Agriculture Reference
In-Depth Information
Water supply
Water supply
Growing medium
Geotextile
Moisture retention layer
Growing medium
Waterproo
ng
membrane
Roof slab
Waterproo
ng membrane
Roof slab
IRRIGATION SYSTEM - SPRINKLER
IRRIGATION SYSTEM - SPRINKLER +
MOISTURE RETENTION LAYER
Water supply
Water supply
Growing medium
Geotextile
Moisture retention layer
Growing medium
Waterproo
ng
membrane
Waterproo
ng
membrane
Roof slab
Roof slab
IRRIGATION SYSTEM - DRIP +
MOISTURE RETENTION LAYER
IRRIGATION SYSTEM - DRIP
Figure 4.12
Irrigation system options
7 Basal irrigation reduces establishment of unwanted plants.
8 Stormwater runoff from the living roof can be harvested for irrigation.
Over the longer term, irrigation requirements are often site-speciic. Vigorous,
turgid plants generally provide greater ET, which dries the growing media
between storms and cools the microclimate for energy demand mitigation, but
over-irrigation can compromise stormwater capture, and generate runoff
hydrographs during dry weather. Daily irrigation is unlikely necessary to maintain
plants adapted to extensive green roof environments. Where possible, to mini-
mize irrigation, the growing media should provide adequate
PAW
to sustain
plants for several days during (or the extent of typical) summer dry periods.
Ideally, irrigation should be determined based on growing media moisture
content, rather than a set schedule and depth. Wherever possible, irrigation
water should be sourced from on-site rainwater harvesting (captured from non-
greened roofs or impermeable areas), or other non-potable sources. Plant water
demand versus hydrologic control requirements should be discussed actively
between the horticultural consultant and the stormwater engineer
4.9.1 Concerns for publicly accessible living roofs
The accessibility of an extensive living roof bears on the performance of the roof's
multiple functions. Accessibility in this context can be deined as direct physical
access from the ground via slope or stairs; physical access via staircase, elevator
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