Polytactics: resilience tactics and adaptation strategies in bushfire prone communities

Polytactics

Team Members: Nigel Bertram, Jordi Beneyto-Ferre, Laura Harper, David E. Mainwaring, Victoria Smith, SueAnne Ware

Introduction and Summary Resilience is defined as “the capacity of a system to tolerate disturbance without collapsing into a qualitatively different state that is controlled by a different set of processes. A resilient system can withstand shocks and rebuild itself when necessary. Resilience in social systems has the added capacity of humans to anticipate and plan for the future.”1 Our proposal explores concepts of resilience and adaptation in bushfire prone communities. It embraces human and natural systems as integrated complex entities which continually adapt through cycles of change, and seeks to understand the qualities of a system that must be maintained or enhanced in order to achieve more sustainable environments.

What adaptive strategies and resilience tactics can designers employ at both individual and community scales to re-consider fire preparation, response and site rehabilitation?

From the outset we have been concerned with how we as a society live with fire and fire based ecologies. Our proposal offers an integrative, resilient approach to living within fire prone environments and working with adapting existing measures which recognise that bushfire management is a dynamic and complex entity. In essence the project re-purposes and reconsiders existing light weight polymer materials currently employed to protect cables during fire events. In our design proposals these polymers are cast into light weight shields, pergola screens at the domestic scale and barricades at the civic scale, which when heated transform into a protective ceramic layer.

The proposal also connects into existing fire preparation regimes at both civic and domestic scales, using lightweight and flexible, adaptable technology rather than permanent infrastructures such as bunkers. Additionally, our proposal embraces multiple conditions over time; it seeks to be a useful entity during periods before, during, and after, fire events. We provide both a series of strategies and a mechanism, simultaneously.

This entry is organised into three constituent parts: firstly we will discuss the how our proposal integrates and compliments existing ‘Fire Ready’ Measures, secondly we offer various ‘Settlement Scenarios’ demonstrating the flexibility and deployment tactics in spatialized settings, and thirdly we interrogate the ‘Material Performance’ of the polymer shields. (See Diagram)

1 Salt, David, and Walker, Brian. Resilience Thinking: Sustaining Ecosystems and People in a Changing World. Island Press, USA, 2006.

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Fire Ready Integration Bushfire is dynamic and can be unpredictable. A resilient system deals with this by maintaining functional diversity or in other words, many different ways of doing things at multiple scales. We recognise that the Victorian State Government through its fire agencies continue to develop and implement a range of fire ready measures at both the individual and the community level. Our proposal aims to key into and thereby enhance this existing armoury of strategies. This demonstrates the impact, practicality and application of the fire shields at a strategic planning level.

The table is an attempt to collate existing ‘fire ready’ measures developed by various fire agencies. We recognise that this list may be a simplistic representation of measures, that it is by no means extensive and that these measures are constantly under development.

We see ‘Polytactics’ as keying into the categories highlighted as described in the table.

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Settlement Scenarios In order to further illustrate how the fire shields operated in times of emergency or extreme fire danger, how they contribute to regeneration, and how they are an amenity under normal non-fire conditions, this section illustrates their deployment in three specific scenarios. During fire events, the shields work in conjunction with other strategies to increase the amount of time available for evacuation, diverting fire components away from housing and road infrastructure, and demarcating safe, visible passageways. More specifically, the road barrier shields are relatively quick to deploy in times of emergency or extreme fire danger; they are lightweight and transportable and can moved to adapt to sites from season to season.

They can be deployed where fuel loads are higher and are moveable to work with shifting wind conditions. They can demarcate protected spots in pull out lanes along road cuts for gathering points during evacuation or as ‘fire holds’ for CFA crews as well as create wayfinding devices in heavy smoke cover. During non-fire conditions, the barriers can be re-purposed and utilised for temporary fencing at civic events. (See Scenario 2) The pergola shields are more permanent structures, they provide a diversion of fire-components (embers, wind gusts, radiation) from roof structures of housing and they augment the amount of time available for evacuation during fire events. During non-fire conditions they offer a shaded deck and water tank system for residential occupants. (See Scenario 1) After the fire, the ceramified material is crushed and degrades into the soil where it can assist in rehabilitation by containing nutrients, wetting agents or even seeds. This will help to stabilise soils and prevent erosion of vital nutrients during fire recovery periods. (See Scenario 3).

