(2) Half of the construction project uses water-saving equipment, including two-sectioned water-saving toilets (water consumption when flushing feces is 9 L; urine, 4。5 L) and water saving taps (1。2 L per use)。 Each bathroom is equipped with a showering nozzle (no bathtub), with a timer device (20 L of water is saved for the showering device without the bathtub, and an extra 10 L of water is saved using the timer device。)
The water-resource index is calculated as follows:
(1) Estimated general daily water-consumption is 250 l per person。
(2)WR=(250-((13-9)×0。5+3。57×(13-4。5)×0。5+4。86×(3-1。2)×0。5+(10+20)×0。5))&pide;250=0。857
WR>0。8; therefore, Case 1 does not achieve the water-resource index, and cannot receive the “Green Building” incentive payment。
Case 2: Brief explanation of the water-saving equipment。
(1) In the above case, water-saving equipment was used only in half of the construction project。 Calculation data is as follows, if the whole project used such water-saving equipment, then, WR = (250 - ((13 -9)×1。0+3。57×(13-4。5)×1。0+4。86×(3-1。2)×1。0+(10+20)*1。0))/250=0。714
 (2) WR<0。8; therefore, Case 2 achieves the water-resource index, and can receive the “Green Building” incentive payment。
Case 3: If the project described in Case 2, could include a system to recycle the rain, then the situation is as follows:
 (1) The roof of the apartment can gather 625 m of rain, and the capacity of the water trough for saving the recycled rain is 35 m。 Therefore, using the recycled water for flushing toilets, cleaning and other uses (for example; watering plants and washing cars), can save 30 L of water per person per day。
(2) The ratio of the water-consumption quantity of the recycled rainwater to the total water-consumption is 0。12 (C =30&pide;250=0。12)。
(3) Then, the water-resource index is 0。594 (WR=0。714-0。12=0。594)。 As a result, Case 3 not only achieves the incentive standard, but is also an exemplary of green building design。
4。 Method for assessing the recycling of rain
Systems for recycling rain and intermediate water are not yet economic beneficial, because of the low water fee and the high cost of water-disposal equipment。 However, systems for recycling rain are considered more easily adoptable than those for recycling intermediate water。 Herein, a method for assessing the recycling of rain is introduced to calculate the ratio (C) of the water-consumption quantity of the recycled rainwater to the total water-consumption。
4。1。 Calculation basis of recycling rainwater
The designer of a system for recycling rainwater must first determine the quantity of rainwater and the demand, which will determine the rainwater collection device area and the storage tank volume。 Rainwater quantity can actually be determined by a simple equation involving precipitation and collection device area。 However, precipitation does not fall evenly spread over all days and locations。 In particular, rain is usually concentrated in certain seasons and locations。 Consequently, the critical point of the evaluation is to estimate and assess meteorological precipitation。 Meteorological records normally include yearly, monthly, daily and hourly precipitation。 Yearly and monthly precipitation is suitable for rough estimates and initial assessment。 However, such approximation creates problems in determining the area of the rainwater collection device and the volume of the storage tank。 Thus, daily precipitation has been most commonly considered。 Hourly precipitation could theoretically support a more accurate assessment。 However, owing to the increasing number of parameters and calculation data increases, the complexity of the process and the calculation time, result in inefficiencies。 Herein, daily precipitation is adopted
in assessing rainwater systems used in buildings [4,7]。 台湾绿色B建筑节水措施英文文献和中文翻译(5):http://www.youerw.com/fanyi/lunwen_134774.html