Energy efficiency : Definition

20 January 2024
2 min

Energy efficiency, a definition

Energy efficiency refers to the ability of a system, whether an appliance, a building or an industrial process, to decrease its energy consumption while providing the same level of service. This concept is particularly relevant in sectors such as motorised transport, industry and construction, which play a key role in overall energy consumption. The aim of energy efficiency is twofold: to reduce the costs associated with energy consumption and to reduce the environmental impact of that consumption.

It is often measured by coefficients such as COP (coefficient of performance) for heat production and EER (energy efficiency ratio) for cooling appliances. Energy efficiency differs from energy saving in that it aims to use less energy without compromising quality or comfort.

Energy efficiency in building management

Energy efficiency comes into its own in the building sector. In the European Union, the building industry is responsible for around 25% of total energy consumption. Against the backdrop of an unprecedented environmental crisis, governments have made decisions aimed at improving the energy efficiency of buildings. From the first directive on the energy performance of buildings in 2002 to the Grenelle 1 law and the 2015 energy transition law, measures to drastically reduce the ecological footprint of buildings are becoming increasingly stringent.

Energy efficiency in buildings can be broken down into two components: passive energy efficiency and active efficiency.

Passive energy efficiency

This refers to the energy efficiency of the building's design, structures, materials and equipment. More specifically, the main elements contributing to its improvement include :

Building structures and architecture:

- Orientation, which determines the building's ability to benefit from natural light and limit climatic effects (heat, cold);

- Internal thermal insulation: double glazing, insulating materials, design of rooms to limit heat loss, etc. and external insulation.

- The ventilation system: to limit energy loss.

- Heating and air-conditioning systems: use of renewable energies and energy-saving processes.

- Electrical equipment: LED lighting and low-energy appliances to limit electricity consumption.

Active energy efficiency and building management systems

In addition to the passive effects of construction, many buildings are equipped with building management systems (BMS). These are computerised systems connected to a building's equipment and sensors, which can be used to control a wide range of parameters relating to energy consumption, equipment maintenance and occupant comfort. To achieve optimum energy efficiency, the devices controlling heating, air conditioning, lighting, etc. need to be configured so that they play their role to the full.

For example, presence sensors tell the heating system if there are people in a room. When this is the case, the room will be heated, then the system will stop or reduce the temperature when the occupants have left.

A solution like the one proposed by Wattsense can be used to implement technical management in small and medium-sized buildings by centralising all the data from equipment, meters and sensors: temperature, humidity, air quality, water management, energy management, etc. Having such data available in real-time means that indicators can be analysed on an ongoing basis. Alarms can then be sent when an element deviates from its target.

It should be noted that non-residential tertiary buildings with heating or air conditioning systems with an effective rated output of more than 290 kW will be required to install a BMS from 1 January 2025, following the BACS (Building Automation and Control System) decree.

The Wattsense solution allows you to optimise the performance of your buildings effectively while keeping costs under control. By allowing you to take back control of the technical equipment in your buildings, whatever their size, condition or use, you can rapidly improve their energy efficiency, maintenance and the comfort of their occupants. Request a demo to find out more.

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