What is Passive Cooling?
Passive cooling works by circulating the water and refrigerant mixture (brine) through the pipework buried in the ground (known as ground collectors or ground arrays), the brine is cooled by the lower temperature of the ground before being circulated to a heat exchanger which further reduces the temperature, providing chilled water. The water is then distributed to cooling fan coil units or underfloor heating. If you're planning to use fan coil units you’d need one in each room which requires climate control.
Pros of Passive Cooling:
- Can be installed as part of your heat pump system saving time, money and space.
- Low cost to run – only uses energy to circulate the brine through the system.
- 100% carbon free if used with renewable electricity suppliers such as Octopus Energy.
- Moves the warm energy from the building and charges the ground with it throughout the summer ready to be extracted in winter months, increasing efficiency.
- Increased comfort levels.
Cons of Passive Cooling:
- If using passive cooling with underfloor heating, care should be taken as condensation can build up in the form of dew. We recommend using a dewpoint measurement which will reduce the temperature of the cooling water to prevent condensation of atmospheric moisture.
- Passive cooling is not as effective as an Active Cooling system as it doesn't operate at the same low water temperatures.
What is Active Cooling?
Active cooling requires the circuits to the evaporator and condenser to be swapped. This allows heat energy to be taken from the circuit which usually provides heating and transfer it into boreholes or water via the ground collectors. This method of cooling is more effective than passive and shares greater performance levels with air-con.
Pros of Active Cooling:
- More effective than passive cooling as a set cooling temperature can be maintained
- Higher performance in line with traditional air conditioning
- Can be installed as part of your heat pump system saving time, money and space
- 100% carbon free if used with renewable electricity suppliers such as Octopus Energy
- Moves the warm energy from the building and charges the ground with it throughout the summer ready to be extracted in winter months, increasing efficiency.
- If the brine gets too warm, the system will become inefficient. This can be caused when the building gets so hot that the temperature of the brine increases slightly with each circulation and so the compressor is unable to lower the temperature so that it’s suitably chilled.
Cons of Active Cooling:
- Requires slightly more energy to operate than passive cooling making which increases running costs (still considerably less than air-con)
- Can be limited by the minimum allowable temperature of the cooling circuit or the ability of the borehole or water source to disperse the heat.