It depends on the property and where the external equipment will be installed. External air-conditioning units can affect the appearance of a building and may raise noise considerations, so permission can be more likely to matter on flats, listed buildings, conservation-area properties or prominent elevations.
Glasgow City Council planning decisions show that air-conditioning equipment can be controlled through conditions dealing with location, colour, external fittings and noise. That does not mean every domestic installation requires a planning application, but it does mean you should not assume external equipment is automatically unrestricted.
For a Glasgow installation, check the property status and proposed outdoor-unit location before work starts. Doherty can assess the technical side of the air-conditioning system, while any required property or planning permissions should be confirmed for the specific address.
