GUIDANCE ON ENERGY AUDITS[1]

  1. Background

The purpose of an energy audit is to determine how energy is used in an existing facility, and to quantify it. This helps to identify opportunities to improve the effectiveness with which energy is used. A typical strategy for energy management is given in Annex 1.

Energy audits can be done for all kinds of installations such as industries, utilities, commercial or office facilities, and homes. This guidance briefly introduces energy audits relevant to office facilities, which is most relevant for INFM members. For more detailed information, a list of relevant information sources is given in Annex 2.

  1. Types of Energy Audit
  • ASHRAE classification

The American Society of Heating, Refrigerating and Air-Conditioning Engineers

(ASHRAE) defines three levels of audits: Level I, Level II and Level III. Each audit level builds on the previous level, with increasing complexity and thoroughness, as well as increasing potential to identify energy savings.

  • Based on coverage
  • Single Purpose Energy Audit

This type of audit provides a detailed analysis on one or more types of equipments or projects. Examples include those that focus only on lighting or boiler/chillerreplacements, or a combination of these.

  • Comprehensive Audit

It covers the entire facility. It considersthe interactive effects of equipments and their energy systems

  1. Process and Methodology

Typically, the process followed would be:

  • Review of energy data

The audit typically begins with a review of readily available data on historical and current energy (electricity and fuel) usage, for the whole facility and its components. This will include energy bills and internal logs for a few years. This information could be used to:

  • Benchmark the facility’s or equipment’s energy use
  • Check variations of energy use and relate to factors such as climate, building occupancy, maintenance schedules etc
  • Prioritise the areas for further study
  • Energy load management opportunities. This includes looking at:
  • Opportunities for avoiding or reducing energy demand
  • Shifting energy use from peak use periods[2] to non-peak periods
  • Looking at opportunities for power factor[3] improvement
  • Study[4] the efficiency, effectiveness of:
  • Building envelope, including the walls, ceilings, floors, windows
  • Motors
  • Energy end use systems, such as the HVAC or water pumping system
  • Energy generation systems, such as the diesel generator or solar photovoltaic system
  • Building energy monitoring, control or automation systems
  • Energy or environment management systems. The equivalent ISO standards are ISO 50001 and ISO 14001, respectively.
  • Options in energy generation, renewable energy, co-generation[5] and fuel substitution[6]
  1. Energy Audit Report

The key elements of the report could be:

  • General facility information
  • Introduction of the energy system and energy flows (eg, electrical and steam distribution diagrams)
  • Climate data
  • Summary of previous audits and retro-commissioning
  • Energy data and measurements
  • Analysis of the energy system, energy flows and energy performance of equipments/systems
  • Energy saving measures, including their cost benefit analysis
  • Prioritisation of the energy saving measures
  1. Energy auditor

Energy auditing services are offered by Energy Services Companies (ESCOs), energy consultants and engineering firms. The auditor needs to have a wide range of knowledge and skills and often this will not be available in adequate measure in a single individual. Few key skills needed are listed below:

Conducting energy and mass balance

This is used to map the energy and mass flowing through the facility and through all major equipments. The sum of the energy or mass outflows should equal the energy or mass inflows. With this information, it is often possible to see opportunities for energy saving and recovery.

Knowledge of energy management options inelectrical and thermal systems

Energy management options are specific to each kind of equipments and detailed knowledge is needed.

Knowledge of bio-climatic design

Building design needs to be optimized for the bio-climatic features of the site. There are specific design priorities for each climatic zone. For example, for a tropical climate the emphasis would be on improving the ventilation, while in a cold climate the emphasis would be on improving solar access. The site features also could also give many clues and strategies for the design.Bio-climatic design involves optimisation of shape and orientation, design of appropriate building envelope (optimisation of wall, roof and floor insulation; glazing etc), optimising access to daylight, landscaping.

Economic analysis, including Life Cycle Costing

Energy modeling and simulation

This can range from simple to complex modeling exercises.

