NC-v4 EAp2: Minimum energy performance

  • A high bar, but still achievable

    This prerequisite is a big one, not only because it’s required for all projects, but also because it feeds directly into EAc2: Optimize Energy Performance, where about a fifth of the total available points in LEED are at stake.

    From the beginning, teams should recognize that the baseline requirements are fairly stringent. Some measures that may have previously contributed to design-case efficiency are now being required just to meet this prerequisite.

    Key updates with ASHRAE 90.1

    ASHRAE 90.1-2010 has introduced a number of new requirements compared to the 2007 standard, including increased efficiencies requirements for envelope, HVAC equipment and lighting; enhanced interior lighting control requirements (occupancy sensors, light level reduction and daylight controls); new exterior lighting and parking garage lighting control requirements; and new automatic shut-off requirements for 50% of receptacles in offices and computer classrooms.

    With these changes, however, comes a helpful update to the prerequisite documentation that will make the review process go more smoothly for both project teams and GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC). reviewers. An updated Energy Performance Calculator is required documentation for your LEED submittal.

    It performs a series of self-checks in the background to flag potential issues, allows the energy modeler to do a step-by-step quality assurance review, and maybe most importantly helps the reviewer to better understand the model, all of which should significantly reduce the quantity of back-and-forth comments and responses required between the modeler and GBCI reviewer. Read more about the calculator, including an overview of how to use it, here on LEEDuser.

    What’s New in LEED v4

    • ASHRAE 90.1-2007 has been updated to ASHRAE 90.1-2010.
    • Process energy no longer has to make up 25% of the overall building energy for your baseline and proposed simulation models.
    • USGBC now requires you to achieve prerequisite compliance without accounting for the cost of generating renewable energy onsite.
    • For data centers, USGBC requires that building power and cooling infrastructure provides 2% of the required 5% energy cost reductions.
    • For Option 2, LEED now includes a prerequisite that the standard for compliance uses the 50% savings version of the AEDG instead of the 30% savings version of the AEDG. This represents an expected savings of 50% over ASHRAE 90.1–2004.
    • To achieve the prerequisites for Options 2 and 3, your project must follow ASHRAE 90.1–2010 mandatory and prescriptive requirements.

    FAQs

    Our proposed design has insulation R-values that are below those prescribed by ASHRAE 90.1-2010. Can we still meet the prerequisite?

    Yes, the R-value of the building envelope is not mandatory. You can install lower R-values. You are only required to meet the mandatory provisions and earn the minimum percent savings.

    Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

    The energy savings are based on the whole building energy use—building and process. LEED does not stipulate exactly where they come from, but there is a greater burden of proof on the project team to demonstrate savings in process energy. As a default, process energy should be modeled the same in both baseline and design case.

    Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?

    No. The energy cost offset from onsite renewable energy sources can no longer be used to earn the prerequisite. Additionally, it is usually more cost-effective to invest in energy savings in the building.

     

  • EA Prerequisite 2: Minimum energy performance

    Intent

    To reduce the environmental and economic harms of excessive energy use by achieving a minimum level of energy efficiency for the building and its systems.

    Requirements

    Option 1. Whole-building energy simulation

    Demonstrate an improvement of 5% for new construction, 3% for major renovations, or 2% for core and shell projects in the proposed building performance rating compared with the baseline building performanceThe annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating. Calculate the baseline building performance according to ANSI/ASHRAE/IESNA Standard 90.1–2010, Appendix G, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.), using a simulation model.

    Projects must meet the minimum percentage savings before taking credit for renewable energy systems.

    The proposed design must meet the following criteria:

    Document the energy modeling input assumptions for unregulated loads. Unregulated loads should be modeled accurately to reflect the actual expected energy consumption of the building.

    If unregulated loads are not identical for both the baseline and the proposed building performance rating, and the simulation program cannot accurately model the savings, follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1–2010, G2.5). Alternatively, use the COMNET Modeling Guidelines and Procedures to document measures that reduce unregulated loads.

    OR

    Option 2. Prescriptive compliance: ASHRAE 50% Advanced Energy Design Guide

    Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1–2010, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.).

    Comply with the HVAC and service water heating requirements, including equipment efficiency, economizers, ventilation, and ducts and dampers, in Chapter 4, Design Strategies and Recommendations by Climate ZoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division., for the appropriate ASHRAE 50% Advanced Energy Design Guide and climate zone:

    • ASHRAE 50% Advanced Energy Design Guide for Small to Medium Office Buildings, for office buildings smaller than 100,000 square feet (9 290 square meters);
    • ASHRAE 50% Advanced Energy Design Guide for Medium to Large Box Retail Buildings, for retail buildings with 20,000 to 100,000 square feet (1 860 to 9 290 square meters);
    • ASHRAE 50% Advanced Energy Design Guide for K–12 School Buildings; or
    • ASHRAE 50% Advanced Energy Design Guide for Large Hospitals. Over 100,000 square feet (9 290 square meters)

    For projects outside the U.S., consult ASHRAE/ASHRAE/IESNA Standard 90.1–2010, Appendixes B and D, to determine the appropriate climate zone.

    OR

    Option 3. Prescriptive compliance: Advanced BuildingsTM Core PerformanceTM Guide

    Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1-2010, with errata (or USGBC approved equivalent standard for projects outside the U.S.).

    Comply with Section 1: Design Process Strategies, Section 2: Core Performance Requirements, and the following three strategies from Section 3: Enhanced Performance Strategies, as applicable. Where standards conflict, follow the more stringent of the two. For projects outside the U.S., consult ANSI/ASHRAE/IESNA Standard 90.1-2010, Appendixes B and D, to determine the appropriate climate zone.

    3.5 Supply Air Temperature Reset (VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas.)

    3.9 Premium Economizer Performance

    3.10 Variable Speed Control

    To be eligible for Option 3, the project must be less than 100,000 square feet (9 290 square meters).

    Note: Healthcare, Warehouse or Laboratory projects are ineligible for Option 3.

