Due to the versatility of compressed air, it is widely used throughout industry to power machinery, valves and actuators, and hand tools. The broad range of industrial sectors where it is used include manufacturing and processing, mineral extraction and power generation.

Compressed air is very convenient, but it's also expensive to generate. In some cases, as little as eight per cent of the total energy supplied to a compressor is actually converted into useful energy that can do work at the point of use. So it's very important to make sure that compressed air systems are operating as efficiently as possible, and that compressed air is not wasted.

Compressed air misuse, wastage and leaks

Many systems waste up to 30 per cent of the compressed air through:

• leaks - in most cases, reducing leaks is the most important energy-saving action you can take
• misuse - because it's so convenient and easy to use, compressed air is often used when it shouldn't be, eg for cleaning machinery
• poor maintenance - a well-maintained compressed air system needs less energy to deliver the required pressure
• poor system control - making adjustments to the system can reduce energy consumption, eg by controlling individual compressors with electronic sequential controllers or using an automatic shutdown control

Legal requirements when using compressed air

There are several legal requirements you need to be aware of when you use compressed air in your business, such as having the system regularly checked by a competent examiner and supplying system operators with comprehensive instructions - find out more from the British Compressed Air Society.

Compressed air systems usually consist of the following components:

• compressor
• air cooler
• air receiver tank
• filter
• dryer
• condensate trap
• distribution system

The compressor produces compressed air at the required pressure.

The air receiver tank acts as a reservoir to store and cool the compressed air and helps make sure the system can cope with variations in demand.

The air cooler, filter and dryer all treat the air at different points in the system. They remove impurities such as water, dirt and oil from the air taken in by the compressor, as well as those added by the compressor.

Compressed air may be fed to various uses on a site via a distribution system. These distribution systems can be relatively straightforward or very complex. Some businesses use portable units, which consist of all of these components in a compact package. Portable units are usually used for small-scale applications, or when a mobile source of compressed air is needed.

Types of air compressor

The main types of air compressor are:

• Packaged rotary air compressors are most commonly used because of their low noise levels and maintenance costs. There are different types of packaged rotary air compressor, including:
  • rotary screw, which is the most widely used type as it is reliable, efficient and only needs basic routine maintenance
  • rotary sliding vane
• Reciprocating compressors are often used for small industrial applications. Their specific energy consumption is equal to or better than rotary compressors. However, they can suffer from reduced performance levels if not maintained properly.
• Centrifugal compressors are generally used for applications that need a high volume of air. At high flow rates, the centrifugal compressor is by far the most energy efficient.

Get a free sustainability report

All Northern Ireland businesses with an annual energy and resource spend of more than £30k can get a free assessment of their environmental performance across areas such as raw materials, energy, carbon, packaging, biodiversity and waste - find out more about Invest NI Sustainability Reports.

The cost of using compressed air is many times greater than that of other energy sources. So it makes sense to only use compressed air where appropriate, and to use cheaper alternatives whenever possible.

Do you need to use compressed air at all?

Compressed air is commonly used for some operations that could be carried as out as effectively - and with far less energy consumption - using an alternative method. For example, compressed air is often used for 'pick and place' applications where the air is used to generate a vacuum that lifts an item and takes it from one place to another. But a vacuum pump would generate the same volume of vacuum for a fraction of the energy.

It's a good idea to take a critical look at all the processes where you currently use compressed air and work out on a case-by-case basis to determine whether there is a more cost-effective alternative.

Switching air compressors off

An idling compressor can still use between 20 and 70 per cent of its full load power. So you can save a significant amount of energy if you turn compressors off when they are not needed. It might be appropriate to have a switch-off procedure for each compressed air process, which you could automate using time-operated solenoid valves or interlocks. These only allow a compressed air line to operate if another piece of equipment is already running.

