LEED Energy and Atmosphere

Wind Energy
Fig 1: Renewable Energy (Photo: ref)

This section of the LEED Scorecard relies on building modeling and the beautiful results technology can bring to the table. We also look at Commissioning, which is sometimes hard to grasp in concept if you haven't been in the industry long enough. We'll break it down into layman's terms here.

The new LEED v3.0 brings 35 points to this section, up from the previous 17. Almost all of the sections doubled in points, so none of the sections were significantly weighted or deemed more important than the previous version. The breakdown you see below is referencing LEED v3.0 which is now pretty much in use for all projects (I doubt in 2011 that many LEED projects are still ongoing from 2009).

Along with the point increases, the percentage breakdowns are all different, so forget what you previously memorized for LEED v 2.0 and find a new way to remember the percentage breakdowns below in EAc1 and EAc2. I've included tables of point breakdowns to help you track and memorize. Good Luck!

Remember to check the USGBC's downloadable forms to see which Regional Priority Credits can be counted as added points towards certification in your project's zip code.


Breakdown of Each Credit in Energy and Atmosphere - LEED v3.0

  • EAp1 Fundamental Commissioning of the Building Energy Systems

Let's explain commissioning. Commissioning is often shortened to Cx, in case you're unfamiliar with the term. Commissioning is the process of making sure the guts of a building perform as they were intended, with efficiencies taken into consideration, and performance of systems. This is typically related to HVAC (heating, ventilation and air conditioning), but can also cover the plumbing and electrical aspects of your project as well. Controls of these systems (think, thermostats are the brains and control your AC in the house) are also commissioned. You want them to control the system how it's supposed to, right? Generally, anything that uses, saves or produces energy should be commissioned.

Typically, when a building is properly commissioned, it will lower the operational cost of the building, because, for example, instead of running the A/C at 72 continuously, controls can be put into place to reduce load on the system by lowering or raising the temperature when occupancy is low to nil (think of programming the thermostat to turn off in an office on the weekends).

To achieve this pre-req, the following requirements must be met:

  1. The project must contract a Cx agent with experience in at least two building projects
  2. Owner must document the Owners Project Requirements (OPR - term to memorize). The team shall also develop the Basis of Design (BOD - term to memorize). The CxA (commissioning agent) will review both of these documents for thoroughness.
  3. The Cx Requirements must be part of the contract documents (the specifications are the place these requirements are often included)
  4. The team shall develop a commissioning plan, entailing how the project will be commissioned
  5. A Cx Report will be completed once the project is to a point where a report can be created (this will essentially confirm the building is operating as it should)

The Cx pre-requisite is SO important to consider during the design phase of the project, and is mandatory for EAc3. Look at the items above and be able to understand when in the project these will take place. Typically, the test will ask you to think about the LEED Design and Construction Schedule, and where these items fall on that timeline (think Schematic Drawing Phase, Design Drawing Phase, Construction Document Design Phase, Construction Phase, and Occupancy of Owner).

Terms to Know:

  1. OPR - This is the Owner's Project Requirements, which should cover the owner and user requirements, the environmental and sustainability goals (what version of LEED are you trying to achieve, typically), Energy Efficiency goals, Indoor Environmental Quality Requirements, Equipment and System Expectations, Building Occupant and O&M Personnel Requirements.
  2. BOD - This is the Basis of Design, which should cover Primary Design Assumptions, Standards (codes) and Narrative Descriptions.

You should reference this section when trying to understand the requirements of EAc3, as they are closely tied.

Applicable standards or agencies: None.
Possible Points: None, required pre-req

  • EAp2 Minimum Energy Performance

This credit is closely ties to EAc1. The strategies of this credit are to meet ASHRAE 90.1 or the local building code, always based on which is more stringent. There are regulated loads that are covered in this credit:

  1. Electric power distribution
  2. Electric motors and drives (on HVAC equip, typically)
  3. Lighting
  4. Service Water Heating
  5. Heating, Ventilation, and Air Conditioning
  6. The Building Envelope (think plaster, windows, roof, siding, etc.)

The project will likely go after EAc1, so you ca re-use the model you will submit for that credit to guarantee this pre-requisite. It will supersede the requirements of this pre-req and therefore work as a submittal.

Really, if you only remember one thing about this pre-req, it's that the project must meet ASHRAE 90.1 mandatory and prescriptive approaches to design.

Applicable standards or agencies: ASHRAE 90.1
Possible Points: None, required pre-req

  • EAp3 Fundamental Refrigerant Management

This pre-requisite is extremely easy to achieve, as most local and state codes already require that no CFC's be used in new base building HVAC and Refrigerant systems. This is usually most difficult when replacing existing systems that were made to rely on CFCs. In these rare cases a phase-out plan is required.

Note: Small items containing less than 0.5 lbs of refrigerant are not considered part of the base building and do not fall under this requirement.

Your project should probably complete a survey to identify any existing systems that may be using CFCs if you are completing a renovation of an older project.