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Each scenario considers: • • • • •

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Time-line – When is the scenario occurring?

Scale – Who is involved or responsible for preparation in this scenario? – Individuals, group, council, authority, etc.

Description – What takes place, which fire ready measure is being put to use?

Philosophy - How does the scenario fit in with the philosophy proposed by our team?

Polymer- How is the polymer technology /characteristics utilised in this scenario?

Scenario 1 Scenario 2

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Scenario 1 Scale: A community or group of households in the near vicinity of each other work together, using an overall masterplan to inform decisions that impact individual blocks and their wider immediate environment.

Existing houses may be fitted with dual purpose polymer elements that act as sun shade.

Existing dead-end driveways and roads are extended with informal tracks to adjacent properties to create multiple escape routes.

Timeline: A long term approach to living in fire-prone areas, beginning from the retrofitting / re-landscaping of existing houses and blocks, to the design of new buildings and subdivisions, to the implantation of guidelines for future buildings.

Architects Bushfire Homes Service house designs can be incorporated into overall landscape strategy. These designs maximise orientation and are designed according to new codes.

Location of emergency resources such as water tanks, toolkits, first aid and fire-fighting materials are considered in this wider context so that there are many options and places to turn to in times of fire. Lightweight polymer shields may be located to protect these.

New gates joinery individual properties via shared clearing with direct road access

The overall nature of the surrounding landscape is considered and a masterplan of entrances and exists, escape routes, common safe places & pathways is overlaid onto the existing property boundaries.

Tertiary Assembly Point (Shared common)

Landscape planning encompasses the whole area, so that elements such as clearings are co-located creating safe places at a larger scale and across property boundaries. Types of species planted, garden design guidelines, fire barrier planting are also considered.

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New houses may have separated decks with polymer sun shades pergolas to the north side – resources such as water tanks may be co-located.

New polymer screens and pergolas can be easily fitted to existing houses and outbuildings in many different configurations.

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The polymer is designed to be utilised throughout the year in applications such as sun-shade, only activating its protective nature as required during a fire situation. It can be retrofitted to existing buildings to shield eaves and gutters, or built into the design of separate deck/pergola structures that deflect wind and heat.

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Scenario 2 Scale: This scenario takes place at the larger community or regional scale, wherein local councils and authorities choose strategic places along roadways or within communities to stockpile emergency resources.

Timeline: Emerging only as required, the planning of these resource points is done on a short-term and dynamic basis being reviewed constantly and changing as required to adapt to variables such as weather, condition of bushland, available water, changes in the built environment, lessons learnt from last year, etc. These plans can also be adapted year to year, as situations develop, before extreme fire days, and when fire danger approaches.

Secondary Assembly Point (location flexible)

Centralised depot points are created for fire crews and locals escaping the area. These points make use of existing natural and man-made landscape features to choose the most appropriate point for stock piling under particular conditions with the dual purpose of acting as a possible defence point for fire-crews in the face of the fire front. Lightweight and flexible barriers allow depot locations to be moved on a seasonal basis depending on actual conditions.

Cross Linked Un-Saturated Polyester Resins with Glass Fibre (Mat) reinforcing to create lightweight rigid forms that are portable and easy to assemble.

Filled with soil and rock to provide stability in extreme conditions.

Configuration of different barriers in varying levels of colour and reflectivity allow them to act as signs and pathways to escape or communal refuge places.

Color and Reflectivity aid escape routes during fire.

Interlocking molded polymer barrier technology.

The barriers are easily transported to chosen locations, configured as required and then filled with dirt or water to secure / create a stockpile.

These barriers are used elsewhere in the town throughout the year for roadworks, town events, football matches, etc.

Combination Sports tennis club and emergency camping facilities Worst case emergency fire-blankets incorporating ceramifying polymer material can be stored at depot points, (similar to the North American example illustrated)

Primary Assembly point (existing community oval)

Combination Sports Club and Emergency Communcations Base

Combination festival ground and vehicle assembly area

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Polymer: The lightweight nature of the polymer means it is easily re-located and reused and can be filled with water or dirt to create barriers and breaks as required.

