Electrical Consumption Measurement: Non-Intrusive Measurement vs. Submetering – Which System to Choose?

The challenges of electrical consumption measurement 


In an ever-evolving energy landscape, the efficient management and thus the measurement of electrical consumption of buildings is emerging as a strategic concern for businesses and public institutions. Faced with the challenges posed by evolving standards and energy costs, as well as the increasing necessity to meet corporate social responsibility (CSR) imperatives, managers of tertiary buildings find themselves at a crossroads. The measurement and analysis of energy data emerge as essential levers for achieving several strategic objectives:


  • Optimising energy bills in a context of rising tariffs: The surge in energy costs increases the financial pressure on businesses. In this context, the implementation of precise and targeted measurement solutions becomes imperative to identify optimisation levers and achieve substantial savings.


  • Meeting CSR objectives and communicating results: The integration of environmental concerns into the overall strategy of companies has become a standard. Effective measurement of electrical consumption plays a key role in achieving CSR objectives, while providing tangible data to communicate transparently about the progress made.


In this article, we will explore these aspects, highlighting the two predominant approaches to measuring the electrical consumption of buildings: the non-intrusive method and submetering. This analysis aims to provide key insights to guide decision-makers in choosing the solution most suited to their specific needs for measuring electrical consumption.


Non-Intrusive Measurement (NILM) and Submetering


Why measure electrical consumption?

Both non-intrusive measurement methods and submetering allow for the detailed measurement of electrical consumption within a larger system, such as a building or industrial facility.

Once collected, this data is analysed to understand the precise distribution of energy consumption in specific areas or equipment. This helps identify consumption trends, peak hours, sources of energy waste, etc.

This information is essential for implementing action plans for the reduction and monitoring of energy consumption.

Indeed, identifying the main sources of electrical consumption often provides the opportunity to target optimisation opportunities, thereby achieving up to 15% energy savings without the need for refurbishment work.


Operating Principles and Implementation

To implement a submetering solution, electric meters are installed by electricians on different branches of the electrical network, often corresponding to specific areas or equipment predefined for new buildings. However, understanding the electrical wiring in existing buildings can be complex, significantly complicating the task.

Depending on the type of meter used (direct or indirect measurement, closed or open cores, rigid or flexible) and the space available in electrical panels, a power shutdown is often necessary during the implementation of this electrical consumption measurement solution.

Meters must be calibrated according to the sensors used for each measured electrical branch. Data is either manually collected by a technician at a contractually established rhythm or remotely collected regularly, which then requires the establishment of a dedicated communication network in the building (wired or via a radio network).

Once all sensors are installed and tested on the electrical inputs of all equipment or areas, a regular maintenance program must be established to ensure the continuous proper functioning of meters (sensors, connectors, measurement, communication, etc.).


Non-intrusive measurement, or NILM (Non-Intrusive Load Monitoring), involves measuring aggregated consumption data and using intelligent algorithms to identify the nature of consuming equipment.

In practice, a single meter is installed at the LVMDP (Low Voltage Main Distribution Panel) with flexible cores that clip on, so without tools and especially without power interruption.

For a single-tenant office building, a single meter per building’s LVMDP is sufficient for a precise breakdown of consumption by usage (heating, ventilation, air conditioning, lighting, computing…).

It is then possible to install an additional meter to isolate a specific area or process, for example, to isolate the consumptions of a restaurant within a building, as it is an area with specific equipment, such as hot plates or cold rooms, which are interesting to analyse separately.

Due to their innovative technology, which requires a minimal number of sensors, these solutions are continuously remotely collected thanks to wireless communication. The installation of this electrical consumption measurement solution is done by an electrician, in one hour, without power interruption.


Differences between NILM and Submetering Solutions


Non-Intrusive, Cost-Controlled:

NILM stands out for its non-intrusive nature, requiring no additional equipment or significant construction work. This characteristic makes it an economical and easy-to-install solution for measuring electrical consumption, especially in existing buildings. In comparison, submetering may involve higher costs and significant electrical work related to the installation of additional meters.


Granular and Precise Data by Usage:

NILM and submetering offer granular data by usage. This allows for the identification of the most consuming equipment by entities. However, unlike submetering, NILM is not dependent on electrical wiring, thus avoiding potential inaccuracies. For example, if electric convectors are plugged into power outlets, NILM will detect electric heating, whereas a submetering solution will measure data labelled power outlets, often associated with computing.

The increased precision of NILM facilitates the implementation of targeted action plans to improve energy efficiency.


Automation and Frequency of Collection:

NILM solutions automatically upload data by the next day, eliminating the need for technicians for manual information collection, unlike some submetering solutions without remote collection. Moreover, the reduced number of measurement points used with NILM provides consumption data every 10 minutes, whereas traditional metering solutions with dozens or hundreds of measurement points are limited to weekly or daily data that can go up to hourly intervals. The 10-minute vision allows for a clear observation of events and the operation of equipment, making it easier to target energy optimisation opportunities or anomalies.


Maintenance and Sustainability:

In terms of maintenance and sustainability, NILM wins with a very reduced number of sensors with a more robust design, reducing the likelihood of faults related to the environment or equipment. Managing many sensors in submetering is often complex and requires dedicated maintenance resources due to potential measurement faults or the need for recalibrations, communication, or changes in the electrical wiring.


Smart Impulse Services: Going Further in Energy Optimisation


Smart Diag: Understanding and Acting

Smart Impulse not only measures your building’s energy consumption but elevates this service with Smart Diag. This advanced analysis provides an insightful report into your building’s energy use by specific categories, available at the onset of your project and during each annual review. It offers a transparent look into your electricity usage and equipment operation, identifying opportunities to conserve energy. An expert accompanies you through each step, interpreting the gathered data to formulate and execute an effective energy management strategy. This approach facilitates the development of targeted action plans to enhance energy efficiency.



Smart Impulse solutions provide interoperability with third-party systems, including multi-fluid platforms and Building Management System (BMS) supervision platforms.




NILM stands out for its non-intrusiveness, controlled cost, and ability to provide precise data without the need for complex installation. In contrast, submetering, while offering similar granularity, may lead to higher costs and disruptions related to the installation of a large number of meters.



More articles are available on our blog:

NILM – Focus on Non-Intrusive Monitoring

Energy Performance: The Challenges of Implementing an Action Plan

How to save energy in commercial buildings in the UK?

Dassault Systèmes & Smart Impulse: From Energy Optimisation to ISO 50 001