Applicable standards or agencies: ASHRAE 90.1
Possible Points:' None, required pre-req

  • EAc1 Optimize Energy Performance

This credit is tied closely to the EAp2, so I suggest you memorize those requirements and apply them to this credit. Consider the minimum percentages and review the table below for the important base information to memorize for the test.

Table 1: Optimize Energy Performance Percentages and Applicable Points
Possible Points New Building Improve by % Old Building Improve by %
1 Point 12% 8%
2 Points 14% 10%
3 Points 16% 12%
4 Points 18% 14%
5 Points 20% 16%
6 Points 22% 18%
7 Points 24% 20%
8 Points 26% 22%
9 Points 28% 24%
10 Points 30% 26%
11 Points 32% 28%
12 Points 34% 30%
13 Points 36% 32%
14 Points 38% 34%
15 Points 40% 36%
16 Points 42% 38%
17 Points 44% 40%
18 Points 46% 42%
19 Points 48% 44%

Applicable standards or agencies: ASHRAE 90.1

Like I said before, this credit is tied closely to EAp2. This point entails a whole building simulation, which compares the design to a baseline. When compared to the baseline, the design must save a certain percentage above and beyond. This is compared by cost savings, and the baseline building meets the pre-requisite by following ASHRAE 90.1, which can make this credit tricky from a design standpoint.

OPTION 1: Whole Building Energy Simulation This is the most common path to take with this credit, so pay attention, as this will likely be on the test. Achieving Option 1 of this credit requires use of a computer model to identify the design with the highest cost-saving strategies. Most Mechanical Designers will subcontract this work to an agency that will compute the energy cost savings using a calculation like this one:

Cost Savings = 100 * \left ( 1 - \frac{Proposed Building Performance}{Baseline Building Performance} \right)

Of course the cost savings are substantiated by use of an energy model. The model compares the two buildings (the baseline and proposed) which will largely share a lot of the same properties, like square footage, climate, process loads must be a minimum of 25% the total calculated loads, and schedules of operation.

I like to think of Process Loads as "plug-ins" that are required for the building to perform its function. Think for a home this would be items like a jacuzzi, dishwasher, washer and dryer, refrigerator, etc. For an office this would be items like a copy machine, refrigerator, or any specialized equipment that isn't directly part of the guts of the building.

Non-Process, or non-essential loads are those that are regulated by some agency, codes or standards. This should be memorized; lighting, HVAC, plumbing, and electricity to support those functions.

When completing the calculations, it makes sense that a minimum of 25% Process loads be assumed for the total load on the building.

OPTION 2: Prescriptive Compliance Path
This option only applies to office buildings under 20,000 SF. The project must comply with the ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004.

OPTION 3: Prescriptive Compliance Path - Core Performance Guide
This option only applies to buildings under 100,000 SF that are NOT health care, warehouse or laboratory projects.

To pass the test, you don't need to know a lot about Options 2 and 3, save for the requirements to fall under those categories. The majority of projects will fall under Option 1, so be sure to memorize those requirements.
Applicable standards or agencies: ASHRAE 90.1

  • EAc2 On-Site Renewable Energy

This credit is aimed at using on-site renewable energy to reduce the impact of the new building on the environment. Depending on the percentage of energy saved, up to seven points can be achieved, which is new from previous versions of LEED. See the table below for point breakdown.

On-site energy savings are tracked for this credit based on annual cost savings.

Renewable Energy Systems Eligible for EAc2: The following systems can help your project achieve points. You should memorize these points.

  1. Electrical Systems which include
    1. Photovoltaic
    2. Wind
    3. Hydro
    4. Wave
    5. Tidal
    6. Bio Fuel
  2. Geothermal Systems which include
    1. Deep earth water
    2. Stream Sources
    3. NOT Vapor Compression Systems, Ground Source Heat Pumps
  3. Solar Thermal Systems which include
    1. Collection Panels
    2. Heat Transfer Mechanical Components

Systems Not Eligible for EAc2: These systems are not eligible for achieving points because they're covered in other areas already. Memorize these.

  1. Architectural Features which could be
    1. Passive Solar and Daylighting Strategies (covered in EAp2)
    2. Geo-Exchange Systems (covered in EAp2)
    3. Green Power (covered in EAc6)

Terms to Memorize:

  1. DOE - Department of Energy
  2. CBEC's - Commercial Building Energy Consumption Survey database

These terms are important, as the DOE's CBEC database is what's used to generate annual electricity and natural gas usage per square foot for different types of buildings. These tables can be used to estimate the baseline as well as approximate cost savings required with on-site renewable energies. Verifying the cost savings should be pursued with a sophisticated model, similar to EAc1.

Calculations:

  1. Default Annual Electrical Costs - Texas Warehouse

100,000 SF x 3.0 kWh/sf-yr x $0.0695 /kWh = $20,850

  1. Default Annual Fuel Costs - Texas Warehouse

100,00 SF x 96.9 kWh/sf-yr x $0.00757 /kBtu = $73,353.30

  1. Default Total Annual Energy Costs - Texas Warehouse

$20,850 + $73,353 = $94,203

Then, this value will help realize what value shall be compensated by on-site renewable energies. If the team were pursuing 3% energy savings, this would be: $2,826 each year in cost savings due to on-site renewable energies. So, if the team planned to use a windmill that produced 100,000 kWh/yr we would compare to average energy costs in Texas at $0.0695/kWh which calculates to $6,950/ yr of energy savings.

