural areas.
3. Cost: Since the coverage is wider and the protocol is based on unlicensed radio frequencies, the cost of setting up a network is substantially lower than a wired or Wi-Fi based system.
How does a LPWAN Work?
The architecture of a LPWAN based network is very similar to wired systems. Figure 1 shows the physical configuration of such a system.
The LPWAN based sensors use the LoRa technology to generate the wireless communication signals of the real-world data (temperature, pressure, location etc.). These are transmitted to the LoRa Gateway. A single gateway can connect from 8 – 64 devices and the data are then transmitted to the network servers. Once data is online, then it can be analysed using data analytics programs to both control and monitor the end equipment’s systems.
Applications of LPWAN
There are many use cases of this technology and with over 100 million IoT devices already deployed, the number is only growing. Due to the wider range and reach of the technology, deployment in smart cities will see more uptake soon. For the building and HVAC ecosystem, the use cases are multitude. The key barrier to automating HVAC system operations has been the high cost and effort associated with installation of wired BMS systems in buildings. With the LPWAN approach, this barrier can easily be overcome as the cost of installation and deployment is relatively low and fast. The setting up of the system is also much easier and faster, with local systems being set up in under an hour. Some of the areas where LPWAN systems are being used in the HVAC and building environment are shown in figure 2:
HVAC Retrofit Applications
Many older buildings and HVAC systems do not have capabilities to integrate with online systems and still depend on highly manpower intensive approaches for operations and maintenance. This not only increases the cost of the operations, it also does not give the operator enough time for responding to breakdowns and emergencies. Installing a BMS system into an existing building is a very laborious task as well as expensive due to the large amount of cabling that needs to be done. Wi – Fi based systems have also not been very effective due to the low penetration of the signals across floors and walls of the buildings. To take advantage of the power of data analytics and machine learning even in such legacy systems and older building, the LPWAN approach is ideal. The quick set up times and lower cost allow an existing building to quickly turn into a smart building with connected systems and online data collection. Legacy chillers, AHUs, pumps, cooling towers can all be connected to a central management tool using the LoRa based sensors that capture temperature, pressure, flow etc. The LoRaAlliance has helped developed a large array of sensors to suit almost any requirement in the HVAC industry and the open protocols allow for new sensors to be developed in short timelines.
Building engineers operating legacy systems in older buildings have always faced a challenge of upgrading these systems and bring them ‘online’ so that the operations can be more effective and efficient. The key issue has been the difficulty in upgrading the wired BMS system or adding on more sensors to the system due to both cost and complexity. The LoRa based systems are an answer to this problem as it frees the system from wiring and at the same time, at an affordable cost. The system reliability is not as high as a wired system but in non-mission critical systems, this slight disadvantage can be compensated by better system design. Data is the new oil in today’s technology driven world and it has the power to transform operations of HVAC systems. This new technology has the power to automate as well as digitize legacy systems and get them onto the data highway.
Executive Director – Operations,
for a leading real estate services firm