This Instructables article has some good info:
- Enclose the stall.
- Install a foot pedal controller
- Add a check valve to make sure the hot water and cold water don’t backfeed when the flow to the head is off.
- Shower head (Recommendations).
This Instructables article has some good info:
“He missed one point that in a full enclosure, shower heads with tiny
droplets are no worse than those with large droplets.
But insulation and mass matter: a 10-minute 1.25 gpm shower in 105 F
water heated from 55 takes 10×1.25×8.33(105-55) = 5206 Btu, with no heat
recovery.
If a 2′x6′x8′ sealed enclosure has R1 walls, that only adds
10/60(105-70)152ft2/R1 = 887 Btu.
But masonry (eg hollow blocks) might have 5 Btu/F-ft2 and require
(105-70)5×152 = 26,600 Btu to warm up.”
-Nick Pine
http://www.sunfrost.com/efficient_shower.html
http://www.sunfrost.com/images/home-power-shower-copy.jpg