GACS in Practice: How to Set Up Energy Monitoring and Data Collection

A GACS starts with reliable data. To monitor energy consumption, assess the performance of technical building systems and identify deviations in time, the right data needs to be available. This data must then be collected, analysed and translated into information that building managers can actually use.

A good GACS solution is therefore more than a dashboard or a collection of smart meters. It is an integrated solution combining measurement, communication, monitoring, analysis, alerts and, where required, control. This is also in line with how the Dutch government describes the required functionality of a GACS.

From Legislation to Day-to-Day Practice

GACS legislation requires the system to be able to continuously monitor, record and analyse energy consumption. It must also be possible to assess the energy efficiency of the building, identify efficiency losses and inform the building manager about potential improvements.

For a building manager, this translates into a number of practical questions: Which systems need to be monitored? Is the existing energy meter sufficient? Where are additional measurement points needed? How can data from different systems be brought together? And how can you make sure that a deviation is not only visible in a graph, but is actually brought to the attention of the right person?

These technical choices ultimately determine whether a GACS delivers real value in day-to-day building management.

Reliable Energy Data as the Foundation

Every GACS solution starts with reliable measurement data. Without accurate data, it is impossible to properly assess energy consumption or the performance of technical systems. A main energy meter provides insight into a building’s total energy consumption. This is an important starting point, but it is often not enough to determine where that energy is being used.

Suppose the electricity consumption of an office building suddenly increases. The main meter shows that consumption has increased, but it does not automatically show why. Is the HVAC system consuming more energy? Is there a technical issue? Have operating hours changed? Or is the increase caused by EV charging infrastructure?

To answer those questions, more detailed data is needed.

Submetering Makes Energy Consumption More Transparent

Submetering allows energy consumption to be broken down into relevant parts of a building. This could include HVAC systems, individual building zones, common services, EV charging infrastructure, solar generation or individual tenants.

This creates a much clearer picture of the energy flows within a building.When total energy consumption increases and it is also visible that a specific system is responsible for the increase, the building manager can investigate the situation much more effectively. Submetering is therefore not an objective in itself. Its purpose is to provide enough detail in the available data to analyse energy consumption and system performance.

The current Dutch guidance on GACS supervision supports this approach. During an inspection, authorities may look at whether the GACS provides the required functionality for monitoring and analysing energy consumption. A building owner or manager may also be asked to demonstrate how the system works.

From Data Collection to Continuous Monitoring

A good GACS solution does not only look at today’s energy consumption. Changes over time are essential for understanding the performance of a building. By continuously collecting measurement data, a historical picture of the building’s performance is created. This makes it possible to identify trends and compare current values with previous periods or expected patterns.

For example, it may become clear that a system is consistently using more energy than before, that a particular consumption pattern has changed or that an installation is operating outside its normal operating hours.

A monitoring platform should therefore provide more than real-time values. Historical data needs to remain available in a way that allows building managers to analyse it effectively.

Alerts Make Monitoring Practical

A building manager cannot continuously check every measurement and graph. Monitoring therefore becomes much more useful when the system can actively identify relevant deviations.Alerts can be used when, for example, energy consumption exceeds predefined limits or when an unusual pattern is detected. The building manager can then receive targeted information about situations that may require attention.

This supports the GACS requirement to identify efficiency losses and inform the building manager about potential improvements.

The aim is not to generate as many alerts as possible. A well-designed monitoring environment should help distinguish relevant deviations from normal changes, allowing building managers to investigate where action may be required.

Analysis Turns Data into Useful Information

Monitoring and alerts provide the most value when the available data can also be analysed.A building manager does not only want to know how much energy a building is using at a specific moment. The development over time is equally important. By comparing periods, building zones or technical systems, trends and deviations can become visible.

This could include comparing energy consumption between different weeks or seasons, or analysing consumption before and after an energy-saving measure has been implemented.

In this way, a collection of measurements becomes useful information that can help building managers understand and improve building performance.

A Modular Approach to GACS

This modular approach is particularly relevant for existing buildings. Not every building needs to be redesigned from scratch. Many buildings already have meters, building management systems and technical installations in place. The first step is therefore to determine what is already available and where additional information or functionality is required.

Which measurement points are already installed? Which systems are connected? Which data can already be retrieved? Where is additional submetering required? And which functions need to be added to complete the GACS solution? From there, the system can be expanded where necessary.

A building could, for example, start with additional energy measurement and monitoring and later add more measurement points, system integrations or additional automation functionality.

This makes GACS less of an all-or-nothing investment and more of a solution that can grow with the building.

GACS as More Than Compliance

Although GACS is driven by legislation, the result does not have to be just a tick in a compliance box.The same data needed to monitor energy consumption can also be used to identify energy waste, optimise technical systems and assess the impact of energy-saving measures.

GACS can therefore develop into a practical tool for better building management. This will become increasingly relevant in the coming years. The Dutch GACS requirements already apply to existing non-residential buildings above the current threshold, while the scope will expand towards 2030.

Investing in a solid measurement and monitoring structure today therefore provides a foundation not only for current compliance, but also for future developments.

From Measurement Point to Complete GACS Solution

A good GACS solution does not start with one specific product. It starts with identifying what information is needed to properly assess the performance of the building and its technical systems.

• Measurement points provide reliable energy data.
• Communication brings data together from different sources.
• ENNY Insight makes the data visible and supports monitoring and analysis.
• Alerts and notifications help bring deviations to the attention of building managers.
• Data export and reporting make the information available for further use.
• Integrations with technical systems can make energy monitoring part of a broader GACS architecture.

CompactIQ can provide a practical solution where additional energy measurement is required and space in the distribution board is limited. The result is an integrated solution in which data is not simply collected, but actually used to understand building performance and identify opportunities for improvement.