Background: Our project is the 25,000 sf expansion of a school campus including three new buildings - two 1-story structures and one 2-story structure. Our goal is to lower energy use as much as possible, including the selection of process load appliances with low energy use. All of the new spaces in the three new buildings are complete build outs, except four classrooms in the 2-story structure that are being built out as core and shell spaces only. These classrooms will be a low-scale lab environment, metal shop, wood shop or some very light work shop component as yet not defined and will be finished as a future tenant improvement. The scope of our current project does not include the installation of any plug or process load equipment for the core and shell space, only HVAC (heating and basic ventilation only, none for process equipment) and lighting shall be installed. The overall core and shell area of this project is relatively small (3000sf) compared to the overall project area. Proposed Modeling Strategy: For the purposes of documenting the baseline and proposed energy use of this combined full build out and core and shell project, we propose the following methodology. For all completely built out spaces, create a model with baseline energy use including process loads at 25% of total baseline building energy use. The proposed case for the fully built out spaces would have the envelope, systems, lighting and process loads modeled as designed, with documentation available for the new process loads. For the core and shell spaces, since these do not have any associated plug or process loads to be installed at this time, we propose to create a separate model for these spaces that only addresses envelope, lighting, domestic hot water and HVAC systems. This model would provide baseline and proposed case annual energy use for these non-process load related components. Once the annual energy use figures are available for both the full build out and core and shell spaces, it is proposed that the baseline energy use figures be added together for both cases to achieve an overall baseline energy use for the project. Similarly, the proposed case annual energy use would be the combined proposed energy use of the fully built out and core and shell spaces. In this way, an accurate representation of the scope of the project can be modeled for both baseline and proposed cases. Request: Please confirm that the following approaches are acceptable to accurately demonstrate the condition of the proposed building. 1. Is it acceptable to keep the baseline process load energy cost at 25% of the baseline total energy cost, while modeling and inputting the actual installed process loads for the proposed case? This would allow the building to achieve some credit for specifying lower energy use plug and process load equipment than a baseline case. Note that the proposed process energy costs may or may not be 25% of the total energy cost, and may or may not be equal to the process energy load for the baseline case. 2. Is it acceptable for the core and shell spaces to not include process loads in the total energy cost for either the baseline or proposed cases? This would most accurately reflect the project condition. Process loads would be included in the model simulation for the purpose of demonstrating heating and cooling load compliance only, but would be separated out when determining total energy cost for the core and shell spaces. 3. Is it acceptable to create two separate building models for the project, one for the full build out portion of the project and a separate model for the core and shell portion? The core and shell model would exclude process energy cost from its total energy cost. Is it acceptable to sum the total energy costs of the full build out and core and shell spaces to achieve the total project energy cost?
The questions will be addressed in the order that they were presented: [1] It is acceptable to vary the design case process load to reflect energy efficiency measures (ie Energy Start Appliances) that affect the process energy load. This is considered an Exception Calculation Method (ECM) and thus full documentation should be provided justifying the differences and highlighting the assumptions and inputs that were used to create both the baseline and design case process energy loads. It is not allowable to use the default 25% process load value for the baseline case if the proposed case process energy has been inputted piece-by-piece (for example, by inputting the energy usage for each computer, copier, etc.). Instead the baseline model must also have piece-by-piece inputs using identical input power and energy rating as the proposed case unless the applicant can demonstrate that the proposed equipment represents a significant verifiable departure from documented conventional practice. In that case, the values for conventional practice may be used for the baseline equipment with the same use schedule as the proposed case. [2] It is NOT acceptable to ignore process energy usage in future build-out spaces. The LEED Core & Shell Reference Guide provides some guidance in how to address future build-out spaces, though it is more geared to address tenant-leased spaces. Key concepts to follow for future build out spaces include, but are not limited to: [A] Model receptacle and other loads (process) based on estimates for the building type. Table G-B of the ASHRAE 90.1-2004 User\'s Manual (note, this is not the same document as the ASHRAE 90.1-2004 Standard) provides acceptable receptacle power densities, occupancy densities, and hot water usage for varying occupancy types. [B] Use the same values for receptacle and process loads in both the baseline and design cases for the future build-out spaces. [C] If default values cannot be found for certain occupancy types, make reasonable estimates based on modeling and design experience. Please note where these values were used and what estimates are based on. [3] Separate building models for the full build-out and core and shell portions of the project are not recommended. Energy usage calculations are compromised when the model is broken apart because, among other issues, the model is no longer able to apply diversity factors across all project spaces or properly size systems based on peak demand. It may be permissible to separate portions of the model for an ECM, but this is only in the case that limitations in the modeling software prevent adequate representation of the design. If this is the case, full ECM documentation will need to be provided, as described in ASHRAE 90.1-2004 G2.5. Applicable Internationally.