ND-v2009 GIBp2: Minimum building energy efficiency

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The following requirement applies to 90% of the building floor area (rounded up to the next whole building) of all nonresidential buildings, mixed-use buildings, and multiunit residential buildings four stories or more constructed as part of the project or undergoing major renovations as part of the project. New buildings must demonstrate an average 10% improvement over ANSI/ASHRAE/IESNA Standard 90.1–2007, with errata but without addenda (or a USGBC-approved equivalent standard for projects outside the United States). Buildings undergoing major renovations must demonstrate an average 5% improvement over ANSI/ASHRAE/IESNA Standard 90.1–2007. For projects outside the United States, consult ANSI/ASHRAE/IESNA Standard 90.1–2007, Appendixes B and D, to determine the appropriate climate zone. Projects must document building energy efficiency using one or a combination of the following:

Produce a LEED-compliant energy model following the methodology outlined in the LEED rating system appropriate to each building’s scope, including demonstration by a whole building project computer simulation using the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1–2007 (or a USGBC-approved equivalent standard for projects outside the United States). Appendix G requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. Projects in California may use Title 24–2005, Part 6, in place of ANSI/ASHRAE/IESNA Standard 90.1–2007. For projects outside the United States, consult ANSI/ASHRAE/IESNA Standard 90.1–2007, Appendixes B and D, to determine the appropriate climate zone.
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide listed below, appropriate to each building’s scope. Comply with all applicable criteria as established in the guide for the climate zone in which the project is located.
- ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004 (office occupancy buildings less than 20,000 square feet or 1,800 square meters).
- ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006 (retail occupancy buildings less than 20,000 square feet or 1,800 square meters).
- ASHRAE Advanced Energy Design Guide for Small Warehouses and Self-Storage Buildings 2008 (warehouse or self-storage occupancy less than 50,000 square feet or 4,600 square meters).
- ASHRAE Advanced Energy Design Guide for K–12 School Buildings (K–12 school occupancy less than 200,000 square feet or 18,600 square meters).
For buildings less than 100,000 square feet (9,300 square meters), comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute, as follows:
- Comply with Section 1, Design Process Strategies, and Section 2, Core Performance Requirements, of the Core Performance Guide.
- Health care, warehouse and laboratory projects are ineligible for this path.

If method (a) is used for all of the floor area evaluated in this prerequisite, the total percentage improvement is calculated as a sum of energy costs for each building compared with a baseline. If any combination of methods (a), (b), and (c) is used, the total percentage improvement is calculated as a weighted average based on building floor area. In determining the weighted average, buildings pursuing (a) will be credited at the percentage value determined by the energy model. Buildings pursuing (b) or (c) will be credited at 12% better than ANSI/ASHRAE/IESNA Standard 90.1–2007 (or a USGBC- approved equivalent standard for projects outside the United States) for new buildings and 8% better for existing building renovations.

AND

For new single-family residential buildings and new multiunit residential buildings three stories or fewer, 90% of the buildings must meet ENERGY STAR or equivalent criteria. Projects may demonstrate compliance with ENERGY STAR criteria through the prescriptive requirements of a Builder Option Package, the Home Energy Rating System (HERS) index (or a USGBC approved equivalent for projects outside the U.S.), or a combination of the two. Project teams wishing to use ASHRAE-approved addenda for the purposes of this credit may do so at their discretion. Addenda must be applied consistently across all LEED credits.

Pilot Alternatives Available

The following pilot alternative compliance paths are available for this credit. See the pilot credit library for more information. EApc107 - Energy Performance Metering Path

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Addenda

7/1/2015 – Updated: 3/29/2018

Regional ACP

Description of change:

Brazil Compliance Path: PBE Edifica

Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories"

Campus Applicable

Internationally Applicable:

Yes

7/1/2014 – Updated: 2/14/2015

Global ACP

Description of change:

Replace the second paragraph with the following: "New buildings must demonstrate an average 10% improvement over ANSI/ASHRAE/IESNA Standard 90.1–2007,with errata but without addenda, (or a USGBC-approved equivalent standard for projects outside the United States). Buildings undergoing major renovations must demonstrate an average 5% improvement over ANSI/ASHRAE/IESNA Standard 90.1–2007. For projects outside the United States, consult ANSI/ASHRAE /IESNA Standard 90.1–2007, Appendixes B and D, to determine the appropriate climate zone."

