BAS

What are the main advantages of using network-based control systems?

Westphal: In this case, the main advantage is the ability to monitor and control the operation of various systems in buildings from anywhere with Internet access and at any time of day using standard browser programs.

The second major advantage is that in Microsoft's Windows operating systems, the browser programs for browsing pages are, in most cases, free.

Lundstrom: Network-based BAS provide easier remote access to the control functions of various building systems for building operators and building managers.

This allows them to carry out troubleshooting work even outside working hours, provided that the IT departments allow remote access through the firewall.

In addition, the time required to train BAS operators to use the relevant systems is significantly reduced, since most of these workers already know how to use web browser programs.

Tom: I believe the main benefit, in this case, is the revolutionary improvement in accessibility.

In the past, very few people knew how to operate BAS, which were designed around dedicated workstations, and often, when technical problems arose, they simply disconnected some of the data points or stopped using entire BAS units due to problems accessing the system's core functions.

Nowadays, engineers, managers, and inspectors can access BAS directly from their computers, and technicians can use laptops to do so, connecting them to wireless networks or to local Ethernet networks in the computer rooms.

Maintenance personnel can access the system from their offices, which reduces maintenance costs by eliminating the need for on-site visits. Consulting engineers can analyze problems from anywhere in the world.

Another advantage is that the system is monitored by many people, and careless operators are less likely to resort to simple temporary solutions when problems arise, which in turn increases the reliability of the system.

Another advantage of network-based systems is the use of Internet-based solutions.

Even the largest HVAC manufacturers used to have only a few specialists developing user interfaces for BAS.

Now, an army of engineers, both in Silicon Valley and around the world, are developing new network-based solutions, many of which can be directly used in BAS.

Does this affect the interoperability of systems?

Tom: For years, engineers have talked about creating energy management systems based on time-of-day energy cost schemes, using weather forecasts to control large refrigeration units, integrating building security systems with command and control systems, and other tasks that require linking large numbers of computers.

The implementation of such schemes has always been possible with the availability of compatible computers and software and an unlimited budget for writing additional programs to integrate all the components of the system into a single whole, but modern developments in technology have made it possible to implement such projects in practice for a wide range of tasks and types of computers.

How popular have building management systems based on network technologies become in the last couple of years?

Westphal: The optional web-based user interface has become an almost mandatory element of the specifications ordered for BAS in recent years, as many manufacturers offer systems with such an interface as part of their product range.

Indeed, some BAS manufacturers use it as the basis for their user interfaces.

It is also implemented because in most cases the presence of such an interface increases the attractiveness of BAS for users and allows to increase the income of their manufacturers.

Lundström: Given a choice, building owners in 99% of cases choose systems based on network technologies, and not based on special software.

As a result, almost all major suppliers of such systems offer their customers at least several solutions based on network solutions.

There are now even small hardware platforms available for $1,000 to $1,500 with built-in web servers that can be mounted on rails in the same niches where building controllers are installed.

These platforms connect to the controller via LAN or IP protocols and are used to create a network graphical interface, set schedules, record trends, and manage alert messages.

How well do these systems handle network security?

Lundstrom: Security is improving, but a lot of it depends on the building owners' IT departments.

Since most of these systems use Windows operating systems, they are subject to all the same standard network security issues that are found in these operating systems.

Even some network controllers that can be configured to act as web servers have embedded operating systems based on the Windows platform.

If not properly protected, they are vulnerable to infection by worms via network connections.

Tom: Network-based BAS require the same network protection measures as any web servers in computer networks.

However, a common and very frustrating situation is when an end user already has several web servers on the network, but the IT department refuses to provide an Internet connection for the BAS. This is mainly due to issues of training and coordination of the IT department employees.

They need to have more information about the BAS, and they must provide these systems with the same level of protection as for other web servers.

In addition, if any part of the IT network is to be set up as part of a BAS, then no matter how extensively the system uses networking support, it is necessary to coordinate the system with the IT department early in its design and maintain these contacts throughout the entire period of the system's creation and use.

How can we ensure that the operator can manage the operation of the various systems in the building even in the event of a network or BAS failure?

Tom: The same measures should be taken as for a normal BAS.

A distributed control and management system based on independent controllers is required to maintain comfortable conditions in buildings, turn on and off various systems according to a specified schedule, and generally maintain normal operation of the BAS until the network is restored.

In addition, each controller must have a local access port that allows operators or technicians to connect a laptop or other portable devices to it to make the necessary changes.

In such a situation, a local operator terminal improves the usability of the system, but it should not eliminate the need for a local access port.

Typically, a local terminal can be used to check the status of system elements, change schedules and settings, and perform other routine functions, but to change the program being used or make other major changes, a local access port must be used.

