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Daylight harvesting progress

Discussion in 'Photovoltaics' started by [email protected], Mar 6, 2007.

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  1. Guest

    About 10 years ago, I noticed a bunch of lights that were on when the sun
    was blasting through lots of clerestory windows above the third floor of
    a local college library, so I donated a photocontrol to turn them off.
    It was never installed. Since then I've noticed a few more such controls
    around campus, controlling outdoor compact fluorescents, but disabled so
    the CFs never turn off :)

    About 1 year ago, I donated an Intermatic K4236 photocontrol (2300 VA,
    $16.05 as Grainger item 5U790) to a local YMCA with lots of lights near
    a dramatic south window, about 40' wide x 20' tall. They are finally
    about to install it, and it should save about $500 per year :) They
    even bought another, which should save another $500.

    Sunoptics prismatic skylights transmit 40% more light than others, with
    no hot spots. They ship the equivalent of 1 MW/week of fluorescents for
    installation in Wal-Mart roofs and other places...

    In 2003, their president Jerry Blomberg wrote to the CA Energy Commission:

    I know that it is not the Energy Commission's job to improve the working
    conditions of the people of California, but if you required an effective
    skylight to floor area ratio of 2% in all new buildings, it would make
    every building in California a delight to work in. There would be fewer
    divorces, less child abuse, fewer dogs or cats kicked when they are in
    the way. The fact is, daylighted space with an ESFR of 2% reduces stress,
    and stress of any kind weakens our immune systems and increases societies'
    medical costs. California could become known for having wonderful work
    environments in all new buildings...

    To demonstrate the cost effectiveness of daylighting space with skylights,
    I would like to compare the State's photovoltaic subsidy to skylights.
    The State would get six to ten times more energy savings if that same
    subsidy was used to subsidize 100% of the cost of daylighting installations
    instead of subsidizing photovoltaic installations at $4.00 per watt. The
    user then has to invest another $4.00 to $5.00 a watt to complete the
    system. One 4 ft. by 8 ft. or 5 ft. by 6 ft. skylight will deliver more
    light than 1 kW of electric lighting during peak demand hours... Over the
    life of a skylight, it replaces electric lighting energy for less than
    $0.015 per kW[h]... we are talking big money here, and by example suggesting
    to society that this is where we should be heading. Truth is, if we were
    to rely solely on PV-generated electricity, we would cut our standard of
    living by 50% or more.

    There is no energy shortage on the planet, nor will there ever be
    a shortage. We may run out of some types of energy sources over time,
    but there will be energy available. The problem is to get those energy
    sources into a useful form... The real shortage in the world is money, and
    that must be honored. An adequate supply of least-cost, least-polluting
    energy should be the Commission's primary goal. Daylighting with skylights
    is one example of how this goal can be achieved.

    From the start of our business here at Sunoptics, we set a fantasy goal
    of daylighting enought space to offset the electricity produced by
    a 1,000 megawatt generating plant. Over the last 25 years the acceptance
    of daylighting as a cost-effective energy conservation measure has grown
    to the point where we now ship enough skylights to offset 150 to 200 kW of
    electricity per day, nearly a megawatt a week... The skylights we have
    shipped to date replace electric lighting electricity of 350 to 400
    megawatts during peak demand hours.

    But they don't help much if lights are still on. Yesterday I was pleased
    to see that most of the lights were off in our local Walmart, except for
    those near the walls. Then the sun dimmed, and every 5 seconds or so,
    another few hundred feet of fluorescents relit.

    Nick
     
  2. Tim Gard

    Tim Gard Guest

    snip ...

    Bravo Nick! Could you effectively bend and transmit daylight into an
    interior room, possibly with ... aww, the name escapes me, glass fiber,
    something or other ... This material would be paid for once and would
    forever transmit light into a naturally dark room that would normally
    consume electricity for light normally. There are a ton of rooms like that
    in a typical office building. Couldn't we do that? Do some cost projections
    for your average CEO and I would bet they would go for it, especially with
    Gov assistance. Then in conjunction with auto engage backup, people would
    hardly notice a difference when the sun goes down.

    In the days of unlimited cheep energy this was not worth the trouble. But
    today ...

    Tim
     
  3. <http://en.wikipedia.org/wiki/Light_guide>
    ....it's being done ;-)

    Jochen
     
  4. Tim Gard

    Tim Gard Guest

  5. I have no idea ;-)

    Jochen
     
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