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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Barton makes a good point with regards to the incoming ground
water temperature and the amount of heat required to bring it up to shower temp.
My recollection is that ASHRAE states 20gal/person/day for the first 2 people,
then 15gpd or 12gpd thereafter. However those rates vary wildly with
consumers, from those that never bathe to the high schooler that needs 3
showers a day. In the northeast water heating can be up to 19% of the total
household energy load for the year. Also, I would recommend the air source
heat pump water heaters if you have significant humidity or an on demand unit.
Water tanks are typically under insulated and can lose 2kWh/day in standby
losses.<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Mike Kocsmiersky<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Principal<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Spirit Solar Inc.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>(413) 734-1456<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Barton Churchill
[mailto:barton@solarips.com] <br>
<b>Sent:</b> Wednesday, March 14, 2018 7:31 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Electric Water kWh/ person<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>You first need to know your ground temperature. Then figure
a delta to 100 or so degrees. Most but not all showerheads flow 2.5gpm and
showers are typically 10 minutes. You can then find a calculator online to
calculate how many Btus are required to raise water temp for your delta per gallon.
Convert to kWh, add some contingency and you should be good. <br>
<br>
On Wednesday, March 14, 2018, <<a
href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a>>
wrote:<o:p></o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:7.0pt;
font-family:"Helvetica","sans-serif"'>Hello Wrenches,<br>
<br>
Is there a good way to estimate the power that will be consumed for electric
water per person per day? We are estimating the amount of power that will be
used by an all electric duplex, and the water heater amount seems high. The
current model we have claims 3493 kWh/ year per 26 gallon tank will be
consumed. With the two units, that would add up to 6986 kWh / year for hot
water, pushing the system size to humongous for a 1300 ft sq building. <br>
<br>
Does that seem high? There will be a maximum of 2 people per unit. <br>
<br>
The owner is considering going to 115 V units with a 15 gallon tanks. I think
the smaller tank would help, but it would seem that the amount of hot water
consumed would be the main issue. <br>
<br>
How can we get a good estimate for a per person energy usage for electric hot
water? Any other suggestions are welcome.<br>
<br>
Thank you,<br>
<br>
Drake<br>
<br>
<o:p></o:p></span></p>
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-- <o:p></o:p></p>
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<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif";
color:#666666'>Barton Churchill</span><span style='font-size:7.5pt;font-family:
"Arial","sans-serif"'><br>
<span style='color:#888888'>406.587.5295 <br>
</span>2430 North 7th Bozeman, MT 59715<br>
<span style='color:#FF9900'><a href="http://www.solarips.com/" target="_blank"><span
style='color:#1155CC'>www.solarips.com</span></a></span></span><span
style='font-size:7.5pt'><o:p></o:p></span></p>
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