Lundstrom:To improve the reliability of BAS operation and the ability to use local control in the event of a system failure, engineers and building owners should consider the following points:

First, carefully review the system architecture and determine how the network GUI will be generated.

Depending on the vendor and platform used, various options for devices can be used to create a graphical interface, including: single web servers, multiple web servers, single or multiple network controllers to implement network services, and hardware servers with the ability to use network functions.

If reliability is a particular concern for the owner, then the choice should be made in favor of systems with multiple web servers or devices that provide additional reliability compared to systems built on single devices.

Second, minimize the software logic for managing building systems at the server or network controller level.

Failure to do so could result in the loss of a significant number of control functions if one of the servers or network controllers “crashes” (fails) while performing some critical calculations.

Third, make sure that the local network is connected to the LAN controller. In this case, if the IP connection is lost or the web server fails, the control functions of the various systems in the building will still be available.

What are the latest advances in developing user-friendly graphical interfaces for BAS users?

Lundstrom:They include everything from simple menus, animated 3D graphics, color-changing backgrounds, photographs, embedded trend charts and links to manufacturers' data sheets, CCD and webcam images, to links to electronics manuals and operation and maintenance manuals for a variety of equipment, including even CNN news and weather forecasts from major channels.

Owners of large buildings are developing control centers that allow BAS operations to be controlled from a single location.

These centers consolidate all operations with the BAS graphical interface.

This involves using one large room with several operator consoles to monitor and control the BAS and manage everything from HVAC to general and fire safety systems.

Tom: Having a graphical interface should help operators understand the operating status of the system in the shortest possible time in the most intuitive way.

In this case, animation has been shown to help users determine what is happening in the system, such as in the case of images showing the rotation of a fan or the actual position of the dampers.

However, animation can sometimes be detrimental, for example if it distracts the operator or draws his attention to information that is of little importance at the moment, such as an image of condensation dripping from a cooling coil.

Another useful feature is the use of slider-based controls, provided that they are easy to operate and provide sufficient resolution for the user.

Sometimes it is useful to have an alternative input system based on direct entry of the required values ​​- this is often easier than trying to set these values ​​using sliders.

Accordingly, a good GUI should be able to use both of these data inputs.

In addition, such an interface makes the most important information as clear as possible and allows for sequential retrieval of more detailed information on different sections.

How practical is it to use PDAs and other devices to monitor and control the BAS?

Westphal:I don't think using a PDA is practical enough in this case.

The cost difference between a cheap laptop and a PDA is fairly small, but the usefulness and range of features of a laptop is many times greater than that of a pocket computer.

This is more of a specification issue at the moment, and for already heavily loaded operators, learning to use a PDA is not very convenient.

Tom:I believe that PDAs are great for the role of an auxiliary interface.

PDAs are very useful for HVAC technicians because they can receive warning messages, reset setpoints, restart equipment, and perform hundreds of other tasks on the fly.

In addition, most test and adjustment technicians find it easier to carry a PDA than a laptop, as long as the PDA has a well-designed interface that allows them to perform all the necessary operations to test and adjust equipment and document the information they collect.

On the other hand, power engineers, systems managers, and other workers who primarily perform their duties from offices require a full-size graphical interface and a full keyboard, which only personal computers can provide.

The problem is determining what information should be displayed on the PDA screen.

If you try to display all the information on a regular computer screen on a PDA screen, it will all become too small for the user to understand.

For this reason, interfaces for PDAs must be designed much more carefully than for personal computers.

What types of operations do BAS operators actually perform?

Lundstrom:Operators use PDAs and SMS messaging on mobile phones to monitor alarms and conditions in the buildings they monitor. Functionally, existing PDAs can be used to perform basic monitoring functions, receiving and processing alarms, and operations using simple menus and simplified graphical interfaces. PDAs are more convenient than pagers for receiving long alarms and reading detailed information, but the size and resolution of PDA screens still do not allow for graphical interfaces equivalent to those found on desktop personal computers.

What technologies need to be improved for network-based BAS to become more widespread?

Lundstrom:Currently, there are still differences in functionality between web-based technologies and more traditional architectures that use web solutions only to create the user interface.

The focus is on using XML technologies for day-to-day data transfer, but it is also important to understand that data can be made available to web services.

Building owners should not expect any existing BAS to be able to provide them with full monitoring, control, and scheduling capabilities through the use of standard web browsers.

The reality is that network services were not originally designed specifically for real-time monitoring and control tasks, but the future is promising.

More and more mechanical systems are being equipped with network hardware servers with pre-installed software to manage and control them during factory manufacturing.

Such mechanical systems can be easily integrated into BAS using simple IP connections.

Small ultra-portable computers with Wi-Fi interfaces for wireless connections will gradually replace PDAs for network interfaces and will be used to run web browsers, email clients, instant messaging, VoIP, and other applications.

Based on material from the journal Consulting-Specifying Engineer (CSE)