- Chiller
- A refrigeration machine that cools water or air (air conditioning, process, cold room) by drawing heat from it. It rejects that heat, plus the energy used by its compressor: it can be recovered instead of being lost.
- Condenser
- The heat exchanger in a chiller or heat pump where the compressed, very hot refrigerant gives off its heat to air or water and turns back into liquid. This is where most of the recoverable heat comes out.
- Refrigerant
- A fluid that circulates in a closed circuit in a chiller or heat pump: it absorbs heat as it evaporates and releases it as it condenses. The most common ones (fluorinated) are powerful greenhouse gases; only certified professionals may handle them.
- GWP (global warming potential)
- An index comparing a gas's warming power with that of the same mass of CO₂ (GWP = 1), usually over 100 years. A leak of 1 kg of R410A (GWP of about 2,000) is thus equivalent to about 2 tonnes of CO₂.
- Waste heat
- Heat produced by a process or equipment whose purpose is something else (furnace, chiller, air compressor, data centre), and often lost. Also called recovery heat, it can be used to heat or preheat water, air or a process.
- Heat recovery
- Capturing waste heat, with a heat exchanger and sometimes a heat pump, to reuse it (heating, domestic hot water, processes) on site or nearby through a heating network. It replaces part of the purchased energy.
- Heat exchanger
- A device that transfers heat from one fluid to another, usually through a wall, without mixing them: for example from the water of a closed circuit to domestic hot water. It is the basic component of most heat recovery systems.
- Adiabatic dry cooler
- A fan-assisted heat exchanger that uses air to cool the water of a closed circuit. In hot weather, it pre-cools the incoming air by evaporating water into it (wet pads or spraying): that is the only time it uses water. Properly used, it carries no Legionella risk, unlike a cooling tower.
- Cooling tower
- A tower that cools water mainly by evaporating part of the water sprayed into an air stream. Effective, it uses water and can spread Legionella: in France, it is a classified installation subject to regular testing.
- AHU (air handling unit)
- A unit that takes in outdoor or recirculated air, filters it, heats or cools it, sometimes humidifies or dehumidifies it, then blows it into the rooms through ducts. The outdoor air can be preheated in it with recovered heat.
- Domestic hot water
- Water heated for washing, cleaning and cooking, separate from heating water. To prevent Legionella, it must in principle exceed 55 °C at the production outlet and 50 °C in the network; recovered heat is most often used to preheat it.
- Heat pump
- A machine that draws heat from a colder medium (air, water, ground or waste heat) and delivers it at a higher temperature to heat water or air. Usually electric, it supplies more heat than the electricity it uses.
- COP (coefficient of performance)
- The ratio between the heat supplied by a heat pump and the electricity it uses: a COP of 3 gives 3 kWh of heat for 1 kWh of electricity. It drops when the source is cold or the water to be produced is very hot.
- Destratification
- In a high-ceilinged space, warm air builds up under the ceiling while the lower part stays colder. Destratification moves this heat back down to floor level, without producing any: the temperature evens out and heating can use less energy.
- Pipe insulation
- Fitting thermal insulation around pipes, valves and equipment that carry a hot or cold fluid. It limits exchanges with the surrounding air: fewer losses on hot networks, less warming and condensation on cold ones.
- Hydraulic balancing
- Adjusting the valves of a water-based heating or cooling network so that each radiator or unit receives the flow it needs. The result: an even temperature from one room to the next, more comfort and less energy used.
- Thermostatic radiator valve
- A valve fitted at the inlet of a hot-water radiator, whose head reacts to the room temperature. It automatically reduces or shuts off the water supply when the room reaches the set temperature, for example thanks to sunshine.
- BMS (building management system)
- A computer system that centralises the monitoring and control of a building's technical equipment (heating, ventilation, air conditioning, lighting…). It collects alarms, operating states and measurements, including consumption, and allows settings to be adjusted for comfort and energy efficiency.
- Variable speed drive
- An electronic device that matches a motor's speed (pump, fan, compressor) to the flow required. Without it, the motor runs at fixed speed and the flow is throttled (valves, dampers): the saving is greater the more often the system runs below its maximum flow.
- Sub-metering
- Additional meters installed downstream of the main meter (electricity, gas, heat, water), by building, zone or use. They show where energy is consumed, reveal drifts and measure the effect of savings measures.
- Thermodynamic dehumidifier
- A device that works like a heat pump: humid air passes over a cold surface where its water vapour condenses, then over a hot surface that warms it up. It comes out dry and warmer, with no need to ventilate, which would waste heat.
- Hot tapping
- Connecting a new line to a pipe that stays pressurised and in service. A clamp fitted with a valve is attached to the pipe, then a machine drills through the wall via that valve: no draining and no network shutdown.
- Occupied site
- A building or site where all or part of the activity continues during the works. Occupants and the worksite coexist, which means splitting the works into zones and stages, separating traffic routes and limiting noise, dust and shutdowns.
- CVC
- Stands for heating, ventilation and air conditioning (HVAC): the systems that control the temperature, humidity and air renewal of a building, and by extension the related trade.
- Final energy
- Energy delivered to users to be consumed on their site (electricity, gas, heating oil…). It differs from primary energy, drawn from nature, before conversions (power plants, refineries) and transport losses.
- DOE (as-built file)
- The file handed over by the contractor at the end of the works, describing the installation as actually built: as-built drawings, data sheets, operating manuals, maintenance instructions and warranties. It is then used to operate and maintain the installation.
- Predictive maintenance
- Maintenance that monitors signs of equipment wear (vibration, temperature, pressure…) and analyses how they evolve to forecast a failure and step in just before it, rather than at fixed intervals.
