Why Carry Out an Energy Audit?

Energy: an essential resource for society

Energy powers production and everyday life. Higher levels of production can increase energy demand. Energy used in industrial processes and daily activities is commonly considered in two main forms:

• Thermal energy is used in production, processing, drying, heating and air conditioning. Specific consumption can be expressed in kJ per unit of product. Fuels such as coal, oil and gas may be used to provide this heat.
• Electrical energy powers motors, processing equipment and lighting. Specific consumption can be expressed in kWh per unit of product. Electricity can be generated from primary energy sources including coal, oil, gas and hydropower.

Historical statistics and the climate context

The fossil-energy chain produces greenhouse gas emissions, particularly CO₂, and can also involve methane emissions. Historical figures included 1.83 kg CO₂ per kg of coal, 2.22 kg CO₂ per litre of petrol, 3.7 billion tonnes of CO₂, 10,000 tonnes of SO₂ and 10,200 tonnes of NOₓ per year from coal-fired power, and an 80%/20% split between energy-related and other greenhouse gas emissions. The data sources and reference years are unspecified; these are historical reference figures and must not be used as current statistics or emission factors. 

Historical estimates indicated a global surface temperature increase of 0.5–1°C since the nineteenth century and sea-level rise of 101–253 mm; these are historical figures rather than a current climate assessment. The United Nations Framework Convention on Climate Change was adopted on 9 May 1992, with the objective of stabilising greenhouse gas concentrations to prevent dangerous human interference with the climate system.

For Vietnam, historical estimates attributed a 0.7°C temperature increase and 20 cm sea-level rise over a fifty-year period to the hydrometeorological authority, and described Vietnam as one of the five countries most exposed to sea-level rise. The reference period and underlying study are not identified. Drought, flooding and environmental pressures reinforce the need to use energy efficiently.

Historical estimates suggested approximately sixty years of oil and gas reserves and one century of coal reserves. Such estimates depend on the reference year, consumption and resource assumptions and should not be treated as current depletion forecasts. Sustainable development requires efficient energy use and continued development of renewable, environmentally appropriate energy sources.

Energy audits: a tool for efficient energy use

Effective energy management starts with a sound assessment of current use. An energy audit evaluates the existing situation and identifies ways to reduce specific energy consumption and operating costs. It can support lower energy use in production and buildings while maintaining or improving capacity, productivity, health, comfort and safety. The focus is on energy-saving opportunities and potential improvements in energy performance. Audits may range from preliminary reviews to detailed assessments.

Measurement for an energy audit

Measurement, inspection and monitoring provide the consumption data needed for the audit. Metering also supports ongoing evaluation of energy-saving measures.

Measurement locations and parameters depend on the production process and may include:

• Electricity consumption (kWh).
• Power factor, cos φ.
• Fuel energy consumption (MJ).
• Production output.
• Specific electricity consumption (kWh per unit of product).
• Specific thermal energy consumption (MJ per unit of product).

Define the indicators to track, install suitable meters and establish data recording forms. Collect and analyse the data to determine the audit priorities.

Preliminary energy audit

An example preliminary audit is carried out annually and covers about 85% of the facility's energy demand. These are planning examples, not universal requirements. A typical sequence includes:

• Preparation: become familiar with the plant, production processes and equipment; prepare questionnaires; arrange measuring instruments and a competent team. This example envisaged approximately four auditors with thermal and electrical expertise.
• Site work: distribute questionnaires, interview managers and operators, review plant operation and measure existing equipment. This example allowed three to five days.
• Analysis and reporting: organise the data, prepare consumption charts and performance indicators, and propose preliminary saving opportunities. This example envisaged reporting within one month after the site work.

Detailed energy audit

An example detailed audit covers about 95% of demand, repeated every three years, with four to sixteen weeks of work, at least five auditors and a report within three months. These figures describe an example approach; actual scope, frequency, staffing and timing depend on the facility, agreed work and applicable requirements. Preparation follows the same basic principles as a preliminary audit.

A detailed audit should distinguish measures requiring no expenditure, low-cost measures and projects requiring substantial investment.

• No-cost measures include management improvements and better operation and maintenance. An illustrative saving potential is about 10%; this is not a guaranteed outcome.
• For low-cost measures, an illustrative potential is about 20%; site-specific analysis is required.
• For capital-intensive measures, prepare a feasibility assessment covering costs, benefits, payback, environmental and occupational health considerations, and implementation priorities. Compare project economics and consider financing from internal funds, bank loans, project support or instalment arrangements.

Practical value

 Energy auditing is an important management tool for production and service facilities, supporting efficient energy use, productivity and sustainable operations.

Reference: UNFCCC — Convention adopted on 9 May 1992