If damaged during fire conditions the integrity is maintained, marking but not obstructing roadways.

The ability of the polymer to be coloured means it acts as a marker within the landscape.

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Scenario 3 Scale: This scenario takes place at the larger landscape scale where infrastructural fire-planning is implemented along fire-breaks, within bushland and reserves by government authorities and bushland management agencies.

Timeline: This scenario is designed to show the aftermath of fire as well as the cyclical nature of living with fire year by year.

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Ceramifying polymers are a useful tool for controlled burnings and fuel management in bushland areas. The material can be used at periodic intervals along fuel-breaks, for example to create fire-resistant shelters that house emergency communications points or a protective wrapping around the trunks and upper branches of trees singled out as important to the biodiversity of the particular landscape.

Following a fire, clean up crews travel along burnt out fuel-breaks, breaking up the burnt ceramic and checking equipment. The broken ceramic is then scattered along the firebreak, creating a heavy mulch that prevents erosion.

To overcome a common difficulty during prescribed burns, the polymer can be wrapped to protect specific natural assets such as trees contributing to the biodiversity of an area. In a similar way, specific infrastructure such as communications towers can also be protected.

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Seeds which have been embedded in the polymer of particular species, activated by fire (serrotinous seeds) and suited to growth along fire breaks, now begin to sprout, commencing the regeneration of the bushland.

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Polymer: The usefulness of the polymer throughout its entire lifetime is demonstrated. Through its transformation into ceramic, the act of burning becomes not an act of destruction but of regeneration.

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Material Performance This section includes novel concepts and initial research studies based upon the existing advanced technologies of ceramifyable polymers and aerodynamic simulations of heat and fire-front wind flows. We have evaluated them through dynamic computer modelling. The deployment of these advanced technologies and their designs are also considered here in the context of an overall portfolio of strategies forming fire management and recovery plans from a material performance perspective.

Ceramifying polymers as passive fire protection Australia ‘s CRC for Polymers and its participant Ceram Polymerik Ltd have developed the world’s first high performance fire cable. Such a product is flexible under normal conditions but forms a protective ceramic barrier when exposed to fire even up to 2 hours at 1000OC. Ceramifying polymers contain minerals and fluxes that allow the polymer to begin to form ceramic materials at relatively low temperatures as the polymer chars thereby maintaining structural integrity through to the temperatures of the fire-front. More recently Ceram Polymeric has been developing and fire testing a series of flexible foam and non-foam ceramifying polymer sheeting that transforms to stable ceramic materials in the range 350OC to 800OC which have similar barrier protection above 1000OC. Aerodynamic design in fire-front shielding Preliminary aerodynamic simulation of heat and fire-front wind flows helped us to initially understand and evaluate the polymer shields in the high intensity and dynamic situations of a fire event. We have also employed Computational fluid dynamics (CFD) which allowed studies of both quantitative data and visualisation of concepts to be verified further. These simulations and models needed to be considered prior to experimental and development phases of any strategies and products because they can provide key information about the effectiveness of and requirements for materials and structures that are to be exposed to these harsh environments. The simulations include; wind blast lift profiles, wind velocities, wind pressures, temperature gradients, and radiation temperatures, as well as turbulent eddies created by infrastructure itself. For the polymer shielding, we carried out detailed preliminary CFD simulation of two possible uses; house protection and protective road barriers. (As discussed in Settlement Scenarios section)

High performance fire cable commercialised internationally by Olex Australia.

Material samples and ceramification temperatures

Transformation of the polymer to a porous ceramic material reduces substantially the heat transfer by conduction as well as radiation. For instance, at a radiant heat flux of 50 kW per m2, the outer surface of a PVC ceramifying polymer barrier rose to 700OC in 75 seconds while the inner surface rose slowly to 300OC over 15 minutes i.e the temperature of a moderate oven.

