Low-flow Fixtures and LEED

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Based on a LEED CIR dated 4/25/2007 (see below) domestic hot water savings
cannot be claimed for the use of low-flow plumbing fixtures, even though
Appendix G addendum a specifically states that credit may be taken through
calculations. Have there been any changes to LEED review methodology
since this CIR was released that allows credit to be taken? Previously we
have taken credit for low-flow fixtures and it has been accepted by the
reviewer, but have recently come across this CIR which seems to state

The reasoning behind not allowing it doesn't make a whole lot of sense.
Water efficiency and energy efficiency are two separate animals, and
getting credits under WEc3 Water Use Reduction does not equate to getting
energy efficiency credit under EAc1. It's not like this would be the
first time LEED has allowed double dipping (EAc2 Renewable Energy is
allowed to be used under EAc1 as well).

Is there a legitimate way to take credit for the energy reduction of
low-flow fixtures for LEED?

Robby Oylear, LEEDR AP

RobbyO's picture
Joined: 2010-11-03
Reputation: 0

Forgot to put the CIR in. Also, I'm just realizing that at the bottom of
the CIR it states that addenda have now been approved for use in LEED.
Wouldn't this invalidate #9, as Appendix G addenda a allows for the use of
low-flow fixtures?

"4/25/2007 - Credit Interpretation Request
The adoption of Appendix G under LEED 2.2 raises all sorts of interesting
questions with respect to the energy modeling protocol.

Please clarify for us and the world of LEED users out there the following:

1. Appendix G Addendum a
Would USGBC for LEED 2.2 adopt the published Addendum a to 90.1-2004
Appendix G which changes a number of areas?

2. Building Orientation
May we choose to not implement in our baseline model ASHRAE 90.1-2004
Appendix G Table G3.1 5. (a) orientation rotation which requires rotating
the model to 4 cardinal directions, and averaging the results. For our
project, orientation with the long axis of the building East-West was not

3. Baseline Fenestration Area and Location
Would the USGBC eliminate the provision under ASHRAE 90.1-2004 Appendix G
Table G3.1 Baseline 5.(c) that requires dividing out the entire design
window area, up to the 40% maximum window to wall ratio, and defining it
as horizontal bands with average window to wall area on all facings and
floors? This change is also proposed under Addendum a to 90.-2004. The
addendum references the section numbering from an earlier version of the
Standard prior to the creation of Table G3.1 in the current version of the

4. Residential Designed Lighting Baseline
Will USGBC for LEED 2.2 adopt the same rules adopted under LEED 2.1 CIR
rulings that established a residential lighting baseline, for designed
fixed lighting? ASHRAE 90.1-2004 still treats residential living area
lighting as exempt (9.1.1 Exception b), and Appendix G does not define a
baseline for this lighting. The rulings defined a process of mapping from
the designed lighting to baseline lighting with conventional incandescent
lighting, with a maximum baseline lighting power density of 2.0 W/s.f. The
rulings also established a 750 hour full load equivalent operating
schedule to be the same in design and baseline.

5. Residential Receptacle Lighting
Will USGBC for LEED 2.2 accept 90.1 Addendum a) change to table G3.1
Design 6 (d) so that receptable lighting energy usage is not subtracted
out from the design and baseline models. This is an inconsistency the
addendum corrects, and is the only case where non-regulated energy is not
counted under the new standard.

6. Lighting Controls
Will USGBC for LEED 2.2. allow Exceptional Calculations regarding energy
savings for occupancy sensor and time-of-day controls that exceed ASHRAE
90.1 code requirements that are greater than the Appendix G Table G3.2.
For example, LEED 2.1 rulings appeared to allow greater than 10% allowed
by Appendix G for occupancy sensors controlling normally 24 hour interior
stair lighting in a multi-family high-rise that would be occupied only a
small fraction of the time.

7. Exterior Lighting
Will USGBC for LEED 2.2 allow credit for exterior lighting that is more
efficient than the new mandatory provision for exterior lighting in
90.1-2004 section 9.4. Appendix G does not address how exterior lighting
should be modeled for the baseline, and therefore the default is that it
should be modeled the same as the design and no credit for savings could
be taken.

8. Residential Appliances and Exhaust Fans
Will USGBC for LEED 2.2. allow for Energy Star rated appliances and
exhaust fans an Exceptional Calculation approach (similar to previous LEED
2.1 rulings for an appliance ID credit) to calculate energy cost savings
for EAc1? Exceptional calculation would be based on Energy Star data to
define design and baseline energy usage?

9. DHW Usage Reduction
Will USGBC for LEED 2.2. allow the approach to claim domestic hot water
energy cost reduction based on low flow fixtures, relative to EPACT
standard allowed fixture flows from earlier LEED 2.1 rulings. Another
approach would be to adopt 90.1-2004 addendum a) revision to Table 3.1
Baseline 11. labeled as a revision to G4.3 under the older numbering

10. Heat Recovery from Condenser Loop
Will USGBC for LEED 2.2 allow the baseline adjustment for heat recovery
from condenser loops to DHW as required in section to be done with
assistance of spreadsheet analysis outside of the model, or will the
provision at Appendix G Table 3.1 Baseline 11 (f) exception that requires
the proposed design to actually include the heat recovery equipment in the
real building, if the modeling software cannot model it. The design
feature cannot be modeled under DOE-2.2 and its interface eQuest, one of
the most widely used and otherwise versatile programs. This provision, if
enforced, requires a significant expense for the project that may not be
cost effective compared to alternatives. This would be a penalty on the
subset of projects that fall under the rules at Normally, the
design does not have to meet the prescriptive requirements of ASHRAE, but
is allowed to make trade-offs to achieve overall energy cost savings.

