From CRACs to HVAC: Building management systems help mission-critical facilities keep humming

July 15, 2016

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By Kevin Callahan
An essential problem with data centres and other mission-critical facilities is that heat, humidity, and dust are electronics’ ‘kryptonite.’ In other words, without carefully planned measures, computer servers and high-tech hospital equipment can rapidly fail. From small in-house server rooms to the cavernous server farms powering the titans of online commerce and social networking, design professionals have become very sophisticated at limiting heat buildup, and controlling humidity and dust.

One tool increasingly relied on is the building management system (BMS). Advanced BMS monitor and control equipment ranging from computer-room air-conditioning units (CRACs) to industrial-scale HVAC systems, as well as cooling systems for specialized diagnostic and therapeutic equipment in healthcare facilities. The BMS monitors and maintains acceptable levels for heat and humidity, as well as monitors the filters used to keep dust and particulates at acceptable thresholds.

A widely cited report by Industrial Market Trends says that mainframe computers and racks of servers generate as much heat as a 2.1-m (7-ft) stack of toaster ovens. ( For more, see the article on “computer room air-conditioning unit [CRAC]” at[1]). Desktop computers dissipate their waste heat with built-in fans and heat sinks, but when dozens—or even thousands—of computer servers or other pieces of large electronic equipment are involved, sophisticated cooling systems are required.

Data centres from the Arctic Circle to the Persian Gulf
From cold Arctic regions to the sweltering Middle East, e-commerce companies are opening massive data centres to handle ever-growing Internet traffic. In all locations, keeping the servers cool is one of the highest priorities for ensuring reliable computer up-time.

Going north to stay cool
Contemporary data centres have become industrial-scale facilities, the largest of which covers 46,450 m2 (500,000 sf) or more. To cool the thousands of servers in row-upon-row of floor-to-ceiling racks in such facilities, some data centre operators are relocating to northern regions. One such area in northern Sweden (latitude 65 degrees north) brands itself “The Node Pole[2]” and now has 10 data centres.

One of those data centres—operated by one of the world’s largest social networks—cools its thousands of servers with the naturally cool, low-humidity arctic air. The fresh air flows into the facility through numerous louvres, while the waste heat from servers rises to a plenum and is moved outside by large banks of exhaust fans.

The brain behind this HVAC operation is an advanced BMS. The data centre’s managers rely on it to monitor thousands of data points, from spot temperatures throughout the facility, to the operating status of the HVAC equipment, to indoor relative humidity (RH). The system annunciates an alarm if anything goes outside specification, so managers can quickly address the problem. Managers also use data from the BMS to predict potential equipment failures so they can take pro-active action to keep the servers cool and within humidity tolerances. Beyond maintaining a comfortable indoor environment for the servers, the BMS also helps ensure servers are consistently well-fed with quality electricity.

Keeping cool in the Middle East
In a climate that is radically different than the Arctic, one of the largest data centre infrastructure providers in the United Arab Emirates (UAE) opened two state-of-the-art facilities in Dubai and Abu Dhabi in 2015. In a region experiencing average high temperatures above 38 C (100 F) for months at a time, the Khazna data centre project team set a goal of 99.997 per cent up-time—no small feat, even in a cool climate.

Ensuring servers in the Khazna facilities experience less than 16 minutes annually of unplanned outages in a hot, dry climate requires aggressive monitoring and control of the buildings’ climate systems. To maintain an indoor temperature between 18 and 27 C (64 and 81 F) and humidity between 25 to 85 per cent (with only 15 minutes allowed out of range per breach), the project team specified an advanced BMS. The BMS monitors and controls a plethora of equipment from CRAC units to chillers and air-handling systems—some 3600 controllers handling 55,000 data points.

The data centre managers experienced a real-world test of the protection provided by the BMS in spring 2015, when a weather station in the area failed. In less than 10 minutes, the temperature in the data halls had risen from 19 to 28 C (66 to 82 F); it was predicted it would reach 40 C (104 F) within 30 minutes unless aggressive action was taken. The BMS annunciated an alarm immediately, which enabled the facility operators to quickly correct the problem and ensure continued server up-time.

