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How to optimize legionella monitoring and prevention with smart buildings?

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How to optimize legionella monitoring and prevention with smart buildings?

Legionella disease is an important public health issue. In order to respond to it, public authorities have set up regulations for monitoring legionella bacteria in buildings open to the public.

The Energisme platform offers a module for monitoring the temperature of domestic hot water networks, to anticipate the proliferation of the bacteria.

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What is legionella bacteria?

Legionella is a bacterium that can cause a serious pulmonary infection: legionnaires’ disease

Legionella bacteria are present in the natural environment, in fresh water (lakes and rivers) and in damp soil. 

They also proliferate in installations that present an environment favorable to their development:

  • Water stagnation
  • Water temperature between 25 and 45°C

Domestic hot water systems are therefore particularly prone to legionella bacteria colonization. They must therefore be subject to a specific monitoring that allows the solution developed by Energisme.

Most of the legionella strains are harmless but some of them can cause human infections. The contamination is done by respiratory way, by inhaling contaminated water diffused in aerosol by the shower, the washbasin, the sink…

In mild cases, exposure to legionella causes a flu-like infection. In more severe cases, it causes Legionnaires’ disease, a potentially fatal pneumonia.

Legionellosis cases and causes

In 2019, the National Reference Center for Legionella recorded 1816  cases of Legionnaires’ disease in France.

This figure reflects a steady increase in contaminations over the last few years (+49% between 2016 and 2019).

The factors of the constant increase of contaminations

The CNR Legionella suggests two explanations for this increase:

  • The emergence of new heating or cooling systems for which there are no regulatory measures yet
  • The absence of systematic investigations in indoor water distribution systems in the home in reported cases

Regulatory obligations for monitoring and prevention of legionella

Legionella risk monitoring
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Legionella risk monitoring

Types of establishments

In France, the risk of contamination by legionella bacteria is considered a major public health issue.

The regulations impose monitoring of  legionnella risk in several types of establishments:

  • Spas
  • Thermal establishments
  • Hotels, tourist residences and campsites
  • Residential buildings, work premises and establishments receiving the public
  • Health and medico-social establishments

The N’Gage platform developed by Energisme includes a module for monitoring the temperature of domestic hot water systems to help establishments meet this regulatory requirement.

Water temperature regulations
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Water temperature regulations

Tourism and health sectors

Tourist establishments are at risk due to the seasonal operation of hot water systems and the operation of aquatic areas. Since January 1, 2011, regulations require annual monitoring of legionella and the temperature of hot water in the collective networks of these establishments.

Health and medico-social establishments welcome people who are potentially vulnerable to Legionnaires’ disease. Increased monitoring of the installations is therefore required from the operators of these establishments in order to guarantee the health safety of the users.

Finally, all buildings, public or private, receiving the public are subject to the following two obligations:

  • regularly measure the temperature of the domestic hot water
  • carry out annual legionella analysis campaigns

What are the innovative solutions to prevent or treat legionella bacteria?

The platform developed by Energisme offers concrete answers to public health concerns raised by the proliferation of legionella bacteria.

The temperature of hot water is clearly identified as a factor conducive to the proliferation of legionella bacteria. 

The fight against Legionnaires’ disease is therefore primarily based on monitoring the temperature of hot water systems in buildings open to the public. This monitoring is a legal obligation.

However, limited monitoring is not sufficient to anticipate all risks. Optimal prevention of legionella risk requires real-time monitoring of temperatures. 

The transition of the building sector towards an intelligent building logic makes it possible to automate this monitoring. By installing IoT (Internet of Things) sensors at various key points in the hot water network, it is now possible to:

monitor the water temperature in real time
configure different alert thresholds in case of abnormal temperature before reaching the critical temperature
identify the part of the network where the temperature is abnormal
alert the manager responsible for the system
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The solution developed by Energisme

This type of device offers significant time savings to rectify the temperature in the hot water network and limit the risks of contamination.

The solution developed by Energisme is based on smart metering to evaluate the sanitary risk. In concrete terms, the smart sensors placed on the hot water network read the temperature of the water but also other relevant data. This information is centralized in the platform, crossed with external data and analyzed. The solution thus offers complete monitoring in terms of legionella prevention.

Alongside connected lighting and the control of multi-fluid consumption, the prevention of the risk of legionella is part of the smart building dynamic for better technical and energy management of the building and better comfort for occupants or users. 

A connected and centralized management of hot water networks also contributes to :

  • the improvement of the building’s energy performance
  • the implementation of an energy renovation action plan

Legionella risk monitoring, use case of temperature measurement

Contamination by legionella bacteria can cause a serious pulmonary pathology: legionnaires’ disease. The bacteria proliferate in installations where the water temperature is between 25 and 50°C.


Contamination by legionella bacteria can cause a serious pulmonary pathology: legionnaires’ disease. The bacteria proliferate in installations where the water temperature is between 25 and 50°C.

This is why regulations require regular temperature control of hot water systems in establishments open to the public, in particular:

  • spas, hotels and campgrounds
  • clinics and hospitals
  • retirement homes and nursing homes
N’Gage platform

The N’Gage digital platform, developed by Energisme, helps limit the risk of legionella by facilitating real-time monitoring of domestic hot water networks.

IoT sensors continuously monitor water temperature data to ensure compliance with the health threshold (between 55°C and 60°C).

If necessary, the platform sends alerts to the people responsible in order to plan an intervention for regulation.