MÉTODO DE FILON

The verification strategy is the general approach used for the verification. It determines the expected scope and approach used to develop the verification plan. The verification strategy is iterative and will evolve as the verification progresses; however, experienced verifiers will generally have a good idea as to the direction the strategy should take before evidence is requested. The verification strategy must be documented in the verifier’s working paper files and in the verification report.

Verification strategies span a spectrum between controls reliance and substantive testing, with most verification approaches falling somewhere in between (see Figure 7). At one end of the spectrum is an approach that relies almost exclusively on substantive procedures as the basis for the verifier’s conclusion. Substantive procedures are verification procedures that are performed at the attribute level or on more granular information (e.g., raw data and evidence). Substantive procedures consist of analytical tests and test of detail.

Controls reliance tests the controls that were used to manage the data and generate the greenhouse gas assertion. Controls reliance can only be used in a relatively robust and mature greenhouse gas data management system. The preliminary risk assessment in a controls reliance approach identifies the controls along the data trail, and develops tests to analyze the design effectiveness of the controls. If the verifier is going to rely on controls, the verifier must test the operational effectiveness of the controls and the data that the control is processing. Data testing is done to a lesser extent in controls reliance verifications than in substantive procedures.

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In most cases, significant controls reliance will not be feasible or appropriate owing to the immaturity of greenhouse gas data management systems. As such, Alberta requires that verification strategies be designed such that much of the evidence required to support the verifier’s conclusion results from substantive procedures.

AESRD will not accept verifications based solely on controls reliance without supporting substantive testing. In all cases, verifiers must assess underlying data to confirm that data is being reported correctly and that responsible party’s data management systems being used are performing as intended.

The verification strategy needs to be tailored to the specific data streams, controls, and evidence available for the facility or offset project. For example a controls approach is used for data tied into the operating systems and a substantive approach is used for data that relies on spreadsheets and manual entries. In cases with small or limited numbers of data points, such as monthly invoices for a calendar year, substantive testing is generally a more efficient and cheaper audit

approach.

Controls reliance is appropriate in situations where there are extensive operational controls that are operating effectively, and where there is a large amount of data in which sampling alone and other substantive procedures are unlikely to yield sufficient and appropriate evidence to support the verifier’s conclusion. For example, readings from a continuous emissions monitor (CEMs) meter are conducted at a high frequency that yields too much data to be tested using substantive testing methods (cannot be economically or efficiently sampled). A controls approach and the use of other auditors work is required to assess this type of evidence.

Table 11: Examples of Tests of the Effectiveness of C0ntrols Potential Misstatement

(Greenhouse Gas Assertion)

Control Test of Operating Effectiveness A greenhouse gas source may be

excluded from the inventory (occurrence, completeness)

Control for authorization of the greenhouse gas inventory and changes to the inventory

Examine source documents for approvals

A greenhouse gas source may be counted twice in the inventory (validity)

Control for totals and double entries in greenhouse gas inventory

Examine totals reconciliation Observe data verification procedures for double entries

A greenhouse gas source may be calculated in the wrong units (accuracy)

Limit and reasonableness checks Examine evidence of test data

CEMS unit malfunction (accuracy) Error codes Examine evidence of error codes,

re-perform conditions of error

A natural gas consumption source may be missing a month in a year (accuracy)

Control for total invoice counts Examine natural gas invoice totals reconciliation

Note: the maturity of greenhouse gas data management systems is approximately a decade old compared to the 40 to 60 years that financial data management systems have had to mature and be tested. As a result, controls reliance in greenhouse gas verification should be undertaken very carefully. The role of control reliance should be reassessed as greenhouse gas data management systems mature.

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In cases where there is a high control risk and the verifier has little or no confidence in the design or the operation of controls, the verifier must use a substantive approach to assess the evidence.

Table 12: Example of Substantive Procedures

In summary,

1) It is not necessary to use a controls approach; a substantive testing only approach can be effective and efficient;

2) Complete reliance on controls is not permitted and any approach must include some substantive procedures on the data;

3) If any reliance is going to be placed on controls, these controls must be tested (operating effectiveness and design effectiveness); and

4) Verifiers can, under the circumstances described in Section 3.5.3, use the results of the work of other auditors/verifiers, including the results of control testing.