Keywords

1 Introduction

Catastrophic disasters induced by natural and man-made hazards are inevitable, but prevention measures will help to reduce the social, environmental and economical adverse impacts immensely. World Health Organization declares that globally, the number of people killed by natural disasters exceeds 90,000 and nearly 160 million people are affected annually. Natural disasters such as floods, droughts, earthquakes, tsunamis, landslides, hurricanes, volcanic eruptions, wildfires, and heat waves not only cause immediate destructions to the physical, biological and social environment, but also impose a long-term threat on the health and well-being of its people [1]. Also, the report ‘Economic losses, Poverty and Disaster—1998 and 2017’ highlights that geophysical and climate-related disasters have killed around 1.3 million people and made another 4.4 billion people injured, disabled, displaced or in need of assistance during the period of 1998 and 2017. During 1998–2017, the countries hit by natural disasters have gone through direct economic losses valued at US$ 2,908 billion [2]. The Munich Re NatCatSERVICE, reports about 850 natural hazard induced disasters occurred in 2018 only. Out of them, 5% was reported to be Geophysical disasters such as earthquakes, volcanic eruptions and tsunamis, 42%, to be storms, 46% to be floods, flash floods and landslides and 7% to be wildfire, cold and heat. 43% of all the disasters have been reported from Asia, 20% from North America, 14% from Europe, 13% from Africa and 10% from other regions [3].

As Sri Lanka is a tropical country, it often meets with frequent rainfalls and increased temperatures throughout the year. Sri Lanka’s climate is governed by the Southwest and Northeast monsoons and two inter monsoon seasons. Behavioral patterns of the Bay of Bengal widely affect the changes in wind patterns and changes in durations of occurrence [4]. Majority of Sri Lankan natural hazards are identified to be hydro-meteorological hazards like floods, high winds, landslides, etc. of which floods are most critical. River floods, urban and flash floods, landslides, cyclones, wildfires are considered to be the main hazards with high risk and coastal erosion, tsunami and droughts are considered to be of medium risk [5]. Out of all, floods and landslides are the most common natural hazards effective for Sri Lanka. Cyclones, droughts, and tsunamis are considered to be severe hazards though their occurrences are of less frequency [5]. Since 1965, 224,760 houses have been damaged due to floods while 128,705 houses have been affected severely from high winds, 105,293 houses have been damaged due to tsunami and 14,761 houses from landslides [6]. Economic losses caused due to natural disasters, accounts for an average annual loss of $380 million which is averagely 3% of total government expenditure, according to World Bank estimates. As a distribution 33.3% accounts for Tsunamis, 30.8% for floods, 29.6% for cyclones and heavy winds and 6.3% due to other hazards during the period of 1990 to 2014 in Sri Lanka [5].

Skyrocketing catastrophic losses and destructions imposed by natural hazards are mainly due to rapid rate of urban growth, unplanned urbanization, poor quality buildings and infrastructure, and the adverse impacts of climate change [7]. A study carried out by the AIT in 2012 has examined on integrating of DRR measures into the national building codes of Sri Lanka for wind, rain and flood and landslides [8]. It manifests that a comprehensive disaster resilient building code could not be found yet in Sri Lanka, which is an essential need to be met in transforming the existing construction industry into a sustainable one. There is an unfilled gap in the GREENSL® Rating System for Built Environment where it could incorporate disaster risk reduction mechanisms. Even a platinum rated green building constructed in a sustainable manner is still prone to damages from natural disasters if proper DRR measures have not been incorporated. As floods, landslides and heavy winds are the most frequent, highly vulnerable and which have caused significant building damages around the country, only the DRR measures related to above three hazards are considered in developing the disaster resilient green rating building tool. There are two types of DRR mechanisms for hazard preparation and mitigation namely structural (hard) and non-structural (soft) measures. Apart from the DRR and disaster resilient global and local frameworks, five green rating tools from four countries were selected based on the factors of, usage and popularity of the tools, vulnerability level of the counties for natural hazards and their world risk index. This research study aims in identifying structural and non-structural DRR mechanisms for floods, landslides and heavy winds aligned with the local and global frameworks for DRR and disaster resilience, developing a set of guidelines using the identified structural and non-structural DRR mechanisms and finally developing a new disaster resilient building tool through incorporating the developed DRR and disaster resilient guidelines into the GREENSL® Rating System for Built Environment.