  1. Studies that could complement an Energy Audit

Few other initiatives such as environmental management, carbon management, maintenance management, water management and Green Procurement, share some common methodologies/procedureswith Energy Management and have co-benefits. Hence it might be worthwhile to check if partial or full audits/studies to cover those issues, could be carried out along with an energy audit. This is briefly touched upon in Annex 3

ANNEX 1

ENERGY MANAGEMENT STRATEGY

The energy management strategy could vary from site to site. A broad strategy is depicted in the figure below.

Step 1: Energy demand reduction or avoidance

The first priority would be to reduce or avoid demand for energy. For example, the possibility for designing a building with optimum level of daylight, thereby reducing use of electricity for lighting.

Step 2: Energy Efficiency

The next step is to consider how to improve energy efficiency in energy generation systems (eg, diesel generators) and energy end use systems (eg, air conditioning system).

Step 3: Energy production options and use of Renewable Energy

The first 2 steps will help to minimize the energy requirements of the facility and identify all energy flows in the system. This will be the right stage to decide on any further changes for the energy supply and production options. This might include looking at options for:

  • Increasing or decreasing the size of existing energy production systems (eg, adding or removing a diesel generator set)
  • Use of renewable energy
  • Co-generation
  • Fuel substitution

ANNEX 2

LIST OF INFORMATION RESOURCES

DOE.Energy Savings Assessment Training Manual.US Department of Energy

DOE, 2010.A Guide to Energy Audits. US Department of Energy

LBNL, 2010. Industrial Energy Audit Guidebook: Guidelines for Conducting an Energy Audit in Industrial Facilities. Ernest Orlando Lawrence

Berkeley National Laboratory

NRC. EnErgy SavingS Toolbox – an Energy audit Manual and Tool. Natural Resources Canada

ANNEX 3

STUDIES THAT COULD COMPLEMENT AN ENERGY AUDIT

Environmental management, carbon management, maintenance management, water management and Green Procurement, share some common methodologies/procedureswith Energy Management and have co-benefits. Hence it might be worthwhile to check if partial or full audits/studies to cover those issues, could be carried out along with an energy audit.

  • Environmental audit

Many energy management actions also reduces environmental impacts and hence common strategies are possible. For example, reducing fuel consumption in a boiler reduces air pollution. An environmental audit could also reveal opportunities for energy recovery (such as energy generation from waste, or waste heat recovery from the exhaust of a boiler)

  • Carbon/GHG audit

Greenhouse gas (GHG) emissions from a UN type facility is mostly from energy consumption, apart from release of refrigerants.

  • Maintenance audit

Better maintenance practices helps to reduce energy consumption (eg, early detection and repair of steam or water leaks). Equipments normally are energy inefficient during start-ups and shut-downs. Many Predictive Maintenance techniques help to prevent or delay breakdowns, and thus avoid energy wastage during start-ups and shut-downs.

  • Water balancing

Reducing water consumption and wastage, helps to reduce the energy used for pumping. Water Balancing studies maps the water input, waste water discharge, and wastage of water within facilities, followed by analysis on how to reduce the wastage or potential for recycling or reuse of water.

  • Green Procurement

Many energy management recommendations would involve procurement actions. Both Procurers and Requisitioners should know how to effectively implement Green Procurement. An evaluation of the Procurement function and activities, could help to recommend the appropriate strategy for ensuring Green Procurement

[1] Also called as energy assessment, energy study, feasibility study, technical assistance report

[2] Many utilities charge a higher rate for energy used during peak load period. It is possible to shift some of the energy consumption activities to non-peak periods (eg, water pumping). Many utilities also charges a steep penalty if the peak demand exceeds a certain level. In such cases, it is important to shift non-critical loads to non-peak periods.

[3]

[4] As per needs, this will involve measurement of operational parameters, performance trials of key equipments and their systems, carrying out energy and mass balance. Loading of all major equipments will also be measured or estimated. At low loads, most systems operate at low efficiency. At the same time, overloading will decrease their life. Hence, it is important to ensure an optimum loading of equipments

[5] Also called as Combined Heat and Power (CHP). It refers to the sequential production of electricity and heat, in either order (eg, a diesel generator produces electricity and the waste heat from the exhaust is used to generate steam or hot water that could be used in the facility)

[6] Fuel substitution is normally done to move from a polluting or less efficient fuel (eg, any solid fuel) to a more cleaner or efficient fuel (eg, any gaseous fuel).