(AS1530 part 4, ISO 834)

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Dwelling fire screening Two and three dimensional model studies were simulated with dwellings situated on both flat ground and on sloping terrain. Two fire-front simulations were evaluated; one (1) a moderate intensity bushfire 60 metres from the dwelling of 830OC and 50 km/h wind, and two (2) an extreme bushfire condition with a fire-front 30 metres from the dwelling of 1000OC and a 100 km/h wind. Houses with and without the polymer pergola screens were evaluated. The polymer screening on a pergola reduces the high temperature fire-front wind as well as the convective and radiant heat transfer. Our initial studies indicate that the temperature reduction across the hybrid ceramic foam screen may be 700OC on the fire side and 300OC on the dwelling side. The pergola then provides a significant reservoir of more static cooler air such that window, and door temperatures and personnel temperatures close to the house are further significantly reduced. If we are successful in the Fire Challenge, further experimental research of this nature will be carried out with optimal ceramifying screening to detail this beyond these initial considerations.

Dwelling fire screening (Flat Terrain)

The Structural Strength of Ceram Polymeric product. This data indicates the flexural modulus and tensile strength of materials to be in the range of 160 MPa and 5 MPa respectively which are in excess of the indicative wind pressures with a fire-front temperature of 1000OC. Future research is proposed to investigate the incorporation of fibre glass mesh within the structure to provide additional reinforcement.

Influence of aerodynamically designed ceramifyable polymer pergola screening on the temperature profile under extreme fire conditions (1000OC fire-front 30m from dwelling in a 100 km/h wind) Dwelling fire screening (Sloping terrain)

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Ceramifying silicone polymer coating sheet.

Fibreglass reinforcing mesh.

Crosslinked ceramiying polymer foam.

Inner side geotextile embedded with nutrients and seeds for regeneration.

If successful we will need to develop further a flexible hybrid material consisting of ceramifyable polymer layers including foam and glass fibre reinforcing mesh. Glass fibre mesh represents an optimal reinforcement strategy since it reacts readily with the fluxes produced during the polymer transformation to a ceramic material. A geotextile layer can be added to provide nutrients and seed beds from the spent fire screen for environmental rehabilitation during recovery.

Air temperatures surrounding house reduced to lower than about 575OC from fire-front temperature 1000OC. The removal of the side-wind is shown by extending the pergola screening 4m beyond the house line.

Front and rear sections of house subjected to wind velocities reduced from 28 m/second (100km/hour) to about a tenth (3 m/ second)

Wind velocity of 100 km/hour in extreme conditions causes a small inflow of 550OC air into pergola area indicating a need to extend the sides of pergola-screening past the ends of the dwellings.

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Road Barrier Screens Fire-front screening and diversion studies were carried also out in 2-D and 3-D simulations with model road barriers applied to road cuttings on sloping terrain. Two fire-front simulations were evaluated; a moderate intensity bushfire 60 metres from the road section of 830OC and 50 km/h wind, and an extreme bushfire condition with a fire-front 30 metres from the road section of 1000OC and a 100 km/h wind. This concept involves the deployment of rigid road barriers in strategic areas of road cuttings to provide evacuation areas or meeting points where fire shielding and aerodynamic fire-front lift are necessary.

Influence of road barriers on lift of high temperatures from the road cutting under extreme fire conditions (1000OC fire-front and a 100 km/h wind) Road barriers shielding the wind pressures within the road cutting.

Existing guidelines for fire barriers There are three types of fire barriers included in current guidelines: putting stone walls in place towards the prevalent fire direction on sloping blocks, constructing earth mounds in this direction with or without trees on top of them, and planting tall trees as a windscreen but at a distance and with heavy clearing of the undergrowth. Although the fire-blast profile is sketched in the guidelines, quantitative aerodynamic studies under fire conditions do not appear to have been carried out. In order to assess the road barriers effectively we will need to perform further CFD modelling to provide comparative effectiveness. Although natural structures such as trees have random turbulence and permeability effects and exact profiles have not been provided. The figures below begin to commence this study.