Controlling air pressure

Regulating the air pressure to the requirement of the particular device being powered can result in significant savings. By comparing the device manufacturer's recommendations with the actual pressure used on site, you can find out if you're using more compressed air than is necessary due to the higher pressure. If you are, you can fit a pressure regulator that's local to the device and will deliver only the correct amount of pressure.

Similarly, it's a good idea to make sure that the system is delivering the air in the most efficient and effective way. For example, many blow guns are just open-ended pipes. Fitting a venturi-type nozzle to these delivers the same performance for up to 30 per cent less air.

It's also very important to keep the distribution system pressure drop as low as possible, typically below 0.2 bar, because a large pressure drop across the distribution system increases energy consumption due to the compressed air having to be generated at a higher pressure.

There are opportunities to improve efficiency throughout your compressed air system, even before the air is compressed.

Improving air intake quality, generation and control

Ideally, your system will deliver air by the most effective and efficient means according to the demand requirements of your equipment. You can increase the efficiency of your system by introducing more effective generation and control. Doing this also reduces energy wastage and improves the performance of the end-use equipment.

The air that feeds the compressor needs to be as close to outside air temperature as possible. So the location of the air intake is important. Filters in the air intake need to be kept in good condition to prevent a drop in system pressure which could increase energy use by as much as 4 per cent.

Make sure that your system is operating at the lowest possible pressure and your control methods closely match your compressors and the demand requirements of end-use equipment. For example, although cascade pressure control is commonly used to control multiple compressors, an electronic sequential controller is generally more efficient.

Detecting air leaks

All compressed air systems have leaks. Regularly testing your system for leaks is one of the most important ways you can improve energy efficiency and save money.

Air treatment

Reducing impurities in the air taken in by the compressor can improve system efficiency, and can increase the life and performance of end-use equipment. Treating air is energy intensive, so you can improve efficiency by:

• only treating air to the minimum required standard
• correctly installing and maintaining the treatment system, and making sure it's adjusted following any change in demand
• making sure timed solenoid condensate drains are set correctly, or using more efficient no-loss type electric condensate drains instead

Air receivers and distributors

Air receivers in most systems are sized only with the compressor in mind. But it's very important that there's enough 'useful storage' to be able to cope with varying levels of demand so that pressure fluctuations are reduced or eliminated. A distribution system needs to be sized to fit the demand and designed to allow adequate air flow with minimum pressure drop.

Waste heat recovery from compressed air

When air is compressed, a huge amount of heat is generated and often wasted. It's possible to recover most of this heat and use it elsewhere.

Monitor compressed air energy use

It's important to monitor the energy consumption of your system so you can quickly identify if you are wasting energy. To monitor the system effectively, you need to install specific pieces of equipment like pressure gauges and meters.

A well-maintained compressed air system needs less energy to deliver the required pressure. There are some straightforward measures you can take to keep your system running smoothly, such as:

• changing filters regularly
• keeping all components clean
• removing little-used or redundant pipework
• reducing the amount of air compressed

Compressed air system maintenance

Planned preventative maintenance is scheduled maintenance that's carried out regardless of whether there is a fault in the system. This type of maintenance is essential for the long-term reliability and energy-efficient operation of your compressed air system.

Breakdown maintenance is reactive and needs to be thought of as a temporary fix in response to a system fault or failure.

Compressed air maintenance checklist

An appropriate maintenance schedule that follows manufacturers' recommendations is an important tool for keeping the components of your compressed air system in the best possible condition. Your schedule is likely to include directions to:

• use the 'listen, look and detect' method to find leaks and system damage
• carry out a lubrication regime and make sure that oil coolers are working correctly
• check and replace filters
• carry out regular system checks
• check drive belt tension and condition
• check valve operation and condensate traps

All compressed air equipment needs to be replaced at some point, either because it has broken down and can't be repaired or because of a change in business requirements. Purchasing equipment that's energy efficient is usually more expensive, but it's cheaper to run and will save money during its lifetime compared with less efficient models.

