BRE 209 Daylight factor & Illuminance (App G – trees & hedges)

BRE 209 Appendix G indicates that in certain situations, for example when trees or hedges are close to a proposed new dwelling or future occupants may want trees cut down due to blocking of light (G2.1), daylight assessment should include the impact of trees & hedges.

BRE 209 Appendix G indicates two calculation methods for this assessment:

Daylight factor: for summer and winter foliage states
Illuminance through the year: hourly simulation with seasonal foliage states

For both methods trees or hedges geometry (or in combination for a boundary) need to be added to the model, foliage transmission defined for both winter & summer states and winter & summer simulations run.

For more information on how to run BRE 209 Appendix G simulations, please refer to BRE 209 Appendix G.