CLIMATOGRAPHY MODEL FOR SUSTAINABLE URBAN BUILT ENVIRONMENT

Abstract

Climatological information is crucial to the development of any Model for Sustainable Urban Built Environment. Traditionally the diverse geo-climatic environments prevailing in India have given rise to diverse vernacular architectural traditions, all of which are resource conserving, climatically appropriate and sustainable. In recent times though the traditional building typology as a whole has lost in popularity to the modern mass producible construction materials and fast and efficient techniques. In the effort towards economizing the building stock, the attention hitherto received by the climate responsiveness of the design solution has waned. The role played by climate responsive attitude towards sustainable development in the building design and construction activity has been accepted widely even at international forums. Collaborative efforts between users, builders, governments, NGOs, teachers and design professionals are need; for successful implementation of strategies emerging from scientific knowledge, traditional wisdom, innovative high and low-tech building solutions; in order to reduce the rate of energy consumption and pressure on the environment. Conversely even if the buildings are designed with utmost respect to climatic consideration, they do participate in modulation of local climate to a certain extent. Lack of climatic information pertaining to the growing number and size of urban settlements, in readily usable form acts as impedance in the generation of the scientific knowledge required for identifying strategies appropriate in those respective settlements. It is impractical for the state legislative to prescribe a separate climatic analysis for every settlement in view of the complexity entering the process due to the absence of contextual climatic data. The climatic classification map hitherto referred for prescribing design strategies is based on obsolete size of data, and as such fails to represent the diverse geo-climatic environment prevailing in India. In the aforementioned context this research inquiry tries to answer the following questions: o How do thermal comfort requirements vary with geographical regions of India? o How do ambient climatic conditions provide a basis for selecting passive design strategies for achieving thermal comfort in urban built environment? iv o Do existing building legislation, regulations, codes and standards support the successive modulation of ambient climatic conditions? The proposed Climatography Model is aimed at enabling modulation of ambient climatic conditions; through incorporation of appropriate passive design strategies in building regulations for achieving a sustainable urban built environment. The objectives identified for fulfillment of this aim are as follows: 1. To Formulate a framework for collation of climate information useful in thermal comfort analyses, at scales of regional geography and urban built environment. 2. To Delineate regions within India based on prevalent thermal stresses, requiring specific combinations of responsive passive design strategies, (a) for standardizing mandatory compliance criteria and (b) for identifying appropriate urban built form. 3. To Recommend revisions in building byelaws, town planning and state energy conservation regulations for, o (a) including identified strategies as mandatory compliance criteria and o promoting built form design interventions in the context of study area o (b) standardizing building performance evaluation criteria Having introduced the research context the First Chapter then proceeds with a discussion on Research Approach and concludes by describing the scope, limitations and thesis outline. The research approach is briefly discussed using a diagram of nested frames ranging in detail from School of Thought at the broadest scale to Strategies at the intermediate scale and then moving to Tactics at the narrowest scale. The details at the scale of School of Thought include the three domains supporting the aim of enabling a sustainable urban built environment; namely Climatology, Responsive Building Design and Building Legislation. The details at the scale of Strategies include trifurcation of the tree domains as follows. Strategies in the domain of Climatology are detailed out as analyses at ‘Regional Level’, ‘Local Level’ and ‘Typical Level’. In correspondence to these strategies, the domain of Responsive Building Design is detailed out into ‘Combinations of Responsive Strategies’, ‘Appropriate Urban Built Form’ and ‘Base Case for Building Performance Simulation’ respectively. Whereas in the domain of Building Legislation, ‘National Building Code’, ‘Building Byelaws’ and ‘Energy Conservation Building Code’ have v been identified as the documents which will be informed by the aforementioned strategies in the domain of Climatology and Responsive Building Design. Chapter Two is an exposition of detailed concepts in the domains of Climatology, Responsive Building Design and Building Legislation. Concepts dealt at length in the domain of Climatology include, Climatography as a branch to Climatology; Scales of Climate Study, and Climate Data. While exploring the various scales of climate study, one gets introduced to, the basis of Koppen climate classification, the notion of geographical regions, and the concepts of Urban Climate and Local Climate Zones. A review of various concept related to Climatic Data starts with secondary aspects such meteorological parameters, collected vide the automatic weather station and urban climate networks, and leads to the computation of climatic normals. These aspects are a precursor to the primary aspect of diagraming and mapping, as part of which one is introduced to composite climate charts (used for representing temporal variation in multiple parameters together), geographical climate maps (use for representing composite charts of multiple cities together), and finally the development of agro-climatic zones. After the study of Agro-climatic zones one understands the use of derived parameters (based on interpolated data) in identifying spatial zones having geo-climatic conditions favorable for achieving high yield of various crops. Concepts dealt at length in the domain of Responsive Building Design include, the frameworks for understanding the linkages between various elements involved in as well as impeding or enabling the application of climatology to various scales of built