This includes associated gardens or amenity space then applications may need to be accompanied by a daylight/sunlight assessment.

Typically this is where, a scheme involves the construction of buildings higher than 2m and within 2 metres of the common boundary with any neighbouring residential property an assessment will be required. However, this is not always the case and the applicants should consult the BRE’s respective 25 and 45 degree rule of thumb to consider whether further assessment is required.

The extent and complexity of the assessment will need to be proportionate to the potential impact. Consider the proposed height of the proposed building, its design and orientation of the existing and proposed buildings and changes in ground levels.
Additional guidance on assessing daylight and sunlight to new and existing buildings is provided by the Building Research Establishment.

Information about the 25- and 45-degree rule of thumb for daylight and sunlight is widely available online, including a free fact sheet.