Compressed air monitoring before you buy

By installing an effective monitoring system you can get a profile of air demand at your site. This will enable you to buy equipment that matches the demand profile as closely as possible, cutting out the need for compressors to waste energy idling.

Ownership costs of new compressed air equipment

When you choose new equipment you need to consider the overall cost of ownership throughout its lifetime. This includes the purchase cost as well as maintenance, repairs and energy consumption. You may decide to sign up for a manufacturer's fixed-length service contract. This may be for basic maintenance only or an all-inclusive package that covers all parts and labour for routine maintenance, as well as any breakdown or repair costs. The manufacturer will be able to tell you the cost of a service contract for a given period.

Generally, manufacturers can also tell you the energy consumption of a particular piece of equipment under different loads, which you can use to calculate your expected energy costs.

Specification of new compressed air equipment

Every compressed air system installation is unique in its design and purpose. So it's very important that you evaluate your own air demand before you buy any new equipment. When you decide which compressor is most suitable there are several factors to take into account, including:

• the level of air quality that the application or process requires - for example, the compressed air may need to be oil free
• the flow rate and pressure that's required
• how much you have available to spend on the initial purchase and the ongoing running costs

You could consider using a variable speed drive to save energy and money by regulating the output of the compressor.

It's also a good idea to think about adding automatic controls and pressure-regulating devices to your system to further improve energy and system efficiency.

It's a good idea to plan the measures your business will take to increase the energy efficiency of your compressed air system. The following steps will help you to understand how you use compressed air in your business, identify opportunities for improving efficiency, and measure the impact of any changes you make.

Step 1 - understand your compressed air system

Look at your system and identify where all the components are situated. Check the condition and operation of the key components. If possible, monitor the power consumption over a certain period (for example, a week) to gain a baseline against which any improvements in energy efficiency can be measured.

Step 2 - understand how your compressed air system is used

Examine the way in which the system is used. Think about issues such as pressure settings, air intakes, system misuse and alternative systems.

Step 3 - identify and prioritise actions

Identify the areas where energy efficiency can be improved and decide how and when energy-saving actions will be implemented. Some measures could be simple to carry out in-house but others may require specialist assistance.

Step 4 - seek specialist help if necessary

Contact a specialist contractor or consultant to discuss the more complex energy-saving options if you need to. The British Compressed Air Society can help you identify a suitable specialist.

Step 5 - make changes and measure the savings

Make the necessary changes to your system to improve energy efficiency. By measuring the savings you will get useful information that will help you make future management decisions about your compressed air systems.

Step 6 - continue to manage your compressed air systems for energy efficiency

Put in place policies and procedures to ensure that your system continues to operate efficiently and that energy savings are maintained in the future.

Due to the versatility of compressed air, it is widely used throughout industry to power machinery, valves and actuators, and hand tools. The broad range of industrial sectors where it is used include manufacturing and processing, mineral extraction and power generation.

Compressed air is very convenient, but it's also expensive to generate. In some cases, as little as eight per cent of the total energy supplied to a compressor is actually converted into useful energy that can do work at the point of use. So it's very important to make sure that compressed air systems are operating as efficiently as possible, and that compressed air is not wasted.

Compressed air misuse, wastage and leaks

Many systems waste up to 30 per cent of the compressed air through:

• leaks - in most cases, reducing leaks is the most important energy-saving action you can take
• misuse - because it's so convenient and easy to use, compressed air is often used when it shouldn't be, eg for cleaning machinery
• poor maintenance - a well-maintained compressed air system needs less energy to deliver the required pressure
• poor system control - making adjustments to the system can reduce energy consumption, eg by controlling individual compressors with electronic sequential controllers or using an automatic shutdown control

Legal requirements when using compressed air

There are several legal requirements you need to be aware of when you use compressed air in your business, such as having the system regularly checked by a competent examiner and supplying system operators with comprehensive instructions - find out more from the British Compressed Air Society.

