Climatic engineering terminology
Aerothermal heating
Heating using heat extracted from the air.
Buried captor
Network of tubes buried in the ground and used to absorb natural energy from the ground.
Refrigerant circuit
Closed circuit containing a refrigerant fluid. The four main components of the refrigerant circuit are the compressor, the condenser, the expansion valve and the evaporator.
Manifold
Distribution unit used to control the various circuits of an underfloor heating system.
Compressor
Mechanical component of the refrigerant circuit enabling the transfer of energy from the ground outside to the inside of the house.
Condensation
Change in the state of the refrigerant from the gaseous to the liquid state accompanied by the release of energy into a medium to be heated.
Condenser
Heat exchanger in which the refrigerant is condensed.
C.O.P.
Coefficient of performance expressing the power output compared with the absorbed power. It measures the efficiency of the generator.
A COP of 3.7 indicates that the generator supplies 3.7 times more energy than it consumes.
Degree-days (uDD)
Sum of the products of "temperature difference x number of days at that temperature", characterising the harshness of a climate.
Losses
The combination of heat losses from a house. Typically:
- 30% by the roof,
- 15% by the walls,
- 15% by doors and windows,
- 15% by the floor,
- 20% due to air changes,
- 5% via thermal bridges.
Expansion valve
Refrigerant flow controller in the refrigerant circuit.
Direct expansion unit
Buried captor consisting of polyethylene sheathed copper tubing, acting as the evaporator and through which the refrigerant fluid circulates.
Groundwater
Water occurring underground, generally at a temperature of between 10°C and 14°C and which, in some cases, replaced the buried captor.
Water/glycol
Water mixed with a glycol based antifreeze filling a buried captor and cooling the ground to below 0°C.
Water based
System that extracts energy from groundwater, comprising a horizontal captor or thermal probes and featuring a hot water heating system in the house.
Thermal survey
Detailed survey of the insulation used in a given dwelling and calculation of the heating powers to be installed and of consumption levels.
Evaporator
Heat exchanger in which the refrigerant fluid is evaporated.
Evaporation
Change in the state of the refrigerant fluid from the liquid to the gaseous state accompanied by the absorption of energy from a medium to be cooled.
Refrigerant Fluid
Fluid which fills the refrigerant circuit and allows the transfer of heat from a medium to be cooled to a medium to be heated.
Freezing
This is simply the change of state from water to ice. However, heat can still be extracted even from ice (absolute zero being -273.15°C).
Geothermal heating
Heating using heat extracted from the ground.
Cycle inversion
Mechanism which extracts energy from inside the house and discharges it outside (into the ground when using a geothermal system or into the air when using an aerothermal system).
Cold surface
In a heated room, the cold surface is a surface which remains at a lower temperature than the rest of the room. The only cold surface that occupants are normally in contact with is the floor, and this problem is overcome by underfloor heating.
Low-temperature underfloor heating
Underfloor heating designed to heat the floor to between 22°C and 25°C, with a maximum of 28°C.
Room cooling
Gentle reduction of room temperature by circulating chilled water in the underfloor heating/cooling system.
Zone temperature control
A means of controlling the temperature in a given area or set of rooms, without being able to control individual room temperatures (ground/floor systems).
Room temperature control
A means of controlling the temperature of each individual room, without affecting the temperature of other rooms (ground-water and water based systems).
Scroll compressor
A high-performance compressor comprising two concentric spirals and doing away with the need for piston, connecting rod and valves, etc.
Ground- water
System using a direct expansion type horizontal captor and featuring a hot water heating system in the house.
Ground- floor
System using a direct expansion type horizontal captor and featuring an underfloor heating system containing refrigerant that is circulated through the house.
Thermal probe or loop
Set of polyethylene tubes installed in one or more boreholes 70 to 100 m deep. Each metre of borehole collects 50 watts of energy.
Average minimum outside temperature
Minimum daily temperature reached at least five times during a winter. This temperature is used to calculate the power of the system to be installed.
Thermodynamics
Field of physics concerning relationships between thermal and mechanical phenomena.
Absolute zero
Minus 273.15°C. It is only at this temperature that there is no heat present at all.