2 Literature Review

2.1 Global Frameworks for Disaster Risk Reduction

In 2015 three international policy frameworks were established namely Sendai Framework for Disaster Risk Reduction (SFDRR) 2015–2030 (March 2015), the Sustainable Development Goals (SDGs; September 2015) and the Climate Change Agreement (December 2015). Before the development and implementation of the SFDRR 2015–2030, Millennium Declaration (2000) and Hyogo Framework for Action (HFA; 2005–2015) were the frameworks used by the countries to manage and prepare for the natural hazards and the induced disaster risks.

As SFDRR was the latest and most updated international policy framework on DRR, it was considered in selecting guidelines required for the disaster resilient green building tool. The main aim of the SFDRR is to prevent new and reduce existing disaster risk through the implementation of integrated and inclusive economic, structural, legal, social, health, cultural, educational, environmental, technological, political and institutional measures that prevent and reduce hazard exposure and vulnerability to disaster, increase preparedness for response and recovery, and thus strengthen resilience [9]. Out of the seven global targets, target 3; Reduce direct disaster economic loss in relation to global gross domestic product (GDP) by 2030 and target 4; Substantially reduce disaster damage to critical infrastructure and disruption of basic services, among them health and educational facilities, including through developing their resilience by 2030 were considered in developing guidelines. Similarly, out of four priorities for action, priority 3; Investing in disaster risk reduction for resilience and out of the twelve guiding principles principle 3, 8 and 9 were considered in developing guidelines for green rating systems. SDGs are a collection of 17 global goals introduced by United Nations [10]. Targets under SDG 11; Sustainable cities and under SDG 9; Building resilient infrastructure have a strong interrelationship between DRR and sustainable development. Resilient Construction, sustainable and inclusive industrialization, innovative, resilient, safe and sustainable human settlements and cities are the main goals of the above two SDGs [11].

2.2 Green Building Councils and Green Rating Systems

A ‘green’ building is a building that, minimizes negative impacts, and make positive impacts, on the environment throughout its life cycle in planning, designing, constructing, or operating [12]. The World Green Building Council (WGBC) is a global leader comprised with nearly 80 green building councils around the world. Green Building Councils develop and lead many of world’s green rating tools. Green building rating systems can be defined as a set of guidelines and criteria which a building or a structure is used to assess and recognize when certain green requirements or standards are met [12]. Out of 100 s of existing green rating tools, this literature review is narrowed down into few rating systems, namely, Leadership in Energy and Environmental Design (LEED) and ReLi of Green Building Council of United States, Comprehensive Assessment System for Built Environment Efficiency (CASBEE) of Japanese Green Building Council, GREENSHIP of Green Building Council of Indonesia and Building for Ecologically Responsive Design Excellence (BERDE) of Green Building Council of Philippines for this research. Table 1 summarizes the existing DRR and disaster resilient mechanisms incorporated into the building tools of the above-mentioned green rating systems.

Table 1 Existing DRR and disaster resilient measures in different green rating tools
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Due to the very high disaster risk profile of Philippines, international, local, government and private organizations have developed many guidelines and frameworks aligned with global frameworks. But the integration of these DRR and disaster resilient mechanisms into the construction industry and BERDE green rating tool is very minimal. The only consideration it has taken is that, during the predesign phase, it is determined whether Environmental Impact Assessment (EIA) and Engineering, Geological, and Geo-Hazard Assessment (EGGA) are needed to be conducted to comply with the requirements in securing Environmental Compliance Certificate (ECC) [15].