    Pilot ACPs Available

    The following pilot alternative compliance paths are available for this prerequisite. See the pilot credit library for more information.

    EApc92: Advanced Buildings™ New Construction Guide
    EApc95: Alternative Energy Performance Metric
    EApc107: Energy Performance Metering Path

    Alternative Compliance Paths (ACPs)

    Canada ACP - NECB

    Projects in Canada may instead demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the National Energy Code for Buildings (NECB) 2011. The same percentage cost improvement in energy performance is required to meet the Prerequisite, and the same points for cost percentage improvement in energy performance are applicable for the Credit.

    The following conditions (where applicable) must be met. Note that unless otherwise noted, CanQUEST (the Canadian energy modelling software based on eQUEST that performs NECB 2011 compliance runs) does not implement many of these conditions correctly and would require corresponding modifications to the Reference case.

    1. Comply with mandatory requirements of ASHRAE 90.1-2010
    2. ASHRAE 90.1-2010 mandatory requirements must be met, in addition to the performance path limitations referenced in the NECB 2011 Sections 3.4.1.2, 5.4.1.2 and 6.4.1.2. In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to.

      The following exceptions apply:

    • ASHRAE 90.1-2010 mandatory items 6.4.3.9, 9.4.1.2b, 9.4.1.4, 9.4.1.5, 9.4.3

  • Apply fenestration area convention similar to ASHRAE 90.1-2010
  • Maintain the same FWR (as defined by NECB, including doors) for the Reference as exists in the Proposed Design, up to the prescribed maximum. If the Proposed Design’s FWR exceeds the prescribed FWR, scale down the fenestrations in the Reference case accordingly.

  • Apply skylight area convention similar to ASHRAE 90.1-2010
  • Maintain the same SRR for the Reference as exists in the Proposed Design, up to the prescribed 5% maximum. If the Proposed Design’s SRR exceeds 5%, scale down the skylights in the Reference case accordingly.

  • Model proposed and reference outside air similar to ASHRAE 90.1-2010
  • Proposed and reference (baseline) outside air rates shall be modeled as per ASHRAE 90.1 – 2010 (G3.1.2.6).

  • Apply ASHRAE kitchen exhaust demand ventilation requirements
  • Provide for the same demand ventilation requirements as described in ASHRAE Appendix G3.1.1.d.

  • Apply ASHRAE’s chiller heat recovery requirements
  • Provide for the same chiller heat recovery requirements as applies to ASHRAE.

  • Apply supply air temperature reset controlled based on warmest zone
  • Reset the minimum supply air temperature to satisfy the cooling requirements of the warmest zone, as stipulated in NECB Section 5.2.8.8. Note that this control setting is already corrected in CanQUEST for the Reference case.

  • Account for uninsulated structural penetrations if they exceed 2% of net wall area
  • The 2% allowance may be applied, but based on the net opaque wall area, not the entire building envelope area.

  • Follow ASHRAE/LEED rules for renovations to existing buildings
  • Model existing components consistent with ASHRAE and LEED provisions.

  • Account for all anticipated energy use in building
  • Fully account for all energy end-uses in the energy performance modelling.

  • DES Systems are to be modeled according to Option 1, Path 1 or Option 1, Path 2 as indicated in the LEED v4 Reference Guide
  • The following exceptions apply:

    • Option 1, Path 1 - Do not apply ASHRAE 90.1-2010 requirements for purchased heating and cooling. Under this ACP, purchased heating and cooling (as applicable) are modeled as cost-neutral in the baseline and proposed case. Local rates for purchased heating (fossil fuel based) and cooling are used to establish the purchased heating and cooling costs. The energy model's scope accounts for only downstream equipmentThe heating and cooling systems, equipment, and controls located in the project building or on the project site and associated with transporting the thermal energy of the district energy system (DES) into heated and cooled spaces. Downstream equipment includes the thermal connection or interface with the DES, secondary distribution systems in the building, and terminal units. Drift water droplets carried from a cooling tower or evaporative condenser by a stream of air passing through the system. Drift eliminators capture these droplets and return them to the reservoir at the bottom of the cooling tower or evaporative condenser for recirculation., plus purchased heating and cooling. NECB clause 8.4.3.6 does not apply for LEED projects.
    • Model baseline systems in accordance with NECB requirements, with DX coils replaced with chilled water coils if purchased cooling is present and fossil-fired furnaces replaced with hot water coils if purchased heating is present.
    • Option 1, Path 2: Do not apply ASHRAE 90.1-2010 requirements for baseline systems. Model baseline systems in accordance with NECB requirements for onsite generated equipment (i.e. assume building is not connected to a DES and the proposed building is modeled with a virtual plant according to LEED v4 Reference Guide requirements).

200 Comments

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Muzammal Abbas LEED AP (BD+C) MEP Engineer Pakistan Green Building Council
May 24 2017
Guest
86 Thumbs Up

Proposed Case-Process Load

Project Location: Pakistan

Hi,

Is there any limitations in LEED V4 regarding process energy that it should be minimum 25% (In proposed case) of the baseline energy cost for the building.

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Marcus Sheffer LEED Fellow, 7group May 24 2017 LEEDuser Expert 69756 Thumbs Up

No this specific percentage has been removed. Projects will however be evaluated based on whether the process loads included in the model are accurately addressing all energy use within the the building.

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Alexandra Mazzoni AIA
May 23 2017
Guest

Minimum Energy Performance

Project Location: France

Hello,
I have a question regarding equivalent standards : Is there an USGBC approved equivalent standard for projects located in France ?

Many thanks in advance for your assistance.

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Marcus Sheffer LEED Fellow, 7group May 24 2017 LEEDuser Expert 69756 Thumbs Up

I am not aware of equivalency being granted for any French or EU standards.

