The purpose of this step is to establish where most of the organization’s energy is being consumed. Once you know which are your most significant energy uses (i.e. processes, systems, equipment, etc,), you will focus most of your efforts on those uses. This will particularly include personnel who influence energy consumption of those uses. You will also focus attention on uses with significant potential to improve, these are areas which may not be your largest consumers but which have high potential for saving energy.
How to implement
In order to identify your significant energy uses (SEUs), you need to know how much energy each process or system consumes. In an ideal world you will have energy sub-meters fitted to all large energy uses and can then simply use these meters to quantify the consumption of each use. In reality, in many cases there are not enough meters to do this perfectly. In that case you need a way of estimating their consumption. You need to carry out this activity for each energy source, i.e. electricity and each fuel type. In some cases it may be more appropriate to think in terms of processes or systems rather than pieces of equipment.
The EnMS Tool spreadsheet includes worksheets/tools to help with the task of determining SEUs.
The steps involved in identifying and quantifying your SEUs are:
Do these steps for each energy source.
Establish the total annual consumption of each source.
List all known uses of each energy source.
Estimate the annual energy consumption of each use. The total should be as close to the total energy consumption as possible.
Select the largest consumers, representing at least 80% of the total of each source.
NOTE: It is desirable that this be as accurate as possible. However, remember the purpose of this is to know where to prioritise your energy management work. A good estimation is often accurate enough.
The spreadsheet includes 3 tools to help you estimate the different uses. These tools are a motor list, a heat use list and a lighting list. You might need to develop other tools like this if you have other types of use.
You need to try to quantify at least 80% of each energy source by user, i.e. you want to know where 80% of your energy is going. If you can exceed 80% that is even better. Some organisations may find the use of Sankey diagrams more useful than other charts but any method is fully acceptable once you know where your energy is being used.
Grouping equipment by energy systems (e.g. process heating, compressed air, steam systems, etc.) is an important best practice. Understanding the dynamics of energy use in a system will lead to optimal energy savings. Process maps with energy flows identified are valuable for organizing equipment into systems.
There are many other techniques available to analyze energy data and create useful information. Tables, pie charts, bar charts, multiple year comparisons, process mapping and energy balances are some of the more important. More sophisticated techniques include statistical analyses that have become popular with six sigma programs in industry.
Methodology for determining SEUs
There are a number of ways of identifying and quantifying your SEUs. These include:
a) If you have sub metering of each or some energy sources then these meters may be able to help or even give a complete picture. You may also be able to identify gaps in your metering needs for future improvement. You may also have sub metering of, for example, electricity but not fuel or vice versa.
b) If you don’t have sub metering, which is very common, you may have to estimate by other means. One of these is by totalling the estimated use of different users. Examples are ER3 SEU Motors, Heat Users and Lighting worksheets in the EnMS Tools spreadsheet. The ER3 SEU Motors worksheet for instance requires each electrical motor of any significance (significance will vary with the size of the operation) to be tabulated and its energy use estimated. By totalling all significant motors you will see what proportion of your total electricity use you are aware of. Typically the principal other use of electricity besides motors is lighting. Some processes use electricity for heating also and if so alternatives should be investigated. Some production processes have no alternative to electrical heating. The same methodology can be used for determining significance of different heat users.
Example
If a particular process has 6 electric motors with nameplate ratings of 7.5 kW and these operate for 12 hours per day, 5 days per week for 50 weeks per year then the total consumption can be estimated by:
1. Power consumption of a motor is usually less than the nameplate, say, 10% less
2. This gives 7.5 kW X 90% X 12 hours X 5 days X 50 weeks
3. Total 20,250 kWh per year.
This equation is very useful for estimating energy consumption:
Energy Consumption = Rated Load (kW) x LF x DF x Hours
Where,
LF = load factor
DF = duty factor
c) If motor loads are stable then spot readings with a power meter will allow you to make accurate estimations. The use of ammeter readings to estimate power is considerably less accurate due to power factor variation. The breakdown can be illustrated using pie charts, Sankey diagrams, bar charts as preferred.
Once you have a breakdown of the different energy users, it is a good idea to check the total against your energy bills.
