This Instructable aims to highlight this design failure and suggests a redesign for the single handle mixer. The purpose is to reduce pointless energy use and consequently to save resources, not only in terms of energy carriers but likewise by reducing energy expenses. As the concept described is improving energy efficiency it can be qualified as Green Design.
This Instructable addresses three user groups:
1.) Designers of mixer taps: intuitive design should make sure that unintentional energy use is being avoided;
2.) Owners of public places and hotels: clients may unintentionally drive up energy expenses by not understanding or not being aware of the functioning of the single-lever mixer tap: user and cleaning person information might help here;
3.) Users of the mixer tap: by understanding the standard single-lever mixer tap it is possible to operate it appropriately and thus to reduce energy expenses.
Now what to do when you own such a mixer tap? Dependent on the type of users and in how far they are approachable (which varies significantly between a hotel-keeper and a parent) various options exist. As the pointless hot water demand of this badly-designed mixer tap might represent a significant share of the annual energy bill, the good news is that there are ways to improve on this:
A.) Replace the single-lever mixer tap by one with a more intuitive design, i.e. with the 'neutral' (i.e. cold water) position in the middle. This might be done by simply fixing the lever handle in a different position, twisted 45° clockwise (note however that this results in different tapping behaviour, see Step 3);
B.) Replace the single-lever mixer tap by a conventional mixer tap, which is more intuitive (but, indeed, also less comfortable and luxurious);
C.) Make sure that users better understand the functioning of the mixer tap. For this purpose banners have been added to this Instructable, stressing the fact that the middle position of the mixer arm involves energy use that might not be needed. The source file of this banner is available on request (PM), see Step 4.
Note that this instructable aims at addressing awareness of the possible unintentional energy use involved in using a badly-designed single-armed mixer tap. It doesn't feature a practical manual on how to execute the redesign as shown in the pictures, since implementing this redesign requires a custom-made approach.
Another Openproducts' Instructable that focuses on energy saving in hot water preparation is Energy Saving by Omitting Stand-By Energy Use in Combi Boiler through Remote Switches.