A KNOWLEDGE BASED COMPUTER-AIDED DESIGN TOOL FOR WATER EFFICIENT DESIGN OF SUSTAINABLE GREEN OPEN SPACES

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1 A KNOWLEDGE BASED COMPUTER-AIDED DESIGN TOOL FOR WATER EFFICIENT DESIGN OF SUSTAINABLE GREEN OPEN SPACES Daphna Drori Edna Shaviv Faculty of Architecture and Town Planning, Technion-Israel Institute of Technology, Haifa, Israel Technion City, 32000, Israel ABSTRACT A Knowledge Based Computer-Aided Design Tool for Water Efficient Gardens (WEG) was developed. Special emphasis was put on the climatic adjustment of the garden for the comfort of the plants and the people, in a similar way that bio-climatic buildings are designed. This includes solar radiation, wind and orientation, in order to minimize the evapotranspiration from the plants and soil. The WEG tool includes a qualitative part that is based on the "Pattern Language", conceived by Alexander and a quantitative part that enables an evaluation of the required water consumption. This tool was used to define the reference gardens for the performance-based method, and the improved gardens for the prescriptive-based method, which are presented in the water chapter of the Israeli Sustainable Building standard. 1. INTRODUCTION The water issue is a crucial matter today, more than ever. Israel is located in a semi-arid climate region, and is characterized by limited water resources. The Israeli water system is under acute shortage following a continuous seven years drought period ( ). In addition, there are human-administrative factors: These include a delay in launching desalination projects, and a significantt decrease in the permeable areas, as a result of an accelerated urban development. This disrupted the gentle balance of demand and supply and caused a shortage in the potable water. An Israeli study enumerated and estimated the combined elements, that effect the tendency of growth in domestic water demands in Israel between (1): 1. The economic growth creates an increase in water consumption, mainly in national development areas in Israel. Due to the rising standard of living, the economic ability to consume water is enlarged. 2. There are two social-cultural processes influencing the increase in water consumption: a continued demographic growth and a growing preference of the public to live in the suburbs. A pattern of single family house type of building increases the water consumption per capita due to garden irrigation's demands. 3. Environmental-climatic conditions influence the domestic water consumption. In hot regions and during the hot and dry seasons the water consumption is higher. 4. Cultural values recognizing the importance of green scenery. The Israeli society nurtures green gardens despite its incompatibility to our region's climate. The Israeli government has taken few actions to deal with the water shortage. The First way is by desalination of seawater in order to increase the water supply. In the epoch of the sea water desalination, theoretically there would not be shortage in potable water in the near future, but 1 cubic meter of desalinated water consumes about four kw/h of energy. Thus, any raise in water usage contributes to the increase of energy consumption. The second way is decreasing the demand for water and adjusting it to the existing supply. These actions include exposing the users to education and information in order to encourage conservation and water saving. In addition to that the users are encouraged to implement the green standard for sustainable building. Another drastic action was to raise the water cost. These actions assisted in reducing water consumption and demand, but since no special allocation for 1

2 irrigation was introduced, this also caused garden owners to dry out their lawns in order to reduce their water bill. As a result, many gardens and open spaces became yellow and neglected. However, the way to implement water efficiency policy is not by eliminating the "green", but by water conscious design, which can keep the gardens flourishing all year round (Fig. 1). which supports a dynamic decision-making process. Instead of linear decision-making process it suggests a semi-lattice one (Fig. 2) and enables a flexible implementation in every project and at any phase of the design. Hence it was found as a suitable methodology to develop a Knowledge-Based Design Tool for water efficient gardens. Fig. 2: The semi - lattice navigation order. Fig. 1: Initiated dried out lawn in private garden in Israel (left), and a water efficient garden (right). 2. THE KNOWLEDGE BASED DESIGN TOOL In order to deal with the reduction of water in open spaces and gardens in the domestic and urban sector, a knowledgebased design tool was developed. The tool displays various design implementations of water efficient gardens. A special emphasis was put on the adjustment of the garden to the environmental and climatic conditions of the site, thus supporting a sensitive and bio-climatic water design of sustainable green open spaces. In addition, the tool is a computer-aided system available for the planner from the first stages of the design process. The tool contains two part; qualitative and quantitative that are integrated within each other and together enable a qualitative design and a quantitative evaluation throughout all the stages of the design process. 