On Sat, 01 Mar 2008 11:22:58 +0000 someone who may be Rob
wrote this:-

For some* things it's impossible to drill down and produce figures to
inform an accurate cost/benefit analysis. Solar energy is one example.

There is a difficulty with heating and ventilating of buildings,
because it is difficult to adequately allow for the weather in
making detailed calculations. There are crude things like
degree-days to make a stab with, but they are crude. If one was to
install weather recording devices at a property one could be rather
more accurate. There is also the question of usage patterns. We know
that sustainable energy installations make many think about their
usage.

If someone installs a condensing boiler the usual suspects do not
demand ever more detailed figures about it. Their double standards
are mildly amusing, but the problem is that they may put off those
who cannot see through their bluster. Anyway, no matter how detailed
the figures are they are unlikely to be accepted, they would
probably just ask for ever more figures, a well known tactic.

Some solar systems are fitted with more customer feedback than
others, though this is generally more than some other energy systems
I can think of. Some only measure the temperature of the cylinder,
IIRC Solartwin provide a digital thermometer display as part of
their kit for installers. This is a good indication in itself,
though some are foolish enough to imply that those who quote such
figures are either lying or too stupid to read the display. Other
solar systems provide additional information, which may include the
kWh the system has produced over various periods (this needs to be
calibrated, but measuring kWh in hot water is a well known technique
used in many places). http://www.navitron.org.uk/page.php?32 third
drawing/photograph shows a screen shot of one (actually taken from
the ethernet software). The kWh figures from a calibrated real
system make an interesting comparison to the assertions of the usual
suspects.

I know many people who've changed perfectly good (IMO) kitchens just for
a new look.

So do I. I doubt if any of them thought of the simple payback
period.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54