2.3 GREENSL® Rating Systems for Built Environment

GBCSL is the pioneer in certifying the green buildings and infrastructures in Sri Lanka using their developed tools such that; GREENSL® Rating System for New Buildings, GREENSL® Rating System for Existing Buildings, GREENSL® Rating System for Cities, GREENSL® Rating System for Transportation Infrastructure and GREENSL® Rating System for Green Products [16]. The GREENSL® Rating System for New Buildings hich is the main focus of the literature survey consists of main 8 categories with prerequisites (mandatory requirements to fulfill without points) and credits (optional requirements to earn points). Eight categories are, Management (4 Points), Sustainable Sites (25 Points), Water Efficiency (14 Points), Energy and Atmosphere (22 Points), Materials and Resources (14 Points), Indoor Environmental Quality (13 Points), Innovation and Design Process (4 Points) and Social and Cultural Awareness (4 Points) [17]. Table 2 summarizes the current extent of integration of DRR measures in this tool.

Table 2 Existing DRR and disaster resilient measures in GREENSL® rating system for new buildings tool [17]
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2.4 Disaster Risk Reduction (DRR) Mechanisms and Disaster Resilient Local Guidelines

This subsection is focused on the DRR mechanisms and disaster resilient local guidelines for floods, landslides and heavy winds which can be divided into two major aspects as; Structural (hard) DRR measures and Non-Structural (soft) DRR measures. Table 3 illustrates the structural and non-structural DRR and disaster resilient local guidelines and mechanism for floods, landslides and heavy winds.

Table 3 Structural and non-structural DRR and disaster resilient local guidelines and measures for floods, landslides and heavy winds
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3 Methodology

Research methodology used for this research study in developing a disaster resilient building tool of the GREENSL® Rating System is illustrated in Fig. 1 which consists of five major steps.

Fig. 1
figure 1

Methodology used for developing a disaster resilient building tool of the GREENSL® rating system

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According to Fig. 1, after the literature review the guidelines identified and developed were incorporated into the existing 8 categories and subcategories of the building tool of the GREENSL® Rating System. Guidelines were incorporated in to the 8 categories under different levels such as incorporated as a new subcategory, incorporated as a new sub-prerequisite or a sub-credit under the existing credits and prerequisites and incorporated as a new minor improvement or an amendment done to sub-prerequisites & sub-credits. After the development and incorporation of guidelines into the existing 8 categories of the building tool of the GREENSL® Rating System, evaluation of those incorporated guidelines was carried out using expert committee meetings. 8 consecutive expert committee meetings were carried out with the participation of 10 experts and professionals from diverse disciplines and backgrounds related to research study such as green building and built environment professionals, green accredited professionals, disaster management experts, civil engineers, electrical and mechanical engineers, architects and engineering-based academics.

Many comments and inputs were suggested by the expert committee throughout the series of meetings for the improvement of the building tool of the GREENSL® Rating System for Built Environment as a disaster resilient tool. Those comments are, (1) Input DRR measures to reduce the risk caused due to lightening hazards, (2) Change few categories which the guidelines were directed and listed based on their relativity and most suitability while listing some guidelines under more than one category or credit/prerequisite (structural health monitoring checks in both commissioning and additional commissioning sub-categories), (3) Remove some guidelines which are already in the building codes, (4) Change criteria limits under certain credits and prerequisites (eg: 150% of rainwater harvesting storage) which will result in enhancing the DRR and sustainability of the rating tool, (5) fire protection & detection mechanisms are suggested to include under commissioning clauses as a prerequisite as it was not an important aspect in the present rating tool, (6) Input a guideline to reduce the risks and enhance the resilience due to infections deceases like COVID-19, (7) Include some difficult achievables as ‘Exemplary Performance’ which may be difficult for the majority of green buildings, (8) Remove some criteria from the building tool due to the difficulty in achieving and transfer them to either city tool or transportation infrastructure tool or both based on the applicability and (9) Better not to mention about certain criteria such as slope stabilization criteria as they may vary with new research studies, instead mention only the link to refer the criteria.

