Many of the systems that go into a commercial building are anticipated to have a long lifetime. We expect building materials such as structural steel or concrete to last for the life of the building. The mechanical and electrical systems are expected to have a service life that may be from 15 to 40 years, depending upon the systems selected. At the same time, there are parts of the building that have fairly short lives. For example, carpet and paint may only be expected to last for five years before needing to be refreshed. If we start looking at the owner’s equipment, we find that much of the IT gear, such as PCs, printers, and networking equipment, may have a service life of 2 to 5 years before becoming functionally obsolete.

So where do controls and BAS fit in this mix? Well, since they are part of the mechanical system, it seems reasonable to expect them to last for up to 40 years. In reality, some parts of the control system (such as dampers or valves) might very well last that long. But the vast majority of the control system is more similar to the owner’s IT gear than to mechanical equipment and is going to have a much shorter lifespan. How short? The answer is “it depends.” Here are some general rules of thumb:

• Software:Expect to do regular updates every few years. Software updates may provide additional features and functions, but are just as likely to repair “bugs.” Software updates are also needed to deal with ongoing changes to operating systems, hardware drivers, etc. Some owners use a service contract to keep software up to date. If you aren’t under some type of agreement, you should plan on budgeting for periodic updates.

• Building / network controller hardware:Most larger controllers, which are connected to a network, share hardware and firmware with PCs. This is hardware that is rapidly evolving and the semi-conductors, drivers, and other components are often only available to OEMs for a 2- to 5-year period. Many BAS suppliers may stockpile parts, but after a certain period of time, these products reach what is called “end of life,” after which replacing failed parts becomes difficult if not impossible.

• Application-specific controllers:The smaller controllers used for I/O controlling equipment such as fancoils, VAV boxes, and rooftops also suffer from obsolescence. In many cases, these devices may have a lifespan that is 5 to 7 years.


One of the goals of using an open protocol-based system is to be able to avoid obsolescence. While it may not make the problem go away, it does give options for dealing with system components that have reached end of life. Owners that are using open protocol systems such as BACnet® or LonMark® can often select replacement controllers from a variety of suppliers in addition to the OEM. If an owner has an older, proprietary system, replacing obsolete devices may provide the ability to move over to open systems. Owners need to be sure to ask for this functionality from their suppliers — to be sure that their upgraded system is open.ES

Paul and Ira first worked together on a series of ASHRAE projects including BACnet committee and “Guideline 13 – Specifying DDC Controls.”  The formation of Building Intelligence Group provided them the ability to work together professionally providing assistance to owners with the planning, design and development of Intelligent Building Systems.

Building Intelligence Group provides services for clients worldwide including leading Universities, Corporations, and Developers. More information can be found at We also invite you to contact us directly at or