Add the following statement: "(or a USGBC- approved equivalent standard for projects outside the United States.)" behind each requirement for using Appendix G of ANSI/ASHRAE/IESNA Standard 90.1–2007"

Add the following last sentence under the second paragraph and Section a: "For projects outside the United States, consult ANSI/ASHRAE /IESNA Standard 90.1–2007, Appendixes B and D, to determine the appropriate climate zone."

Add the following statement: "(or a USGBC- approved equivalent standard for projects outside the United States.)" to the last paragraph, behind "Home Energy Rating System (HERS)" index.

Campus Applicable

Internationally Applicable:

Yes

7/19/2010 – Updated: 2/14/2015

Reference Guide Correction

Description of change:

In the eighth line of the first paragraph of the first item, remove the parenthesis after "processes" so the text becomes "...or commercial processes. Building..."

Campus Applicable

Internationally Applicable:

7/19/2010 – Updated: 2/14/2015

Reference Guide Correction

Description of change:

In the first line of the text, make the words "This section" not bold

Campus Applicable

Internationally Applicable:

8/1/2011 – Updated: 2/14/2015

Reference Guide Correction

Description of change:

At the end of the first sentence of the paragraph, add ", Version 2006."

Campus Applicable

Internationally Applicable:

4/1/2012

LEED Interpretation

Inquiry:

We request a ruling regarding building ventilation and its impact on EAp2/EAc1. The question is two-fold: (1) Will USGBC/GBCI allow credit for a design that increases ventilation effectiveness other than Displacement Ventilation (a noted exception for PDV now exists in ASHRAE 62.1-2010), and, (2) will USGBC/GBCI allow credit for reduced ventilation by decoupling the outdoor air from the multi-zone VAV system, which requires increased ventilation rates to ensure the appropriate airflow is reaching all of the zones? Project Design Information:The project is a multi-story office space undergoing a major renovation. In accordance with ASHRAE Standard 90.1-2007 Appendix G, the baseline system is System 8. Ventilation is handled by VAV air handling units, thus requiring multi-zone calculations. Due to elevated terminal heating temperature, zone air distribution effectiveness (Ez) is 0.8.Similarly, the proposed system will employ a VAV system, but with decoupled constant-volume ventilation, thus foregoing multi-zone calculations and reducing outdoor air. Ventilation is room neutral resulting in an Ez of 1.0.Referenced Standards/Guidelines/Research:Ez factors and ventilation rates are determined from ASHRAE Standard 62.1-2007 Tables 6-2 and 6-1, respectively.ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.8 Design Airflow Rates states:(D)esign supply airflow rates for the baseline building design shall be based on supply-air-to-room-air temperature difference of 20°F

This exceeds the 15°F limit from Table 6-2. ASHRAE 62.1-2007 User’s Manual (page 6-27) instructs to use the worst case factor, which is the heating Ez of 0.8.

ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.5 Ventilation states:

(V)ventilation rates shall be the same for the proposed and baseline building designs.

Reviewing the User’s Manual for this section adds:

(V)ventilation can be a major contributor to building energy consumption, but it is not considered an opportunity for energy savings... (V)ventilation is energy neutral as far as tradeoffs are concerned.

Spare a recent exemption for using PDV to reduce outdoor air rates via an allowable manipulation of Ez, no other exemptions exist. Yet, ASHRAE research recognizes the advantages of decoupling ventilation in its ability to reduce ventilation volume and therefore energy costs. From Jeong, J.W., et. al, ASHRAE Transactions 2003, Volume 109, Part 2:

“All-air [VAV] systems are widely used in many types of buildings, [even though] these common systems have several significant deficiencies. …(T)he multiple spaces method must be used to increase the [OA fraction... This increase… may add significantly to energy consumption and operating cost…

“The challenge of conforming to [ASHRAE Standard 62] in an energy efficient manner can be met with a dedicated outdoor air system (DOAS)… The DOAS provides 100% of the required ventilation air at constant volume”

In addition, EPA’s Technical Report PNNL-18774 (Strategies for 50% Energy Savings in Medium Office Buildings) recognized DOAS as a primary energy savings strategy using the previous research by ASHRAE noted above as support and justification.