After addressing the comments received from the expert committee, the new disaster resilient building tool of the GREENSL® Rating System for Built Environment consists of 2 new subcategories, 11 new sub-prerequisite or a sub-credit under the existing credits and prerequisites and 9 new minor improvement or an amendment done to sub-prerequisites & sub-credits. Initially the credits were awarded with points (starting from 1 point) depending on the importance and weightage of the DRR and disaster resilient guideline towards the greenery and sustainability of the building. Then the credited rating system was evaluated and reviewed using the same expert committee involved in evaluation of the incorporated guidelines. After the inputs and comments received from the expert committee, the rating system was re-credited with the suggested amendments and directed for the next round of review process. After couple of rounds of reviews by the expert committee, the credited rating system was ready for validation. Building Tool of the GREENSL® Rating system for Built Environment, incorporated with DRR and disaster resilient measures was comprised of extra 20 points, summing the total number of points into 120 points. The score card of the credited, disaster resilient building tool is shown in Table 4. Newly added content and the amendments done are underlined for better and clear identification purposes.

Table 4 The score card of the credited, disaster resilient building tool of the GREENSL® rating system for built environment [17]
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The credited new disaster resilient building tool was then directed for applicability evaluation and validation process. Applicability evaluation and validation were carried out through a series of surveys carried out using green certified buildings by GBCSL. Eleven certified buildings were chosen depending on their geographical location based on hazards and rating levels such that, 2 buildings located in flood prone areas, 3 based in landslide prone areas, another 3 in high wind areas and final 3 buildings located in less or zero hazard prone areas. Then the certified and scored project/building reports of above 11 buildings together with the building tool and newly developed disaster resilient building tool were used for the validation surveys. Score cards of the newly developed disaster resilient building tool were filled based on the current conditions and hazard vulnerability of the buildings. Then the new score card with the new certification type received based on new disaster resilient building tool was compared with the original or old score card with its certification type based on the existing building tool.

4 Results and Discussion

Although 20 points are allocated for DRR in this tool, points are allocated based on the applicable hazards for the respective building site. Therefore, number of applicable points may be varied depending on the location and vulnerable hazards. The summary of the 11 surveys conducted using the new disaster resilient building tool are analyzed and tabulated in Table 5. Points earned and the certification obtained using the existing building tool and the new disaster resilient building tool are compered while suggesting the possible and most effective applications of the tools.

Table 5 Summary of the 11 surveys conducted using the new disaster resilient building tool of GREENSL® rating system for built environment
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According to Table 5, buildings situated in flood prone areas have dropped their certification at least by one level. Droppage of points has also varied between 8 and 9 points, highlighting the considerable impact on the certification obtained using the existing building tool. Therefore, it is better to use the new disaster resilient building tool in certifying the buildings situated in flood prone areas due to the high frequency and impact created by flood hazards on built environment in Sri Lanka. Same observation can be noticed the buildings situated in landslide prone areas as well. 7 to 8 points have dropped in all 3 surveys carried out while dropping the certification also by one level. Therefore, it can also be recommended to use the newly developed disaster resilient building tool to certify the buildings which are prone to landslides. One special aspect which can be noticed here is that all 3 buildings considered here have incorporated the basic design principles applicable to land slide hazard in constructing the buildings. There is a slight difference in the scores and certification variation with the buildings situated in high wind areas. As most of the buildings considered here are placed in the east coastal belt of Sri Lanka, those buildings are also highly vulnerable to Tsunami risk as well. Although the scope of the research study was out of tsunami risks, during awarding the points, this aspect was taken into consideration. One of the positive aspects noticed in these selected green certified buildings are that they have considered the wind effect and alkaline effect (due to the locations are near the sea) in architectural and structural design aspects of the building. In these scenarios, points have been dropped by 6 or 7 points due to the moderate consideration of DRR measures against high winds in the selected 3 buildings compared with their existing green certification. Other than one building, the certification level of the rest of the 2 buildings have dropped by one level. Therefore, it also can be recommended to use the building tool incorporated with DRR in certifying the buildings in high wind areas. If we have a look at the buildings which are situated out of any hazard vulnerable zones, the droppage of points were only limited to 3 or 4 points. Apart from one building, the rest of the certification levels remained same in the rest of the 2 buildings which the survey was conducted. Even that certification level drop was mainly due to the certification level being marginal to the lower limit of the certification. Therefore, it can be recommended to use the existing building tool in certifying the buildings which are not situated in hazard prone areas. However, incorporating the applicable general DRR measures of the new building tool incorporated with DRR measures is encouraged due to the increasing treads of natural hazards and climate change conditions in the present world and Sri Lanka which will be beneficial in transforming the green buildings into sustainable buildings.

