Building Automations Expected to Fail?

Building automations are not expected to fail if they are designed, installed, and maintained correctly, but they do fail more often than they should due to common oversights. This article explains the main reasons for failures, how to prevent them, and how to plan for the inevitable glitches that occur in any complex system.

Formula

The average pace is the total time divided by the distance. In symbols:

pace (min/km) = t (minutes) / d (km)

The average speed is the distance divided by the time in hours. Since time is given in minutes, convert to hours by dividing by 60:

speed (km/h) = d (km) / (t (min) / 60)

Variables:
t = total time in minutes
d = distance in kilometers
pace = minutes per kilometer
speed = kilometers per hour

Worked Example

Using the default values: t = 50 minutes, d = 10 km.

Pace = 50 / 10 = 5.00 min/km

Speed = 10 / (50/60) = 10 / 0.8333 = 12.00 km/h

The calculator shows an average pace of 5.00 min/km and an average speed of 12.00 km/h.

What Building Automations Do

Building automation systems (BAS) control heating, ventilation, air conditioning (HVAC), lighting, and sometimes security and access. They use sensors, controllers, and software to maintain comfort while saving energy. A typical system reads temperature, humidity, or CO2 levels, then adjusts dampers, valves, or fans to keep conditions within setpoints.

These systems range from a single thermostat to a campus-wide network of thousands of points. The larger the system, the more chances for failure, but even small systems can have problems if the basics are ignored.

Why Automations Fail in Practice

Most failures are not due to the hardware wearing out. They come from design, installation, and maintenance issues.

• Poor sensor placement: A temperature sensor in direct sunlight or near a door reads false values, causing the system to overheat or overcool a room.
• Incorrect setpoints: Setting a heating setpoint higher than the cooling setpoint creates a deadband conflict, so the system cycles or does nothing.
• No scheduling or holiday calendar: Without proper schedules, the system runs at full capacity 24/7, wasting energy and wearing out equipment.
• Lack of alarms: If no one is notified when a sensor fails, the problem goes unnoticed until occupants complain.
• Network issues: Communication dropouts between controllers and sensors cause erratic behavior or frozen outputs.
• Power surges: Electrical spikes can reset controllers to default settings or damage input/output boards.

How to Choose a System That Won’t Fail

Choosing a BAS is about matching the system to the building’s needs and the staff’s ability to maintain it.

1. Assess your building’s complexity: A small office with one HVAC unit does not need a full DDC system; a simple programmable thermostat may be more reliable.
2. Evaluate the vendor’s support: Look for local support, training, and a track record of responding to service calls. A system that is hard to get help for will fail in practice.
3. Check compatibility: Ensure the system can talk to existing equipment (e.g., via BACnet, Modbus, or proprietary protocols). Mismatched protocols are a common source of “ghost” failures.
4. Plan for future expansion: A system that cannot add new controllers or sensors without replacing the whole network will become obsolete and fail to meet needs.
5. Consider cybersecurity: Modern BAS are IP-based and can be hacked. A breach can cause the system to shut down or operate erratically. Choose systems with strong authentication and encryption.

Common Problems and How to Fix Them

Even with good design, problems occur. Here are typical issues and their solutions:

• Sensor drift: Sensors lose accuracy over time. Calibrate them annually or replace them every few years.
• Stuck actuators: Valves or dampers can stick, especially if not exercised. Run a weekly stroke test to keep them moving.
• Software bugs: Firmware updates can introduce new bugs. Always test updates on a small segment before deploying to the whole system.
• Battery failures: Wireless sensors run on batteries that die. Set up low-battery alarms and replace batteries on a schedule.
• Incorrect time settings: After a power outage, controllers may reset to a wrong time, causing schedules to be off. Use a network time protocol (NTP) server to keep clocks synced.

Costs and Benefits of Reliability

Investing in reliability upfront saves money in the long run. A well-maintained BAS can reduce energy use by 10–30% compared to a poorly controlled system. But the cost of a failure can be high: an undetected temperature spike in a server room can destroy equipment, or a failed ventilation damper can lead to poor indoor air quality and health complaints.

Preventive maintenance costs are modest: typically a few percent of the system’s installed cost per year. That includes cleaning sensors, checking actuators, reviewing alarms, and updating software. Skipping maintenance is the most common reason a system “fails” after a few years of trouble-free operation.

Safety and Best Practices

Safety is a critical part of building automation. A failure in a safety system—like a fire damper or a gas valve—can be life-threatening. Always ensure that safety interlocks are hardwired and not solely dependent on software. For example, a fan should have a direct speed switch that stops it if the belt breaks, rather than relying on a pressure sensor that could fail.

Also, never bypass alarms or safety limits to keep the system running. If a high-temperature alarm trips, investigate the cause before resetting it. Ignoring alarms is a leading cause of catastrophic failures.

Frequently Asked Questions

How often should building automation systems be serviced?

Most manufacturers recommend a preventive maintenance check at least twice a year, ideally before the heating and cooling seasons. This includes calibrating sensors, testing actuators, verifying schedules, and updating software. High-occupancy buildings or those with critical processes may need quarterly checks.

Can building automations work with existing old HVAC equipment?

Yes, in many cases. Older equipment can be retrofitted with new controllers and sensors if it is in good mechanical condition. The key is to use a BAS that supports common communication protocols like BACnet or Modbus, and to have a professional assess the equipment’s condition first.

What is the most common cause of BAS failure?

The most common cause is lack of maintenance—specifically, sensor drift and dirty or stuck actuators. These issues are easy to prevent with scheduled inspections, but they are often ignored until the system stops working or occupants complain.

How long do building automation systems last?

Hardware like controllers and sensors typically last 10–15 years, but software and user interfaces may become outdated sooner. The mechanical components they control (valves, dampers) may last 20 years or more. It is common to upgrade the BAS while keeping the HVAC equipment.

Is it better to use a cloud-based BAS or an on-premises system?

Cloud-based systems offer easier remote access and automatic updates, but they depend on internet connectivity. On-premises systems are more reliable if the internet goes down, but they require more IT support. Many modern systems use a hybrid approach: local control with cloud monitoring.

Can a BAS be hacked?

Yes, any internet-connected device can be hacked. To reduce risk, use strong passwords, enable two-factor authentication, keep firmware updated, and segment the BAS network from the main IT network. Physical security is also important—someone with direct access to a controller can cause damage.

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in t | Finish time | min | 50 | 0
in d | Distance | km | 10 | 0
out pace | Average pace | min/km | t / d | 2
out speed | Average speed | km/h | d / (t / 60) | 2