Direct Current Power Systems | U.S. Green Building Council
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LEED BD+C: New Construction | v4 - LEED v4

Direct Current Power Systems

Possible 18 points

Intent

To achieve increasing levels of energy system efficiency, resilience and reliability by integrating DC power systems into buildings.

Requirements

Projects must document all Minimum Energy Performance prerequisites separately.

OPTION 1: Prescriptive approach for major energy systems (1 point)

Operate 95% of the load of at least one major energy system in the project directly off DC power, from a central DC source such as an on-site PV system, fuel cell, shared DC power supply or battery storage. Qualifying systems include:

  • Elevators
  • Escalators
  • Indoor Lighting
  • Outdoor Lighting
  • Electric Vehicle Charging
  • Heating
  • Cooling
  • Ventilation
  • Fans
  • Plug Loads
  • Information Technology
  • Process Loads
OPTION 2: Whole-building energy simulation– Pilot Alternative Compliance Path for Optimize Energy Performance Credit (18 points possible)

Comply with all requirements of LEED BD+C Optimize Energy Performance credit Option 1. Whole Building Energy Simulation

Analyze efficiency measures during the design process and account for the results in decision making. Use energy simulation of efficiency opportunities, past energy simulation analyses for similar buildings, or published data.

Analyze efficiency measures, focusing on DC Power strategies appropriate for the project. Consider integrating renewable energy systems and electricity storage in the design. Model the energy efficiency improvements due to the implementation of DC systems compared to a baseline building. Details are listed below:

  1. Following Optimize Energy Performance credit modeling requirements, model the Proposed Design building (Dp) without including a DC power system and calculate the performance improvement (Pd) of the Proposed Design (Dp) compared to the Baseline Building (B90).
  2. Following Optimize Energy Performance credit modeling requirements, incorporate efficiency measures for the DC integrated Design Building (DDC – i.e. Dp with the addition of DC power systems) into the model and calculate the performance improvements from the DC Design Building (DDC) compared to the Baseline Building (B90).

Points for this credit are achieved based on the energy performance improvements, as follows:

  1. If Pd is less than DCO, projects will follow the original Optimize Energy Performance credit and will be awarded one Innovation in Design (ID) point for analyzing the potential integration of DC power into their designs.
  2. If Pd is greater than DCO, projects will be awarded points based on their energy performance improvements, as follows:
Table 1. Points for percent improvement in energy performance

New Construction Major Renovation Points (except Schools, Healthcare) Points Healthcare Points Schools
6% 4% 1 3 1
8% 6% 2 4 2
10% 8% 3 5 3
12% 10% 4 6 4
14% 12% 5 7 5
16% 14% 6 8 6
18% 16% 7 9 7
20% 18% 8 10 8
22% 20% 9 11 9
24% 22% 10 12 10
26% 24% 11 13 11
29% 27% 12 14 12
32% 30% 13 15 13
35% 33% 14 16 14
38% 36% 15 17 15
42% 40% 16 18 16
46% 44% 17 19 -
50% 48% 18 20 -

Submittals

General

Register for the pilot credit

Credits 83-103

Documentation/Submittals:

OPTION 1: Prescriptive approach for major energy systems (1 point)

Complete the DC Power Calculation Sheet

OPTION 2: Whole-building energy simulation– Pilot Alternative Compliance Path for Optimize Energy Performance Credit (18 points possible)
Exceptional Calculation Method Requirements

Whole building energy simulation software is in the early stages of being capable of directly modeling performance improvements from DC power systems. Exceptional calculations can be used by project teams provided sufficient documentation of either the theoretical or empirical basis of the exceptional calculation method’s accuracy and results is provided. Exceptional calculations must comply with the following unless approved by USGBC:

  1. no changes in the following input parameter values are permitted when calculating DCO;
    • weather data
    • purchased energy rates
    • space use classification
    • occupancy and schedules
  2. provide input and output documentation that facilitates the enforcement of the reviewer and meets the formatting and content required.

Complete the DC Power Calculation Sheet

Survey Questions
  • Where is this project located (city, state/province, country)
  • Does the country/region the project is located in have any DC power transmission or distribution?
  • Prior to attempting this credit, what was your understanding of DC power loads in buildings and the availability of direct DC powered systems?
  • Prior to the work the project team did on this credit, were DC powered systems required in any standard project spec used by the project team?
    • if yes, what specific language was used?
    • if no, did the project team develop standard specification language for future use?
  • What was the most challenging aspect of attempting this pilot credit:
    • Identifying DC powered systems?
    • Convincing the owner/project?
    • Identifying energy savings/modeling?
    • Other?
  • Was energy performance documentation/data on DC powered systems readily available from your suppliers?
    • What documentation were they able to provide?
    • Do you know if this was the first time that a project team asked the supplier for documentation/DC powered systems?
    • Who, on the project team, was responsible for documentation? Did the project team need to hire an outside expert to facilitate achievement?
  • Did this credit influence or change any other aspect of the project? Specification of renewable energy systems, battery systems, DC microgrid, ultimately used on the project?
  • How transformational do you think this credit can be for project teams?
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