<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
Tim:<br>
<br>
<br>
As usual, the answer is 'it depends"... The (annual) efficiency of
instantaneous hot water heaters is a
controversial topic and is a function driven primarily by whether or
not the a standing pilot is used, the frequency and duration of hot
water loads, and the estimated amount of cold water usage 'wasted'
if/when users are waiting for hot water to be delivered or when the
minimum flow requirements are exceeded and the hot water draw becomes
cold. <br>
<br>
At any rate, the TREAT (Targeted Residential Energy Analysis Tools)
software suite allows one to model the annual effects of changing from
a tank storage type of system to a tankless type of system. <br>
<br>
More importantly, TREAT employs a very unique savings determination
algorithm which allows
users to combine multiple individual improvements into 'packages' to
see the interactive effects - which more accurately capture and
quantify the
'interactive' savings that occur when multiple improvements are
simulated. For example, TREAT could accurately quantify the interactive
savings from changing out existing shower-heads and faucet aerators
with 'low flow' devices, while switching hot water heaters from say a
tank type 40 gallon electric to a tankless propane model, combined with
improving the insulation of the DHW piping (piping surface areas are
user specified) in unconditioned spaces from from R1 to R4, and
resetting the DHW temperature from 135 degrees F to 120 deg F. <br>
<br>
As always, users must provide accurate input (GIGO), if they expect
accurate output, which is especially important when working with
simulating an existing building. To assist with this, TREAT integrates
a billing analysis tool for use against the baseline building model
which compares baseload (weather independent) and heating/cooling slope
(weather dependent) energy consumption of the model against utility
billing data. Good data from residential utility bills are required for
this feature, and the data is weather normalized (corrected) using
daily high/low temperatures correlating to the billing data period,
while the model uses TMY2 30 year average weather data . If billing
analysis
is used to 'match' the baseline model , users can improve the
confidence of their predictions when investigating baseload (hot water,
appliance and lighting) energy improvements. <br>
<br>
This is probably more than you wanted - but I wanted to make sure you
were aware of the possibilities when you are considering annual
simulations. You can download a 30 day fully
functional trial version of TREAT (including program documentation)
from <a class="moz-txt-link-freetext"
href="http://www.treatsoftware.com">http://www.treatsoftware.com</a>. <br>
<br>
Have fun - Chris<br>
<br>
<br>
Chris Balbach, P.E., LEED AP<br>
Manager of Energy Engineering Services<br>
Performance Systems Development<br>
<a class="moz-txt-link-freetext" href="http://www.psdconsulting.com">http://www.psdconsulting.com</a><br>
(607)-277-6240<br>
<br>
tim wrote:
<blockquote
cite="midMDAEMON-F200703181042.AA4220250pd80002753723@gard.com"
type="cite">
<meta http-equiv="Context-Type"
content="text/html; charset=ISO-8859-1">
<div>Any thoughts on modeling tankless water heaters v. traditional
storage tank DHW heaters for a residential application?Obviously there
are no stand-by losses but how about efficiency(HIR)? How much more
efficient are these systems? </div>
<div> </div>
<div>thanks</div>
</blockquote>
<br>
<br>
<PRE>
======================================================
You received this e-mail because you are subscribed
to the BLDG-SIM@GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE@GARD.COM
</PRE></body>
</html>