What are seasonal energy efficiency ratings?

Seasonal energy efficiency is now mandatory for all energy products throughout Europe. Discover how to correctly calculate your energy efficiency ratio. 

If you’re debating installing a new air conditioning system for greater seasonal energy efficiency, you’ve probably encountered various rating acronyms in the sales literature. Those acronyms reveal the energy efficiency and can help you compare the performance of each model.

Seasonal energy efficiency ratings are vital since between 40% and 60% of the energy usage in your home or commercial space can be consumed by your HVAC system. The problem is the equipment manufacturers don’t make it easy to understand how to interpret those numbers. So, to avoid any more confusion, here’s a look at seasonal energy efficiency ratings, what they mean, and what to look for.

What is the seasonal energy efficiency ratio?

Seasonal efficiency is a new way of measuring the true energy efficiency of heating and cooling technology over an entire year. This measurement gives a more realistic indication of the energy efficiency and environmental impact of a system.

The new method of rating energy efficiency is driven by the EU’s energy-related products (ErP) Directive (the Eco-design Directive) which specifies the minimum eco-design requirements that manufacturers must integrate into their energy-using products.

Conforming to seasonal efficiency demands all manufacturers maintain a new rating system for heating and cooling products. These include:

  • The Seasonal Energy Efficiency Ratio (SEER) value in cooling
  • The Seasonal Coefficient of Performance (SCOP) value in heating

Nominal ratio vs seasonal efficiency

Previously, the air conditioning industry used a ‘nominal’ ratio for cooling and heating. However, this resulted in a significant gap between predicted performance and what’s produced by air conditioning and/or heat pump systems.

The nominal ratio indicates the efficiency of an air conditioner when operating at full load in normal conditions. Rectifying this requires a more accurate method known as the ‘seasonal efficiency’ ratio. This method measures the real-life energy efficiency of air conditioning and/or heat pump systems.

Seasonal efficiency indicates the efficiency of an HVAC system when operating over an entire cooling or heating season (giving a more realistic efficiency measure).

What are the new seasonal energy efficiency ratings?

The new seasonal ratings reflect energy consumption based on a system’s energy efficiency over an entire year. SEER and SCOP measure annual energy consumption and efficiency in typical day-to-day use.

In the longer term, they consider temperature fluctuations and standby periods to give a clear and reliable indication of the typical energy efficiency over an entire heating or cooling season.

New heat pump products comply with the EU’s ErP for seasonal efficiency. As a result, they are more efficient and emit fewer CO2 emissions.

Understanding your seasonal energy efficiency rating (SEER) can also help you with significant savings on costs. For every kilowatt of power saved each hour, you can save approximately four tons of CO2.

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How to work out your energy efficiency ratio (EER)

First, you must work out the energy efficiency ratio (EER), which measures how efficiently your cooling system operates when the outdoor temperature is at a particular level.

EER looks at the cooling capacity of an air conditioning unit (in British thermal units, BTU per hour) compared to the power input of the unit (watts) to measure how much heat energy the unit can remove. It’s a ratio usually used for indoor room air conditioners, like split system air conditioning units.

Essentially, the higher an air-con unit’s EER rating, the more efficient it is by having a higher cooling capacity per watt of power.

Calculating your energy efficiency ratio

If EER is not provided when shopping for air conditioning, you can easily calculate it yourself. All you need is the unit’s wattage and BTU values which you can usually get from the manufacturer or supplier.

EER = (output cooling energy in BTU/input electrical energy in Watt)

Although EER is a reliable and valuable way to determine the overall efficiency of an air conditioner, you should be aware that the actual efficiency can vary due to various external factors like weather and humidity. The bigger the difference in temperature between indoors and outdoors, the harder your unit will have to work and the less efficient it will be able to run.

The seasonal energy efficiency ratio (SEER)

In countries where the climate changes drastically between seasons (like in the UK), many manufacturers and suppliers will also use seasonal energy efficiency ratios (SEER). SEER works like EER but considers seasonal factors and air conditioning usage rather than rating a unit’s efficiency all year round.

SEER is more specific and granular by calculating the cooling capacity (BTU per hour) and power input (watts) but only throughout the crucial cooling period as opposed to all year. For example, in the UK this would mean summertime.