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Aaron Luthien
May 10 2017
Guest
394 Thumbs Up

Waste Heat from Landfill Gas Plant

Project Location: Germany

Hello all,

We have an office project which utilizes waste heat from the neighbor landfill gas plant. The plant and office is owned by the same company. The plant produces electricity from landfill gas from nearby landfill (200 meters away) and delivers it to the grid. The office will use the waste heat generated during the electricity production for heating and cooling purposes. All cooling and heating energy will be provided by waste heat. The waste heat from the plant is not going to serve any other buildings and there is more than enough heat for the building.

We believe that this strategy should contribute to the energy efficiency and renewable energy credits since landfill gas is accepted as renewable energy resource and waste heat is utilized. However, we are not sure how to document it. Do you have any experience about it?

I appreciate any advise.

Thank you!

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Marcus Sheffer LEED Fellow, 7group May 24 2017 LEEDuser Expert 69756 Thumbs Up

There are probably some variables which would enable you model this a few different ways.Here is what I would probably do.

I would model the baseline according to Table G3.1.1A using the column for purchased heat. I would model the proposed as designed. I would use the same fuel rates for both models. Then zero out the energy cost for heating and cooling in the proposed by counting all the waste heat as a renewable energy source.

You should provide some sort of narrative justification for the baseline and use some local fuel rates. You could probably justify natural gas or purchased energy for heating. Also provide a narrative justification for treating the fuel source as renewable.

I think this is the simplest way to do it. There may be some other variations that would work but essentially you want renewable credit for the fuel source.

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R2M Solution Srl R2M Solution Srl
May 09 2017
LEEDuser Member
226 Thumbs Up

Existing Equipment

Project Location: Italy

The 90.1-2010 User's Manual states:
"In some cases, a complete HVAC system already exists (...) the proposed building and baseline building models are the same and are based on the existing HVAC system".
Is that statement valid also for the ventilation air flow rates (i.e., is exception c. of G3.1.2.6 not valid?)?

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Marcus Sheffer LEED Fellow, 7group May 10 2017 LEEDuser Expert 69756 Thumbs Up

That is correct if the existing system remains unchanged. The existing system is modeled identically. It must, however, also comply with ASHRAE 62,1. So if is does not comply it must be modified to do so. If it is modified then G3..1.2.6 (c) is valid.

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Nicole Isle Chief Sustainability Strategist Glumac
Apr 27 2017
LEEDuser Member
36 Thumbs Up

Baseline window Visible Light Transmittance (VLT)

Hi Marcus,
Do you know if USGBC has taken a position on what the baseline window VLT should be? Now that daylighting is included in the baseline, this plays a much bigger role than it did in v3. I don't see anything about this in 90.1-2010.
Thanks as always!

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Marcus Sheffer LEED Fellow, 7group Apr 27 2017 LEEDuser Expert 69756 Thumbs Up

ASHRAE 90.1-2013 addresses this issue as a ratio of 1.1 VLT/SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.. I assume that would be used. I'll see what I can find out.

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Marcus Sheffer LEED Fellow, 7group Apr 27 2017 LEEDuser Expert 69756 Thumbs Up

I am not aware of any particular ruling on this issue. Typically if the standard is silent you would model it the same as the Proposed VLT.

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Apr 28 2017 LEEDuser Member 11053 Thumbs Up

Some modeling programs are set up to model real life physics. Just like energyplus has a hard time to model a large window with rediculous SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. (unless you have almost more frame than glass), some combinations of VLT, SHGC and U-Values are just not going to occur due to that irritable real life factor that we try our best to describe with modern physics. Bottom line is that, although Markus is right, it might not always be possible to use the same VLT with a different window. That ratio approach sounds good to me. We just need LEED to accept it for 90.1-2010.

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Cory Duggin Energy Project Engineer, TLC Engineering for Architecture Apr 28 2017 LEEDuser Member 173 Thumbs Up

The ratio of 1.1 VLT/SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. is what I have successfully used on LEED projects, and to my knowledge it is the only reference 90.1 makes to VLT.

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Sarah Sachs Buro Happold
Apr 26 2017
LEEDuser Member
319 Thumbs Up

Account for local and utility central energy plants

Project Location: United States

We are building an addition to an existing building that has a central plant that is outside of our LEED boundary. However, we also have a contract to improve the performance of the central plant. We are purchasing steam from Con Edison. Under LEED, we are allowed to either Option 1 Path 1, where by we assign costs to all purchased energy, or Option 1 Path 2, whereby we account for the central plant. Is it possible to use Path 2 to account for the central cooling plant, which is owned by the project owners, without accounting for the central heating plant, which is owned by ConEdison? In this scenario, we would still use the purchased rate of steam to price our heating energy.

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Marcus Sheffer LEED Fellow, 7group Apr 26 2017 LEEDuser Expert 69756 Thumbs Up

I think you could apply different options to the different plants. So you could do Option 1 for heat and Option 2 for cooling.

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Sefa Sahin
Apr 26 2017
Guest
6 Thumbs Up

Sea Water Cooled Chiller Modeling

Project Location: Turkey

Dear All,

Our project building is located in Istanbul/Turkey. Cooling will be provided by centralised two chillers. There is not a cooling tower. The project building location is very close the sea and this chillers will be fed by the sea-water condenser system.
There is a titanium plate type heat exchanger between sea-water and chiller condenser water. Sea water condenser flow and return temperatures 22C(71.6F) and 27C(80.6F).
Chiller condenser water flow and return temperatures 29C(84.2F) and 23C(73.4F). In addition, condenser total water flow rate is 340 kg/hr at 250 kPa.
How can sea-water condenser system be modeled in eQuest?

Thank you,
Best Regards.

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Marcus Sheffer LEED Fellow, 7group Apr 26 2017 LEEDuser Expert 69756 Thumbs Up

I think this would be possible with some type of water cooled condenser. Without going into the program and trying to figure it out I can't give you a step-by-step set of instructions. For LEED if it can't be modeled directly a work around would be required. If it is required make sure to follow G2.5 and provide a thorough narrative describing the work around.

You might also consider posting your question on the eQUEST users forum at onebuilding.org. Someone there would be more likely to have an answer to your question.

