28. Generally, it will fall to planning authorities in the first instance to consider whether a proposed development requires EIA. For this purpose they will first need to consider whether the development is described in Schedule 1 or Schedule 2 to the Regulations (see figure 1):
Schedule 1 development
Development of a type listed in Schedule 1 always requires EIA.
Changes or extensions to Schedule 1 or Schedule 2 developments
Changes or extensions to Schedule 1 or Schedule 2 developments which may have significant adverse effects on the environment also fall within the scope of the Regulations. Where the change or extension itself would fall within one of the descriptions in Schedule 1, it constitutes a Schedule 1 development and EIA is always required 7. Otherwise, and if the change or extension may have significant adverse effects on the environment, it is considered to be a Schedule 2 development. A screening opinion or direction is then required on whether the development is likely to have significant effects on the environment
Identifying Schedule 2 Development
29. Schedule 2 development is development of a type listed in Schedule 2 which:
a) meets one of the relevant criteria or exceeds one of the relevant thresholds listed in the second column of the table in Schedule 2; or
b) is located wholly or in part in a 'sensitive area as defined in regulation 2(1) (see paragraph 36).
30. It is stressed that development in a sensitive area should only be considered to be Schedule 2 development if it falls within a description in Schedule 2. Most of the types of development listed in Schedule 2 have an inherent scale. It follows that the majority of development proposals such as householder or small business developments will not fall within any of the descriptions. The criteria and thresholds in the second column of the table apply equally to changes or extensions to relevant development as they do to new development.

Paragraph 13(a) of Schedule 2 provides that, in such cases, the thresholds and criteria are to be applied to the change or extension itself, not to the thing being changed or extended.
31. Development falling below the thresholds or meeting none of the criteria in the second column of the table in Schedule 2 does not require EIA. However, there may be circumstances in which such small developments might give rise to significant environmental effects. In those exceptional cases Scottish Ministers can use their powers under regulation 4(8) (see paragraph 78) to direct that EIA is required.