Compressed air systems usually consist of the following components:

• compressor
• air cooler
• air receiver tank
• filter
• dryer
• condensate trap
• distribution system

The compressor produces compressed air at the required pressure.

The air receiver tank acts as a reservoir to store and cool the compressed air and helps make sure the system can cope with variations in demand.

The air cooler, filter and dryer all treat the air at different points in the system. They remove impurities such as water, dirt and oil from the air taken in by the compressor, as well as those added by the compressor.

Compressed air may be fed to various uses on a site via a distribution system. These distribution systems can be relatively straightforward or very complex. Some businesses use portable units, which consist of all of these components in a compact package. Portable units are usually used for small-scale applications, or when a mobile source of compressed air is needed.

Types of air compressor

The main types of air compressor are:

• Packaged rotary air compressors are most commonly used because of their low noise levels and maintenance costs. There are different types of packaged rotary air compressor, including:
  • rotary screw, which is the most widely used type as it is reliable, efficient and only needs basic routine maintenance
  • rotary sliding vane
• Reciprocating compressors are often used for small industrial applications. Their specific energy consumption is equal to or better than rotary compressors. However, they can suffer from reduced performance levels if not maintained properly.
• Centrifugal compressors are generally used for applications that need a high volume of air. At high flow rates, the centrifugal compressor is by far the most energy efficient.

Get a free sustainability report

All Northern Ireland businesses with an annual energy and resource spend of more than £30k can get a free assessment of their environmental performance across areas such as raw materials, energy, carbon, packaging, biodiversity and waste - find out more about Invest NI Sustainability Reports.

The cost of using compressed air is many times greater than that of other energy sources. So it makes sense to only use compressed air where appropriate, and to use cheaper alternatives whenever possible.

Do you need to use compressed air at all?

Compressed air is commonly used for some operations that could be carried as out as effectively - and with far less energy consumption - using an alternative method. For example, compressed air is often used for 'pick and place' applications where the air is used to generate a vacuum that lifts an item and takes it from one place to another. But a vacuum pump would generate the same volume of vacuum for a fraction of the energy.

It's a good idea to take a critical look at all the processes where you currently use compressed air and work out on a case-by-case basis to determine whether there is a more cost-effective alternative.

Switching air compressors off

An idling compressor can still use between 20 and 70 per cent of its full load power. So you can save a significant amount of energy if you turn compressors off when they are not needed. It might be appropriate to have a switch-off procedure for each compressed air process, which you could automate using time-operated solenoid valves or interlocks. These only allow a compressed air line to operate if another piece of equipment is already running.

Controlling air pressure

Regulating the air pressure to the requirement of the particular device being powered can result in significant savings. By comparing the device manufacturer's recommendations with the actual pressure used on site, you can find out if you're using more compressed air than is necessary due to the higher pressure. If you are, you can fit a pressure regulator that's local to the device and will deliver only the correct amount of pressure.

Similarly, it's a good idea to make sure that the system is delivering the air in the most efficient and effective way. For example, many blow guns are just open-ended pipes. Fitting a venturi-type nozzle to these delivers the same performance for up to 30 per cent less air.

It's also very important to keep the distribution system pressure drop as low as possible, typically below 0.2 bar, because a large pressure drop across the distribution system increases energy consumption due to the compressed air having to be generated at a higher pressure.

There are opportunities to improve efficiency throughout your compressed air system, even before the air is compressed.

Improving air intake quality, generation and control

Ideally, your system will deliver air by the most effective and efficient means according to the demand requirements of your equipment. You can increase the efficiency of your system by introducing more effective generation and control. Doing this also reduces energy wastage and improves the performance of the end-use equipment.

The air that feeds the compressor needs to be as close to outside air temperature as possible. So the location of the air intake is important. Filters in the air intake need to be kept in good condition to prevent a drop in system pressure which could increase energy use by as much as 4 per cent.

Make sure that your system is operating at the lowest possible pressure and your control methods closely match your compressors and the demand requirements of end-use equipment. For example, although cascade pressure control is commonly used to control multiple compressors, an electronic sequential controller is generally more efficient.

