Peter Parry wrote:
On 1 Dec 2005 00:02:31 -0800, wrote:
Peter Parry wrote:
Of course you can reduce water consumption dramatically. There is no
requirement to wash at all,
There you go off on something neither sensible nor relevant.
It is both.
- snip -
I dont think we're about to come to that, or anywhere near, so I dont
think it is myself. Sure there are challenges and increased energy
costs ahead, but not so much increased that we'll consider no longer
bathing. So lets leave that one alone.
Whilst I agree there is scope for considerable improvement in new
house constriction there is no sign of it being planned, never mind
realised and even if it happens it will have negligible overall
effect for many decades.
fwiw here, retrofitting energy saving measures seems to be a real gain
area. High efficiency boilers, programmable thermostats, TRVs,
draftproofing, double glazing is debated, cavity insulation is big
business, loft insulation, etc
In the meantime people are using more energy. In the 70's there were
still quite a few taking only a weekly bath and showers were both
relatively unusual and very anaemic. Hot water use per person was
about 30% less than it is today. It is possible to reduce water
consumption - there is no indication that people would accept it
happily
since it can be done without any loss of function, I think they will.
As more people go over to metered supplies, the interest in water
saving measures is gradually increasing.
At the same time there is a huge growth in appliances using
electricity. Society is showing no significant sign of becoming less
energy hungry and any savings due to efficiency will be neutralised
by expanding energy use.
yes, more or less for now. But the current drive for energy efficiency
will become much hotter as the decades roll by and those bills climb
ever higher. There is plenty of scope for improvement yet. When
electric bills double, more people will switch to CFLs, more will
replace their 500w halogen garden lights with 20w CFLs, 18w sodiums, or
100w filaments. Etc, there is much yet undone.
The only way to make a severe impact on energy use is to put fuel
prices up three or fourfold and any government that was in power when
that happened wouldn't be shortly thereafter.
Price increase will be taken care of by capitalism, nothing to do with
government. As long as future energy consumption is kept down to what
is available, we'll manage. And that will occur due to capitalism.
A great deal could be done (at a cost) to new buildings but much of
what could be done requires room - which runs directly against the
present policy of trying to cram as much as possible into as small a
space as possible.
I'm not sure what youve got in mind. There are also things that dont.
But paying for a house is such a stretch here, due to our barmy
planning laws, that noone wants to invest another x,000 in energy
saving features when buying. Later, when the mortgage is lower and the
person wealthier, many do.
just spend the money you were going to waste on solar
panels on more effective ways of conserving and gaining energy.
I agree with that. But the interest is almost exclusively with DHW for
some reason, and has been for decades.
Probably because it is the only practical system which can be
retrofitted and can be demonstrated to "work" in that it produces hot
water in the summer.
solar space heating is a far better investment.
It has a market, and in time I
think it will pay, once the sleeping industry is roused by a competent
competitive team. And I think it will be at some point. Rising energy
costs will help as well.
That's what was said 30 years ago :-).
and its still true. Perhaps some thought it would happen within those
30 years.
Competition only works if
there is some.
Capitalism will work when there is the _opportunity_ for competition.
Today there is opportunity. It will be discovered and commercialised,
when I dont know. Its not a very hot market. But there's money in it
for the right approach, and some are working on it.
Solar water heating is a niche market with prices all
at the same sort of level and everyone involved making a comfortable
living out of it. That isn't a market where significant price
competition develops.
This cant be true. There are plenty of people who would like to make a
comfortable living. If SDHW does, they will enter, and companies will
compete. I havent seen company accounts, so I cant know, but I honestly
doubt those companies are making a comfortable living. Its the same old
pattern of many people chasing a dream, one they can never catch,
because there just arent the customers there for it. Not at their high
prices, which come with the territory of their poor designs.
30 years ago there actually was some limited
price competition and one or two national companies with aspirations
to become very large invested a lot in marketing themselves. They
fell by the wayside. There simply isn't a commercial incentive to
try to do better.
So if I can produce a solar system for half the price that gives warm
water in winter, and hot in summer, greater payback at lower cost, you
think theres no commercial incentive?
Funnily enough that was exactly what was said in about 1975. In the
meantime the "technology" (there really isn't that much involved) has
progressed minimally
If you review the patents granted since then I think you'll find there
are many new technologies. There have also been some significant trials
since then.
The effectiveness at gathering energy is not going to increase
significantly, systems in 1975 were about 70-90% effective, the
figures are not much changed at the present and getting much above
that figure in the future is unlikely. Different manufacturing
techniques and materials may lower the production cost after a time
but not in the short term if R&D costs are to be recovered.
This is the classic confusion imho. Firstly energy efficeincy is the
always quoted figure of merit for solar DHW, and it is the WRONG
figure. Entirely. It doesnt matter one hoot whether your system covers
the entire roof at 20% efficient, or 20% of the area at 100%. No
difference whatever.
The one and only figure of merit with solar DHW is ROI. There is lots
of room for systems that cost less and pay back more.
I'm also curious as to how you would achieve 90% energy efficiency in a
practical DHW system, or more to the point, why you'd want to. That
implies high cost collectors, and using the energy gathered more or
less all the time the sun shines. That implies a steady increase in
stored water temp through the afternoon, maxing out at final use temp.
Since a lot of water use occurs in in the morning, this implies 2 water
stores with overnight heat storage. It sounds like a horrid way to
design things. And a simple demo of why the energy efficiency figure is
not the relevant figure of merit. Regrettably too many solar designers
simply continue designing financially hopelessly inefficient systems,
concentrating on energy efficiency instead of financial efficiency.
Moreover
most companies in a non-price sensitive market will use lower
production costs to boost profits - not to lower prices.
Solar DHW is price sensitive. It is a market with few customers because
of price. If system cost dropped substantially, the market would wake
up, it would grow to maybe 100x the size.
And its fair to say that DHW is not the hottest
area of solar research, since there are bigger fish to catch elsewhere.
For new builds especially - at least if the problem of shedding
excess heat in the summer can be solved :-)
thats all known science.
What you do with
existing housing stock is a different problem.
The market has existed in many countries for centuries, you simply
can't develop what isn't there to develop.
There is more than enough insolation on lots of house roofs to heat DHW
with a 50% efficient system. You keep saying there isn't enough over 2
sqm, but I'm not sure that tells us a great deal, except that the
commercial systems you refer to are basically expensive novelty
products.
The 2sq/m is representative of typical retrofit installations. With
present systems there are minimal economies of scale - if you go for
10sqm you have hot(ish) water most of the year but the installation
cost rises proportionately and you just lose more money.
I addressed this in another post earlier today. Your statement there
contains erroneous assumptions.
NT