Download Reaction to fire of Green Facades and Roofs

Reaction to fire of Green
Facades and Roofs
Nataša Knez
ZAG Ljubljana, Slovenia
[email protected]
Brussels, 12th November 2014
BBRI/ENBRI Workshop
Fire laboratory
Standard testing
• Fire resistance
• Reaction to fire
• Testing for shipping
• Large scale testing
Research and development
• Numerical analyses
• Testing of new materials
Involvement in legislative
work
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Green facades in Slovenia
climbing plants
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Last decades - green roofs
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Requirements of Building Regulations
fire safety in buildings
• Spread of fire to adjacent building or fire
compartment through facade or roof
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Test methods for external fire
exposure to roofs CEN/TS 1187:2012
• Test 1 – with burning brands
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Dimensions of test specimen
min. 0,8 m × 1,8 m
Brand: 600 g of wood wool
Tested pitch:
– 15° valide for pitches up to 20° in practice
– 45° valide for pitches greater than 20° in
practice
– Other tested pitches valide only for the same
pitch in practice
Criteria:
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Fire spread
Through openings
Internal glowing combustion
Burning material falling from exposed side
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Reaction to fire tests for building products –
building products excluding floorings exposed to the thermal
attack by a single burning item EN 13823:2012
• 30 kW burner for 20 min
• Dimensions of test specimen
corner 0,5 m + 1 m by 1,5 m
Criteria:
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Total heat release (THR)
Fire growth rate (FIGRA)
Lateral flame spread
Total smoke production (TSP)
Smoke growth rate (SMOGRA)
Flaming droplets
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Fire risk - type of green facades
Climbing plants
hydroponic
modular
rooted
ground or planters
Mesh, geotextiles,
fabrics, mineral
wool…
Inside cells
support
Wall, steel wires
or mesh,…
System fixed to
supporting frames
modules
substrate
soil
Water and nutrients Growing medium
Irrigation system
yes
in ground not
needed, otherwise
yes
yes
Fire risk
Combustible
(wooden) support
No irrigation
Combustible
modules,
malfunction of
irrigation system
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Combustible
support,
malfunction of
irrigation system
Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Climbing plants
Green – no fire risk
Dry – no leaves
fire load is small
Architect Plečnik‘s house
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Fire risk - type of green roof system
extensive
semi-intensive
intensive
Substrate
80 mm – 150 mm
100 mm – 200 mm
> 200 mm
Organic content
< 20 % of growing
layer
high
high
Maintenance
Normally not
required
Dependent upon
plant species
required
regularly
Irrigation system
Not needed
Recommended
(Recommended to permanent
be available for
drought periods)
required
permanent
Fire risk
No maintenance
and irrigation
High organic
content
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High organic
content
Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Fire hazard of green roofs and walls
• Green roofs and walls may constitute a fire
hazard
• As long as the green roof or wall is kept moist
(which is the normal case in order to keep the
roof alive) it is likely to be very resistant to
ignition
• If the green roof or wall dries out (such as might
happen in a drought if no irrigation is provided)
then they might present more of a fire risk
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
How to decrease a fire hazard
• Maintenance plans must ensure that the vegetation
present on a green roof, wall or facade does not create
fire hazards. Dead or dry vegetation must be removed as
part of regular maintenance.
• Fire performance can be improved by installing breaks in
the vegetation or using plants with low biomass (such as
native grass tussocks with a low amount of leaf matter).
• Green facades made of climbing plants with leaves or
evergreen climbers are unlikely to create a fire risk as
long as dry leaf litter falls away cleanly and is removed
during routine maintenance.
• Vegetation on green walls that receives regular irrigation
and maintenance does not pose a fire hazard.
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
How to decrease a fire hazard
Extensive roofs without irrigation
• Substrate depth should be greater than 30 mm
• Organic content of growing media does not
exceed 20%
• Non-vegetative portion of the roofs must be non
combustible
• Full-grown height of vegetation will not exceed
0,9 m
• Use of grasses and mosses should be avoided,
instead plant with high moisture / low resin
content should be used
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
How to decrease a fire hazard (cont.)
Intensive roofs with irrigation system
• Irrigated and regulary maintained roofs with thick
substrate layer impose no greater risk than
conventional roof finishes (e.g. gravel).
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Testing of facade - issues
• Testing is (very) rare – some research was done
in the past.
• There are some requirements found: German
building codes require a 600 mm fire break in the
planting every 40 m. Fire-activated sprinkler
irrigation can further reduce risk.
• It might be neccesary to establish knowledge
base (common ENBRI supported project?) to
enable CWFT declaration.
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Questions to be answered clearly
1. What are realistic fire loads in full range variety of
structures (considering type of vegetation, size,
substrate, climate, accessibility, maintenance,…)
2. What are realistically possible worst-case scenarios
(incl. cultural effects)
3. What are best derived testing conditions reflecting (1)
and (2)
4. How to express test results (classification) and when it
is safe to declare CWFT
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014
Conclusions
• Fire risk in green roofs and facades is normally
expected to be minor
• Because of that there is no extensive field of test
experience
• Nontheless in innovative solutions it might be
neccesary to consider fire issue as well (e.g. in
double ventilated green facades)
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Nataša Knez| BBRI/ENBRI Workshop, 12th November 2014