Environmental

• reducing heat gain from roof
• creating wildlife habitat
• improve the aesthetic quality

Social and Educational (Mainly for Roof Greening)

• using the green roof for teaching activities, e.g. general plant science, environmental science, etc.
• utilize the green roof for extra-curricular activities, attached with educational purpose, e.g. organic farming, medicinal plant, etc.
• utilize the green roof for simple scientific experiment, e.g. temperature difference between vegetated and heat-absorbing surface

Financial

• cost of construction and on-going maintenance.

Technical

• Sustainable design in terms of selection of suitable growing medium and plant species

• safety concerns (mainly for roof greening) related to:

  • structure loading capacity, e.g. imposed load (Building (Construction) Regulations, Chapter 123B, Regulation 17)

  • fence height requirement

    • 1.1m for roof with no restriction (Building(Construction) Regulations, Chapter 123B, Regulation 8)
    • 2.5m for roof used for recreational purpose, e.g. student activity (Education Regulations, Chapter 279A, Regulation 17)
  • loading capacity during construction
• requirement for access for the disabled and submission to Advisory Committee on Barrier Free Access of Buildings Department
• employment of qualified contractors
• timing for construction works with reference to school time-table and calendar