[Equest-users] DHW Savings LEED NC 2.2

[Paul Diglio]

Mark:

I would be interested to hear what the public health researcher has to say.

It is my understanding that Legionella forms in untreated cooling tower water.  
I have not caught it yet even though I have serviced and treated many scummy 
open cooling towers.

I have never heard of it being in the public domestic water supply.

Paul Diglio





________________________________
From: Mark Darrall <MDarrall at a2so4.com>
To: Bruce Easterbrook <bruce5 at bellnet.ca>; Carol Gardner <cmg750 at gmail.com>
Cc: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>; 
Tai Lieu <tailieu at gmail.com>
Sent: Thu, June 2, 2011 5:19:22 PM
Subject: Re: [Equest-users] DHW Savings LEED NC 2.2


Yikes! Is Legionella actually growing in chlorinated public domestic water 
supplies? I recall hearing of it in non-potable water (cooling towers and drain 
pans, anyone?)… strong bugs we make these days.
 
The International Plumbing Code (and maybe others – check your state model codes 
and state amendments) requires the use of temperature mixing valves in domestic 
hot water supplies, so you could, theoretically, run 160F water all the way to 
the fixture (or bank of fixtures) and temper it there, but that’s pretty 
expensive both in equipment and energy.
 
I’m going to bounce this off a public health researcher I’ve met – maybe he can 
share some insight.
 
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
 
 
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
 
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana46225
TEL  317 388 8850
FAX  317 280 0692
MOB 765 749 0841
www.a2so4.com
 
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From:equest-users-bounces at lists.onebuilding.org 
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bruce 
Easterbrook
Sent: Thursday, June 02, 2011 4:48 PM
To: Carol Gardner
Cc: Tai Lieu; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] DHW Savings LEED NC 2.2
 
A caution to the maximum storage temperature for hot water. Legionella bacteria 
show no growth above 135F/57C.  A 140F/60C tank setting can leave portions of 
the water system at risk of contamination.  In electric water heaters with a 60C 
setting 40% of heaters remained contaminated in one study.  This is at the heat 
source, what about further down the lines?  Multi-unit or multi story 
apartments.  This contamination is not typically found in gas or oil fired units 
set at 140, but their lines are still susceptible to contamination.  140 should 
be treated as the minimum storage temperature.  Scalding is definitely a problem 
but care is required to address both problems in the building you are 
designing.  With larger buildings I will start at 160 at the tank and then start 
looking at the whole system design.  WHO recommends the tap temperature to be 
120F, so to a designer that is the furthest outlet.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2094925/
Bruce Easterbrook P.Eng.
Abode Engineering

On 02/06/2011 02:39 PM, Carol Gardner wrote: 
Thanks, Aaron, for providing much more detail than me. You have covered it very 
well. For inlet cold water temperatures I have always seen 50-55 F provided as 
the average temp: it may be hotter in the summer and colder in the winter but 
overall I think those work. 


Carol
On Thu, Jun 2, 2011 at 11:17 AM, Dahlstrom, Aaron <ADahlstrom at in-posse.com> 
wrote:
Tai:
 
In general, I tend to follow the procedure laid out in WEc3 for the hot water 
savings from low-flow fixtures. I’ve found their calculation procedure for total 
flow (gallons / year) to be accepted by LEED reviewers.
 
This does not address water flow from fixtures outside the WEc3 scope, like 
service sinks, so the ASHRAE handbook or a reasonably documented 
project-specific assumption sounds like the way to go to get total water use per 
year for these fixtures.
 
Like you mentioned, this also does not specify the water temperatures, which are 
needed for the calc. 

 
Different hot water uses in a building often have different temperature needs 
(ie handwashing, dishwashing, showers, etc), so even if we know the total water 
use for each of these fixtures, we’d need to get the expected discharge 
temperature of each use in order to figure out how much hot water is required.
 
Most of the time I get the temperatures I need from the project plumbing 
engineer, who has a better familiarity with these targets than I do.
 
If you don’t have access to a plumbing engineer – 
-          For the inlet cold water temp, per the eQUEST dictionary, if you 
don’t specify the temp eQUEST uses the monthly average ground temp. I hope this 
would be available via an hourly report, although I haven’t checked.
-          For the discharge hot water temp, various plumbing codes (IPC, NPC) 
specify limits on the hot water temp to prevent scalding, and I’ve seen 
engineers take a factor off of that to estimate the average hot water use temp. 
I’ve heard 110 deg F for showers and 105 deg F for lavs in our office. Service 
sinks might have something higher (say 120?).
-          For the water storage temp, this is also something that should be 
obtainable from the plumbing engineer. As a starting point I’ve heard 120 – 140 
deg F in our office as well. I believe the IPC limits the maximum storage water 
temp to 140.
 
This should enable you to calculate the quantity (gal / year) of hot water 
leaving the water heater to serve the annual total flow needed.
 
Finally, you need to turn the gallons HW / year into a GPM PROCESS-FLOW, if 
you’re inputting into eQUEST. One way to do this is to take whatever 
use-schedule you had been using (ie eQUEST’s default, ASHRAE 90.1-2007 User 
Manual’s, or project-specific) and integrate it, to determine the annual total 
equivalent full load hours. Dividing total annual gallons by annual full-load 
hours (and converting units), you should be able to arrive at a GPM to enter as 
a process flow.
 
Yours,
 
Aaron Dahlstrom , PE, LEED® AP
In Posse– A subsidiary ofAKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 
19102 

d: 215-282-6753| m: 267-507-5470| In Posse: 215-282-6800| AKF: 215-735-7290
e: ADahlstrom at in-posse.com | in posse web: www.in-posse.com | akf web: 
www.akfgroup.com
 
 
 
From:equest-users-bounces at lists.onebuilding.org 
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Tai Lieu
Sent: Wednesday, June 01, 2011 11:20 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] DHW Savings LEED NC 2.2
 
Hello  All

We're being audited on the energy model for the dhw saving.  I'm just wondering 
if this make sense and from your experience if it would be acceptable to the 
LEED reviewer.

What I've done is taken numbers from ASHRAE Handbook HVAC Applications DHW 
consumption per fixture for office use.
7.6 L / hr for lavatory fixtures

Showers, kitchen sinks, and Lavatory sinks.
Service sinks I'm not quite sure whether i should include all 5 service sinks 
(one on each level) or just one sinks since there won't be any mopping done 
since most of the building Under floor air distribution and i'll do a write up 
of course to explain my reasoning.

I took the consumptions per fixture numbers multiplied by the amount of fixture 
then by the demand factor given.

7.6 L/h x 55 # of fixtures x 0.3 demand factor

for each type i took the savings percentage based on each fixture. So baseline 
is 2.5 and proposed case is .5 for lavatory fixtures

.5 proposed case  / 2.5 base case

So the proposed domestic hot water demand is 25.08 L / hr or 0.11 gpm.

The reviewer had asked for percentage of hot water vs cold water, and 
temperature at the fixtures, i found that harder to substantiate.  So I thought 
this process would be a lot better.

Tai Lieu

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