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R2M Solution Srl R2M Solution Srl
Apr 15 2017
LEEDuser Member
226 Thumbs Up

Demolished and rebuilt envelope

Project Location: Italy

If the envelope is demolished and then rebuilt with the same shape does Table G3.1 part 5., baseline, point f apply? It states: "For existing building envelopes, the baseline building design shall reflect existing conditions prior to any revisions that are part of the scope of work being evaluated."
Best Regards

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Marcus Sheffer LEED Fellow, 7group Apr 17 2017 LEEDuser Expert 69756 Thumbs Up

No, it becomes new construction. It is no longer existing when it this torn down.

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Quentin Jackson Sustainable Design Leader Aurecon
Apr 13 2017
LEEDuser Member
55 Thumbs Up

Energy Modelling - Australia

Project Location: Australia

We have a Green Building Council in Australia that has a very advanced energy simulation methodology that achieves the same outcomes as the ASHRAE 90.1 process outlined in LEED. It is also well aligned to local requirements for demonstrating compliance with local codes. Our project (a stadium) now needs to create numerous energy models to essentially demonstrate the same thing by different methodologies creating an inordinate amount of extra work for no useful output.

It wouldn't be hard to use the Green Building Council of Australia's energy modelling methodology and adjust the points scale to match LEED and thus allow Australian projects to follow the GBCA Method instead of ASHRAE 90.1.

Has anyone successfully done this in other countries - to use a more appropriate local methodology instead of ASHRAE 90.1 get the LEED energy points? If so keen to understand how we can develop a conversion process to convince the USGBC to agree! (would save a huge amount of modelling work whilst ensuring the outcomes are still met).

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Marcus Sheffer LEED Fellow, 7group Apr 13 2017 LEEDuser Expert 69756 Thumbs Up

It has been done in a few places. The process is spelled out in this document - http://www.usgbc.org/resources/leed-reference-guide-green-building-desig... - I have not seen one specific to v4 but I think the process would be the same.

It is a pretty involved process which is usually undertaken by a governmental entity or nonprofit with funding to do so. Here is the process:

The following process is used to determine the equivalency of a local standard to ANSI/ASHRAE/IESNA Standard 90.1–2010.
1. A group interested in determining equivalency of a particular standard should email a request to USGBC through commonlanguage@usgbc.org.
2. USGBC will collaborate with the group to establish a method for creating an equivalency study and a timeline for completion.
3. The group will conduct the study.
4. USGBC will review the study and bring its recommendation to the LEED International Roundtable with approval by the LEED Steering Committee.
5. Typically, the group putting forward the standard will cover the cost of the study and USGBC review.
6. Priority of USGBC review will be determined based on market transformation potential and representation of the country on the LEED International Roundtable.
7. Approval of equivalency will be determined by the LEED Steering Committee and communicated to the group.
8. Upon approval by the LEED Steering Committee, the equivalency will be made available to projects through a USGBC-administered LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org..

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Martin Meehan Principal Meehan Associates
Apr 11 2017
LEEDuser Member
448 Thumbs Up

Air Barrier for Existing Building

Hi all,

This query follows on a similar theme to the previous topic.

We are working on an existing building that is intending to improve the envelop performance by internally adding insulation to all external walls.
There will be no other alterations to the envelope.

1) Given that we are altering and thermally improving the existing external wall - do we have to also install an air barrier per 5.4.3.1.2?
2) Are the other envelope elements that remain unchanged such as the floor/roof exempt from air barrier requirements?

Thanks!

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Marcus Sheffer LEED Fellow, 7group Apr 11 2017 LEEDuser Expert 69756 Thumbs Up

I think you do what is accessible during construction. So implement everything you can. You would not be required to significantly alter the wall assembly to install any component that you cannot physically install without a major disassembly of the walls.

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Alex Parella Architect_LEED AP
Mar 30 2017
LEEDuser Member
151 Thumbs Up

ASHRAE installations mandatory provisions in Major Renovations

Dear all,

We intend to certify and existing office building, which is going to be retrofitted with the following criteria:

-No intervention in the envelope
-Partial replacement of the HVAC (both production and distribution systems) and lighting/electrical.

In principle, the envelope ASHRAE mandatory requirements should only be met by the modified elements.

Does the same principle apply for the HVAC and lighting installations?
Or should they be totally renewed in order to fulfill the ASHRAE mandatory requirements?

thanks in advance

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Marcus Sheffer LEED Fellow, 7group Mar 31 2017 LEEDuser Expert 69756 Thumbs Up

I agree that you only need to meet the mandatory provisions relative to the items you change. Any unchanged system components are modeled identically.

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Alex Parella Architect_LEED AP Apr 01 2017 LEEDuser Member 151 Thumbs Up

Thanks Marcus,

Another question arises from your answer:

The modeling procedure for the Envelope of Existing buildings in the Baseline is totally explicit in Apendix G:

"f. Existing Buildings. For existing building envelopes, the baseline building
design shall reflect existing conditions prior to any revisions that are part of
the scope of work being evaluated."

Do the systems follow the same logic? That means, modeling the "baseline" systems according the current state.
Or should they be settled following "TABLE G3.1.1A Baseline HVAC System Types"?

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Marcus Sheffer LEED Fellow, 7group Apr 01 2017 LEEDuser Expert 69756 Thumbs Up

No. Unchanged lighting and HVAC is modeled identically. If you change it then the baseline is Appendix G.

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Alex Parella Architect_LEED AP Apr 03 2017 LEEDuser Member 151 Thumbs Up

Thanks Marcus

Last question:

The current HVAC system is going to maintain its typology, but almost all the units will be replaced by more efficient ones (VRV and generation). The pipelines won't be replaced.

We interpretate that:

-All these replaced units have to fulfill the ASHRAE requirements.

-We can simulate our current HVAC system typology in both, the "baseline" and the "proposed", only changing the efficency and specific parameters (required by ASHRAE) of the replaced units.
(instead of using the generic reference system for the "baseline" defined in the Appendix G)

Is that right?

