May 2014
Article
AutomatedBuildings.com

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When Building Automation Fails to Deliver

Thwarting the pitfalls of modern DDC

Zach Denning
Zach Denning
Engineering Sales
Western Allied Mechanical


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Control Solutions, Inc

We’ve all heard how amazing building automation is and of the advancements in the last ten years –  faster, energy efficient, the “total building package.” So why read this article?  Does your building, despite its intricate control system, still suffer from energy and control issues? What really drives energy reduction in a building and how can you fine tune your equipment to achieve those efficiency standards? Launching into the world of building automation requires engaging in a hybrid role of HVAC energy specialist and IT liaison – yes, this does mean a global understanding of networking! Even through complex installations, advanced control of equipment and expert commissioning, an automation system is still condemned to failure without proper operation and maintenance.

So what is the primary role of an automation system in a building? DDC controls the HVAC operation throughout a building including schedules, setpoints, and general monitoring of equipment; all in an attempt to reduce overhead costs of an onsite engineer. If the building engineer had to constantly walk around the building to observe equipment operation his preventative maintenance role would increase as much as 30-40% - and that’s not accounting for equipment failure response and associated costs. A well-installed, fine-tuned automation system can deliver amazing utility savings and reduce overhead time associated with maintenance, so how do you prevent it from costing you money?

Typical modern control systems deal with intricate, multi-faceted designs that are prone to failure, including:

Communication and network failures affecting scheduling, setpoints, etc.

Typical automation is run under two wiring networks including Ethernet and RS-485 or two conductor wires. Rarely do you find building automation systems that are left standalone within a building and lack Internet connectivity. Most new installs not only utilize the existing Ethernet infrastructure in a building, but also rely on the Internet for weather updates to help optimize sequencing.

Communication failures within automation are a common occurrence and can often take a minimum of four hours to uncover the network issue. Permitting network failures prevents high level, energy savings functions like setpoint resets, optimal start/stop sequences, and scheduling from working correctly. Even losing Internet connection can prevent some sequences that require updated weather data from proper operation.

Solution:

A solid understanding of networking and IT related issues (port blocking, MAC address changes, etc.) can easily help you uncover problems and keep your DDC saving energy. During the contractor training period have your installing contractor run through key networking locations that might be prone to failures. These could include network switches that overheat or routers that have an especially high amount of traffic and therefore could be overworked.

As soon as you spot a communication failure it is best practice to trace the system in an attempt to identify the broken link. If you can’t fix it yourself, look to get a controls contractor onsite as soon as possible to alleviate poor equipment operation that could lead to hundreds or thousands of dollars a day in lost revenue to energy.

Setpoint changes when the operator doesn’t understand how the equipment functions.

Easy control sequences don’t equate to high energy savings! Unfortunately for engineers, the time of simple controls is coming to an end as the energy wave continues to sweep through commercial buildings.

The most common user related errors that adversely affect automation are based around setpoint changes. New control sequences are based on regulatory standards with ASHRAE Title: 24 leading the way in energy conservation. These advanced sequences require finite controls including numerous, highly sophisticated settings to properly operate.

Often end users will begin changing setpoints in response to uncomfortable tenants or in an attempt to save money. But did you change the correct setpoint? Energy efficiency is directly related to cascading controls; turning up room temperature in a large space will ultimately cause an air handler to throttle back, lowering the duct static and possibly raising supply temperature. This effect is often overlooked when manipulating the automation in response to a problem.

Solution:

Be sure to ask plenty of questions about your new automation system during the contractor training period. Bring a copy of the sequences and control drawings with you so that the contractor can explain how the sequence relates to the control graphics that they setup for you. Often contractors will make the control drawings accessible from the new graphics via a hyperlink so that you can better understand how the system works.

When considering your graphical layout of each system, adding every control setpoint can often lead to unnecessary changes that distort controls. If you see setpoints you don’t understand, have your contractor explain what they do so that you both can decide if they truly belong on the graphic or should remain in the programming only. Alleviating the temptation of manipulating the system will save you money in the long run.

Failing to adjust the control system to account for occupancy and building changes including degradation.

Control Solutions, Inc After a control system is installed, commissioned, and working to save money something unexpected always happens and is rarely accounted for - tenants! Occupancy and space usage can be the downfall of any control system no matter how efficient it originally operated. What if the tenant added more computers? How do you account for more occupants than originally estimated? If your building is five years old is your automation still saving you energy?

Building HVAC systems typically start to consume more energy within five years even with proper maintenance. Adding more overall load to a building requires HVAC to be scheduled on longer and run harder.
   
Solution:

Changes to a building need to be constantly evaluated and your automation updated to continue saving energy. Setpoints including minimum flow and temperature for tenant spaces need to be updated when accounting for occupancy changes. By calculating new minimum setpoints you can prevent the system from overcompensating and radically consuming energy.

Automation service contracts, when properly implemented, should provide more value than common controller failures. Typically installed automation equipment is robust and lasts for 5-7 years even in the harshest conditions. Maximize the potential of your service contract by having your controls and mechanical contractor coordinate to ensure that the system is running efficiently. The mechanical contractor will know how to better adjust setpoints and sequencing that can then be implemented by your controls contractor.

Resources like EnergyStar have defined the building energy saving model as dynamically evolving with technology. A building in 2005 that was branded EnergyStar compliant (A score greater than 75) could easily fall off the chart by 2010 with the increased ability to easily save energy. Building owners and engineers should constantly be looking at low-cost measures to reduce utility usage and improve baseline consumption. Energy consumption within buildings continues to be scrutinized more by “green tenants” due to its increase on total operational costs of leasing a building. Lowering building consumption and obtaining EnergyStar & LEED certifications can attract higher paying, energy driven tenants.



About the Author

I currently maintain an engineering sales position at Western Allied Mechanical. Our business is consulting customers on energy consumption and reducing costs through a joint mechanical and automation venture. I’m an avid follower of the industry and am always open to new opportunities and approaches. You can reach me at zdenning@westernallied.com or my cell at  650-798-4154.

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