1.1 The Qualitative Tool The qualitative tool is based on "The Pattern Language" conceived by Christopher Alexander (2) that was implemented by Edward Mazria in "The Passive Solar Energy Book" (3). The language is composed of elements called "Patterns". Each pattern deals with a design problem connected to human activity in its environment, describes its origin and its unlimited ways of interpretation. The sequence of patterns which are being used during the decision-making process is specific for every project and covers a wide range of subjects and scales from the site and concept to the details and finish. There are three advantages in choosing "The Pattern Language" as a methodology for the WEG Tool. First, "The Pattern Language" is eminent for being a design method "The pattern Language" is characterized by a framework based on hypertext connections. The navigation is performed according to context and demands of the designer. Thus, a computerized format was chosen for the developed tool, as opposed to the written version of Alexander and Mazria. While the latter requires slow awkward procedure of turning pages, the computerized interface is simple and convenient for use. The third advantage of "The Pattern Language" is the capability of working both with the qualitative and quantitative contents. Similar to the energy calculations at "The Passive Solar Energy Book", it is essential for a design tool for water efficient gardens to evaluate the reduction of water for irrigation. Hence, the tool includes a quantitative computer-aided tool. "The Pattern Language" performs as an open framework, which can be widened and updated according to the development of the subject The Qualitative Tool's Structure The qualitative tool includes 87 different patterns, represented in five major branches dealing with the subjects: Landscape Design, Irrigation, Agro-Technical Methods, Runoff and Non Potable Water (Fig. 3). Fig. 3: The map of the "Water Efficient Gardens" (Level 1). 2

3 The lower levels of the "Landscape Design" branch demonstrate the hierarchical layout of the tool (Fig. 4). of one will lead the designer to another pattern in the tool. It can be either a pattern of the same familial branch (In Fig. 6 the "Climate" pattern in the "Evapotranspiration" branch), or a link based on a conceptual relation to a pattern located in another branch of the tool (In Fig. 6 - the "Soil" pattern in the "Evapotranspiration" branch). Fig. 4: The map of the "Landscape Design" branch The Pattern's Structure The patterns have a constant format with a definition, illustrations, recommendations, and informative knowledge, including quantitative information. This unity of the patterns strengthens the orientation of the user in the tool. These subjects were demonstrated in detail in a previous paper (4). Fig. 6: Hierarchical and semi-lattice link in "Evapotranspiration" pattern page. Besides the semi-lattice link some other sorts of links were developed and are used in the tool: hierarchical links and external links. The former enable the navigation back to higher level in the tool and to hierarchical maps (Fig. 6). The hierarchical links improve the clarity of orientation in the branched system, which is essential in the case of a large and complicated knowledge framework, as has been developed in this study. The latter ties up the tool to other knowledge structures like: governmental sites and case studies. This action implants the tool in the realm of knowledge and broadens its limits of influence (Fig. 7). Fig. 5: The The pattern Structure Navigation with Links The navigation is carried out by the words embedded in the text. These are actually links to related contents or connected patterns. There are three different types of links: The first is the common semi-lattice navigation from pattern to pattern, as it exists in "The Pattern Language". A selection Fig. 7: External link to governmental site in "Evapotranspiration" pattern page. 3

