Determination of Key Factors for Energy Management System Certification Audit Timing

The determination of the audit time for the energy management system certification is a crucial part of implementing the certification planning, directly affecting whether the certification body and the on-site audit team can fully and effectively carry out the certification audit activities. However, according to ISO 50003:2021, the main factors influencing the audit time for the energy management system certification are the number of effective personnel in the organization's energy management system, the annual comprehensive energy consumption, the number of energy types, and the quantity of main energy usage. During audit planning, certification bodies may have inconsistent grasp of these factors, leading to deviations in the determined on-site audit time, causing some inconvenience to the audit team or the auditee, which may further affect the sufficiency and effectiveness of the certification audit process.

Based on my own practical experience and the results of industry research projects I have undertaken, I would like to share and discuss the method for determining the key influencing factors of the energy management system certification audit time.

1. Determination of the Number of Effective Personnel in the Energy Management System

1. Categories of Effective Personnel in the Energy Management System

When determining the effective personnel of the energy management system, all possible personnel should be considered first, including all fixed, full-time, temporary, and part-time personnel, as well as contractors or external service providers who affect energy performance or energy performance improvement.

According to the requirements of clause A2.2 in ISO 50003:2021, when determining the number of effective personnel in the energy management system, personnel who have a substantial impact on energy performance and the effectiveness of the energy management system should be considered, including but not limited to:

2. Part-time Personnel

Based on actual working hours, the number of part-time personnel can be reduced or increased and converted into equivalent full-time personnel, which can be calculated using the following formula:

Equivalent full-time personnel = (working hours / 8 hours) × number of part-time personnel

For example: 30 part-time personnel working 4 hours per day are equivalent to 15 full-time personnel.

3. Personnel Involved in Similar or Repetitive Processes

When the proportion of effective personnel performing similar or repetitive processes in the energy management system is high, it is allowed to reduce the number of personnel within the certification scope on a clear, reasonable, and consistently applied basis for each enterprise. The reasons and criteria for determining effective personnel involved in similar or repetitive processes should be documented.

Generally, the reduction should not exceed 20% of the number of personnel involved in similar activities; in special cases, the maximum reduction can be up to 50%. For example, if on-site workers only perform simple maintenance of equipment and facilities (such as cleaning or replacement) and/or simple auxiliary production tasks (quality inspection, manual packaging, handling, etc.), the number of personnel can be reduced to 50% depending on the situation.

4. Shift Personnel

If important parts of the operation are in shift form and there is no significant difference in activity type and intensity between shifts, the effective number of shift personnel can be converted as follows:

Effective number of shift personnel = (total number of shift employees) / (number of shifts - 1)

For example, a chemical workshop operates continuously with four teams, each with 12 people, rotating shifts in the morning, afternoon, and evening (i.e., four shifts with three operating). The effective number of shift personnel is 16, calculated as: 12*4/(4-1) = 16.

2. Determination of Annual Comprehensive Energy Consumption

The organization should calculate its annual comprehensive energy consumption based on all the following principles and according to the method specified in GB/T 2589—2020.

1. Energy consumed by all activities within the boundary and scope of the energy management system for which the organization applies for certification

Regarding the defined scope and boundary of the EnMS, the actual energy consumed by the organization usually includes:

Energy used for the production of the product to be certified and industrial operations, including energy used as raw materials, materials, fuel, and power;

Energy used as auxiliary materials in the production/service process of the product to be certified;

Energy used in the production process of the product to be certified;

Energy used in new technology research, new product trials, and scientific experiments;

Energy used in various repair processes related to industrial production activities;

Energy used for labor protection within the production area;

Energy used to provide power, electricity, mechanical repair, water supply, air supply, heating, and cooling for the enterprise;

Energy consumed by the production command system (plant department), various management departments, and non-commercial departments serving production (such as canteens, vehicle fleets, bathhouses, etc.).

2. The energy consumption statistics period should be the comprehensive energy consumption of the most recent year

Based on the certification application submitted by the organization to be certified, its annual comprehensive energy consumption is determined by:

For enterprises with stable and continuous production, it can be determined as the comprehensive energy consumption of the previous year or the 12 months before the application;

If the enterprise's energy consumption statistics cannot reflect the status of a full year or there are significant changes, the annual comprehensive energy consumption should be estimated based on the current situation.

The statistics of annual comprehensive energy consumption must follow the principle of "calculate consumption when put into use," strictly controlling the time boundary of energy consumption statistics.

3. The annual comprehensive energy consumption should be expressed in the form of standard coal consumption

Standard coal is a simulated comprehensive calculation unit for calculating total energy. In China, the calorific value of one kilogram of standard coal is defined as 7000 kcal. The calculation can be performed as follows:

(1) Determination of the conversion coefficient to standard coal

① For enterprises with measured calorific values, the conversion coefficient to standard coal is calculated as follows:

② For enterprises without measured calorific values, the conversion coefficient to standard coal can refer to GB/T2589.

