A Study on the Storage and Reuse of Rainwater: Taipei's Elementary Schools for Example
Date Issued
2006
Date
2006
Author(s)
Wung, Tsai-Chung
DOI
zh-TW
Abstract
Currently in green building labels, the replace ability of water resources has become an important link in building techniques and rules. Rainwater collected undergoing simple filtering to become water without coming in contact with the human body is the most common way adopted by new buildings. The status quo, however, presents a great discrepancy and is unsuitability inasmuch use is concerned, in that the taxonomy which the current criterion relies upon is too simplistic. For this reason, this study aims at Taipei's elementary schools by exploring the rationality and feasibility of the use of rainwater storage for flushing toilets in dedicated building types. Based upon existing campuses, the present work attempts to propose rainwater storage and flushing system suitable for elementary school.
This study lays emphasis on practical applications. Starting with Taipei's rainfall using 15 weather stations, it discusses the influence of variations in Taipei's topography on rainfall. By characteristics of rainfall distribution, seasonal change, probability of precipitation, Taipei is divided into four areas and seven sub-areas. Rainfall of locations is corrected based upon the distance between campus and measuring stations. The result shows that according to the influence of Taipei's topography on precipitation, it is indeed improper to base rainfall storage design on a single rainfall station alone.
After surveying types and areas available for collecting rainwater on the campuses, it is found that campuses collect rainwater by prioritizing roofs, followed by the hard tracks of playgrounds. In respect to rainwater collection, the result indicates that campus roof rainwater collection is concentrated in approximately 20% of the area, and that the highest collection is concentrated in September due to precipitation conditions. According to the campuses' means from weather stations in terms of roof areas alone, differences in extreme values of rainfall are close to 20 times. Extreme values at one single weather station are nearly 7 times at maximum. If collection of playgrounds is included, there is a difference of 7 times in weather stations' means. The result shows that factors that affect the difference of times at weather stations in the same areas include collection areas, in addition to the campus position. Differences between campuses at one single weather station are affected by the factor of whether monthly rainfall is even. According to an analysis on water use on campuses, the population is the factor that has the biggest influence. The study has formulated a relation between population and rainfall supply needed. The supply-demand relation indicates that by raising the collection of playgrounds, the number of campuses with a supply-demand replacement ratio at 100% all year round can increase from 3 to 8.
The study clustered the campuses, set up reference time-points against supply-demand replacement ratios, and compared with newly built campuses using the lowest replacement ratios. The result indicates that using roof rainfall collection design, the lowest point of clustering control is Shipai Weather Station's supply-demand ratio of 13% in January. If rainfall collection of playground tracks is included, the lowest point is Tianmu Weather Station at 25%. These two areas are in the low-rainfall A-1 area. Data that show differences in rainfall constitute an influence.
The study attempted a rational storage for seven months of actual use, but provided instead a 6-month comparison mechanism for campuses with an overly low replacement ratio. The result shows that for a number of campuses, there was little difference in storage use rates in six months or seven months. But when set values for capacity were increased (100 M3), the initial cost could be reduced to shorten the period of return on investment (ROI), and the overall efficiency could be enhanced.
Comparing the difference between actual conditions and design can change a rational storage design. Moreover, evaluation can be made according to the ROI of initial equipment costs. Finally, the study discusses the current establishment problems and makes suggestions on facilities in order to propose a rainwater storage system to serve as a reference for existing and new campuses in single construction or in overall establishment.
Subjects
替代率
雨水貯留
氣象站
群集分析
elementary schools
replacement ratios
rainwater storage
weather stations
cluster analyze
Type
thesis
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