Detecting air leaks

All compressed air systems have leaks. Regularly testing your system for leaks is one of the most important ways you can improve energy efficiency and save money.

Air treatment

Reducing impurities in the air taken in by the compressor can improve system efficiency, and can increase the life and performance of end-use equipment. Treating air is energy intensive, so you can improve efficiency by:

• only treating air to the minimum required standard
• correctly installing and maintaining the treatment system, and making sure it's adjusted following any change in demand
• making sure timed solenoid condensate drains are set correctly, or using more efficient no-loss type electric condensate drains instead

Air receivers and distributors

Air receivers in most systems are sized only with the compressor in mind. But it's very important that there's enough 'useful storage' to be able to cope with varying levels of demand so that pressure fluctuations are reduced or eliminated. A distribution system needs to be sized to fit the demand and designed to allow adequate air flow with minimum pressure drop.

Waste heat recovery from compressed air

When air is compressed, a huge amount of heat is generated and often wasted. It's possible to recover most of this heat and use it elsewhere.

Monitor compressed air energy use

It's important to monitor the energy consumption of your system so you can quickly identify if you are wasting energy. To monitor the system effectively, you need to install specific pieces of equipment like pressure gauges and meters.

A well-maintained compressed air system needs less energy to deliver the required pressure. There are some straightforward measures you can take to keep your system running smoothly, such as:

• changing filters regularly
• keeping all components clean
• removing little-used or redundant pipework
• reducing the amount of air compressed

Compressed air system maintenance

Planned preventative maintenance is scheduled maintenance that's carried out regardless of whether there is a fault in the system. This type of maintenance is essential for the long-term reliability and energy-efficient operation of your compressed air system.

Breakdown maintenance is reactive and needs to be thought of as a temporary fix in response to a system fault or failure.

Compressed air maintenance checklist

An appropriate maintenance schedule that follows manufacturers' recommendations is an important tool for keeping the components of your compressed air system in the best possible condition. Your schedule is likely to include directions to:

• use the 'listen, look and detect' method to find leaks and system damage
• carry out a lubrication regime and make sure that oil coolers are working correctly
• check and replace filters
• carry out regular system checks
• check drive belt tension and condition
• check valve operation and condensate traps

All compressed air equipment needs to be replaced at some point, either because it has broken down and can't be repaired or because of a change in business requirements. Purchasing equipment that's energy efficient is usually more expensive, but it's cheaper to run and will save money during its lifetime compared with less efficient models.

Compressed air monitoring before you buy

By installing an effective monitoring system you can get a profile of air demand at your site. This will enable you to buy equipment that matches the demand profile as closely as possible, cutting out the need for compressors to waste energy idling.

Ownership costs of new compressed air equipment

When you choose new equipment you need to consider the overall cost of ownership throughout its lifetime. This includes the purchase cost as well as maintenance, repairs and energy consumption. You may decide to sign up for a manufacturer's fixed-length service contract. This may be for basic maintenance only or an all-inclusive package that covers all parts and labour for routine maintenance, as well as any breakdown or repair costs. The manufacturer will be able to tell you the cost of a service contract for a given period.

Generally, manufacturers can also tell you the energy consumption of a particular piece of equipment under different loads, which you can use to calculate your expected energy costs.

Specification of new compressed air equipment

Every compressed air system installation is unique in its design and purpose. So it's very important that you evaluate your own air demand before you buy any new equipment. When you decide which compressor is most suitable there are several factors to take into account, including:

• the level of air quality that the application or process requires - for example, the compressed air may need to be oil free
• the flow rate and pressure that's required
• how much you have available to spend on the initial purchase and the ongoing running costs

You could consider using a variable speed drive to save energy and money by regulating the output of the compressor.

It's also a good idea to think about adding automatic controls and pressure-regulating devices to your system to further improve energy and system efficiency.