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K Nakamura
Mar 14 2017
Guest
101 Thumbs Up

Elementary School

Project Location: United States

Is there any special considerations for a project registered (v2.2) and designed 10 years ago is now being constructed. V2.2 and v2009 have expired so we need to register it for v4. However, since it was designed to ASHRAE 90.1-2004, it does not comply with ASHREE 90.1-2010.

Thank you.

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Marcus Sheffer LEED Fellow, 7group Mar 15 2017 LEEDuser Expert 69756 Thumbs Up

Does it comply with 90.1-2007?

Probably your only option would be to upgrade your registration to LEED 2009. If the project was registered already you should be able to transfer the registration. I would think USGBC would let you. It can't hurt to ask.

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Mark Benson
Mar 10 2017
Guest
398 Thumbs Up

Using different energy rates between CHP Proposed and Baseline

Project Location: United States

I know that the 90.1 and the LEED Reference Guide generally tell you to use the same utility rate structures for both the Proposed and Baseline models. But what happens when the Proposed model uses Full Accounting of DESDistrict energy system: a central energy conversion plant and transmission and distribution system that provides thermal energy to a group of buildings (e.g., a central cooling plant on a university campus). It does not include central energy systems that provide only electricity. and includes DES-CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source.-supplied electricity and steam, while the Baseline uses On-site Boilers and grid-tied electricity? The DES is charged $0.45/therm while a new gas service at the Baseline Project Building would be charged $0.73/therm due to inherently different rate structures).

I've provided a link below to a CHP LEED Calculator (provided by the EPA CHP Partnership) which instructs the user to use $0.45/therm in the Proposed model since it is a special price for CHP gas and $0.73/therm in my Baseline model (See Inputs tab, rows 14 and 17). Is this acceptable from a USGBC perspective? Thanks!

http://epa.gov/chp/documents/chp_leed_calculator.xlsm

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Marcus Sheffer LEED Fellow, 7group Mar 13 2017 LEEDuser Expert 69756 Thumbs Up

The rates must be identical for LEED. The Baseline system in this case is a virtual DESDistrict energy system: a central energy conversion plant and transmission and distribution system that provides thermal energy to a group of buildings (e.g., a central cooling plant on a university campus). It does not include central energy systems that provide only electricity. so it must use the same rate as the Proposed case.

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R2M Solution Srl R2M Solution Srl
Mar 07 2017
LEEDuser Member
226 Thumbs Up

Treatment of District or Campus Thermal Energy in LEED v4

Project Location: Italy

Can the document "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction" be used also for LEED v.4? Any news about an updated version of that document?
Best Regards

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Marcus Sheffer LEED Fellow, 7group Mar 07 2017 LEEDuser Expert 69756 Thumbs Up

The v4 version of this document is now embedded in the LEED v4 Reference Guide.

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R2M Solution Srl R2M Solution Srl Mar 07 2017 LEEDuser Member 226 Thumbs Up

Thank you. It seems that there is no more the points cap for the simplified option that there was in the document "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction" (10 points for Table 1).
Correct?

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Jim Quillin Mechanical Engineer, Henderson Engineers Mar 20 2017 Guest

I am also interested in this topic and its answer.

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Marcus Sheffer LEED Fellow, 7group Mar 21 2017 LEEDuser Expert 69756 Thumbs Up

Correct. The point cap and floor are not longer part of the DESDistrict energy system: a central energy conversion plant and transmission and distribution system that provides thermal energy to a group of buildings (e.g., a central cooling plant on a university campus). It does not include central energy systems that provide only electricity. guidance.

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R2M Solution Srl R2M Solution Srl Apr 14 2017 LEEDuser Member 226 Thumbs Up

Thanks. What does the following sentence mean exactly?
"If tariffs or rates are not available from the district plant serving the project, such as for campus or military plants, calculate the rates based on the virtual electric and fossil fuel rates from the model."
I mean, which method or equation shall be used to calculate the tariff rates?

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Marcus Sheffer LEED Fellow, 7group Apr 14 2017 LEEDuser Expert 69756 Thumbs Up

You enter the rates for electric and gas in the area in the model. The virtual rate is the rate generated by the model in $/units of energy by fuel source. If you use a flat rate it will be identical to the virtual rate. If using a more complicated rate the virtual rate will be the outcome in the model.

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R2M Solution Srl R2M Solution Srl Apr 15 2017 LEEDuser Member 226 Thumbs Up

Thanks. I got how the virtual rates are calculated from the modeled rates. As for the modeled rates, does "enter the rates for electric and gas in the area in the model" mean that I have to investigate the tariffs in the town where the building is located?
Best Regards

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Marcus Sheffer LEED Fellow, 7group Apr 17 2017 LEEDuser Expert 69756 Thumbs Up

That is the most accurate way to determine the rate for the project. We almost always enter the tariff in our models. Alternatively there are flat rates you are allowed to use. It could be from some published national or regional average cost. It could be derived from a similar local facility on the same rates. Depending on the project maybe the owner has other buildings you can get data for and determine the flat rate they pay.

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André Harms Ecolution Consulting
Feb 21 2017
LEEDuser Member
216 Thumbs Up

Motor efficiency in 50Hz countries

Project Location: South Africa

In response to the ASHRAE 90.1:2007 mandatory requirements for the efficiency of 60Hz motors, some had used the European IE2 standard for 50Hz motors and demonstrated equivalency. The ASHRAE 90.1:2010 standard and user manual have however clarified that all 50Hz motors are exempt. The user manual states that the motor types that are exempted are due to the fact that they “serve a special purpose”, are “not appropriate for …” and “not common in … general building systems” or “have a small energy impact”. This is obviously not true in a country where nearly all motors are 50Hz, but they seem clear on the matter. Whilst we support and would advocate for the use of higher efficiency motors on projects, it seems like high-efficiency motors are no longer (or never were) a mandatory requirement we can enforce? For context, IE1 motors are the current minimum requirement in South Africa, although the implementation of the IEC standard is intended in the future.

