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Natural Light Leads Changes in Permitted Development


In July this year, the government published new rules (that came into force on the 1st August 2020) amending permitted development (PD) rights to require the provision of “adequate” natural light in any developments consented under this route.

An explanatory memorandum to the regulations, published late last month, makes clear that the measure has been brought in, in response to concerns about “the quality of homes delivered in some developments” under change of use PD rights such as those allowing office to residential conversions. It follows an outcry after a judge ruled that a council couldn’t prevent the conversion of an industrial building in Watford into flats despite many of the apartments having no windows.

The new regulations revise the General Permitted Development Order (GPDO), used by practitioners by now making the need for “adequate natural light in all habitable rooms” a matter for prior approval consideration. It applies to conversions from offices, retail, light industrial and barn buildings to residential, as well as the new upward extension right for freestanding blocks of flats.

Developers will be required to submit:

  • detailed floor plans indicating the dimensions and proposed use of each room,

  • the position and dimensions of windows, doors and walls, and

  • the elevations of the homes.

Against which planners at Local Panning Authorities will now judge whether light is adequate.

Importantly, planning authorities will be required to refuse prior approval applications where inadequate natural light is provided.

The regulations do not state how “adequate” light should be measured.

Potentially, this could be based on an existing Building Research Establishment (BRE) daylight standard. This is many years old, however, and does not reflect current home designs. Although time will tell if other resources are brought in to use as an assessment tool.

However, a critical impact of the new rules is that it will make it very difficult to use existing change-of-use PD rights to convert buildings that don’t have many existing windows.

Previously, developers would propose to add new windows or other material changes to the outside of buildings through the submission of a planning application but following the approval of say an office to residential prior approval. Now making it unlikely that such buildings would be able to pass the natural light test of prior approval in the first instance.

Time will tell as to how natural light is assessed and no doubt will be a detailed discussion point in the first few planning appeals as Inspectors grapple with its interpretation.

Watch this space!

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