A 10-minute shower will cost approximately 21p. If you were only to take a 7.5-minute shower this would reduce the cost to roughly 16p.
So, if you were to have a 7.5-minute shower every day, you can expect this to cost you approximately £60 a year.
The technical bit - how did we work out the above costs?
Data from the Energy Saving Trust shows that the average shower time is 7.5 minutes.
10-minute shower calculations:
If we assume a 41°C shower with a flow rate from the shower head of 0.12 litres per second, this will require 15kW of heat from the Heat Interface Unit (HIU). A 10-minute shower would therefore use 2.5 kWh’s (2.5 units of heat).
So, for a shower lasting 10 minutes, or 0.167 hours, and with a heat network tariff of 8.38 pence per kilowatt-hour, the cost is calculated as follows:
0.167 x 15kW x 8.38p = 20.95 pence (or 2.5kWh’s x 8.38p/kWh)
7.5-minute shower calculations:
For a 7.5-minute shower our calculation is:
0.125 x 15kW x 8.38p = 15.71 pence (or 1.875kWh’s x 8.38p/kWh)