If all the 50Hz electrical motors on a project are indeed exempted from the mandatory efficiency requirements, how would this be reflected in the modelling? In ASHRAE 90.1-2007, Table G3.1-'Modelling Requirements, sub-section 12 – Receptacle and Other Loads' states that "where no efficiency requirements exist……equipment" (incl. motors covered by section 10) "…shall be identical b/w the baseline and proposed…”. Would this clause be applicable in the case of a project where 50Hz motor is exempted for the reasons stated above? Or, the lowest efficiency for the 60 Hz electric motor as specified under Tabled 10.8B of Section 10 will be considered for baseline modelling whereas, the proposed will be as per the actual design?

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Feb 21 2017 LEEDuser Member 11053 Thumbs Up

"the proposed will be as per the actual design" Yes.
Because the standard does not have a minimum efficiency for 50Hz motors, they are UNREGULATED and therefore modeled the same as the design.
Although that is a huge oversight by the 90.1 commitee!

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Marcus Sheffer LEED Fellow, 7group Feb 21 2017 LEEDuser Expert 69756 Thumbs Up

I would check the newer versions of 90.1 to see if this has been addressed. If not perhaps an ASHRAE Interpretation is in order.

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John Krutko Sr Project Manager Osborn Engineering
Dec 19 2016
LEEDuser Member
29 Thumbs Up

Updates Differences Between 90.1-2007 and 90.1-2010

Does anyone have a link to a concise list of the differences between 90.1-2007 and 90.1-2010?

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Marcus Sheffer LEED Fellow, 7group Dec 22 2016 LEEDuser Expert 69756 Thumbs Up

If you search - comparison of 90.1-2007 to 90.1-2010 - you get some links to summaries of the changes.

The Department of Energy does a study on the difference in relative stringency of the various versions of the standard which you can get from https://www.energycodes.gov/

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Jean Marais b.i.g. Bechtold DesignBuilder Expert
Dec 14 2016
LEEDuser Member
11053 Thumbs Up

Thank you USGBC for Energy Performance Calculator

Thank you USGBC for Energy Performance Calculator. I remember the days before...where you had to make your own more or less whilst fumbling through projects. I've not tested this, but it looks fantastic. A road map.

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Amrit Kaur Association for Energy Affordability
Dec 05 2016
LEEDuser Member
13 Thumbs Up

Code is surpassing 90.1-2010

In a Jurisdiction where code is surpassing ASHRAE 90.1-2010 LEED buildings are required (by code) to meet the more stringent requirements but measure their energy score based improvement from ASHRAE 90.1-2010 is that correct ? or would the baseline be code requirement ? (There used to be a clause establishing the latter in LEED v2 but in V4 it is not there)

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Marcus Sheffer LEED Fellow, 7group Dec 05 2016 LEEDuser Expert 69756 Thumbs Up

You are correct. Projects in states with more stringent codes start out ahead of states with less stringent codes.

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Carol SR
Nov 30 2016
Guest
5 Thumbs Up

Baseline HVAC System Type - for laboratories

Project Location: Portugal

Hello!

I am constructing a building model which spaces are half offices, half laboratories.
The HVAC system chosen is system 5 (packaged VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with reheat) for all building, since it is considered a single thermal block.
In order to meet G3.1.1 c., is it necessary to model laboratories area itself with an independent system 5 or 7? Or should I model the entire building with a single HVAC (system 5)?

Thanks

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Marcus Sheffer LEED Fellow, 7group Nov 30 2016 LEEDuser Expert 69756 Thumbs Up

Any applicable exceptions to G3.1.1 must be included in the baseline model.

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Robyn Dowsey Owner Eco-Build Strategies LLC
Nov 28 2016
LEEDuser Member
179 Thumbs Up

EA - Pre-Conditioned Air

Project Location: United States

Has anyone used Pre-Conditioned Air to support energy savings or IN credit compliance?

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Marcus Sheffer LEED Fellow, 7group Nov 28 2016 LEEDuser Expert 69756 Thumbs Up

G3.1.2.4 requires a preheat coil in the baseline if there is one in the proposed.

How are you preconditioning the incoming air?

IN?

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Robyn Dowsey Owner, Eco-Build Strategies LLC Nov 29 2016 LEEDuser Member 179 Thumbs Up

Innovation
Preconditioned Air (PCA) Systems:
Preconditioned Air (PCA) systems provide for cooling of the aircraft cabin while parked at the
gate, and can offer PBB cooling. Alternatives for providing PCA include mobile ground based
units, Central Plant systems (with or without thermal storage), and Point of Use (POU) Systems.
Central plant systems typically are the most efficient over the facility life cycle, and providing
thermal storage can significantly reduce chiller size and energy consumption, although they have
a higher capital cost and greater interior space requirements. Central plant systems distribute a
glycol water solution to air handling units mounted directly on each PBB. POU systems utilize
self-contained direct expansion (DX) refrigeration package units that also mount directly to the
PBB. POU systems typically have the lowest initial capital costs, but highest long term
operation and maintenance costs. Mobile PCA units are typically only used at remote parking
positions, or on a temporary basis in the event of an equipment failure at gate.

