Dudley Council states that "We have identified 22 Conservation Areas in Dudley Borough" and that in conservation areas "planning permission is required for extension and alterations, these controls being applied more strictly in Mushroom Green, The Leasowes and Love Lane where an Article 4 direction is in-place, (where minor alterations will also trigger the requirement for planning consent)". Its published table records two conservation areas in and around Halesowen: The Leasowes, Halesowen, designated February 1976, and Lutley Mill, Lutley, designated February 1975 and amended on 26 May 2022.
On Article 4 directions the council lists among the works needing permission: "Remove, replace or alter windows and doors. Planning permission is also needed to insert a new window or door opening into an existing wall". It states that "Special consideration is given to the preservation of historic and architectural detail of buildings, including features like single-glazed timber framed sash windows. These can be replaced on a like-for-like basis without having to meet energy efficiency standards." It also warns that "conducting unauthorised works to a Listed Building is a criminal offence".
The Planning Portal states that "An external window or door is a 'controlled fitting' under the Building Regulations" and that "Since 1 April 2002 building regulations have applied to all replacement glazing". It gives two routes: "an installer registered with the relevant competent person scheme", who provides a certificate on completion, or an unregistered installer or do it yourself, "in which case approval can be sought from the relevant Building Control Body". GOV.UK names Blue Flame Certification, CERTASS, Certsure, Fensa, NAPIT and ASSURE for replacement windows and doors in existing dwellings.
We would explain how you check the conservation boundary, any Article 4 direction and the proposed work before confirming whether permission is needed, with The Leasowes and Lutley Mill named and dated on the same page.