Once you have identified your SEUs, you will focus most of your efforts on these. The selection of your SEUs as mentioned earlier can be either based on absolute energy use or on the scale of potential savings.
What is this?
The purpose of this step is to establish where most of the organization’s energy is being consumed. Once you know which are your most significant energy uses (i.e. processes, systems, equipment, etc,), you will focus most of your efforts on those uses. This will particularly include personnel who influence energy consumption of those uses. You will also focus attention on uses with significant potential to improve, these are areas which may not be your largest consumers but which have high potential for saving energy.
How to implement
In order to identify your significant energy uses (SEUs), you need to know how much energy each process or system consumes. In an ideal world you will have energy sub-meters fitted to all large energy uses and can then simply use these meters to quantify the consumption of each use. In reality, in many cases there are not enough meters to do this perfectly. In that case you need a way of estimating their consumption. You need to carry out this activity for each energy source, i.e. electricity and each fuel type. In some cases it may be more appropriate to think in terms of processes or systems rather than pieces of equipment.
The EnMS Tool spreadsheet includes worksheets/tools to help with the task of determining SEUs.
The steps involved in identifying and quantifying your SEUs are:
NOTE: It is desirable that this be as accurate as possible. However, remember the purpose of this is to know where to prioritise your energy management work. A good estimation is often accurate enough.
The spreadsheet includes 3 tools to help you estimate the different uses. These tools are a motor list, a heat use list and a lighting list. You might need to develop other tools like this if you have other types of use.
You need to try to quantify at least 80% of each energy source by user, i.e. you want to know where 80% of your energy is going. If you can exceed 80% that is even better. Some organisations may find the use of Sankey diagrams more useful than other charts but any method is fully acceptable once you know where your energy is being used.
Grouping equipment by energy systems (e.g. process heating, compressed air, steam systems, etc.) is an important best practice. Understanding the dynamics of energy use in a system will lead to optimal energy savings. Process maps with energy flows identified are valuable for organizing equipment into systems.
There are many other techniques available to analyze energy data and create useful information. Tables, pie charts, bar charts, multiple year comparisons, process mapping and energy balances are some of the more important. More sophisticated techniques include statistical analyses that have become popular with six sigma programs in industry.
Methodology for determining SEUs
There are a number of ways of identifying and quantifying your SEUs. These include:
a) If you have sub metering of each or some energy sources then these meters may be able to help or even give a complete picture. You may also be able to identify gaps in your metering needs for future improvement. You may also have sub metering of, for example, electricity but not fuel or vice versa.
b) If you don’t have sub metering, which is very common, you may have to estimate by other means. One of these is by totalling the estimated use of different users. Examples are ER3 SEU Motors, Heat Users and Lighting worksheets in the EnMS Tools spreadsheet. The ER3 SEU Motors worksheet for instance requires each electrical motor of any significance (significance will vary with the size of the operation) to be tabulated and its energy use estimated. By totalling all significant motors you will see what proportion of your total electricity use you are aware of. Typically the principal other use of electricity besides motors is lighting. Some processes use electricity for heating also and if so alternatives should be investigated. Some production processes have no alternative to electrical heating. The same methodology can be used for determining significance of different heat users.
Example
If a particular process has 6 electric motors with nameplate ratings of 7.5 kW and these operate for 12 hours per day, 5 days per week for 50 weeks per year then the total consumption can be estimated by:
1. Power consumption of a motor is usually less than the nameplate, say, 10% less
2. This gives 7.5 kW X 90% X 12 hours X 5 days X 50 weeks
3. Total 20,250 kWh per year.
This equation is very useful for estimating energy consumption:
Energy Consumption = Rated Load (kW) x LF x DF x Hours
Where,
LF = load factor
DF = duty factor
c) If motor loads are stable then spot readings with a power meter will allow you to make accurate estimations. The use of ammeter readings to estimate power is considerably less accurate due to power factor variation. The breakdown can be illustrated using pie charts, Sankey diagrams, bar charts as preferred.
Once you have a breakdown of the different energy users, it is a good idea to check the total against your energy bills.
Once you have identified your SEUs, you will focus most of your efforts on these. The selection of your SEUs as mentioned earlier can be either based on absolute energy use or on the scale of potential savings.