(2) Determination of comprehensive energy consumption

Comprehensive energy consumption = Σ (consumption of a certain type of energy × conversion coefficient to standard coal for that energy type)

4. Comprehensive energy consumption should not be counted repeatedly

When calculating the organization's comprehensive energy consumption, double counting is not allowed. In particular, energy media (such as water, oxygen, compressed air, etc.) that enter the enterprise and are converted through processing to obtain energy should not be separately counted in the enterprise's comprehensive energy consumption.

5. The principle of "who consumes, who accounts" should be followed

"Who consumes, who accounts" is a basic principle that energy statistics should follow, meaning that the entity that actually consumes the energy, regardless of whether it pays for it, is responsible for the statistics.

3. Determination of the Number of Energy Types

Energy refers to electricity, fuel, steam, thermal energy, compressed air, and other similar media. Energy includes various forms, including renewable energy. According to the GB/T2589-2020 standard and the national energy statistical reporting system, energy types can generally be divided into three categories based on their basic forms in nature: primary energy, secondary energy, and energy-consuming working substances:

Primary energy refers to energy that exists naturally in the environment, mainly including: raw coal, crude oil, natural gas, hydropower, wind energy, solar energy, biomass energy, etc.;

Secondary energy refers to energy products processed and converted from primary energy, mainly including: washed coal, coke, coal gas, gasoline, kerosene, diesel, fuel oil, liquefied petroleum gas, purchased thermal energy, electricity, etc.;

Energy-consuming working substances refer to working materials consumed during production that are neither used as raw materials nor incorporated into products, but require direct energy consumption during production or preparation, mainly including: fresh water, softened water, deoxygenated water, compressed air, oxygen, nitrogen, carbon dioxide, acetylene, calcium carbide, etc.

Considering the requirements of China's energy statistical system and/or the economic impact of energy use, the energy quality purchased by the applicant organization may vary. However, based on the similarity of their usage methods and principles, this document classifies energy types as shown in the table below.

According to the requirements of ISO 50003:2021, when calculating the audit time for the energy management system, only energy types crossing the boundaries of the energy management system are considered, including:

First, energy types extracted (such as crude oil, natural gas, coal) or captured (such as solar energy, wind energy) within the proposed certification organization's boundary and used for production or service activities should be counted as energy types crossing the boundary.

Second, for energy-consuming working substances, two situations can be considered when counting energy types:

Generally, energy-consuming working substances do not carry energy when entering the organization's boundary. The energy is obtained after processing and conversion within the enterprise. When calculating the enterprise's comprehensive energy consumption, they are not counted separately; therefore, their impact is not considered when identifying energy types.

In some special cases, such as the cascade utilization of energy-consuming working substances in industrial parks based on circular economy, or when applying for certification as part of the entire organization using energy-consuming working substances provided outside the boundary (such as cooling water, compressed air, etc.), their usage amount can be considered as energy types.

Based on the consumption of different energy types (converted into standard coal equivalent according to actual physical consumption), their proportion is calculated and sorted from largest to smallest to determine the number of energy types covering 80% of the organization's total energy consumption.

For example: if an organization consumes 40% coal, 34% electricity, 15% natural gas, 5% diesel, 3% gasoline, and 3% other fuels, the number of energy types determined for the organization is 3.

4. Determination of the Number of Major Energy Uses

The number of major energy uses is obtained from the energy review of the proposed certification organization. When determining the number of major energy uses, the certification body should first obtain the criteria for determining the organization's major energy uses, i.e., what constitutes large energy consumption and/or significant potential for energy performance improvement.

Major energy uses can be identified and confirmed based on different levels of the organization, such as facilities (warehouses, workshops, offices, etc.), equipment (motors, boilers, etc.), processes or systems (lighting, steam, transportation, electrolysis, motor drives, etc.).

Generally, major energy uses can be classified and counted based on the commonality of energy use structure, working principles, and energy-saving technologies. Common energy use categories include boiler systems, oilfield heaters, industrial furnaces, gasoline engines, diesel engines, steam turbines, gas turbines, industrial electric heating equipment, motor systems, transformer systems, pump systems, fan systems, compressor systems, central air conditioning systems, heat pumps, cold storage, pumping units, oil drilling, machine tools, electric welding machines, lighting systems, etc.

The above content mainly focuses on classification based on energy use forms and energy-saving measures, which vary in different industries and enterprises. In practical application, classification can be determined according to different manifestations and management requirements (such as subdivision or combination).

Conclusion

The author hopes this article can provide a reference for certification bodies in determining the audit time for energy management system certification and improve the consistency of the audit time determination process and results, thereby ensuring the adequacy and effectiveness of the energy management system certification audit process.