Daylight & Sunlight Layout Planning by AH

Custom AccuCities 3D site model of Slough Trading Estate has been used by Anstey Horne to conduct Vertical Sky Component (VSC) testing to the façades of the neighboring residential properties in the immediate vicinity of the site. The results of this study indicated what extent the daylight (VSC) of the neighboring residential properties will be affected by the proposed envelope for the SPZ massing. Further to the initial daylight testing, they also considered the sunlight performance of the gardens and amenity spaces attached to the neighboring residential properties, as well as the sunlight performance of the façades of the neighboring residential properties.

Anstey Horne have carried out their assessments of Slough Trading Estate in accordance with the BRE Report 209, Site Layout Planning for Daylight and Sunlight: A guide to good practice (third edition, 2022). Their computer model of the surrounding context was compiled from the 3D land survey model provided by AccuCities, GPS data collected during our site visit on 18 October 2023 and aerial photography from Google Earth. They have been through an iterative process with the design team, working closely with SEGRO’s architects to inform the design from a daylight and sunlight perspective.

In the first round of assessment, Anstey Horne modelled the SPZ massing based on Chetwoods Architects’ 2D drawings received on 7 August 2023 and the heights advised by Stantec. They then carried out a Vertical Sky Component (VSC) testing to the façades of the neighbouring residential properties in the immediate vicinity of the site to see what extent their daylight (VSC) will be affected by the proposed envelope for the SPZ massing. In the initial VSC façade testing, detailed elements of the façade of the neighbouring residential properties such as balconies or other projecting overhangs were not considered.

Given the number of neighbouring residential properties that they considered in the assessment, Anstey Horne have distilled these down into property groups. They have tested 27 property groups in total and the results of the VSC façade testing helped us identify six ‘pinch points’ (property groups that did not satisfy the BRE recommended VSC values). Using these pinch points as the main drivers for further investigation, Anstey Horne have created a VSC envelope that represents an SPZ massing to allow the receptors identified better access to daylight. Further to the initial daylight testing, they also considered the sunlight performance of the gardens and amenity spaces attached to the neighbouring residential properties, as well as the sunlight performance of the façades of the neighbouring residential properties. You can read the Full Report (PDF) here.