In a nut shell
An EnPI is a standard or point of reference against which comparisons can be made. It is a valuable tool, through the process of benchmarking, for assessing energy performance, allowing you to compare the performance of similar activities or facilities and determine the scope for improvement. Use of EnPIs will help you make realistic assessments of relative performance and judge what is attainable under Energy MAP.
In general EnPIs may be based on consumption, cost or environmental (CO2 ) measures. Remember, benchmarking is a means to an end, the key question is what will be done with the information?
Why does this matter?
As with any benchmarking exercise, it is important to compare your performance against other internal or external reference standards, in order to determine how well you are actually performing. EPIs can be used to develop relative measures of energy performance, track changes over time, and identify best energy management practices. Use EnPIs to:
- Establish baselines and track performance;
- Identify best practices and set targets;
- Identify savings potential;
- Prioritise your efforts;
- Identify problems;
- Communicate results and achievements.
Remember that EnPIs may not be solely technical measurements. You may wish to communicate performance to other audiences within your organisation in a non-technical manner. For example, in a hospital, energy performance or savings may be expressed in terms of medical equipment that could be bought as a result of energy savings. Alternatively, energy waste expressed in terms of the number of staff jobs can deliver a stark message.
Indicators can be established in a variety of ways, however the two main approaches are:
- Best Practice – a comparison against established practices considered to be the best in the industry or sector.
- Past performance - comparison of current versus historical performance.
In general, best practice indicators relate to external comparisons, while past performance and other measures to compare performance between different sites or operational units etc., focus more on internal indicators. Separate indicators may also be used for fossil fuel and electricity. Provided the information is available, benchmarking can be carried out on any scale, even down to individual items of plant or equipment.
Whether internal or external comparisons are used, if the level of energy consumption exceeds the EnPI, this indicates that performance can probably be improved, savings made and environmental impacts reduced.
The characteristics of an effective EnPI include:
- Simple and understandable
- Contains boundaries
- Relevant to what your organisation does
The main steps in applying EnPIs include:
- Select the scope of the EnPI
(internal/external, best practice/past performance, etc.)
- Determine the focus of the EnPI
(building type, industrial process line, organisational wide etc.)
- Develop the measurement criteria
(consumption, cost, CO2, other non-technical measures, electricity, fossil fuel etc.)
- Select the time frame for analysis
- Obtain energy data
- Carry out the comparisons
- Track performance over time
This activity will normally be carried out by the energy co-ordinator or manager.
Internal benchmarking may be carried out at more regular intervals. For example, average seasonal or monthly EnPIs may be compared. However, these should be normalised for weather and activity based factors, such as production levels (industry) or out of hours use of buildings etc.
Starting from afresh, it will be necessary to collect a minimum of one year’s consumption data before any meaningful global comparisons on energy performance can be made. However, monitoring of the EnPIs generated is an ongoing process.
Challenges and pitfalls
Data quality and availability
The two most important factors affecting the application of EnPIs are energy consumption values and floor area (for buildings). Accuracy of these values is essential in calculating realistic benchmarks. Incomplete energy consumption data and inaccurate building floor areas can result in misleading conclusions and erroneous decision making. For buildings, floor area is generally taken as gross internal floor area in m2.
Other potential problems include the lack of suitable EnPIs for your sector, building type or industry. In Ireland EnPIs may be available from SEAI, through information for Display Energy Certificates. A wide range of performance indicators are also available from the UK Carbon Trust.
EnPIs may be ‘normalised’ to take account of a range of variables that affect energy consumption. Depending on whether you are dealing with industrial processes or buildings, influencing factors include weather, hours of use, occupancy levels and production levels.
In industry, the most common measure of performance is energy use per unit of production (specific energy consumption). It is often best to relate industrial EnPIs to saleable product, as costs are often based on this measure. The calculation appears to be relatively straightforward, however, energy use does not always depend on production throughput. The less sensitive energy use is to production, the more sensitive the EnPI will be to changes in production. In this respect it is important to identify the actions under your control that influence energy use and also the factors outside your control that may affect it. You may therefore need to adjust your EnPI for changes in production output and other factors such as weather, shift patterns, etc.