4 The link concept enables a quick decision-making process both associative and knowledge-based. 1.2 The Quantitative Tool The necessity in a tool that can make the evaluation of the foreseen water reduction for irrigation of the designed garden is evident. The calculator accomplishes the qualitative design process with a numerical evaluation of the suggested design. The evaluation is an excel sheet that rapidly executes a high volume of data, on varied parameters simultaneously, and represents immediate results. The calculator is recommended for use at any stage of the process, including the early design stages, or performing an update and recalculation, in order to get better results of water saving The Calculator's Factors Inspired by the bio-climatic design of buildings, a special emphasis was put in the WEG tool on the climatic adjustment of the garden to the comfort of the plants. The bio-climatic design includes identification and application of these factors in the design for achieving reduction in irrigation. The quantitative tool enumerates two kinds of bio-climatic factors in the calculation process: The local climate: includes: the average annual and monthly precipitation and evapotranspiration data. The microclimate conditions: are the specific climate conditions which differ from their surrounding due to the alteration in solar radiation, wind velocity and humidity. The microclimate factors influence the irrigation water consumption, which is reflected in improving or worsening the irrigation requirements. A set of design principles should be used to improve the thermal comfort, welfare of plants and people and for achieving the reduction of irrigation water consumption. The designer should encourage the creation of a specific microclimate conditions for the entire garden or for special spots in it. Among the factors are: high or low temperature, humidity, solar radiation, exposure to the breeze or wind protection, and exposure to precipitation or protected spots. Different Shaded or protected modes are among the factors that assist reducing the irrigation demands. The opposite situation is strong wind and intense radiation which worsen the irrigation requirements. Each of these factors: Shadow, northern orientation (in the northern hemisphere), wind protection and the Albedo of the material surface is evaluated accurately and individually. Agro-technical factors provide solutions related to preparing the ground and treating the plants in the garden like: soil amending, and mulching. The implementation of these technical solutions will improve the plant's appearance and achieve a substantial reduction in irrigation water consumption The Calculation Process The calculator that was developed for the WEG tool is based on the Israeli Ministry of Agriculture calculator (MOAG) (5), which provides useful information to incorporate the consolidation of the garden after the construction phase, and to monitor the current consumption. In contrast with the MOAG calculation method, the Drori - Shaviv calculator takes into account the bio-climatic factors. The quantitative evaluation demonstrates the significance of the bio-climatic factors, and encourages their implementation in the design. Moreover, the computerized calculation procedure is quick and accurate. Thus, it is recommended to evaluate quantitatively the qualitative design even during the first phases. According to the results, the designer may consider to perform another phase of design and improve the garden's performance. Similar to the LEED calculation method (6), the Drori Shaviv calculator is intended to emphasize the foreseen relative saving which can be achieved in the designed garden in comparison to a reference garden that was defined using this WEG tool (see section 3.3). The Drori Shaviv calculator estimates the percentage of irrigation water reduction for the designed garden in regards to the reference garden. As part of the calculation of the garden's water efficiency, the nonpotable water is calculated and reduced from the total water applied Running the Calculator The calculator is edited as a set of questions to be filled. The questions deal with the following topics: 1. Climatic region: There is a selection of five climatic regions: North, Center, South, Jordan Valley and Arava. 2. Vegetation type: First, there is a selection of one out of three different subcategories: Lawn, Flowers and Vegetables, Trees and Shrubs (only one at a time). At each subcategory there are more focus questions to choose whose aims are characterizing the vegetation type and its accurate water consumption (Fig. 8). 3. Soil type: There is a selection of 4 different types of soil which will set the recommended irrigation intervals. 4. The garden's microclimate conditions: Here appears questions like: Is the soil mulched? Is it shaded? Is the area northern oriented? Is the area a wind protected? Is there any built element next to the vegetation, What is its albedo? 5. Agro-technical questions: What is the quality of the soil? Is it amended or poor? 6. What is the size of the area? 7. What is the name of the area? 8. Are there any paved area in the garden? Are these pervious or impervious? 9. Is there any source of non-potable water for irrigation? 4

