In this article mechanical engineer, Steven Mantine, explains how Australia’s energy efficiency ratings work and how the new standards are a significant improvement on previous attempts to rate air conditioners. He covers COP, SEER and everything in between.
In recent years, Australia has invested considerable resources in both reforming and enforcing regulations for energy efficiency of electrical goods.
As part of the “The Greenhouse and Energy Minimum Standards” reforms, Australia has transitioned to seasonal ratings moving away from EER/COP which is a positive change. It benefits end users greatly and I will explain why.
The definition of energy efficiency varies between the different electrical products depending on the nature of the product. Mostly products ranked on a scale of between best efficiency, and the lowest (Allowed) efficiency. Products below the lower efficiency threshold cannot be marketed in Australia.
Some products are very simple when it comes to determining efficiency. For example, the energy efficiency of a light bulb is tested by the ratio of lumens (visible light emitted by a source per unit of time) per Watt; lm/W. The higher the number the higher the rating. The power consumption of the bulb will change minimally if it is illuminated by day, night, winter or summer*, not so in air conditioners.
When we are approaching air conditioners, the old standard defined efficiency by the “Coefficient Of Performance” (COP), which is defined as the output capacity provided by the air conditioner divided by the electric consumption (in Europe it is common to use the term EER - Energy Efficiency Ratio - to test efficiency in the cooling process and COP for testing efficiency in the heating process.
The greater the coefficient number is, the better the efficiency. A higher ratio meant less power consumption by the air conditioner for transferring the same unit of energy [1kW], or the unit will deliver more energy for every kW of electricity it consumes.
Based on this, consumers head out to their nearest store and purchase the air conditioner with the highest energy rating.
The problem with this method is the way units were tested and how efficiency was defined.
In the old standard, efficiency testing was carried out under constant conditions of 35 degrees (DB) outside = Outdoor unit load, and 27C (DB)/19C (WB) (47%RH) inside – Indoor unit load.
Heating efficiency tests were done at 7C (DB)/6C (WB) Outside and 20C (DB) inside.
Until a couple of years ago and for many years there was only on/off air conditioners market, air conditioners with a single compressor output - the thermostat would switch the compressor to work or turn off according to requirements (reaching SETPOINT).
Since the air conditioner in the test is constantly loaded, we checked the power consumption of the system because the compressor is the main power consumption in it. This method ignored the power consumption change due to conditions changing and as the compressor was constantly loaded, it ignored the “spikes” in energy consumption every time the compressor turned on. It also ignored the Standby mode, and the actual time and load the unit was working under.
Today in the era of inverter air conditioners compressors change their output according to load and accordingly their power consumption changes. Therefore, the catalogues show a capacity range instead of a single capacity as it was in the ON/OFF units. Today's advanced controls allow the air conditioner to control capacity at +-1%level.
Real world conditions
Another column in the catalogue is the nominal data. By the old standard, it is a necessity as the unit performance and efficiency were dictated at those test conditions. The trouble was the correlation to real-life conditions, performance and energy ratings. In Victoria, for example, 35-degree outdoor conditions only happen in exceptional extreme conditions that do not reflect the everyday situation in that state. Most of the time the air conditioner only works in partial load, and other regions will have different conditions.
What happened if we operate in half load or when the conditions change? The old standard didn’t provide answers to these questions.
As I mentioned, the old standard was missing on two main levels that the new AS/NZS 3823.4:2014 standard covers. It didn’t reflect the unit performance and efficiency under changed conditions (as they do change throughout the day and the seasons) or standby (as the system is consuming energy even in Standby mode).
It also didn’t factor in the different regions as some areas are colder or warmer than others and the new standard has addressed this issue.
The new standard tests the air conditioner under several conditions in full and partial load, and it divides Australia into different zones based on their climate conditions (three zones to be exact). Combining these factors provides more accurate energy ratings based on location. End users can select the most efficient air conditioner to use in Melbourne or Brisbane depending on the climate conditions.
Australia has three zones and the standard considers the zones by dictating different operating hours in heating/cooling to every zone.
In Hot and humid we take into consideration 2,247 hours of cooling operation, but only 277 hours of heating operation (and 6,236 hours in Inactive mode) per year.
In a Mixed temperature region, we consider 840 hours of cooling operation and 1,291 hours in heating operation (and 6,629 hours in Inactive mode) per year. In Cold regions, we consider 545 hours of cooling operation and 2,660 hours in heating operation (and 5,555 hours in Inactive mode) per year.
On top of that, the standard allocates different weight to different loads based on their proportion in the season, for example in the cold zone, a load of 30C outdoor temp will be allocated 48 hours which are 8.8% of the total operating hours (in the cold region). However, in the warm zone, a load of 30C outdoor temp will be allocated 223 hours which are 9.9% of the total operating hours (in the warm region).
It all comes to this formula (in cooling) (it is magnificent in its simplicity, but there is a lot behind it).
