Whole building energy simulations, or simply energy models, are a powerful tool not only necessary to earn LEED certification, but more importantly, to assist the project team in accurately evaluating energy reduction strategies that maximize both energy and cost efficiency and minimize the impact on the environment. Energy models create estimations of energy usage for new construction and renovations of existing buildings. The analysis is based on the actual design and occupancy assumptions and is used to examine the energy performance in comparison to a baseline. The baseline is generally the minimum building code requirements such as ASHRAE 90.1 or other equivalents. The analysis should be used to optimize the building design and system performance before construction ends. The energy models can now address the complexity of projects and different emerging mechanical systems. Most state and local governments now require proof of energy efficiency measures to secure grants and tax incentives.
The energy modeling process starts at the design development phase and begins with collecting general building design data: architectural drawings, MEP specifications, and the owner's goals. The data is used to create a virtual copy of the building. We can create an accurate daily usage calculation by creating hourly usage schedules for the entire year. Finally we compare the virtual copy with a baseline version and run a report. From these reports we can determined how much the proposed building will perform to EPAct, LEED or other project goals. Our energy modeling reports will clearly identify the energy and cost savings above the baseline, will show all inputs modeled, and will verify that all there were no warnings or errors in the simulation. Multiple models of a building can created but in the end, the baseline and proposed models need to be based on the actual design and set hvac zones.
All of the programs can produce a raw report of the annual energy usage in the building but still needs to be interpreted correctly. A small change can mean the difference between an incorrect input and the correct results. As mentioned above, some programs need tweaks and tricks to make the simulation run correctly.
ENERGY MODELING SOFTWARE
Building information modeling covers geometry, spatial relationships, light analysis, geographic information, process and non-process loads, quantities and properties of individual building components from manufacturers. The energy model must be capable of analyzing the reactions of the building’s skin and equipment to the external climate conditions and internal loads for each hour for a full year (8,760). Internal loads include heat from occupants, equipment, and lighting. External conditions include outside air temperature, solar heat gains, and infiltration. The simulation software also models the efficiency of the mechanical systems and local utility rates.Energy reductions can be divided into three categories: prescriptive methods, system upgrades and improvements, and integrated whole building design. Candid Sustainability uses all of the latest Energy modeling software, including: EnergyPlus, DOE2 eQuest, Google Sketchup, Autodesk Revit, Autodesk Green Building Studio, Autodesk Ecotect, ArchiCAD, and Wrightsoft CHVAC. The reason we are fluent in the multiple programs is because each program has it's capabilities and limitations. For general energy efficiency studies we rely on the Department Of Energy designed eQuest program.
ENERGY MODELING FOR LEED
The US Green Building Council's goal is to encourage whole building design approaches that integrate various building systems. LEED uses energy modeling to quantify energy efficiency and rewards teams for sustainable whole building approaches. Energy Modeling in LEED offers a maximum of 19 points under Energy and Atmosphere Credit 1: Optimized Energy Performance. The same model and report is also used for Energy and Atmosphere Prerequisite 2: Fundamental Energy Performance.
ENERGY MODELING FOR EPACT 2005
The Energy Policy Act of 2005 (EPAct) allows for a tax deduction of $1.80/SF for commercial buildings that can demonstrate a 50% reduction in total annual energy and power costs. The bill also allows for partial deductions of $.60/SF for one of the three components - Lighting, heating and cooling, or building envelope. The 50% reduction can be demonstrated through the use of a DOE approved simulation program, such as eQuest, EnergyPlus, and Green Building Studio. Call us for more information or visit KMR Design Group.