By the look of it

An inspector has declined to issue a lawful development certificate for two air conditioning units at a house in Bedfordshire after deciding that they materially affected the external appearance of the building (DCS Number 400-035-038).

The inspector explained that Section 55 of the Act excludes from the meaning of development alterations to a building which do not materially affect the external appearance of the building. The case of Burroughs Day v Bristol City Council [1996], she continued, further establishes that for works to ‘materially affect’ external appearance, the changes must be visible from a number of vantage points and material to the appearance of the building as a whole.

The air conditioning units sat one above the other on the side of the house, the inspector recorded. The units and the ducting which linked them to the building were coated in a material which sought to mimic the brown brickwork of the house to which they were attached. She observed, however, that from some angles it was out of sync with the layout of the brickwork. The units were also clearly visible from the rear garden serving the house and in the context of the rear elevation. Combined with the projecting nature of the units on supporting brackets, the appearance of the fans inside the unit and the ducting, she found that the units had a material effect on the external appearance of the building.

In addition, the upper unit and the ducting were visible from the street adjacent to the driveway serving the garage next door and from the opposite side of the road when facing the appeal site. Thus, she concluded, at least parts of the units were visible from a number of vantage points.

The inspector concluded that the air conditioning units constituted development. 

There is further information relating to Burroughs Day at section 4.3151 of DCP Online: Material effect on external appearance.