VESDA

Atrium Fire Protection

®

Increased use of Atria within buildings

• Atria add space and light

to facilities

• Attractive architectural

feature

• Useful link to multiple

occupancy facilities

• Often main escape route

Challenges for Atria

• Can move buildings outside scope of fire codes

• Smoke stratification

• Smoke dilution

• Solar radiation

• Changes in airflow

• Maintenance access

• Building movement

• Environmental obstructions

• People gathering, egress issues

Potential Scale of Atria

• Ceiling height of over 60m

• Large open areas exceeding 10,000m2 (110,000ft2)

Solar Radiation & Stratification

Environmental Obstructions

Access problems

Design requirements

• Immunity to – building movement– direct sunlight– false alarms due to site features

• Ability to overcome stratification and smoke dilution

• No labour intensive maintenance

• Multiple alarm outputs for staged warning

• Flexible design to provide protection where needed

Detection solution comparisons

Point Detectors

• Difficult to mount in atria

• Effected by stratification

• Effected by dilution

• Major maintenance issues

• High cost of ownership

Detection solutioncomparisons

Beams

• Beams at lower than 600 mm from ceiling level require separation 12.5% of height (BS 5839). Solution becomes very expensive.

• False alarms due to building movement & seasonal decorations

• Affected by stratification

• Affected by dilution

• Susceptible to damage from seasonal decorations

• Access problems for maintenance

Detector solutionscomparison VESDA

VESDA

• Vertically as well as horizontal sampling pipe within architectural structure

• Installed at ceiling level or at different heights

• Not affected by building movement or seasonal decorations

• Overcomes smoke stratification and dilution

• System design to accommodate environmental conditions

• Low cost of maintenance

Detector solutionscomparison VESDA

• Sampling pipes can be installed along:

- structural beams

- vertical air handling columns

- roof structure

- the wall cavity (concealed)

- vertical advertisement columns

Recap

• Atria increasing feature of modern buildings

• Complex environmental situations

• Standard methods of detection don’t work well

• Stable detection with ease of maintenance required

• Multiple alarm settings for early fire detection as well as orderly evacuation to minimise business interruption

VESDA

Case Study

Gaylord Texan Resort &

Convention Centre, USA

®

Gaylord Texan Resort & Convention Centre

Building Description

• 1511 guest rooms, more than 37,180 m2 (400,000ft2) of pre-function, meeting and exhibition space

• Atrium with a 64m (210ft) high glass domed ceiling. The size of the atrium area alone is approximately 8,100 m2

(87,000 ft2)

• Four cupola exhaust fans installed on the ceiling structure with a total ventilation capacity of nearly 100 m3/s (3,500 ft3/s), approx 60 (2,100) to 70 m3/s (2,500 ft3/s) of fresh air is supplied into the atrium.

Project Considerations

Attributes Performance Based Design

Smoke Control, Detection & Tenability

Designed to meet performance requirements in terms of size and type of fires, detection response time for 5 MW fire (peak) within 5 minutes from fire start

Technology Fit VESDA air sampling system was assessed in direct comparison with other technologies such as beam detectors

Unique Architecture Considered stratification, structure, fire locations, HVAC operation, etc.

Innovation Aesthetics, VESDA provides unobtrusive detection, easy maintenance

Performance Assessment

Successful in-situ smoke tests to verify designs and prove fire modelling.

Benefit of computeraided modelling

• System can be modelled with fire in various locations

• System can be modelled with a range of fuel types with different fire characteristics

• Results can be verified with actual smoke tests in accordance with acceptable test methods

• Impact from environmental conditions can be evaluated

• Airflow characteristics can be modelled to ensure an optimal placement of detection points

• System performance can be quantitatively assessed to meet design criteria

VESDA Design

• Pipe work

– 32 sampling holes per VESDA zone

– Placed 32-60 m (105ft – 197ft) above floor in atrium

• Alarm Functions– Alert: Supervisory

signal in the fire

panel, investigation – Action: Actuates

the smoke control

process– Fire 1: Activates

the building fire alarm

system through the

fire panel– Fire 2: Evacuation

Performance: Modelling

• Environmental conditions• Detection requirements• Technology used• Different fire scenarios• Detection within 5 mins

5 MW fire, 45 to 60 °C, 34m to 60m(113 to 140 °F, 112ft to 197ft)

500 KW fire, 25 to 40°C, 34m to 60m(77 to 104°F, 112ft to 197ft)

5MW fire model - Press to start video

500KW fire model - Press to start video

Modelling Results

• VESDA detected smoke in all simulated stratification

conditions within 5 minutes from ignition of a 5 MW fire• In fact, much smaller fires (0.5MW) were detected within

the required detection time of 5 minutes

CSIRO developed test

• Test method as developed by CSIRO, suitable for the assessment of Early Warning Detection Systems in large open spaces

• Test underway

CSIRO developed test

Performance: In-situ Tests

• Fire started at centre of atrium (under Zone 7)

• Detection Time < 5 minutes

Zone

#

6 3’ 05” 3’ 15” 3’ 29” 0.12787 3’ 56” 5’ 25” 5’ 48” 0.18595 4’ 52” 6’ 51” 7’ 35” 0.11943 7’ 37” 10’ 20” 12’ 33” 0.05444 8’ 36” 9’ 55” 11’ 04” 0.08818 10’ 39” 14’ 36” NA 0.0291

Alert Action Fire 1Peak

Smoke Level (%/ft)

Performance test across zones

Technology comparison

KPIs VESDA Beam Detector

Early Fire Detection Yes No

Affected by smoke stratification layers No Yes

Staged alarms for good emergency response plan

Yes No

False alarms due to movement of building structure

No Yes

Affected by sunlight (Glass domed ceiling) No Yes

False alarms due to dust contamination No Yes

False alarms due to obstruction of beam path No Yes

Access for maintenance and testing Easy Difficult and costly

Aesthetics Unobtrusive Devices highly visible

Cost of total system ownership Lower Higher

Conclusion

• VESDA successfully provided early fire detection in this grand atrium

• Performance Based Design methodology was applied to meet the fire safety system design requirements

• Computer modelling proved the system design in a difficult environment of high airflows, and where the effects of stratification were highly variable

• In-situ smoke tests confirmed the accuracy of the VESDA modelling