EAc1: Optimize Energy Performance is, by far, the most important credit in LEED, based on the number of points available. Up to 21 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 have some options to choose from. 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. Refer to EAp2 for detailed steps on LEED compliance and documentation.
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 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.)
Three options, but only one gets you many points
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 prerequisite—no further information is required to earn a point under the credit.
Three compliance options are available.
- Option 1 offers the potential to earn the maximum number of points available for this credit, for improved energy efficiency. This requires whole building energy simulation using a computer model. Your project must reduce energy cost by a minimum of 10% (5% for an existing building) to meet the prerequisite, EAp2. Under EAc1 you can earn one point for each additional 2% 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.
- If your project pursues the prescriptive compliance paths of Options 2 and 3, you automatically earn one point under EAc1 simply by documenting your prerequisite compliance.
- Option 3: Compliance with the prescriptive measures of the Core Performance Guide (CPG) offers an opportunity for a maximum of 3 points. One point is earned for compliance with the CPG. An additional one or two points are available for meeting any three or six requirements, respectively, of Section 3 of the 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.
Design and technology choices
With clearly defined goals and committed team members, your project should be able to achieve an energy cost reduction of 10% to 15%, 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
- Reducing the lighting power density
- Demand-controlled ventilation
- Efficient mechanical equipment
- Occupant sensor lighting controls
- Energy Star appliances
- A modest onsite renewable energy system.
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 appropriate 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 2009 lets you take advantage of improved system efficiencies. Although not permitted for use with EAp2, 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.)
