Why does air conditioning require so much power?

  • By: cooladmin
  • Date: September 5, 2022
  • Time to read: 4 min.
Table of Contents

    Introduction – Why does air conditioning require so much power?

    The energy efficiency of air conditioning does not come cheap. Air conditioning represents one of the largest single operating costs for commercial buildings, accounting for up to 60% of the summer electric bill in some locations.

    This high energy demand is driven by two key factors: first, the cooling process itself requires a lot of power; and second, as much as 90% of the energy consumed by an air conditioner goes towards heating and circulating refrigerant rather than directly chilling the indoor air.

    To understand why this is so and how we can address these challenges, let’s take a look at what makes up the modern air conditioning system.



    The fundamental operating principles of air conditioning

    We can distinguish two main types of air conditioning systems based on their operating principles – evaporative cooling and condenser-based chilling. Evaporative cooling, which is used in desert climates, delivers air that is very dry and is cooled by the evaporation of water from wet cooling pads.

    The air is then blown through the building and extracted from the building interior and the cooling pads. Condenser-based chilling is the most common type of air conditioning system and is used in humid climates as well as buildings where indoor humidity must be strictly controlled.

    In this system, cool outdoor air is drawn into the system through an outdoor compressor/condenser unit and then flows through the indoor evaporator coil, cooling and dehumidifying the air. The cooled air is then distributed to the building interior through the HVAC system.

    Evaporative cooling

    Evaporative cooling, which is used in desert climates, delivers air that is very dry and is cooled by the evaporation of water from wet cooling pads. The air is then blown through the building and extracted from the building interior and the cooling pads.

    Cooling water is sprayed onto a cooling pad, which may be made of porous material, gravel, or other materials. Air flows through the cooling pad and picks up heat as the water evaporates. The cooled air is moved into the building by conventional air ducts.

    Condenser-based chilling

    In this system, cool outdoor air is drawn into the system through an outdoor compressor/condenser unit and then flows through the indoor evaporator coil, cooling and dehumidifying the air. The cooled air is then distributed to the building interior through the HVAC system.

    The main components of an air conditioning system are – an outdoor compressor, an indoor evaporator, and indoor and outdoor air ducts. The compressor is used to compress refrigerant gas, which is then sent to the condenser unit to be cooled and liquefied.

    The refrigerant is then sent to the evaporator unit through the HVAC system and is used to cool the indoor air.

    Variable refrigerant operation

    New techniques for operating refrigerant, such as variable refrigerant flow, allow the use of a single compressor for both the cooling and heating seasons. These systems use electronic control to monitor outdoor conditions and regulate the flow of refrigerant between the outdoor compressor and indoor evaporator coil.

    This allows them to operate in both cooling and heating modes, reducing energy consumption by up to 10% compared to classical air conditioning systems. Variable refrigerant flow systems can be further improved by coupling with thermal storage to reduce the need for electricity during peak demand.

    Thermal storage allows for the use of off-peak electricity to charge a unit that is then used to reduce peak demand on the grid.

    How to improve the efficiency of air conditioning?

    Finally, while improving the energy efficiency of air conditioning cannot be done at the equipment level, there are a few things that we can do to lower the demand for the system. Increasing insulation, installing energy-efficient windows, and improving airflow management are some of the easiest things we can do to lower the energy demand on air conditioning systems.

    And while these measures do not directly impact the energy consumption of the air conditioner, they do impact the amount of energy that the system has to remove from the indoor environment. This can make a significant difference for building occupants, who will feel a lower impact from the air conditioning system.

    Conclusion

    Air conditioning is a crucial part of modern society, but its energy consumption is immense. Achieving sustainable progress in air conditioning will require a combination of research and development, policy change, and better consumer awareness.

    The first step is to understand the challenges and opportunities that lie in improving the energy efficiency of air conditioning. This will help to identify a path towards lowering its impact on the environment.