Planning
Is the national or local/state government able to mandate green initiatives via the planning/zoning regime (e.g., district heating systems on large developments)?

Technically, yes. For example, an applicant requesting permission to develop on land designated as a "Comprehensive Development Area" must prepare a master layout plan for the Town Planning Board's approval. The Town Planning Board may issue planning briefs to set out broad planning parameters and development requirements to facilitate the preparation of the master layout plan. The planning brief can mandate green initiatives (such as achieving a certain grade of green building certification for new buildings).

That said, promotion of green initiatives is more effectively carried out via the GFA concessions introduced by the Hong Kong government in April 2011 for green features of real estate projects. Concessions are made available so that certain green features, such as balconies and communal podium gardens, can be disregarded when calculating whether a building's permitted GFA has been used up. Certification by BEAM Plus is a prerequisite of taking advantage of a GFA concession for green features. The Buildings Department announced through the revised Practice Note "PNAP APP-151" that, starting from 30 June 2024, building projects will generally need to obtain a BEAM Plus Gold rating or above to be eligible for GFA concessions for green and amenity features. The concessions have an overall cap of 10% of the GFA. Certain features, such as communal sky gardens, are not subject to this overall cap.