A Guide to Energy Audits Standard - AS/NZS 3598:2014

The energy audits standard sets out minimum requirements for commissioning and conducting three prescribed types of energy audits (Type1, Type2 and Type3) that identify opportunities for cost effective investments to improve energy performance. These energy audits encompass all forms of energy used within the organization and are undertaken by appropriately competent personnel either internal or external to the organization.

It is intended for use by any organization, and anyone involved in the assessment of energy use and identification of opportunities to improve the management of energy within the organization.

When to undertake audits:

An audit of an appropriate type should be undertaken every 3 to 5 years or whenever there are-
1 Proposed and recent significant changes in site use, such as systems, tenancies, changes to fuel systems or processes.
2 Site developments or refurbishments.
3 Proposed and recent revisions of working practices.
4 Substantial changes in energy costs or availability.
5 Significant changes in the energy performance indicator (EnPI) for the site or audited object.
6 Proposed and recent changes in technology; or
7 Regulatory or other requirements to do so.

Energy Audit Types

TYPE 1: Basic energy audit

Simple and cheap, broad brush energy audit
Type 1 audits are typically suitable for smaller sites with lower energy expenditures, or as a scoping audit for larger sites. Audits of this type offer a quantitative overview of energy performance and identify no-cost and low-cost opportunities with payback periods of up to 2 years. The accuracy of costs and benefits would generally only be sufficient for low-cost operational expenditures or as a method for prioritizing opportunities for more detailed assessment.

Type 1 audits calculate energy savings by reconciling against the end-use breakdown (greater than 20% of total site consumption), considering daily energy consumption profiles.

Type 1 audits provide indicative or typical savings calculated using rules of thumb or industry acceptable benchmarks, with indicative costs used to provide a simple payback. Costs and energy savings are therefore to a broad estimate level.

TYPE 2: Detailed energy audit

Standard model for a site-wide energy audit
Type 2 audits provide detailed analysis of energy performance to quantify the full range of opportunities for a site. It defines a detailed level of audit involving a comprehensive review and analysis of equipment, systems, and operational characteristics of the whole site to enable quantified energy savings recommendations. Type 2 audits are required to include financial analysis of recommended energy performance improvement actions based on agreed financial criteria to rank opportunities. The accuracy of costs and savings should generally be sufficient for operational expenditures or medium­ scale capital investments and should be commensurate with organization’s approval processes for expenditures at those levels.

Audits of this type may include on-site measurements but would not normally involve the installation of additional monitoring equipment. As a result, some major projects or opportunities may require further investigation beyond the scope of the audit to fully quantify the energy performance improvements, costs, and benefits. Such work may become the brief for a Type 3 audit.

Type 2 audits calculate energy savings by reconciling against the end-use breakdown (greater than 10% of total site consumption), considering daily energy consumption profiles. Costs of implementation are based on a build-up of both capital and labour items including site, internal and project management costs. Type 2 audit requirements provide costs and benefits to a medium level of accuracy.

TYPE 3: Precision subsystem audit

Detailed audit focused on a particular subsystem on a site

Type 3 audits are detailed audits of specific subsystems, with additional data gathering and measurement to provide a higher level of accuracy. Audits of this type are typically focused on a process or subsystem level, such as for HVAC, building management systems, compressed air, or lighting, rather than the whole site. Type 3 audits involve onsite measurements to monitor energy data over a period long enough to capture the various operating conditions and relevant variables which require their own set of measurements to quantify the business case for energy saving measures more accurately than is possible under a Type 2 audit.

Audits of this type would normally involve representatives from the organization in the development of cost estimates, to provide the level of accuracy required by the company's capital expenditure processes.

Type 3 audits calculate energy savings by reconciling against the detailed energy end use breakdown (greater than 10% of total site consumption), considering the additional measurements taken during the audit. Costs of implementation are based on a build-up of both capital and labour items including site internal and project management costs, to the level of accuracy required by the company's capital expenditure process. Type 3 audit requirements provide costs and benefits to a higher level of accuracy, developed with input from the organization.

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