environment ranging from the region, to the settlement, and down to building element. Other concepts dealt here, include the various diagrams (called bioclimatic charts) used for identify thermal stresses experienced at a place though out the year, that help in the selection of appropriate design strategies. The finer aspects related to Climatic Suitability of Built Environment also include Psycho-Physiological model of thermo regulation related to the idea of thermal preference as well as the cyclic method in which the architectural design strategies are implemented for modulating the ambient climatic conditions. Concepts dealt at length in the domain of Building Legislation include, the phenomenon of Urbanization, Constitutional provisions enabling urban local bodies for regulating vi construction activity (with the help of building codes and standards) as well as general environmental conditions (with the help of environment impact assessment of development projects), Urban and regional plan formulation and implementation guidelines. The finer aspects related to the concept of Energy Conservation Building Code, include the various compliance criteria as well as the typical weather file required in the whole building performance method of compliance. Here, the scant number of typical weather files available for India is identified as a concern. The Green rating systems are closely related to various sustainable concepts including energy conservation. Last but not the least the review deals with the standardized development control regulations at national and state level that can be targeted as vehicles for implementing responsive design strategies. Chapter Three is a compilation and comparison of alternative case studies used for selecting components in the research framework. The climatic classification criteria available across the world are distinguished into forward analysis and backward analysis on the basis of the stage in the design process where it is to be implemented. Finer aspects in the concept of Climatic Data Modeling include, Spatial Interpolation, Physical basis of variation in Urban Climate, and Temporal Interpolation. The finer aspects in the concept of Climate Modulation Strategies include the Design Matrix of all possible strategies, Mahoney Tables criteria of prioritizing between conflicting requirements and detail exploration of specifications related to the built form, building envelope and opening design. Lastly the finer aspects related to the concept of GIS are described, including physical and human geography, continuous and discrete data, interdisciplinary subsystems. The literature review conducted in Chapter Two and Three lays the platform for fulfillment of the First Objective achieved in Chapter Four through the formulation of analytical framework. The analytical framework consists of three inter connected analytical workflows. Second objective of this research is completed after implementing two workflows, namely Regional Climate level analysis and Local Climate level analysis. In the Regional Climate level analysis published interpolated (temperature extremes) and modeled (relative humidity) climate data is used to perform cartographic modeling in GIS application on the basis of Mahoney Table criteria and compile thermal stress maps. In vii the next step the stress maps are subjected to positional notational codes to generate strategy maps. Finally the eight strategy maps are superimposed to delineate Thermal Comfort Design (TCD) Zones. In the Local Climate level analysis on the one hand Local Climate zones (LCZ) are to be delineated in selected city by performing supervised classification on remote sensing images as per WUDAPT procedure, while on the other hand diurnal micro-meteorological measurements are to be collected from various LCZ. In the next step LCZ map and diurnal measurements are to be correlated using Energy Flux model to obtain Modeled Local Climate Data. A second iteration of regional climate level analysis is to be performed using this Local Climate data to identify Appropriate Urban Built Form. In the Typical Climate level analysis climatic normals or collated gridded data are used as input in an automated spreadsheet based on a published algorithm to generate local typical weather file based on the paper translated from Portuguese attached as APPENDIX 3. The base case used in building performance evaluation is to be designed as per the applicable TCD Zone. Whole building simulation completed using base case designed as per TCD Zone and Local typical weather file completes part (b) of Third Objective. The TCD Zones are assessed and discussed at length in Chapter Five. Google Earth app enables the straight forward identification of the unique combination of responsive design specifications at any location across India with the help of a pop-up that appears when one searches and clicks besides that location. All major cities (population more than 1 million) are located within 31 out of 62 TCD Zones delineated across India. Only 16 of these TCD Zones encompass 5 or more major cities. Flyers for these 16 TCD Zones containing spatial extents, duration of climatic indicators and recommended design specifications are attached as APPENDIX 1. Spatial analysis using uniform Hexagonal grid and Thiessen Polygons around existing Typical weather file stations is useful for identifying neighborhoods with high TCD Zone variability. Generation of additional local typical weather file is recommended for cities located in these neighborhoods. Detailed spatial analysis has been done for the extents of Maharashtra State to enable regionalization of Development and Control Regulations. Out of the 12 TCD Zones found across Maharashtra, 5 TCD Zones are restricted to the Konkan viii region, which signifies the role of TCD Zone in identifying regional thermal comfort requirements. List of 254 ULBs of Maharashtra along with their assigned TCD Zone has been included in APPENDIX 2 along with the matrix of design strategies applicable in each zone. The matrix is useful for identifying the variation in DC&P Rules with respect to individual TCD Zone. Recommendations have been made in the Sixth Chapter for including the identified strategies as part of Building Byelaws, which completes part (a) of the Third Objective. Future Scope for extension of this research has been enumerated in the Conclusion Chapter. Thus all objectives identified for achieving the aim of this research have been fulfilled