5 The questions numbered 4 to 9 are performed to each vegetation group in the garden. There is an option to run another set of calulations after updating the data The Summery Table of the calculator The summery table (Fig. 10) includes the relevant data of the proposed project. This data includes: the region and the soil type, the vegetation type (divided into areas based on the designer s decision), the size of the areas together with the impervious and pervious paved areas (in Dunam), the irrigation intervals (in days), the weighted Species factor of the plants including the microclimate factors, the annual and monthly total water applied for every vegetation group (Cubic Meter). The top lines of the table summarize the total water applied for irrigation (Cubic Meter) after taking into account the average precipitation amounts on site. The upper line presents the total non-potable water including waste water which is being used in the garden for the final calculation of the potable water for irrigation. "Waste water" is the term for the unused cold running water coming from the shower tap before the arrival of the hot water. The "waste water" is being collected in a bucket and used for irrigation. Fig. 8: The species factor. Fig. 9: Irrigation intervals in days. Remark: Dunam was a non-si unit of land area used in the Ottoman Empire. It is now defined as 1 Dunam=1000 m 2. Fig. 10: Calculated annual and monthly irrigation requirements (Cubic Meter). 5

6 1.3 The Integration of the Qualitative Tool with the Quantitative Tool The advantage of the WEG Tool is the effort to display a full integration of the two parts of the system. While the qualitative part directs the designer to reach a water efficient garden, the quantitative part evaluates numerically the suggested design. The connection from the quantitative tool to the qualitative one is performed by a link to the relevant pattern (Fig 11). Fig. 12: An example of a quantitative information in pattern "Evapotranspiration" and a link to the calculator. 3. IMPLEMENTATION IN A CASE STUDY In order to experience the design tool in action, the model was demonstrated in a retrofit process of an existing private garden. The retrofit process included the implementation of the qualitative "pattern language" design tool, and a quantitative monitoring of the water consumption for irrigation during three years of the study The garden case study is located in the northern zone of Israel, where comfortable climate conditions prevail. Although the annual amount of precipitation is not little in the northern zone of Israel, yet, as all over Israel, the precipitation is limited to about three or four months of the year (Fig. 13). Therefore, the irrigation of the case study garden is essential for eight months of the year. Fig. 13: Annual average of rain in mm and daily average Evaporation in mm - Newe Ya'ar regional center. Fig. 11: A link to the pattern "Shading". Vice versa, there are two possible connections from the qualitative to the quantitative tool: one, as quantitative information embedded in the text describing the pattern, and second as a link that transfers the planner to the quantitative tool (Fig. 12). The implementation of the qualitative part of the knowledgebased computer-aided design tool was documented. 47 patterns out of 87 have been used in the decision-making process of the garden case study (Fig. 14). Naturally, in every design procedure of a garden, a unique sequence of patterns will be chosen. It depends on the environmental conditions and the climate of the place, limitations of budget, users' requirements and their priorities. 6

7 Fig. 14: Patterns Used in the Case Study. 3.1 The Actual Water Consumption Besides using the qualitative tool, the upgrade included monitoring the garden's actual water consumption for irrigation. This quantitative analysis was designated to measure the reduction that has been obtained using the qualitative design tool. The analysis measured the garden's water consumption during the course of the study and calculated the percentage of saving in comparison to the year before the upgrade started. In 2007 the irrigation of the garden was the common inefficient one. During the following three years, various designed changes were carried out in the garden, and achieved efficiency in water consumption (Fig. 15). Fig. 15: domestic water consumption for indoor and irrigation of the case study garden. A usage of the tool and the implementation of the recommendation accordingly assist minimizing 49% of the water consumption for irrigation, and a decreasing of 40% of the domestic water consumption. In 2007 the water consumption for irrigation was 48% of the total domestic water consumption. In 2010 it was only 42% of the total household water usage. These results show the embodied saving potential of using the qualitative tool for achieving a water efficient garden. 3.2 The Water Consumption's Calculator Monitoring In addition to the validation of the qualitative design tool that enables reducing the water consumption by 49%, validation of the quantitative design tool was carried on as well. The validation was made by using the actual water consumption for irrigation measured in the garden case study. The Drori- Shaviv calculator was used in order to evaluate the total water requirements before and after the retrofit of the garden. The objective was to compare the calculated amounts of water to the actual amounts applied (Table 1). The results obtained showed a reduction of 44% in irrigation water consumption. The results are not exactly identical. The reason for this is that the calculator is based on statistical data, while the actual results are based on the very specific conditions for the years Nevertheless the results are similar. 7

