EAc1: Optimize Energy Performance is, by far, the most important credit in LEED, based on the number of points available. Up to 10 points are at stake here based on how much you’re able to reduce the project’s predicted energy cost. That large amount of points also reflects the great importance LEED places on reducing energy use and forestalling climate change.
You’ll need to choose your approach. For certain buildings types you can opt to skip the energy modeling option and simply follow a list of prescriptive requirements, but you can’t earn nearly as many points that way, and you won’t have the benefit of the energy simulation to guide you to the most cost-effective energy efficiency measures.
This credit is documented in concert with EAp2: Minimum Energy Performance.
Energy efficiency pays
An energy-efficient building can cost more to build, through components like efficient mechanical equipment and high-performance glazing. On the other hand, those same higher-cost measures can generate construction-cost savings by reducing the size of mechanical systems. And of course, dramatic financial savings can come during the operational phase. Energy modeling can help determine the “sweet spot” for your project.
Your project may also qualify for financial incentives offered by utilities or local, state, and federal authorities, that help offset the premiums of system upgrades and renewable energy implementation. In many states, utilities or other local entities provide financial incentives in the form of rebates or tax breaks to alleviate the cost premiums associated with installing systems and purchasing equipment geared toward energy efficiency. (See Resources for incentives.)
Four options, but only one gets you maximum points
The LEED Reference guide gives three options, but per USGBC addenda, an additional compliance option has been added to EAc1 for projects registered after June 26, 2007. Documentation for this credit happens along with documentation for the associated prerequisite, EAp2: Minimum Energy Performance. In fact, for the prescriptive options, all you have to do is document the credit—and use the same documents for EAp2.
All four of the following options are available to projects registered before June 26, 2007. Option 1, 2 or 3 must be used for projects registered after June 26, 2007. (These compliance options meet the two-point prerequisite requirement for projects registered after June 2007).
Option 1: Whole Building Energy Simulation
Option 1 offers the potential to earn the maximum number of points available for this credit. This requires whole building energy simulation using a computer model. Your project must reduce energy cost by a minimum of 14% (7% for an existing building) to meet the prerequisite, EAp2, which will also earn your project two points. Under EAc1 you can earn one point for each additional 3.5% of energy cost reduction from the referenced standard (see the table in the credit language for exact amounts). The energy modeling and documentation process is identical for EAp2 and EAc1, Option 1. The exact reduction is established when you run your energy model.
Option 2: ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004
The Advanced Energy Design Guides is published by ASHRAE for office occupancy projects less than 20,000 ft2—so if you don’t fall into that category, you’re not eligible for this path.
This guide outlines strategies to reduce energy use by 30% from 2001 levels, or an amount equivalent to approximately 10%–14% reduction from ASHRAE 90.1-2004. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting all of them.
Option 3: Advanced Buildings Core Performance Guide
Option 3: Compliance with the prescriptive measures of the Core Performance Guide (formerly the Advanced Buildings Benchmark Program) offers an opportunity for a maximum of 5 points. Projects must comply with Section 1 & 2 of the Core Performance Guide. An additional point is available for meeting any three additional requirements, of Section 3 of the Core Performance Guide (CPG). These requirements range from installing a renewable energy system to adding filters to air-handling systems. Review these requirements with your team to select the three or six that are most applicable to your project.
The Core Performance Guide path is a good option if all of the following are true:
- your project is smaller than 100,000 ft2,
- you cannot pursue Option 2 because there is not an ASHRAE guide for the building type,
- your project is not a healthcare facility, lab, or warehouse,
- and you would rather not commit to the energy modeling required for Option 1.
Comply with all requirements within Sections 1 and 2 of the guide. If you choose this path, become familiar with the list of prescriptive requirements and commit to meeting them.
It’s important to note that this path is not just a list of prescriptive requirements, but a prescribed process for achieving energy efficiency goals. Follow the design process from day one after assembling your team. Most of the requirements are difficult to demonstrate for documentation purposes if you didn’t accomplish them at the right stage. You must demonstrate that you considered a couple of alternate designs, for example, and that certain team meetings were held.)
Option 4: Advanced Buildings Benchmark
Option 4 option earns one point and is available to only those projects registered before June 26, 2007. Follow Advanced Buildings Benchmark v1.1, Basic Criteria and Prescriptive Measures of the Advanced Buildings Benchmark Version 1.1 as described in LEED-NC v2.2 Reference Guide.
Regardless of credit compliance approach - Reduce energy loads first
Energy efficiency offers a clear combination of environmental benefit and benefit to the owner through reduced operational expenses, and potentially reduced first costs, if you’re able to reduce the size and complexity of your HVAC system with a more efficient envelope.
High-tech HVAC systems, and onsite renewable energy generation are often signature components of green buildings, but consider these strategies more “icing” on the cake, rather than a place to start. Start with building orientation and passive design features first. Also look at envelope design, such as energy-efficient windows, walls and roof, before looking at HVAC and plug loads. A poorly designed envelope with a high-tech HVAC system is not, on the whole, efficient or cost-effective.
Design and technology choices
With clearly defined goals and committed team members, your project should be able to achieve an energy cost reduction of 14% to 17.5%, through measures such as the following.
- Making conscious design decisions to reduce energy loads
- Minimizing glazing areas on the east and west exposures
- Passive solar design
- Energy-efficient glazing
- Daylight harvesting
- Reducing the lighting power density
- Natural ventilation
- Demand-controlled ventilation
- Efficient mechanical system
- Lighting controls
- Energy Star appliances
- A modest onsite renewable energy system.
- Reduced process loads
If you want to aim for higher targets of 20%–50% energy savings or higher, consider measures such as the following.
- Natural ventilation
- Daylight harvesting with automatic dimmers/switching on electric lighting
- Reducing heating and cooling loads through improved glazing, insulation, and exterior shading devices
- Energy recovery ventilation
- A larger onsite renewable energy system.
The most cost-effective measures vary by building type and location—refer to ASHRAE Advanced Energy Design Guides and case studies for examples of strategies in your building. (See Resources.)
Integrated design
Building energy performance is a result of interactions between various different building components and systems. The mechanical system consumes energy based on factors such as architectural design, operating schedules, programming and climate. To significantly reduce energy it is very important for all team members to share design ideas and collaborate on strategies. The integrated design process will support constant communication, fast response on new ideas, and can help eliminate misunderstandings or assumptions—consider using it as a central strategy to earning points for this credit.
Special considerations for district energy
If your project is connected to a district energy system, LEED-NC v2.2 lets you take advantage of improved system efficiencies. Although not permitted for use with EAp2 (up to 14% energy use reduction has to be demonstrated without inclusion of the district system), you may include the improved efficiency over baseline of the district energy system in the energy model you develop for EAc1. In this scenario, you develop a separate model from the one for EAp2 compliance. (See Resources for more details through the updated guidelines.)
Look for incentives
Focusing on energy efficiency and renewable energy generation can seem to add costs to a project, but there are a variety of utility-provided, as well as state, and federal incentives available to offset those premiums. (See Resources.)