It's a good idea to plan the measures your business will take to increase the energy efficiency of your compressed air system. The following steps will help you to understand how you use compressed air in your business, identify opportunities for improving efficiency, and measure the impact of any changes you make.

Step 1 - understand your compressed air system

Look at your system and identify where all the components are situated. Check the condition and operation of the key components. If possible, monitor the power consumption over a certain period (for example, a week) to gain a baseline against which any improvements in energy efficiency can be measured.

Step 2 - understand how your compressed air system is used

Examine the way in which the system is used. Think about issues such as pressure settings, air intakes, system misuse and alternative systems.

Step 3 - identify and prioritise actions

Identify the areas where energy efficiency can be improved and decide how and when energy-saving actions will be implemented. Some measures could be simple to carry out in-house but others may require specialist assistance.

Step 4 - seek specialist help if necessary

Contact a specialist contractor or consultant to discuss the more complex energy-saving options if you need to. The British Compressed Air Society can help you identify a suitable specialist.

Step 5 - make changes and measure the savings

Make the necessary changes to your system to improve energy efficiency. By measuring the savings you will get useful information that will help you make future management decisions about your compressed air systems.

Step 6 - continue to manage your compressed air systems for energy efficiency

Put in place policies and procedures to ensure that your system continues to operate efficiently and that energy savings are maintained in the future.

Due to the versatility of compressed air, it is widely used throughout industry to power machinery, valves and actuators, and hand tools. The broad range of industrial sectors where it is used include manufacturing and processing, mineral extraction and power generation.

Compressed air is very convenient, but it's also expensive to generate. In some cases, as little as eight per cent of the total energy supplied to a compressor is actually converted into useful energy that can do work at the point of use. So it's very important to make sure that compressed air systems are operating as efficiently as possible, and that compressed air is not wasted.

Compressed air misuse, wastage and leaks

Many systems waste up to 30 per cent of the compressed air through:

• leaks - in most cases, reducing leaks is the most important energy-saving action you can take
• misuse - because it's so convenient and easy to use, compressed air is often used when it shouldn't be, eg for cleaning machinery
• poor maintenance - a well-maintained compressed air system needs less energy to deliver the required pressure
• poor system control - making adjustments to the system can reduce energy consumption, eg by controlling individual compressors with electronic sequential controllers or using an automatic shutdown control

Legal requirements when using compressed air

There are several legal requirements you need to be aware of when you use compressed air in your business, such as having the system regularly checked by a competent examiner and supplying system operators with comprehensive instructions - find out more from the British Compressed Air Society.

Compressed air systems usually consist of the following components:

• compressor
• air cooler
• air receiver tank
• filter
• dryer
• condensate trap
• distribution system

The compressor produces compressed air at the required pressure.

The air receiver tank acts as a reservoir to store and cool the compressed air and helps make sure the system can cope with variations in demand.

The air cooler, filter and dryer all treat the air at different points in the system. They remove impurities such as water, dirt and oil from the air taken in by the compressor, as well as those added by the compressor.

Compressed air may be fed to various uses on a site via a distribution system. These distribution systems can be relatively straightforward or very complex. Some businesses use portable units, which consist of all of these components in a compact package. Portable units are usually used for small-scale applications, or when a mobile source of compressed air is needed.

Types of air compressor

The main types of air compressor are:

• Packaged rotary air compressors are most commonly used because of their low noise levels and maintenance costs. There are different types of packaged rotary air compressor, including:
  • rotary screw, which is the most widely used type as it is reliable, efficient and only needs basic routine maintenance
  • rotary sliding vane
• Reciprocating compressors are often used for small industrial applications. Their specific energy consumption is equal to or better than rotary compressors. However, they can suffer from reduced performance levels if not maintained properly.
• Centrifugal compressors are generally used for applications that need a high volume of air. At high flow rates, the centrifugal compressor is by far the most energy efficient.

