Warning - long ramble.

http://www.theguardian.com/commentis...r-once-a-week-
polluting-environment

Interesting use of statistics.

"The average 10-minute shower uses 60 litres of water. A power shower uses
three times that and a bath about 80 litres. So a family of four each
having a daily 10-minute power shower (I know that is a very conservative
estimate for some teenagers) will consume a staggering 0.25m litres of
water every year. The annual average cost for electricity for four 10-
minute showers per day would be up to about £400, or £1,200 if a power
shower is involved. Even worse, the power-shower family would be emitting
a staggering 3.5 tonnes of CO2. As we can afford only one tonne of carbon
emissions per person €“ for everything from food to transport €“ if we are
to keep global temperatures below the critical 2C threshold, this would
consume nearly all of the familys carbon budget."

For all you DIYers, some of these figures may seem a little strange.

"The average 10-minute shower uses 60 litres of water"

Well, at 6 litres per minute this must be a pretty feeble shower -
although I sized our combi to heat 15 litres per minute so it could
service two showers. However that was 15 litres of hot water, and doesn't
count the mixed in cold.

http://www.harwoodandassociates.co.u...low-rates-for-
taps-showers-and-baths/

has some rule of thumb figures, but my brain started to hurt trying to
compare everything.

It does say of power showers "A 12 minute shower with a flow rate of 15 l/m
would use 180 litres of water." which seems to tie in with the "three
times" figure for normal vs power shower.

Using Google for bath volume, I find
http://www.waterwise.org.uk/news.php...facts-figures-
and-misconceptions
from 2011 which seems to be remarkably similar to this 2016 puff piece but
with the opposite spin.

Although it has an 8 minute shower using 62 litres of water.

Using the site from above:

http://www.harwoodandassociates.co.u...es-a-bath-use/


"According to BS6700 a standard 1700mm x 700mm bath uses approximately 100
litres of water at 40C. This is split into 60% hot and 40% cold water
when hot water is stored at 60C."
So about 60l of hot water from store or combi.

But, of course, the variable volumes are only the start.

"The annual average cost for electricity for four 10-minute showers per
day would be up to about £400, or £1,200 if a power shower is involved"

Note the words "up to" - often used in shop SALE signs as "up to 50%
reduction" where all but one item has only 5-10% knocked off.

We (like many others) have a gas combi boiler which provides our hot
water. I am struggling to see how I use anywhere near £400 (or £100 per
person) when I shower using a mains pressure gas combi.

On flow rates, the Triton Aire fitted to our bath has a maximum flow rate
of 15.5 l/min at 1 bar (or 8 l/min with the flow limiter fitted). I've
grumbled in thread passim about the seemingly weedy flow. Not yet measured
it but 6 l/min for the average shower does seem slow.

Googling for flow rates for electric showers doesn't seem to turn up much
from the manufacturer, however:

https://ask-a-saint.silversaints.com...ctric-showers-
testing-the-water-inlet-pressure-and-flow-rate

says "For a 8.5KW or 9.5KW Triton showers the minimum required water
pressure is 1.0 Bar with a minimum flow rate of 8 litres per minute.
A Mira 8.5KW or 9.5 KW showers only require a maintained water pressure of
0.7 Bar and 8 litres per minute. This is one of the primary reasons we
always specify a Mira shower over Triton."

Which suggests that 6l/min is too low for your average electric shower!
However to give an electricity cost of £100 per year per user they must
surely be using an electric shower (or possibly immersion heater?).

O.K. - well into a long ramble.

Anyway, so far we may have established that the minimum flow rate for a
modern electric shower is around 8 l/min, and DIYers may well note that
electric showers are generally held to be not very good compared to a tank
or combi system, which suggests a satisfying shower could require 10 l/min
even with an "Economy" shower head.

TL;DR I am a little surprised that the average (I think) flow rate for a
shower at around 10 l/min would fill the average 100 l bath in 10 minutes.
Then again although shower time is an alternative Universe I don't think I
spend an average of 10 minutes under the shower.

I leave the "Even worse, the power-shower family would be emitting a
staggering 3.5 tonnes of CO2. As we can afford only one tonne of carbon
emissions per person €“ for everything from food to transport €“ if we are
to keep global temperatures below the critical 2C threshold, this would
consume nearly all of the familys carbon budget." for the dedicated
environmentalists on this NG to debate.

Pro tip - "Get out of that shower, Jennifer, you're destroying the
planet!" may have more moral high ground than effectiveness.

Oh, and don't use soap because this ex-ballet dancer once met someone who
had a bad reaction.

Cheers

Dave R



--
Windows 8.1 on PCSpecialist box