The efficiency of rainwater storage tanks is assessed from the utilization rate of rainwater and the substitution rate of tap water。 Differences in annual precipitation and rainfall distribution yield different results。 Figs。 5 and 6 illustrate the results of the mentioned calculation procedure, to analyze differences in rainwater utilization and efficiency assessment。 The simulation runs over a period often years, from 1985 to 1994, and includes storage tanks with four different volumes。 When the volume of the rainwater tank is 50 m, the utilization rate of rainwater exceeds 80% with about 25% substitution with tap water。 Using this approach and the assessment procedure, the volume of rainwater storage and the performance of rainwater use systems in building design, can be determined。
In the formula of the water conservation index, C is a special weighting for some water recycling equipment that intermediates water or rain, and is calculated as the ratio of the water-consumption quantity of the recycled rainwater to the total water-consumption。 Therefore, this assessment procedure can also offer an approximate value of C for the water conservation index。
5。 Green building label and policy
“Green Building” is called “Environmental Co-Habitual Architecture” in Japan, “Ecological Building” or “Sustainable Building” in Europe and “Green Building in North American countries。 Many fashionable terms such as “Green consumption”, “Green living”, “Green illumination” have been broadly used。 In Taiwan, currently, “Green” has been used as a symbol of environmental protection in the country。 The Construction Research Department of the Ministry of the Interior of the Executive Yuan has decided to adopt the term “Green Building” to signify ecological and environmental protection architecture in Taiwan。
5。1。 Principles of evaluation
Green Building is a general and systematic method of design to peruse sustainable building。 This evaluation system is based on the following principles:
(1) The evaluation index should accurately reflect environmental protection factors such as material, water, land and climate。
(2) The evaluation index should involve standardized scientific quantification。
(3) The evaluation index should not include too many evaluation indexes; some similar quality index should be combined。
(4) The evaluation index should be approachable and consistent with real experience。
(5) The evaluation index should not involve social scientific evaluation。
(6) The evaluation index should be applicable to the sub-tropical climate of Taiwan。
(7) The evaluation index should be applicable to the evaluation of community or congregate construction。
(8) The evaluation index should be usable in the pre-design stage to yield the expected result。
According to these principles, the seven-index system shown in Table 4 is the current Green Building evaluation system used in Taiwan。 The theory evaluates buildings’ impacts on the environment through the interaction of “Earth Resource Input” and “Waste Output”。 Practically, the definition of Green Building in Taiwan is “Consume the least earth resource and create the least construction waste”。
Internationally, each country has a different way of evaluating Green Building。 This system provides only the basic evaluation on “Low environment impact”。 Higher level issues such as biological persity, health and comfort and community consciousness will not be evaluated。 This system only provides a basic, practical and controllable environmental protection tool for inclusion in the government’s urgent construction environment protection policy。 The “Green Building” logo is set to award Green Building design and encourage the government and private sector to pay attention to Green Building development。 Fig。 7 is the logo of Green Building in Taiwan [6,8]。