Drinking water consumption for non- residential buildings is heavily depend- ent on use. Hotels, hospitals and senior care homes have a proportionally high- er requirement that can be accounted for, primarily, through washing and cat- ering needs. In office buildings, on the other hand, the requirements can be explained primarily by cleaning (façade and general cleaning). High levels of drinking water consumption also lead to high levels of energy consumption for heating, while also placing addi- tional load on wastewater systems and sewage facilities. However, water con- sumption can be reduced by up to 50% through the following measures: ad- justment of habits, installation of wa- ter-conserving devices and use of natu- ral and renewable resources (rainwater and grey water). Habits Water consumption for washing can be reduced by up to 35% if, let’s say, one would shower instead of taking a bath. Over 75% of water consumption used for tooth brushing could be saved if the tap were only opened during those stages of tooth brushing when water is actually required (rinsing etc.). When washing, the pre-wash cycle should only be used for heavily soiled laundry. A normal cycle suffices completely to get the washing clean and it uses 20% less water. Water-conserving Appliances and Technologies The installation and use of water-con- serving appliances leads to a notice- able reduction in water consumption. The most important measures are: • Lavatory flush with economy switch • Water-conserving taps (single lever handle faucet) and shower fittings • Public sector: fittings with infrared sensors • Hot water in administrative buildings only to be supplied in kitchens and sleeping areas • Vacuum urinals Fig. B 2.24 Water Consumption spread for the average household Water Requirements Fig. B 2.23 Comparison: Water Consumption in different European Nations Drinking and Cooking 5 % Personal Grooming 37 % Washing Dishes 6 % Toilet Flush 31 % Laundry 13 % Cleaning 4 % Garden Watering 4 % Great Britain France Romania Netherlands Norway Austria Belgium Bulgaria Germany Spain Poland Switzerland Sweden Hungary Czech Republic Denmark Consumption (Mio.) in m 3 /a Conscientious Handling of Resources
63 Water conservation can also be ap- plied to existing buildings if dripping taps and faulty toilet flushes can be avoided and if existing water pipes are repaired (Figure B 2.25 ) . Rain Water Use Systematic rainwater utilization can reduce drinking water consumption by about half. Rainwater can be used for flushing, washing and cleaning, as well as for watering the garden. This requires a rainwater cistern and a sec- ond piping system. Since rainwater is soft, less washing powder is needed for the laundry. For watering the gar- den, rainwater is especially useful due to its high mineral content, which means that the plants like it better than regu- lar drinking water. Another advantage of rainwater use is that it takes load off the wastewater systems. Further, the cistern serves as a buffer for rainfall volume peak caps. For this reason alone,
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- Fall '17