Get a free sustainability report

All Northern Ireland businesses with an annual energy and resource spend of more than £30k can get a free assessment of their environmental performance across areas such as raw materials, energy, carbon, packaging, biodiversity and waste - find out more about Invest NI Sustainability Reports.

The cost of using compressed air is many times greater than that of other energy sources. So it makes sense to only use compressed air where appropriate, and to use cheaper alternatives whenever possible.

Do you need to use compressed air at all?

Compressed air is commonly used for some operations that could be carried as out as effectively - and with far less energy consumption - using an alternative method. For example, compressed air is often used for 'pick and place' applications where the air is used to generate a vacuum that lifts an item and takes it from one place to another. But a vacuum pump would generate the same volume of vacuum for a fraction of the energy.

It's a good idea to take a critical look at all the processes where you currently use compressed air and work out on a case-by-case basis to determine whether there is a more cost-effective alternative.

Switching air compressors off

An idling compressor can still use between 20 and 70 per cent of its full load power. So you can save a significant amount of energy if you turn compressors off when they are not needed. It might be appropriate to have a switch-off procedure for each compressed air process, which you could automate using time-operated solenoid valves or interlocks. These only allow a compressed air line to operate if another piece of equipment is already running.

Controlling air pressure

Regulating the air pressure to the requirement of the particular device being powered can result in significant savings. By comparing the device manufacturer's recommendations with the actual pressure used on site, you can find out if you're using more compressed air than is necessary due to the higher pressure. If you are, you can fit a pressure regulator that's local to the device and will deliver only the correct amount of pressure.

Similarly, it's a good idea to make sure that the system is delivering the air in the most efficient and effective way. For example, many blow guns are just open-ended pipes. Fitting a venturi-type nozzle to these delivers the same performance for up to 30 per cent less air.

It's also very important to keep the distribution system pressure drop as low as possible, typically below 0.2 bar, because a large pressure drop across the distribution system increases energy consumption due to the compressed air having to be generated at a higher pressure.

There are opportunities to improve efficiency throughout your compressed air system, even before the air is compressed.

Improving air intake quality, generation and control

Ideally, your system will deliver air by the most effective and efficient means according to the demand requirements of your equipment. You can increase the efficiency of your system by introducing more effective generation and control. Doing this also reduces energy wastage and improves the performance of the end-use equipment.

The air that feeds the compressor needs to be as close to outside air temperature as possible. So the location of the air intake is important. Filters in the air intake need to be kept in good condition to prevent a drop in system pressure which could increase energy use by as much as 4 per cent.

Make sure that your system is operating at the lowest possible pressure and your control methods closely match your compressors and the demand requirements of end-use equipment. For example, although cascade pressure control is commonly used to control multiple compressors, an electronic sequential controller is generally more efficient.

Detecting air leaks

All compressed air systems have leaks. Regularly testing your system for leaks is one of the most important ways you can improve energy efficiency and save money.

Air treatment

Reducing impurities in the air taken in by the compressor can improve system efficiency, and can increase the life and performance of end-use equipment. Treating air is energy intensive, so you can improve efficiency by:

• only treating air to the minimum required standard
• correctly installing and maintaining the treatment system, and making sure it's adjusted following any change in demand
• making sure timed solenoid condensate drains are set correctly, or using more efficient no-loss type electric condensate drains instead

Air receivers and distributors

Air receivers in most systems are sized only with the compressor in mind. But it's very important that there's enough 'useful storage' to be able to cope with varying levels of demand so that pressure fluctuations are reduced or eliminated. A distribution system needs to be sized to fit the demand and designed to allow adequate air flow with minimum pressure drop.

Waste heat recovery from compressed air

When air is compressed, a huge amount of heat is generated and often wasted. It's possible to recover most of this heat and use it elsewhere.

Monitor compressed air energy use

It's important to monitor the energy consumption of your system so you can quickly identify if you are wasting energy. To monitor the system effectively, you need to install specific pieces of equipment like pressure gauges and meters.