Conclusions:
It is clear that, as written, the ventilation volumes should be the same in both models. But we respectfully ask the LEED® Reviewer to provide us feedback on whether this makes sense for the current LEED® Rating Systems. It appears the rules are evolving (ex. Displacement Ventilation) as technologies and techniques evolve. And yet full credit for decoupled ventilation systems doesn’t currently exist and therefore may discourage designers and owner from investing in a system that often has higher first cost. We recommend and endorse this investment because of the excellent returns both in terms of dollars saved and carbon emissions reduced. We ask for your ruling to create an exception that allows credit for increased ventilation effectiveness and reduced ventilation rates (compared to multi-zone VAV systems) using a DOAS.

Ruling:

Credit cannot be taken for ventilation effectiveness in systems other than displacement ventilation, such as a dedicated outdoor air unit, using an Ez of 1.0 in the proposed case, with an Ez of 0.8 for the baseline case (VAV system).Addendum bj to ASHRAE 90.1-2007 states that the Baseline Case ventilation airflow rates can be calculated using an Ez value of 1.0 only if the Proposed Case Ez value is greater than 1.0. The project team may not take credit unless the Proposed Case Ez value is greater than 1.0, because 90.1 does not set a Baseline Case standard for that scenario. Equivalent to ASHRAE 90.1 may be used.

Campus Applicable

Internationally Applicable:

10/1/2013

LEED Interpretation

Inquiry:

Can a four or five story residential building eligible to use the ENERGY STAR low-rise residential path in GIB Prerequisite 2: Minimum Building Energy Performance and GIB Credit 2: Building Energy Performance?

Ruling:

Yes, four and five story residential buildings may use the low-rise ENERGY STAR path if they are eligible for it. The project must determine eligibility by following EPA’s ENERGY STAR protocol.

Campus Applicable

Internationally Applicable:

Yes

10/1/2013

LEED Interpretation

Inquiry:

What is considered “hybrid” heating?

Ruling:

**Update 1.11.2019: LI is applicable to LEED v4 projects.

Clarification is requested regarding when a building heat source in Table G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric".

The ASHRAE 90.1-2007 User's Manual states that a fossil/electric hybrid source "refers to a system with any combination of fossil and electric heat, and the baseline system for this is a fossil fuel system". Therefore, the predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. The heating source for any building space would be considered “Fossil Fuel/Electric Hybrid” if the space is heated by any combination of fossil fuel and electricity. This includes backup heating, heating of ventilation air serving the space, or preheating, But does not include emergency backup heat sources. The predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. (Note: Emergency back-up heating refers to heating that runs when the primary system fails or needs to be shut off in an emergency, and does not refer to a backup system which may be used to provide additional capacity as needed.)

Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional system type(s) for non-predominant conditions (i.e. residential/non-residential or heating source) if those conditions apply to more than 20,000 square feet of conditioned floor area.

EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION:
The Baseline heat source from Table G3.1.1A for the following Proposed Case system types would be fossil fuel since the proposed system design includes a combination of fossil and electric heat serving the same space for the majority of the building:
1. Variable air volume system with gas furnace preheat and electric reheat
2. Packaged terminal heat pumps with outside air tempered by fossil fuel furnace
3. Water source heat pumps with fossil fuel boiler
4. Ground source heat pumps with backup fossil fuel boiler
5. Residential condominium units with packaged terminal heat pumps, that have any amount of ventilation air provided to the space from air handling unit(s) where the supply air is tempered with fossil fuel.

The following buildings would be modeled with an electric heat source for the Baseline Case since the heating source serving the majority of spaces is electric-only:
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 10,000 square feet is conditioned with fossil fuel furnaces
2. 50,000 square feet is conditioned by electric heat pump systems. 15,000 square feet is conditioned with fossil fuel radiant heaters.