8 TABLE 1: THE REDUCTION IN THE WATER CONSUMPTION FOR IRRIGATION THE CASE STUDY The garden case study was used also to examine the convenience of using the tool. The qualitative tool doesn't require any former knowledge to work with and was found to be user friendly. The navigation that is carried out not as checklist but as links, is an advantage for the decision making process because it expresses flexible adjustment to specific requirements of every project. Moreover, the qualitative tool is feasible and effective while the quantitative tool displays reliable results. 3.3 Implementing the Tool in the Green Standard The WEG Tool was implemented as a research tool for determining a reference garden for the Israeli Sustainable Building standard. Actually, a set of reference gardens was identified for each climate zone, and presented in the normative appendix C of the SI 5281 standard (7). The performance-based evaluation method defines the percentage of saving of the proposed project in regards to the reference garden. Furthermore, it was also used to define a set of the improved gardens for the Prescriptive / descriptive Based method of SI 5281 standard. These improved gardens enable a reduction in water consumption of 10%, 30% and 50% referring to the reference garden. Details of the development of the reference and the improved gardens will be presented in a future paper. 4. SUMMERY AND CONCLUSIONS The benefit of the WEG Tool, which was developed in this study, is that it contains two parts: the qualitative design tool and the quantitative one that are integrated together and complete each other. The design process will not be complete if it is merely a qualitative work, creative and good as could be. The quantitative part will provide numerical evaluation, but it is insufficient without the valuable qualities provided by the former tool, which guides the designers by providing those recommendations, information, illustrations and relevant case-studies. Moreover, it is most significant that the combined quantitative and qualitative design tools work together as one system. The meaning of the integration is that it is possible to move from one to another easily. Hence, the designer can evaluate the performance of his proposed design, in an on going process, from the very first stage of the design. The use of the semi-lattice links in the WEG tool is flexible according to the unique demands of the project, while at the same time the quantitative evaluation creates a feedback on the qualitative proposal according to the details of the design stage. It assists the designer to reach the proper decisions in each design stage, based on accurate and reliable information. It also provides him/her with some useful information for the consolidation phase of the garden, and encourages monitoring the current and future water consumption. Consequently, the WEG Tool may accompany the Architect and the Landscape Architect throughout the whole design and maintenance process. The WEG Tool was examined in the garden case study and was found to be effective in implementing a retrofit process. The case study garden transformed into a water efficient garden with a 49% reduction of the annual irrigation water consumption throughout the three years of the study, in which different improvements were tried and implemented. The fact that the WEG tool was used to define the reference garden and the improved gardens for the Israeli standard SI 5281 for sustainable building indicates the tool's importance, ability and relevance to the design of sustainable green open spaces. 5. REFERENCES (1) Portnov B. A. & Meir I., Urban water consumption in Israel: convergence or divergence? Environmental science & policy [Online] 2: , 2008 (2) Alexander C., Ishikawa S., Silverstein M., A Pattern Language: Towns, Buildings, Construction, Oxford University Press, New York, 1977 (3) Mazria, E., The Passive Solar Energy Book, Rodale Press, Emmaus, 1979 (4) Drori D., Shaviv E., A Pattern Language Design Tool for Water Efficient Gardens: A Knowledge Based Computer- Aided Design (KBCAD) tool for water efficient landscape design, PLEA2011: 27 th International conference on Architecture & Sustainable Development, 2011 (5) Kremer O. & Galon I., Coefficient Tables of water consumption for irrigation in the gardens, The Ministry of Agriculture & Rural Development, (6) LEED for New Construction & Major Renovations, (7) Drori D., Shaviv E., Appendix C of SI 5281 (Normative): a reference garden. The Standards Institution of Israel,