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Robyn Dowsey Owner, Eco-Build Strategies LLC Nov 29 2016 LEEDuser Member 179 Thumbs Up

The Central PCA design provides an opportunity to significantly lower energy use and operating
costs. Since PCA is considered “process equipment” and not part of the comfort cooling HVAC
for the building, it is exempt from the Energy Compliance defined in the Florida Energy Code and
ASHRAE 90.1-2010. We highly recommend that the base buildingThe base building includes elements such as the structure, envelope, and building-level mechanical systems, such as central HVAC, and materials and products installed in the project (e.g., flooring, casework, wall coverings). design team consider
submitting exceptional calculations for the energy savings between a Central PCA system and a
Point-of-Use (POU) system under the LEED V4, Energy and Atmosphere or Innovation credits.
This should be explored because the PCA will be coupled with the CEP, and if it is not pursued
as an Energy Conservation Measure (ECMEnergy conservation measures are installations or modifications of equipment or systems intended to reduce energy use and costs.), it would otherwise dilute the total building energy
savings. The expected energy use is half of the POU annually, which will comprise a healthy
portion of the total building energy consumption.
This system arrangement has (2) key ECM’s;
1. Using 42⁰F CHWS for 1st stage of cooling. This lowers the EWT into the PCA chillers
from 60⁰F to 44⁰F.
2. Using 56⁰F CWR for the PCA Chiller Condenser Water Source.
System Descriptions for Exceptional Calculations;
1.4.2 - ASHRAE 90.1 Section 6: HVAC (Air-Side)
Include units for all relevant inputs
Model Input Parameter / Energy Efficiency Measure Baseline Case Proposed Case
Primary HVAC Type1 PC Air Unit PC Air Unit
Unitary Cooling Capacity Ranges3 25-90 Tons 25-90 Tons
Unitary Cooling Efficiency4 2.5 KW/Ton 0.75 KW/Ton
Unitary Heating Capacity Ranges5 same as proposed TBD
Fan System Operation VFDA variable frequency drive (VFD) is a device for for controlling the speed of a motor by controlling the frequency of the electrical power supplied to it. VFDs may be used to improve the efficiency of mechanical systems as well as comfort, because they use only as much power as needed, and can be adjusted continuously. VFD
Outdoor Air Design Min Ventilation7 100% OA 100% OA
HVAC Air-side Economizer CycleA heating, ventilation, and air-conditioning (HVAC) conservation feature consisting of indoor and outdoor temperature and humidity sensors, dampers, motors, and motor controls for the ventilation system to reduce the air-conditioning load. Wherever the temperature and humidity of the outdoor air are more favorable (lower heat content) than the temperature and humidity of the return air, more outdoor air is brought into the building. Y Y
EconomizerAn economizer is a device used to make building systems more energy efficient. Examples include HVAC enthalpy controls, which are based on humidity and temperature. High-Limit Shutoff 40 DEG F 40 DEG F
3 | P a g e
1.4.3 - ASHRAE 90.1 Appendix G: HVAC (Water-side)
Include units for all relevant inputs
Model Input Parameter / Energy Efficiency Measure Baseline Case Proposed Case
The Project Has District Heating (Y/N) N N
The Project Has District Cooling (Y/N) N Y
District Cooling Plant Efficiency
-
CHILLER KW/TON +
PUMPS KW/TON +
COOLING TOWER
KW/TON
ESTIMATED = 0.9
KW/TON
District Cooling Plant PCA Capacity - 600 TONS
PCA Plant - Number of Chillers - 3
PCA Chiller Part-Load Controls1 - VFD
PCA Chiller Capacity (Per Chiller) - 300 TONS
PCA Chiller Efficiency2 - 0.58 KW/TON
PCA Glycol Water Loop Supply Temperature - 20 DEG F
PCA Glycol Water (CHW) Loop Delta-T - 40 DEG F
PCA GS Loop Temp Reset Parameters
TBD. EXAMPLE:
OAT<40 DEG F, GST
= 28 DEG F.
PCA Glycol Loop Configuration3
VARIABLE PRIMARY
Number of Primary CHW Pumps 3
Primary CHW Pump Power 75 HP
Primary CHW Pump Flow 324 GPM
Primary CHW Pump Speed Control VFD
Condenser Water Leaving Temperature 66 DEG F
Condenser Water (CW) Loop Delta-T 10
CW Loop Temp Reset Parameters -
Number of CW Pumps 3
CW Pump Power 25 HP
CW Pump Flow 922
CW Pump Speed Control CV
PEAK DESIGN DAY LOAD PROFILE

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Marcus Sheffer LEED Fellow, 7group Nov 29 2016 LEEDuser Expert 69756 Thumbs Up

So your project is an airport terminal and you are seeking to show process load savings? Assuming so it would not be eligible for an innovation credit since energy savings are already addressed by an existing LEED credit. It may be eligible for an exceptional calculation. The key to a successful exceptional calculation is built on the justification used for establishing the base case. The base case should be based on standard practice in the industry in that location. You will need to provide justification that the base case you select is standard practice. This can come from a variety of sources like previous projects in the area, utility rebate programs, studies, trade group letters, exceeding minimum code requirements, etc. The more you can find to justify the base case the better off you will be.

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Jennifer Holmes Chief Mechanical Engineer Design Alaska
Nov 22 2016
LEEDuser Member
3 Thumbs Up

V4 District Thermal Energy

What guidelines should be used for district thermal energy systems in v4 when using option 1, specifically combined heat and power systems? The credit language does not clarify how it should be modeled and I could not find any guidance documents on USGBC's website. ASHRAE 90.1-2010 has a section on purchased heat but this section was excluded in v2009.

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Marcus Sheffer LEED Fellow, 7group Nov 23 2016 LEEDuser Expert 69756 Thumbs Up

The DESDistrict energy system: a central energy conversion plant and transmission and distribution system that provides thermal energy to a group of buildings (e.g., a central cooling plant on a university campus). It does not include central energy systems that provide only electricity. modeling methodology has been incorporated into the Reference Guide for v4 and is now mandatory. It is under Further Explanation - Project Type Variations.

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Charalampos Giannikopoulos Senior Sustainability Consultant DCarbon
Nov 16 2016
Guest
1908 Thumbs Up

Industrial or non-regular process load

For a facilities with increased process load (more than 60%), other than data centers, including but not limited to industrial facilities, is there a particular guidance in establishing a baseline case different from the design one similar to the approach used for data centers with the corresponding energy performance calculator? Unless an exceptional calculation method is used it seems that for such facilities the energy prerequisite might be unattainable. Finally, would Interpretation 10291 for high unregulated process loads applicable to v4? Thank you in advance.