The following buildings would be modeled with an additional system type with a different Baseline heating source in accordance with Section G3.1.1 Exception (a):
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 20,000 square feet is conditioned with Packaged DX systems with fossil fuel furnaces. In this case, the 90,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel furnace).
2. 50,000 square feet is conditioned by water source heat pumps with a fossil fuel boiler, and 25,000 square feet is conditioned by electric heat pumps. In this case, the 50,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV with hot water reheat), and the 25,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #4 - Packaged Single Zone Heat Pump).

Campus Applicable

Internationally Applicable:

Yes

4/1/2012

LEED Interpretation

Inquiry:

The project consists of a consumer products manufacturing facility.The energy intensive manufacturing process exceeds an estimated 90% of the facility\'s total energy load. The Project Client has developed a new manufacturing process which consumes approximately 15% less energy per produced than the previous generation process.The new proprietary process has recently been installed at a similar facility and energy reduction has been demonstrated. Since industrial energy for manufacturing is not covered by ASHRAE 90.1-2007 and the building cannot be accurately modeled using the Appendix G method, project team is seeking to establish and obtain approval of an alternative compliance path.Following the Appendix G procedure would be very challenging because there are so many interacting process and non-process systems. Artificially segregating the systems in the model would not reflect energy consumption patterns accurately. Focusing on non-process components that represent less than 10% of the total energy consumption would not demonstrate the majority of the facility\'s energy savings. Manufacturing process improvements targeted at the other 90% of energy usage have a much greater impact on the entire facility\'s energy consumption. Instead of creating an energy model, baseline and proposed energy consumption will be compared by utilizing an Energy Consumption Index (ECI), which is recognized by the Association of Energy Engineers as an accepted methodology for calculating energy consumption in a manufacturing facility. The Project Client has tabulated historical overall site energy data and production at an existing facility which uses only the previous generation manufacturing platform and is also tabulating data from a site with new generation equipment. The energy data from both of these plants is not sub-metered between process and building loads because there is little economic benefit to meter the small building-only loads. An alternative compliance path will be established using the overall site ECI. Please verify that the following method may be used for determining the entire facility\'s energy cost savings.PROPOSED COMPLIANCE PATH:1. Baseline Building:The existing baseline site

Ruling:

Using the Energy Consumption Index instead of ASHRAE 90.1-2007 Appendix G to determine the annual cost savings of the building is not acceptable. The manufacturing process(es) should be calculated using the Exceptional Calculation methodology. A narrative should describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the project savings. The narrative and energy savings should be reported separately from efficiency measures in the template Section 1.7. Additionally, documentation should be provided to verify that the manufacturing process is not standard practice for a similar newly constructed facility by including a recently published document, a utility incentive program that incentivizes the new process, or by documenting the systems used to perform the same function in other newly constructed facilities. While it is acceptable to use monitored data from a similar facility (constructed within the last five years) to document these exceptional calculation savings using a per product or per pound metric, sufficient information must be provided to document the nature of the efficiency improvements made, and to confirm that the data has been normalized appropriately. Specific product names are not required, and the specific details of the manufacturing process are not required; however, the description of the efficiency improvements to the manufacturing process must be adequate to allow the reviewer to confirm that improvements in energy consumption are tied to improved equipment or controls efficiency, and are not associated with decreases in building square footage, differing project locations, local climate data, quantity of shifts operating per day, etc. Any process energy differences related to local climate or weather (such as refrigeration energy, boiler energy, etc.) should be accounted for in the data normalization process, and the method used for normalizing must be clearly indicated. Ensure the same utility rate is used for the proposed case, baseline case, and exceptional calculation. Additionally, all mandatory requirements of ASHRAE 90.1-2007 must be met."

Campus Applicable

Internationally Applicable:

7/1/2012

LEED Interpretation

Inquiry:

This LEED Interpretation pertains to the requirement to limit voltage drop for Energy & Atmosphere Prerequisite 2 for Minimum Energy Performance. The current limit is posing a significant hardship to tall buildings relative to satisfying the mandatory requirements of ASHRAE Standard 90.1-2007 (also applicable in 90.1-2010), referenced in the prerequisite.