A well-maintained compressed air system needs less energy to deliver the required pressure. There are some straightforward measures you can take to keep your system running smoothly, such as:

• changing filters regularly
• keeping all components clean
• removing little-used or redundant pipework
• reducing the amount of air compressed

Compressed air system maintenance

Planned preventative maintenance is scheduled maintenance that's carried out regardless of whether there is a fault in the system. This type of maintenance is essential for the long-term reliability and energy-efficient operation of your compressed air system.

Breakdown maintenance is reactive and needs to be thought of as a temporary fix in response to a system fault or failure.

Compressed air maintenance checklist

An appropriate maintenance schedule that follows manufacturers' recommendations is an important tool for keeping the components of your compressed air system in the best possible condition. Your schedule is likely to include directions to:

• use the 'listen, look and detect' method to find leaks and system damage
• carry out a lubrication regime and make sure that oil coolers are working correctly
• check and replace filters
• carry out regular system checks
• check drive belt tension and condition
• check valve operation and condensate traps

All compressed air equipment needs to be replaced at some point, either because it has broken down and can't be repaired or because of a change in business requirements. Purchasing equipment that's energy efficient is usually more expensive, but it's cheaper to run and will save money during its lifetime compared with less efficient models.

Compressed air monitoring before you buy

By installing an effective monitoring system you can get a profile of air demand at your site. This will enable you to buy equipment that matches the demand profile as closely as possible, cutting out the need for compressors to waste energy idling.

Ownership costs of new compressed air equipment

When you choose new equipment you need to consider the overall cost of ownership throughout its lifetime. This includes the purchase cost as well as maintenance, repairs and energy consumption. You may decide to sign up for a manufacturer's fixed-length service contract. This may be for basic maintenance only or an all-inclusive package that covers all parts and labour for routine maintenance, as well as any breakdown or repair costs. The manufacturer will be able to tell you the cost of a service contract for a given period.

Generally, manufacturers can also tell you the energy consumption of a particular piece of equipment under different loads, which you can use to calculate your expected energy costs.

Specification of new compressed air equipment

Every compressed air system installation is unique in its design and purpose. So it's very important that you evaluate your own air demand before you buy any new equipment. When you decide which compressor is most suitable there are several factors to take into account, including:

• the level of air quality that the application or process requires - for example, the compressed air may need to be oil free
• the flow rate and pressure that's required
• how much you have available to spend on the initial purchase and the ongoing running costs

You could consider using a variable speed drive to save energy and money by regulating the output of the compressor.

It's also a good idea to think about adding automatic controls and pressure-regulating devices to your system to further improve energy and system efficiency.

It's a good idea to plan the measures your business will take to increase the energy efficiency of your compressed air system. The following steps will help you to understand how you use compressed air in your business, identify opportunities for improving efficiency, and measure the impact of any changes you make.

Step 1 - understand your compressed air system

Look at your system and identify where all the components are situated. Check the condition and operation of the key components. If possible, monitor the power consumption over a certain period (for example, a week) to gain a baseline against which any improvements in energy efficiency can be measured.

Step 2 - understand how your compressed air system is used

Examine the way in which the system is used. Think about issues such as pressure settings, air intakes, system misuse and alternative systems.

Step 3 - identify and prioritise actions

Identify the areas where energy efficiency can be improved and decide how and when energy-saving actions will be implemented. Some measures could be simple to carry out in-house but others may require specialist assistance.

Step 4 - seek specialist help if necessary

Contact a specialist contractor or consultant to discuss the more complex energy-saving options if you need to. The British Compressed Air Society can help you identify a suitable specialist.

Step 5 - make changes and measure the savings

Make the necessary changes to your system to improve energy efficiency. By measuring the savings you will get useful information that will help you make future management decisions about your compressed air systems.

Step 6 - continue to manage your compressed air systems for energy efficiency

Put in place policies and procedures to ensure that your system continues to operate efficiently and that energy savings are maintained in the future.