Knowledgebase
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Low Flow showers in SBEM
Posted by Andrew Bairstow on 10-Aug-23 11:53 AM
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Specifying Low Flow showers in the DHW dialogue can reduce the demand of a DHW system by up to 35%. However in many cases, low flow showers and showers employing Waste Water Heat Recovery may not reduce the demand at all. The SBEM database includes a field representing the Shower Fraction for an Activity. This can take a value as high as 0.88 (ie 88% of hot water demand is from showers) or as low as zero. For the majority of activities the value is zero. A DHW System will likely serve multiple types of activity so a saving as high as 35% would be unusual, however, activities with a high shower fraction also have very high demand for hot water so a value close to this is feasible. Note that all activities with a shower fraction of 0.88 are 'Changing Room with Showers' activities. All these have an exceptional DHW demand that often skews a BRUKL or EPC calculation. Employing low flow technology in such buildings may well significantly reduce ratings. The following activities have a shower fraction of 0.7. DHW systems supplying these could have a reduced demand of 28% with all low flow showers.  The following activities have a shower fraction of 0.12. DHW systems supplying these could have a reduced demand of 5% with only low flow showers. All other activities will be unaffected by the presence of low flow or WWHR showers. 
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