Abstract
Domestic Hot Water (DHW) production constitutes a significant proportion of the energy demand of modern buildings, and as the building envelope is improved the share increases. This article shows results from a measurement campaign on two equal hotel blocks, in the same hotel. There are different basin and shower mixing taps installed in the two hotel blocks, one with original mixers (13–14 l/min) and one with touch-free operated water saving mixers (5–6 l/min). The number of guests were registered separately for the two blocks. The results indicate almost a one-to-one relationship between the difference in mixer and total water consumption, resulting in a potential energy saving of 50–60%. There are no indications that the reduced water flow results in increased duration of each individual shower. However, it is not known if this is due to the use of touch-free operated mixers. Feedback through complains from guests indicate somewhat reduced perceived comfort level from the water saving mixers, and some annoyance caused by the touch-free operation. The results indicate that optimal balance between user comfort and water saving is slightly higher water flow than the applied 5–6 l/min.
Highlights
1.1 Water and energy consumption for domestic hot water (DHW)In the last decades, there has been an increasing focus on the energy demand in buildings, and the building regulations are moving towards zero energy buildings [1]
The average water flow for the shower mixers of block A is below 6 l/min, which is considered to be in the lower range of the minimum required 4-12 l/min for thermostatic shower mixers [10]
A measurement campaign has been performed on two equal hotel blocks, but with different basin and shower mixing taps
Summary
1.1 Water and energy consumption for DHWIn the last decades, there has been an increasing focus on the energy demand in buildings, and the building regulations are moving towards zero energy buildings [1]. As the building space heating demand is reduced, the relative importance of the energy for domestic hot water (DHW) increases. Willis et al [4] showed a potential for almost 50% savings in water consumption for showers by switching from high flow mixers to low flow mixers [4]. In [5] Mayer et al evaluated the effect of retrofitting low water flow shower mixers (9.5 l/min) in single-family homes (water flow of original mixers where not known). They found a 16% average decrease in water consumption per shower, due to both reduced duration and water flow.
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