5 Conclusions

Disasters induced by natural hazards are inevitable. Yet taking necessary DRR and disaster resilient measures become a vital necessity with the rapid increment in natural disasters which brings catastrophic damages to the environment, society and the economy. Disaster risk in Sri Lanka has been increasing mainly due to rapid unplanned commercialization and development of cities, infrastructure with poor quality, and the impacts of climate change which has exposed the built environment severely vulnerable to natural hazards. Out of all the hazards, floods, landslides, heavy winds and tsunamis are considered to be the events with highest number of occurrence and also with the highest number of losses and damages during last 30 years in Sri Lanka.

Although GBCSL has initiated encouraging sustainability and reduced consumption of energy and other resources usage in buildings, it could not specifically identify the need of integrating DRR mechanisms into their green rating tools. Even a platinum rated green buildings with lot of sustainable and green related concepts, cannot be sustainable in nature if they are not withstanding against the natural hazards. Therefore, incorporation of DRR and disaster resilient mechanisms into the residential and other buildings, is a transformation towards a sustainable built environment. This research concerns the recognition of structural and non-structural DRR measures for floods, landslides and high winds, developing guidelines and then coming up with a new disaster resilient building tool for GREENSL® Rating System for Built Environment under main 8 categories of the existing building tool for GREENSL® Rating System for Built Environment V2.0.

After developing the new disaster resilient building tool for GREENSL® Rating System, eleven surveys were carried out in green certified buildings situated in hazard vulnerable areas for the floods, landslides and high winds as well as less or no hazard prone areas. Those surveys reveled that, it is highly recommended to use new disaster resilient building tool in certifying buildings situated in floods and landslides prone areas, moderately recommended to use the new tool for certification in high wind areas and finally it is acceptable to use the existing building tool for GREENSL® Rating System for Built Environment V2.0 for the buildings situated in less or no hazard prone areas. However, it is advised that the new disaster resilient building tool is in use even for the buildings situated in less or no hazard prone areas by at least incorporating general DRR measures due to the increase of natural hazards and climate change conditions in the modern world and Sri Lanka which will be beneficial in the process of transforming normal buildings to green buildings.

6 Recommendations

There are number of important recommendations to be suggested at the end of my research work for future references and continuation of this research as follows,

  • Some DRR guidelines may be difficult to achieve for a developing nation like Sri Lanka, where greening is also not a very popular concept due to the extra cost incurred. Therefore, incorporating DRR measures may incur another extra cost apart from greening.

  • Some DRR measures contradict with greening and sustainability concepts such as zero-carbon emission, life cycle assessment and resources and energy resilience. As an example, use of concrete as a hazard resilient construction material and installation of HVAC systems predicting future climatic changes may consume more energy and recourses as well as emit more carbon to the environment which will contradict with green building concepts. Therefore, it’s better to carry out a proper analysis to identify most sustainable options out of these concepts.

  • Only 11 surveys were carried out due to lack of green certified buildings situated in hazard prone areas. Also, the recommendations to use the new disaster resilient building tool is in high, moderate, and no or low levels for different hazards or less or no hazard prone areas, it can vary depends on building type and its usage as well. Therefore, this tool can be further developed as a more practical tool if more surveys can be conducted.