Calculating your seasonal energy efficiency ratio (SEER)

  1. Find the BTUs per hour of your air conditioner. This value is found either on the air conditioner or in the owner’s manual.
  2. Find the number of watts used per hour for your air conditioner. This value is also located either on the air conditioner itself or in the owner’s manual.
  3. Calculate the number of BTUs used in the summer months. Use 1,000 hours, which equates to about 125 days or four months, to represent the late spring and summer months when air conditioners are used. Multiply the number from step one by 1,000 to get the number of BTUs used in the summer months.
  4. Calculate the number of watts-hours used in the summer months by multiplying the number from step two by 1,000.
  5. Divide the BTUs used in the summer months (the result of step three) by the number of watts-hours consumed in the summer months (the result of step three) to arrive at the SEER rating.

At part load conditions, working out your SEER provides a realistic overall system efficiency rate on a seasonal basis.

The seasonal coefficient of performance (SCOP)

As with SEER, the seasonal coefficient of performance (SCOP) measures a heat pump’s energy consumption based on its energy efficiency over a year. It considers temperature fluctuations and standby periods to provide clear indications of energy efficiency.

To work out your coefficient of performance (COP), divide the total power input by the total power output. The higher the number, the more efficient the system will be.

Working out your SCOP will depend on the average climate. For the correct calculation of SCOP, the heat pump is tested at a series of temperatures.

Efficiency factors

The new seasonal energy efficiency ratio (SEER) and seasonal coefficient of performance (SCOP), determine multiple factors to provide a much more realistic view of energy efficiency in real-life conditions, including:

  • Energy performance in different climate zones
  • Efficiency at partial load capacity as well as a full load
  • Energy consumption in auxiliary and standby modes
  • Different load requirements through the seasons

Seasonally efficient products

Seasonal efficiency calculations give consumers a reliable performance rating they can easily understand when buying a heating or cooling device. The new energy label includes multiple classifications from A+++ to G reflected in colour shadings ranging from dark green (most energy efficient) to red (least efficient).

Information on the new label includes not only the new seasonal efficiency ratings for heating (SCOP) and cooling (SEER), but also annual energy consumption and sound levels.

Label requirements

The energy label can be found in the box of the outdoor unit. The SEER/SCOP rating and the energy label must be displayed on product literature, data sheets and websites. Any dealer or wholesaler displaying the outdoor unit must also display the label.

Do you need planning permission for commercial air conditioning?

The benefits of higher SEER and SCOP ratings

As mentioned earlier, higher SEER and SCOP ratings are generally a benefit. This will depend on how low outdoor temperatures are during the year and how often the system is running per day. Other benefits include:

  1. The first thing to note is energy consumption. Higher SEER/SCOP-rated systems use less energy to operate, translating to lower energy bills. In contrast, those with much higher SEER and SCOP ratings will need to run for several hours to see the cost savings.

  2. Larger capacity air conditioners need variable speed fans and compressors to keep the refrigerant moving and remove heat. This also translates into more humidity being removed.

    High SEER units have multi-speed fans and compressors, allowing them to take a larger role in humidity control.

  3. Because technology requires that SEER and SCOP values keep going up, more efficient systems are being built each day. This means a massive drop in noise levels. Since compressors and fans now operate on multi-speed and variable speed technologies, they don’t produce as much noise.

    From homes to different sectors such as education or commercial offices, quiet systems are a wonderful benefit.

  4. By using less electricity, you also help the environment. While it may not be a direct correlation, over time, higher SEER and SCOP appliances, air conditioners, and other systems will reduce carbon emissions, require less energy, and take a major strain off existing networks and systems. Find out more on the race to net zero and how the HVAC industry is involved.

  5. Improved efficiency also directly translates into improved airflow. When an air conditioning system is working with less effort, it produces less heat. This means it spends less time cooling the air and more time moving it around.

    With high SEER air conditioners, you will notice they run less often, for shorter times, and the indoor air quality and circulation are improved.

How Mid-Tech services can help with your seasonal energy efficiency ratings

Mid-Tech Services install and service a wide range of energy-efficient systems manufactured by leading brand names such as Daikin, Mitsubishi, Hitachi, Panasonic and more. With highly accredited and qualified HVAC engineers deployed to install all HVAC systems, each job is completed to the highest standards with minimal disruption to any ongoing operations.

So, if you’re struggling to understand the SEER or SCOP requirements for your appliances, our trained engineers are on hand to help. We’re happy to answer your questions and support your energy efficiency intentions. Get in touch to find out more.

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