Specifically, the requirement in Standard 90.1 to limit voltage drop to not greater that 2% for electrical feeders and 3% for branch circuits (section 8.4.1) has proven to be problematic for large projects which often contain feeders of extended length. By comparison, the National Electric Code does not explicitly regulate voltage drop, but suggests model Code language that limits either electrical feeder or branch circuit voltage drop to 3%, with the combined voltage drop of both feeders and branch circuits when added together not to exceed 5%.

This may appear to be a minor difference, However, when applied to long copper electrical feeders which are present in tall buildings, this absolute constraint from Standard 90.1 on the feeder voltage drop (of 2%) results in a significant increase in the required quantity of copper conductors and associated conduit.

As an example of a higher density regions attempting to resolve this issue, the New York City Electrical Code has adopted the National Electric Code model language as mandatory for all buildings and also included an exception for residential occupancies within buildings to limit electrical feeder voltage drop to 4%, and the combined voltage drop of both feeders and branch circuits to not more than 5%.

This change is in recognition of the inherently short branch circuit lengths in typical NYC apartments, and is based on measured testing results which indicate that voltage drop is often negligible due to the conservative feeder and circuit sizing requirements mandated by other aspects of the Code. Thus, for residential buildings the allowable voltage drop of 4% is twice the allowable voltage drop of 2% as required in 90.1. Depending upon the length and capacity of a particular feeder, this difference can equate to a 3X variance in the required quantity of copper conductors and conduit, with a significant associated cost premium.

The magnitude of the cost premium to satisfy the 90.1 criteria in tall buildings, as compared with New York City Code requirements, can be equal to the total of all of the other cost premiums (hard and soft) associated with achieving LEED certification (at the Silver or Gold level) for a medium to large project in New York City.

In order to resolve this issue, we are proposing an alternate compliance path that we believe would meet the intent of the prerequisite, while at the same time preventing cost prohibitive use of significant amounts of additional copper.

Voltage drop is literally the loss of electrical energy (converted to heat) within a building, therefore regulating voltage drop is no different than regulating the energy efficiency of any electricity consuming device in a building (such as light fixtures or HVAC motors).

Several approaches could be implemented within the LEED rating system to address this disproportionate prescriptive requirement of Standard 90.1. A simple and straight forward approach would be to allow buildings utilizing Appendix G energy modeling as the LEED energy compliance path to include voltage drop as a regulated parameter within both the Energy Cost Budget and Design Energy Cost models. Under this approach, the 90.1 criteria (2% for feeders and 3% for branch circuits) would included in the Energy Cost Budget model, but the Design Energy Cost model would be allowed to include the actual voltage drop that will be implemented in the project design.

This approach would achieve the direct intent of the voltage drop requirement of Standard 90.1 in regulating the energy efficiency of power distribution systems, but through the inherent trade-off methodology of Appendix G would allow projects the flexibility to eliminate a disproportionate cost premium that is otherwise incurred by a prescriptive requirement.

Ruling:

The proposed alternative compliance path for meeting the mandatory requirement of ASHRAE 90.1-2007/2010 Section 8.4, Voltage Drop Limitation, allowing voltage drop as a regulated parameter within the energy models, is not acceptable; however, a simplified alternative compliance path can be approved. As noted in the Formal Inquiry, code requirements and guidelines allow flexibility in meeting voltage drop guidance in feeders and branches as long as the overall voltage drop from service entrance to the worst-case connection is within limits. For the purposes of this prerequisite, the mandatory provision of ASHRAE 90.1-2007/2010 Section 8.4 will be met as long as the total voltage drop does not exceed 5%. Internationally applicable.

Campus Applicable

Internationally Applicable:

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Pilot Alternatives Available

The following pilot alternative compliance paths are available for this credit. See the pilot credit library for more information. EApc107 - Energy Performance Metering Path

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ND-v2009 GIBp2: Minimum building energy efficiency Required

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