[Greenbuilding] Office Buildings as Peaker Plants

[Richard Garbary]

An excerpt from this site:

http://www.ailr.com/water_heater_control.htm

"The high morning demand is caused by the lower elements of the water
heaters.  For most homes, the water heater will be full of hot water
when the residents arise.  The heavy use of hot water in the morning
will cause all the lower elements (and a few of the upper elements) to
turn on at about the same time.  Since the lower element is typically
4.5 kW, the electrical demand is very high.

However, very few homes need a 4.5 kW lower element to prevent
hot-water run-outs.  While the upper element must have a high wattage
to meet short but high levels of hot water use, the lower element
operates more as a "baseload" heat source.  Its wattage should more
closely match the energy needed for water heating averaged over 24
hours.  For many homes, a 700 watt to 1,500 watt lower element is
adequate.

If homes had lower wattage lower elements, the morning peak for the
water heating load would be smaller.  The problem, however, it that it
is difficult to know which homes need a high-wattage lower element and
which will be happy with a lower wattage element.  Our controller
solves this problem by reducing the 15-minute average power to the
lower element to the lowest value that avoids excessive operation of
the upper element (i.e., it avoids hot-water run-outs)."




===================================================================================
On Tue, Jul 31, 2012 at 5:07 PM, Reuben Deumling <9watts at gmail.com> wrote:
> This reminds me of a story that circulated during the 2001 CA energy crisis.
> Someone figured out that a nontrivial percentage of the load experienced
> during the peak summer hour was due to electric clothes dryers. The fact
> that this coincided with the hottest/sunniest hour of the year in CA--a
> rather low humidity place in summer--struck many of us at the time as
> symptomatic of the (demand side) problems the State was experiencing.
>
>
> On Tue, Jul 31, 2012 at 2:02 PM, Richard Garbary <richard6 at gmail.com> wrote:
>>
>>
>> If you exceed either of the limits in a Rate, you are kicked up to the
>> next Rate. OUCH!
>>
>
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