11. Solar Hot Water-Clarify Eligibility for EAc1&2
Will USGBC state that solar hot water generation, that does not generate
any electricity is eligible for credit under EAc1 and EAc2? Requirements
language paragraph 1 for EAc2 does not state if energy generated from a
renewable source is electric or thermal, although other parts of the
chapter allow for solar hot water, but the second paragraph refers to a
method to just estimate electricity generation. Just want to be sure there
is no question that solar hot water generation is eligible for both
4/25/2007 - Ruling
[REVISED 10/30/07 to allow energy savings for exterior lighting.]

1. No. Since multiple projects are already in process and the LEED-NC v2.2
Reference Guide specifically mentions that ASHRAE 90.1-2004 is applicable
without addenda; any addenda not included in the completed standard will
not be accepted at this time.

2. No. The Appendix G method of distributing the glazing equally on all
orientations normalizes this issue. The question raised by Appendix G is -
Is your building designed to respond to the specific solar orientation?

3. No. See points 1 and 2 above.

4. Yes. The calculation methodology should be considered equivalent for
LEED-NC v2.2.

5. The LEED modeling protocol addresses this issue by setting the process
load as 25% of total energy by default, unless it is a process dominated
building. For a typical residential building, process loads will never be
above 25% and therefore should not be an issue.

6. Exceptional Calculation for any measure that is not accounted for in
the modeling protocol is accepted on a case-by-case basis.

7. Yes, project teams can take credit for efficient exterior lighting
within ASHRAE 90.1 Appendix G. Credit may only be taken for the tradable
surfaces listed in ASHRAE 90.1-2004 Table 9.4.5. All other exterior
lighting must be modeled identically in the Baseline and Proposed case.
The Baseline case exterior lighting power allowance should be calculated
using the methodology outline in Section 9.4.5.

8. Yes. Page 184 of the LEED-NC v2.2 Reference Guide describes Exceptional
Calculations for residential appliances.

9. No. Credit for saving water is already granted in the Water Efficiency
section of the LEED Rating System. The Domestic Hot Water (DHW) loop will
be sized for design flows and the PRM does not allow credit for changing
loop flows for DHW.

10. No. The requirements for the loop sizing have been set in Appendix G
and to maintain integrity of the modeling protocol, such exceptions cannot
be taken.

11. Yes. On-site energy generated can be taken credit for using the
Exceptional Calculations under EAc1, Optimize Energy Performance, and as
percent of total energy for EAc2, On-Site Renewable Energy.

Note: ASHRAE Addenda have been approved for use in LEED projects, as
stated on our website: http://www.usgbc.org/ShowFile.aspx?DocumentID=2664"

Robby Oylear, LEEDR AP

RobbyO's picture
Joined: 2010-11-03
Reputation: 0

Thanks for pointing that out Robby. You are correct DHW savings can be
counted under EAc1. As a review firm we have always granted such savings.
As a member of the EA TAG I will ask staff to correct the CIR you

Marcus Sheffer

Marcus Sheffer2's picture
Joined: 2011-10-02
Reputation: 0

Thanks Marcus,

Could you also recommend LEED NCv2.2 CIR dated 6/30/2009 be updated as
well? This CIR also discusses that only non-regulated water use can be
taken credit for under EAc1.

Robby Oylear, LEEDR AP

RobbyO's picture
Joined: 2010-11-03
Reputation: 0

Is there a standard for how the savings will be calculated? The CIR requests that the savings be relative to WEc3, but many of the fixtures contributing to savings in WEc3 do not involve hot water (flush fixtures) and many use hot water only sporadically (lavatories, kitchen sinks, janitor sinks). I always assumed that was a large part of the reasoning behind not allowing DHW savings.

Best Regards,

Gregg Liddick, EIT, LEED(r) AP

Gregg Liddick's picture
Joined: 2011-09-30
Reputation: 0

You can use the proposed gallons under flow fixtures divided by the
baseline gallons under flow fixtures to calculate a percent savings to
adjust your DHW flow by. This is only really accurate if you don't have
other hot water process loads in your building like laundry and clothes
washers, in which case you should account for it in another fashion.

The New York Energy Smart Simulation Guidelines for multifamily projects
has a good system developed for domestic hot water savings with clothes
washers and laundries included.

Robby Oylear, LEEDR AP

RobbyO's picture
Joined: 2010-11-03
Reputation: 0

You can only take credit for hot water flow fixtures - I typically only
consider restroom lavatories, showers, and dishwashers (assuming clothes
washers may be run with cold water). I use the following procedure for this,
although I'm sure there are other approaches:

1. Determine all hot water flow fixtures in projects
2. Create realistic hourly schedules for each distinct usage (i.e. one
schedule for lavatories, one for showers, one for dishwashers)
3. Determine peak and baseline gpm for actual design for each distinct

So in eQUEST, I have 3 separate process loads with different peak gpms and

Kendra Tupper, PE, LEED AP

Kendra Tupper's picture
Joined: 2011-09-30
Reputation: 0