A comparison.

While cooling has not always been considered in the South African context, it’s becoming increasingly important as the earth heats up and we experience heat waves and extreme weather conditions. As numerous clients are considering cooling options, aside from ceiling fans, late night swimming and cold showers, here is what I have discovered.

There are two main cooling systems available for residential applications:

  1. Split system Air conditioners (think LG, Samsung etc)
  2. Evaporative cooling Units

Aircon unit uses refrigerant and is designed to work in a sealed space. Evaporative cooling units pump air through pads that have been cooled with water, and then pump the air through the house. Evaporative cooling is designed for use with the doors and windows open and sucks fresh air into the house and flushes the entire air volume in the house every 2 minutes or so. At the onset evaporative cooling seems more suited to the South African lifestyle where we always have a door or a window open!

Both units run on electricity, however the evaporative cooling units are much more efficient and use less electricity, so if you are generating your own power it would mean that your cooling system could still run even when Eskom is in the blink. Whereas split units are just not viable to run on PV power as they run constantly and require a lot of power.

Evaporative cooling units are ducted so do require a ceiling void or bulkhead for the duct to run in. One also needs to mount the unit somewhere and they are fairly unsightly, so should be considered from the onset of the project.

Pros of Evap cooling:

  • Air quality: Evaporative constantly brings fresh air in to the house, rather than reticulating the same air repeatedly, the house is constantly flushed with fresh air not just cold air.
  • Moisture levels: “Evaporative coolers use their simple cooling technology to inject moisture into the air, cooling your home or office through evaporation. This added moisture can keep your eyes and skin from drying out. Traditional air conditioners remove moisture from the air, which can be difficult on your eyes and can cause your skin to dry out and crack. If you suffer from asthma or allergies, an evaporative cooler can help with your symptoms. Dry air can aggravate allergies and asthma, especially in children and the elderly, so an evaporative cooler and the added moisture it provides can be particularly beneficial.” http://www.air-n-water.com/evaporative-cooler-ac-comparison.htm
  • Running Noise: Evaporative units are much quieter than conventional aircon units to run
  • Emit less CO2 than split units
  • Lower running costs
  • Produce less CO2 than aircon units

Cons:

  • Can use up to 80 liters of water per hour
  • Require slightly more maintenance than Aircon
  • Are not suited to humid climates
  • Units are designed to be roof mounted and can be unsightly
  • Require a void for the ducting to run in.

Split Aircon Units

Pros:

  • Aircon units can also be used for heating
  • May be more affordable initially as units can be added as finance become available

Cons:

  • Units Split systems do not run efficiently if windows and doors are left open, as they recycle the air.
  • Dry the air out
  • Most effective at cooling the area where the head is located, multiply units will be required for different rooms
  • Compressor unit must be situated outside the house and can be unsightly (depends on the unit chosen)
  • Interior units are generally mounted on a wall in the room (Ugly)
  • Power thirsty
  • Create more CO2 than evaporative units

 

Conclusion:
From an air quality perspective Evaporative cooling is superior and is more suited to our South African lifestyle as its designed to work when doors and windows are open and sucks fresh air into the building flushing it every 30 seconds with fresh air. Further more the air is moistened which seems suited to our dry highveld conditions, which is better for allergies, sinus etc.

The only application where evaporative cooling is not suitable is in humid areas.

If it’s within reach of the budget Evaporative cooling is the best option for cooling, in this architect opinion. Please remember to tell your architect upfront if you plan to install an evaporative cooling system as it requires ducts to get the air through the building and this needs to be part of the planning g of the building from the onset!

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