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Marcus Sheffer LEED Fellow, 7group Nov 16 2016 LEEDuser Expert 69756 Thumbs Up

Some of the guidance is concrete and some not so much. If you can point to some sort of standard it is clear - say boiler efficiency for a process boiler you can point to 90.1. This could apply to motors, chillers, etc.

For specialty equipment the baseline is standard industry practice in that area. This gets harder to define. So you have to do the research to justify the baseline. There is just so many different specialize process equipment that it would be extremely difficult to create a baseline for each.These types of facilities need to do an exceptional calculation to show enough savings.

I think that the documentation methods in that interpretation would still apply to v4.

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Charalampos Giannikopoulos Senior Sustainability Consultant, DCarbon Nov 20 2016 Guest 1908 Thumbs Up

Thanks Marcus. That said I guess that Interpretation 10291 still applies to v4.

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Victoria Watson
Sep 28 2016
LEEDuser Member
250 Thumbs Up

Tri-gen

Project Location: United States

Hi, I am QA'ing a model for a building that will be fed via a cogenerationThe simultaneous production of electric and thermal energy in on-site, distributed energy systems; typically, waste heat from the electricity generation process is recovered and used to heat, cool, or dehumidify building space. Neither generation of electricity without use of the byproduct heat, nor waste-heat recovery from processes other than electricity generation is included in the definition of cogeneration. plant (with absorption chillers) and therefore is a little complicated. The cogen plant is owned by the utility (which is technically owned by the municipality which owns the building being built). The building will purchase the electricity from the utility at a reduced rate and get the waste heat for free.

It has been modeled as:
- The proposed purchases the electricity generated by cogen at the reduced rate with the remainder being purchased at standard rate (15% more)
- The baseline is modeled with standard systems and uses the grid supplied gas rate and standard rate for all electricity
- The proposed pays for gas at the grid supplied rate for the purpose of the model

Does this approach sound valid?

Key Q's I think are:
1) is it ok to use different fuel costs for the electricity generated vs. consumed (and therefore proposed and baseline blended rates will be different) if this is as per the contract

2) Should the proposed pay for gas (even if free in reality) and if so should it be a direct purchase amount for the load or should it take account of the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. efficiency (E.g. 40% thermal)

Thanks

Victoria

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Marcus Sheffer LEED Fellow, 7group Oct 31 2016 LEEDuser Expert 69756 Thumbs Up

1. You will need to follow one of the paths in Appendix D of the DESv2. Then follow the rate guidance in section 2.4.2.2.

2. Yes you pay for the gas accounting for the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. efficiency.

You will use the same rates for both models but the difference plays out in the allocation of energy use associated with the central plant. In particular the proportional CHP production of electricity gets entered in the form as a negative value.

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Charles Daze Project Engineer Burns & McDonnell
Sep 26 2016
LEEDuser Member
58 Thumbs Up

100% OA Laboratory System

Project Location: United States

I have a HVAC system with labs on it requiring 100% outside air systems. Following all the guidance in 90.1 these spaces require a dedicated Sys 5/7 because they are over 5,000 cfm. Also my proposed design varies lower than 50% during unoccupied times with air quality sensing.

It is my understanding that the baseline should not vary less than 50% and I can show savings for that difference.

I have seen other comments on the internets about that difference in airflow not being allowed to be OA. Is this accurate? This seems illogical to me on a 100% lab system. Why would be baseline get savings potential of being able to return lab air?

Anyone have any insight on modeling Lab systems for LEED.

-Thanks

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Marcus Sheffer LEED Fellow, 7group Oct 06 2016 LEEDuser Expert 69756 Thumbs Up

Sounds like you are citing the exception to G3.1.3.13. There is more to this than the 50% limit, so make sure the Baseline is modeled accordingly.

Under 90.1-2007 the OA must be identical. In 90.1-2010 the OA will vary (Baseline is minimum 62.1-2010 calculated and Proposed is as designed).

I would think that this is an area where you could demonstrate savings through an exceptional calculation.

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Victoria Watson
Sep 21 2016
LEEDuser Member
250 Thumbs Up

Demand Control Ventilation

Can you take credit for occupancy sensors that control HVAC systems? I am thinking probably not for system operation E.g setbacks, agree? But I am unsure for the ventilation. It seems a bit waffly trying to determine when the spaces are "occupied" as technically they are 24/7 but occupant will come and go during that time. Should the baseline be 24/7 for ventilation and the proposed as per expected design for ventilation taking account occupancy sensors...? Thanks

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Marcus Sheffer LEED Fellow, 7group Sep 23 2016 LEEDuser Expert 69756 Thumbs Up

You can do so as an exceptional calculation. See the Appendicies of the Advanced Energy Modeling Guide for LEED for an example. Make sure you can defend the schedule adjustment associated with the occupancy patterns..

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Julien Richard Artelia
Sep 08 2016
Guest
121 Thumbs Up

Exterior lighting power

Project Location: France

Hello,

We have a project where some luminaires have more power than what it is required by the mandatory provisions of exterior lighting power.
However the actual power necessary to obtain the lumens needed for the project is below the power requirement. So we plan to lock the power of the luminaire during its installation so it will never exceed the mandatory requirement. We think of this approach because the exterior lighting designer cannot find a luminaire with the exact wattage needed.

1) Do you think this approach is acceptable?
2) How to show compliance during the design review as the technical documentation of the luminaires will show a non-compliant wattage? Does it seems acceptable if we include the requirements of blocking the power in the construction documents?

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Marcus Sheffer LEED Fellow, 7group Sep 08 2016 LEEDuser Expert 69756 Thumbs Up

I am a bit confused by the question since compliance is determined based on the watts/area or linear feet and not by the individual fixture. So individual luminaires can't have more power than required.

1. Maybe. See the exception to 9.1.4.
2. Demonstrate compliance with the exception to 9.1.4.

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Julien Richard Artelia Sep 13 2016 Guest 121 Thumbs Up

Thanks Marcus! The exception seems to apply.

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May 26 2017
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