FTCSP = cooling performance factor=SEER
= Cooling seasonal total load
= Cooling seasonal energy consumption
CIAE = Inactive Energy consumption
In this article mechanical engineer, Steven Mantine, explains how Australia’s energy efficiency ratings work and how the new standards are a significant improvement on previous attempts to rate air conditioners. He covers COP, SEER and everything in between.
In recent years, Australia has invested considerable resources in both reforming and enforcing regulations for energy efficiency of electrical goods.
As part of the “The Greenhouse and Energy Minimum Standards” reforms, Australia has transitioned to seasonal ratings moving away from EER/COP which is a positive change. It benefits end users greatly and I will explain why.
The definition of energy efficiency varies between the different electrical products depending on the nature of the product. Mostly products ranked on a scale of between best efficiency, and the lowest (Allowed) efficiency. Products below the lower efficiency threshold cannot be marketed in Australia.
Some products are very simple when it comes to determining efficiency. For example, the energy efficiency of a light bulb is tested by the ratio of lumens (visible light emitted by a source per unit of time) per Watt; lm/W. The higher the number the higher the rating. The power consumption of the bulb will change minimally if it is illuminated by day, night, winter or summer*, not so in air conditioners.
When we are approaching air conditioners, the old standard defined efficiency by the “Coefficient Of Performance” (COP), which is defined as the output capacity provided by the air conditioner divided by the electric consumption (in Europe it is common to use the term EER - Energy Efficiency Ratio - to test efficiency in the cooling process and COP for testing efficiency in the heating process.
The greater the coefficient number is, the better the efficiency. A higher ratio meant less power consumption by the air conditioner for transferring the same unit of energy [1kW], or the unit will deliver more energy for every kW of electricity it consumes.
Based on this, consumers head out to their nearest store and purchase the air conditioner with the highest energy rating.
The problem with this method is the way units were tested and how efficiency was defined.
In the old standard, efficiency testing was carried out under constant conditions of 35 degrees (DB) outside = Outdoor unit load, and 27C (DB)/19C (WB) (47%RH) inside – Indoor unit load.
Heating efficiency tests were done at 7C (DB)/6C (WB) Outside and 20C (DB) inside.
Until a couple of years ago and for many years there was only on/off air conditioners market, air conditioners with a single compressor output - the thermostat would switch the compressor to work or turn off according to requirements (reaching SETPOINT).
Since the air conditioner in the test is constantly loaded, we checked the power consumption of the system because the compressor is the main power consumption in it. This method ignored the power consumption change due to conditions changing and as the compressor was constantly loaded, it ignored the “spikes” in energy consumption every time the compressor turned on. It also ignored the Standby mode, and the actual time and load the unit was working under.
Today in the era of inverter air conditioners compressors change their output according to load and accordingly their power consumption changes. Therefore, the catalogues show a capacity range instead of a single capacity as it was in the ON/OFF units. Today's advanced controls allow the air conditioner to control capacity at +-1%level.
Real world conditions
Another column in the catalogue is the nominal data. By the old standard, it is a necessity as the unit performance and efficiency were dictated at those test conditions. The trouble was the correlation to real-life conditions, performance and energy ratings. In Victoria, for example, 35-degree outdoor conditions only happen in exceptional extreme conditions that do not reflect the everyday situation in that state. Most of the time the air conditioner only works in partial load, and other regions will have different conditions.
What happened if we operate in half load or when the conditions change? The old standard didn’t provide answers to these questions.
As I mentioned, the old standard was missing on two main levels that the new AS/NZS 3823.4:2014 standard covers. It didn’t reflect the unit performance and efficiency under changed conditions (as they do change throughout the day and the seasons) or standby (as the system is consuming energy even in Standby mode).
It also didn’t factor in the different regions as some areas are colder or warmer than others and the new standard has addressed this issue.
The new standard tests the air conditioner under several conditions in full and partial load, and it divides Australia into different zones based on their climate conditions (three zones to be exact). Combining these factors provides more accurate energy ratings based on location. End users can select the most efficient air conditioner to use in Melbourne or Brisbane depending on the climate conditions.
Australia has three zones and the standard considers the zones by dictating different operating hours in heating/cooling to every zone.
In Hot and humid we take into consideration 2,247 hours of cooling operation, but only 277 hours of heating operation (and 6,236 hours in Inactive mode) per year.
In a Mixed temperature region, we consider 840 hours of cooling operation and 1,291 hours in heating operation (and 6,629 hours in Inactive mode) per year. In Cold regions, we consider 545 hours of cooling operation and 2,660 hours in heating operation (and 5,555 hours in Inactive mode) per year.
On top of that, the standard allocates different weight to different loads based on their proportion in the season, for example in the cold zone, a load of 30C outdoor temp will be allocated 48 hours which are 8.8% of the total operating hours (in the cold region). However, in the warm zone, a load of 30C outdoor temp will be allocated 223 hours which are 9.9% of the total operating hours (in the warm region).
It all comes to this formula (in cooling) (it is magnificent in its simplicity, but there is a lot behind it).
FTCSP = cooling performance factor=SEER
= Cooling seasonal total load
= Cooling seasonal energy consumption
CIAE = Inactive Energy consumption