In previous columns, I’ve examined several credit categories within LEED. One credit category that has not been discussed in-depth is Energy and Atmosphere. The energy section of the LEED 2009 rating system has more prerequisites and voluntary credits than any other single credit category. This section of the rating system is heavily weighted, but, surprisingly, it is not discussed as frequently as other credit categories. This is because the prerequisites and credits in this category are complicated, so they can be difficult to understand.
Prerequisites:
There are three prerequisites in the Energy and Atmosphere category: fundamental commissioning, minimum energy performance and fundamental refrigerant management. The first prerequisite focuses on how well the equipment in the building is running at the end of construction and just prior to occupancy. It requires a third-party commissioning agent inspect the equipment after installation and at startup. The second prerequisite requires the building to meet minimum energy standards as compared to a baseline building. The third prohibits CFC-based refrigerants from any equipment used in the project. All of these must be satisfied as a part of the certification process.
On the surface, this may seem like an easy thing to do in any building. And while this may be true when it comes to commissioning and purchasing equipment that is free of CFC refrigerants, minimum energy performance can be a different story, depending on the building type and location. On a non-LEED project, the energy performance of a building is rarely tracked, predicted or documented.
LEED buildings, however, must demonstrate compliance with the prerequisites, which require the delivery team to produce documentation that demonstrates the energy performance of a building when compared to a baseline building. Typically, the energy performance of a building is made by comparing the base building and the design case within an energy simulation model. This takes into account all energy that is consumed in a building. Contrary to what most people think, energy consumption consists of more than just the lights and the HVAC equipment.
LEED requires that all the energy used in the building must be considered as part of the building and included in the model. This is a situation where building type and/or function has an effect on the energy model used. The LEED building design and construction system was created for office-type buildings. While the USGBC has made additional guidance available for various building types, the industrial sector is one where little guidance is provided other than “all end use” energy must be included. In the case where there is manufacturing taking place in the building, the energy used for the process equipment must be included in the models, both baseline and design case.
The simulation model is used to create the baseline building, defined as the building that is being constructed with all systems (those things that consume energy) equal to the allowance provided in the American Society Heating Refrigerant and Air Conditioning Engineers (ASHRAE) 90.1 standard. This standard provides guidance on what a typical building or building system should consume. Once the base building is created in model space, the design case is then entered into the model to draw the comparison. The design case represents the building that has been designed and will be constructed as a part of the project. The comparison is made in the model between the building with all input data set to the ASHRAE standard and the designed building with all of its energy conserving measures. This comparison is used to demonstrate and document that the building that will be constructed is predicted to operate at energy efficiency levels required by this prerequisite.
Voluntary Credits
There are a total of 35 points a team can achieve within the Energy and Atmosphere category. Nineteen of the available points are awarded for the optimization of the energy-consuming equipment in the building, as well as the building itself. Through optimization, the building owner can find operational savings when compared to the same building with no energy-conserving measures (the base building).
This credit and its associated 19 points is demonstrated and documented with the same model that is used to satisfy the prerequisite. In this case. however, the project team will need to demonstrate that the building performs better than the minimum predicted energy use. The more efficient the building and its systems are, the more points the team can earn and the more money can be saved through reduced energy bills in the future.
The remaining balance of the points within this category addresses other energy-related issues. There are seven points available for incorporating alternative energy sources, such as wind power or photovoltaic panels, into the project. The USGBC offers these credit points to building owners who wish to demonstrate their commitment to sustainability by adding this type of technology into their buildings. The points are associated with the amount of energy contribution they may have to the building. Percentages are based on the results from the energy model. First, the building is created as a baseline, then the design is compared to the base to demonstrate energy optimization. The amount of alternative energy produced is figured in as a percentage of the overall energy the building (design case) may consume.
The remaining nine points within this category can be achieved by extending the commissioning services from the first prerequisite for a period of one year, omitting any HCFCs or halons from the building, providing for ongoing measurement and verification of the building and for purchasing Renewable Energy Credits.
The Energy and Atmosphere credit category is an important part of any LEED certification. Success in this category does not come from one energy savings measure. Energy savings is a combination of all things within the building, as well as the building envelope and any process within the building.
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Thomas Taylor, a 30-year veteran of the construction industry and noted expert on sustainability, is a principal and co-founder of St. Louis-based Vertegy LLC. His book, “Guide to LEED 2009: Estimating and Preconstruction Strategies,” provides step-by-step information about the LEED 2009 for New Construction process. To learn more about Vertegy or Taylor, visit www.vertegyconsultants.com.