Advanced building management systems (BMS) are used to monitor and control essential HVAC equipment in mission-critical facilities.
 Images courtesy Alerton

Helping healthcare equipment
In the same way a BMS helps data centres maximize up-time, healthcare facility managers rely on the systems to meet their mission-critical needs. For example, the radiation-oncology department at Emerson Hospital in Concord, Massachusetts performs external beam radiation treatments using a linear accelerator. Similar to a server, the sophisticated cancer-fighting equipment must be maintained within tight temperature specifications. Hospital staff use a BMS to monitor the temperature of the accelerator’s water coolant, and annunciate an alarm if there is a problem.

Specifying a BMS
When specifying a BMS for mission-critical facilities—including, data centres and hospitals—two important performance attributes are:

System interoperability
In a mission-critical facility, the BMS might have to monitor and control dozens of different building HVAC components and systems from multiple manufacturers, such as:

The BMS might also serve as the central point for specialized alarms related to ensuring quality power, or for monitoring and controlling other building systems such as lighting.

Such ‘interoperability’ of building systems is facilitated by the industry standard BACnet protocol that was developed by the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE). Many building systems manufacturers use BACnet, which allows a single BMS to monitor and control equipment supplied by many parties. Therefore, rather than controlling HVAC equipment and power distribution from different systems, a BACnet-enabled BMS manages both from a single platform, which greatly simplifies work for facility operators. Further expanding interoperability, some BMS control modules incorporate multiple protocols.

Mobile access
Given the mammoth size of today’s data centres, managing these facilities efficiently and effectively requires remote access to the BMS. It is inefficient to have one person in the field and another back in the control room, communicating via walkie talkie or cellphone.

Thanks to the mobile technology revolution, building operators/engineers can now access their facility’s BMS from anywhere in the world with an Internet connection. A person in the field working on a malfunctioning CRAC or air-handler can now immediately see the outcome in the BMS via portable tablet. By untethering from the desktop, building professionals can accomplish more tasks during their shifts and can increase independency.

Healthcare facilities often use their BMS to help monitor and control environmental conditions for sensitive life-saving electronic equipment.

This freedom was made possible by wireless networking and communications, including both cellular and Wi-Fi technologies. Some BMS are built on the latest edition of HTML (HTML5), which now delivers complete user management of trend logs, alarms, and schedules via a web browser without the hassle and potential compatibility problems of installing a third-party’s plug-in. As a result, facility professionals can monitor and control building systems from tablets, smartphones, or any Internet-enabled device, including their desktop computer. This is especially important in large data centres where employees must use scooters to travel throughout the cavernous indoor space.

While connecting to a BMS by cellphone is possible, most operating personnel prefer a tablet because a cellphone screen is too small for many BMS applications. However, at least one BMS developer is working to empower its dealers to customize the system for a smartphone ‘form factor’ (i.e. small screen size), which will look and function like other cellphone apps.

What about energy efficiency?
In facilities such as K–12 schools, universities, offices, and hotels, the driving factor for specifying a building management system is often a desire to minimize energy-consumption costs. However, in mission-critical facilities, energy use tends to take a backseat to ensuring continuous operations of crucial equipment.

That is not to say power consumption is not important in mission-critical facilities, which use enormous amounts of electricity. Rather than focusing on total power consumed, data centre operators evaluate power usage effectiveness (PUE), which is the ratio of total energy used in a facility to the energy consumed by the IT equipment. By paying careful attention to this metric, the goal is to use as little power as possible for anything other than the computers themselves.

As in other buildings using BMS, an appropriately appointed system allows data centre professionals to monitor trend logs on energy usage to figure out places to squeeze out more savings, while still keeping the computers humming 24-7.

Kevin-Callahan-AlertonKevin Callahan works for Alerton, a Honeywell business specializing in building management systems. He has 39 years of experience in the building control technologies field, including control systems design and commissioning, facilities management and user training. Callahan can be contacted via e-mail at[3].

  2. The Node Pole:

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