Thus, $6,950 / $94,203 gives 7.3% or 4 points toward this credit.

You won't need to memorize the tables to pass the exam, but you will need to memorize which forms of on-site renewable energy are eligible for this credit.

Applicable standards or agencies: ASHRAE 90.1

Table 2: Onsite Renewable Energy and Applicable Points
Possible Points % Of Renewable Energy
1 Point 1%
2 Points 3%
3 Points 5%
4 Points 7%
5 Points 9%
6 Points 11%
7 Points 13%

Applicable standards or agencies: ASHRAE 90.1

  • EAc3 Enhanced Commissioning

Credit 3 is closely tied to the prerequisite EAp1. The thing to remember with the credit is that early planning in the design phase of the project is required to achieve the credit. This means the Commissioning Agent (CxA) will need to be brought in early in the process for design comments and input on an efficient system design. Eac3 also extends beyond construction, requiring operations assistance by way of training and a verification of the systems' performance.

In short, remember that the EAp1 will take place mainly during construction, while the EAc3 takes place during design, construction and operations of the system.

Here are six items to remember about the Requirements of EAc3:

  1. The project must contract a CxA
  2. The CxA must be involved with design, perform a design review
  3. The CxA must review the contractor submittals
  4. The CxA must put together a training manual for the operating staff
  5. Training of the operating personnel
  6. Contract to re-Cx 10 months later

Again, the CxA is a third party, not part of the mechanical contractor's company, etc. Usually the owner will contract the CxA, but in a design-build scenario, the Contractor may opt to hire a CxA.

Potential Points: 2 Points Possible

  • EAc4 Enhanced Refrigerant Management

Enhanced Refrigerant Management is an easy credit to achieve if your project's existing conditions do not have refrigerants in use. The Mechanical Engineer is the responsible party to ensure this credit can be achieved.

There are two ways to achieve this credit:

  1. Do not use Refrigerants (easy, right?)
  2. Select Refrigerants that are less harmful to the earth and complete calculations to prove it complies with the max. threshold for contribution to ozone depletion and global warming potential.

Calculation:

LCGWP + LCODP x 10^5 \leq 100

Definitions:

LCODP = [ODP x (Lr x Life + Mr) X Rc] / Life
LCGWP = [ GwPr x (Lr x Life + Mr) x Rc] / Life
LCODP = Lifecycle Ozone Depletion Potential (lb CFC 11/Ton-Year)
LCGWP = Lifecycle Direct Global Warming Potential (lb CO2/ Ton-Year)
GWPr = Global Warming Potential of Refrigerant (0 to 12,000 lb CO2/ lbr)
ODPr = Ozone Depletion Potential of Refrigerant (0 to 0.2 lb CFC 11 / lbr)
Lr = Refrigerant Leakage Rate (0.5% to 2.0%; default of 2% unless otherwise proven)
Mr = End of Life Refrigerant Loss ( 2% to 10%; default of 10% unless otherwise proven)
Rc = Refrigerant Charge (0.5 to 5.0 lbs of refrigerant per ton of Gross ARI rated cooling capacity)
Life = Equipment Life (10 years; default based on equipment type, unless otherwise demonstrated)

Now, don't worry too much about memorizing the equation, but do be sure to memorize what each of the parts of the calculation are, and what governs this credit (leakage rate, equipment charge, etc.

Potential Points: 2 Points Possible

  • EAc5 Measurement & Verification

This credit is pretty easy to achieve. It's an intent to to implement the required measurement and verification plan. It must follow Options B or D of the 'International Performance Measurement and Verification Protocol (IPMVP) Volume III: Concepts and Options for Determining Energy Savings in New Construction.

For purposes of memorization, just think of IPMVP Standards. Realistically, to meter the energy usage for a year after construction, this should be incorporated into the budget of the project. The owner should be willing to pay this fee to achieve the credit.

Submittal Requirements: The submittal would include the project's plan for measuring and verifying the energy savings match the design intent.

Responsible Parties: The Mechanical Engineer, CxA or M&V Agent could all be considered responsible for guaranteeing the credit will be achieved.

Potential Points: 3 Points

  • EAc6 Green Power

This credit is entirely up to the owner. If the owner chooses to purchase a minimum of 35% of the building's electricity with green energy, then the project will be eligible.

The Center for Resource Solutions (CRS) will define what green energy is eligible for this credit.

This credit requires the baseline electricity use as calculated from EAc1. If EAc1 was not pursued, then the DOE Commercial Building Energy Consumption Survey database can help determine estimated energy use.

Strategies include getting the owner to purchase the green energy, as it is often more expensive than regular energy. If the owner is a tenant leasing a space in a large building with shared energy, this may not even be an option.

Potential Points: 2 Points


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