Images compare the static temperature distributions corresponding to a model with an aerodynamic optimized screening with a 4 m wall height indicating cooler air pockets induced by aerodynamic shid

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Self-appraisal of knowledge gaps and weaknesses to be addressed

Conclusions

Further Industry engagement • Participation of an industry partner with a background in the area of polymeric building products and preferably passive fire protection is critical to both the development and verification phases as well as the implementation phase of potential products. Ceram Polymerik Pty Ltd (www.cerampolymerik. com) has indicated strong support for participation in the future development and are currently assisting the design team in formulating an appropriate research, evaluation and development path. As well as the technical performance of these materials, their optimal implementation requires the guidance of both the fire and reconstruction agencies as well as the community itself. Ceram Polymerik also have significant experience in such developments, in regards to appropriate standards and their fire testing both in Australia and Europe. Through Ceram Polymerik discussions have been initiated with Victorian reconstruction authorities and various state government departments about what is involved in the way forward for these concepts.

• Participation of various fire management and reconstruction agencies as well as community organisations will be integral to linking the polymer products to various fire survival plans. We will need to call together various stakeholders during the next phase of development to consider further how our shields can be further adapted to suit the varied conditions and interested constituencies.

The recent devastating effects of bushfires have engendered all sectors and levels of the community to redesign its fundamental thinking about strategies and processes towards preparedness and the aftermaths of such fire-outbreaks. The innovation in this proposal is that it takes an existing technology and adapts it from its current use, the protection of cables, towards a wider application. The shields become part of a holistic strategy through embedding them within existing fire preparatory measures at the domestic and civic scales. They also have use beyond their fire capacities in that they become multi-purposed, the pergola is a living amenity; and the barricades are multi-functional fencing device. The shields aim to assist in the regeneration and the resilience of the landscape after the fires occur. The multiplicity of this proposal to various scenarios (sites) and during various times (before, during, after) demonstrates the inherent flexibility and ingenuity of this proposal. The dynamic nature and complexity of the living with fire challenges designers from various disciplines to transform their thinking. We believe that the strength of our proposal is that each disciplines’ specific knowledge informs the other and through that we generate a response which has a layered, multi-faceted response. We contend that our thinking about and through the design of tactics, built environments, and polymer materials could not have occurred without this unique mix of participants. Transdisciplinarity is evident throughout the teams’ multivalent approach to the challenge.

Many of our research and development issues (listed below) will re-shape the mechanisms (polymer shields) which will then inform and shift the strategies for deployment and our tactics. So while we have elected to highlight future endeavours necessary to develop the shields further, we are mindful that this will no doubt have flow on effects.

Research and development issues and plans: • Refinement and design of optimal housing screens and road barrier options: • Detailed structural design of the shielding and barriers needs to be carried out by the addition of mechanical/structural engineers to the design architects team.

• Systematic research to assemble and optimize various potential product types as well as understand their thermo-chemistry and validate their performance. Materials include; flexible hybrid sheeting involving layers of ceramifyable silicone polymer and polyurethane foam polymer, with and without glass fibre mesh reinforcing and rigid glass reinforced ceramifyable polyester resin materials for roadway barrier shielding.

• Further CFD modelling of dwelling protection screening with the temperature profiles computed in close proximity to structural elements of the house as well as well as the optimal shape of the fire screening.

• Further CFD research is required to detail the optimum size and profile of the deployable road barriers.

• CFD modelling to be validated further by quantitative (drag force and lift force) and smoke trail visualisation in wind tunnel runs on scale models to 100 km/hour utilizing the RMIT industrial wind tunnel.

This will involve Dr Firoz Alam (a wind tunnel mechanical engineer) and Professor Bob Shanks joining the design team.

• Trials on destruction of the ‘spent’ shielding during the recovery phase including seed germination trials. Participation of the DSE will be sought to validate role of nutrients and seeds in revegetation post fire events.

• Deployment evaluation - Fire testing of assembled material options is critical to their eventual deployment as well as their consistence with existing design standards and regulations or their incorporation with newly established ones.

• Cost benefits Analysis and financial viability of product(s) leading towards eventual development and testing of full-scale proto-types for further testing.

• An ARC-linkage grant application is planned for round 1 2010 to provide research support commencing in last quarter 2010.

• Discussion with Ceram Polymerik and the CRC for Polymers exploring significant funding opportunities such as a potential CRC Extension Round bid. Industry and agency partners will also be sought to include these development activities in a CRC Extension bid funding 27

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