For buildings, heating energy consumption can be normalised for the influence of weather-related temperatures. This is carried out through the use of ‘degree days’, which provide a measure of the severity and duration of weather conditions. Information on the application of degree days is available from SEAI. In some buildings, such as hotels, occupancy levels may influence consumption patterns. Whereas in other buildings such as older hospitals, the building volume may be a factor to take into account. Such ‘external’ factors may need to be brought into the equation in order to arrive at meaningful performance indicators.
EnPIs provide a broad measure of the performance of energy consumption and should be used with caution. If external factors are not accurately taken into account, then the resultant EnPIs can mask actual trends in energy consumption and lead to erroneous decision making.
Further information and guidance
Energy Benchmarking For Success. SEAI
E3 Energy Management Bureau for universities.
The Carbon Trust
For specific information on EnPIs in different sectors see ‘Energy Consumption Guides’ in the Publications section
Carbon Trust Civil estate benchmarking guide
The BESS project has benchmarking information for SMEs working in the following sectors: dairies, meat processing, bakeries, breweries, and textile dyeing. http://www.bess-project.info/
Energy Star Portfolio Manager
US benchmarking and labelling programme
California building benchmarking tool
Commercial Buildings Energy Consumption Survey,
From the US DOE Energy Information Administration
TM46 Energy Benchmarks. CIBSE. 2008
CIBSE Guide F: Energy efficiency in buildings (Section 19: Benchmarking, monitoring and targeting and Section 20: Benchmarks). CIBSE, UK.
BSRIA Guidance Note, ‘Rules of thumb’ (UK) guidelines for assessing building services. BSRIA, UK. Pages 24-38.
Global Industrial Energy Efficiency Benchmarking. United Nations Industrial Development Organization. 2010:
Applying Current Known International Benchmarks for Buildings in an Irish Context. Commercial Buildings Special Working Group Technical Panel. Sustainable Energy Authority of Ireland.
The following benchmarking guides are available from the UK Carbon Trust (but please check website links above for up-to-date online versions):
ECG013 Energy Efficiency in Public Houses
ECG019 Energy use in offices
ECG036 Energy Efficiency in Hotels: A Guide for Owners and Managers
ECG049 Energy Efficiency in the Laundry Industry
ECG051 Energy efficiency in sports and recreation buildings - a guide for owners and energy managers
ECG054 Energy efficiency in further and higher education - cost-effective low energy buildings
ECG072 Energy consumption in hospitals
ECG073 Saving energy in schools. A guide for head-teachers; governors; premises managers and school energy managers
ECG075 Energy use in Ministry of Defence establishments
ECG077 Energy Efficiency in the Dry-Cleaning Industry
ECG078 Energy use in sports and recreation buildings
ECG081 Benchmarking Tool for Industrial Buildings – Heating and Internal Lighting
ECG082 Energy Use in Court Buildings
ECG083 Energy Use in Government Laboratories
ECG084 Energy Use in Prisons
ECG087 Energy Use in Local Authority Buildings
ECG020 Rubber Compounding in the Rubber Processing Industry
ECG027 Energy Use in the Glass Container Industry
ECG038 Non-Ferrous Foundry Industry
ECG040 Compressing Air Costs - Generation
ECG041 Compressing Air Costs - Leakage
ECG042 Compressing Air Costs - Treatment
ECG043 The UK Non-Fletton Brick making Industry
ECG047 The Minerals Industries of Northern Ireland
ECG055 Extrusion of Thermoplastic Pipes & Profiles. (Updated).
ECG063 Energy Consumption in the Manufacture of Domestic; Borosilicate and Specialist Glass
ECG065 Cutting Energy Costs in the Soft Drink Industry
ECG066 Steam Generation Costs
ECG067 Steam Distribution Costs
ECG068 The UK Corrugated Package Industry
ECG069 Cutting Energy Costs in Carpet Manufacturing
ECG070 Energy Use in the Minerals Industry of Great Britain
ECG074 Energy Consumption in Continuous Steel Reheating Furnaces
ECG080 Energy Use in the Animal Feed Sector
ECG092 Steam Distribution Costs
ECG062 Energy Bills in Craft Bakeries: Are you Paying Too Much? A Benchmark for Your Bakery
ECG089 Energy Use in Pig Farming
ECG091 Energy Benchmarks for Protected Greenhouse Horticulture in the UK
Return to Step 18.