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When Building Automation Fails to Deliver
Thwarting the pitfalls of modern DDC
Western Allied Mechanical
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.
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.
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.
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.
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.
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.
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.
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.
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
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 email@example.com or my cell at 650-798-4154.
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