FEDS can be run on a machine connected to a network. In some circumstances FEDS can even be run remotely from a network computer or file share. However, because each network is different and interference and connectivity issues are possible, for the best performance (and to lower the risk of problems) it is recommended to run FEDS from a local machine.
On the *.txs report, the electricity dollar values listed under the "Annual Installation Energy Use by Fuel Type" and "Annual Energy Use by Building Set and Fuel Type" pages include both energy and demand charges. To determine how much of that total cost is attributable to the energy vs. demand, the demand component (reported on the following page) may be subtracted from this total value.
Yes. FEDS now models and evaluates lighting controls, including occupancy sensors. To model existing lighting controls, the user must select the appropriate "yes" response to the "Existing lighting controls?" input and review the existing utilization factors. To infer reasonable utilization factors for the controlled lighting, specify the appropriate space type for the space where the lights exist.
FEDS will also automatically evaluate the savings potential and cost-effectiveness of lighting controls where they do not currently exist. In this scenario, select "no–evaluate occupancy sensor" and identify the most applicable space type. In this case, the "existing" utilization factors identify the portion of time that the lights are currently on, while the "with controls" utilization factors will be used by FEDS to model the impact of the occupancy sensor controls. The "number of sensors required" is used by the cost model to identify how many sensors need to be installed to control the current lighting.
Sometimes when the system or software crashes, certain files are locked in the system's memory which can cause strange or unstable behavior upon restarting. If this occurs, try quitting FEDS and restarting again. When closed properly, FEDS will tidy up the system resources and work properly the next time it is run.
Each lamp and ballast modeled within FEDS has a rated life (specified in hours) associated with it. Actual replacement intervals are calculated within the model based on the light's modeled operating hours (based on utilization factors and occupancy schedules) and rated life of each component. When a lamp or ballast fails, FEDS accounts for the cost to replace the component by figuring both materials and labor requirements. These costs are tallied over the economic study period and reported as the non-annual maintenance cost. FEDS uses the non-annual maintenance cost along with energy and capital costs in determining which fixture can best provide the required level of service at the lowest life-cycle cost.
Emissions factors are used and relate a quantity of pollutant emitted (e.g., tons of CO2) per unit of fuel burned. There are factors for each of the six pollutant types corresponding to each main fuel type. To estimate emissions, FEDS multiplies the consumption value for each fuel type by the appropriate emission factor. The emissions factors for certain fuel types, (for example electricity) can vary significantly depending on factors, such as plant type (coal, gas, nuclear, hydropower) and source fuel composition (e.g., sulfur content) such that state average values are applied based on the typical generation resource mix supplying that state.
Exterior lighting, such as security or parking lot lights can be included in FEDS by selecting the exterior fixture location. This will set the heat to space to 0 and alter the calculation of utilization factors appropriate for typical nighttime operation.
The best way to check the accuracy of a model is to run FEDS without optimization and compare the annual consumption estimated by FEDS to actual metered data. To do this, go to "Exclude Building Sets" from the "Optimization" option on the "Simulation" screen. Make sure the "Pick Building Sets" method is selected then press the "Select All" button on the left side of the screen (under the list of building sets). After saving, go back and run FEDS. This will take from a few seconds to a couple minutes for FEDS to run the baseline load and consumption calculations for the buildings. Alternatively, running with the analysis type set to "Calibration" will accomplish the same thing. Once complete, review the *.txs report for the case and check the following data:
General case and building inputs on the first five pages (for any obvious input errors)
Energy consumption data by fuel type (page 7)
Electric peak demand value and time of occurrence (page 8)
Annual energy consumption by fuel type and end use (page 10)
Do not expect these to be identical to the metered data—this is a model representation of your buildings and even if extremely precise, will vary due to discrepancies related to actual vs. average weather, human behavior, and more. Therefore, achieving consumption values from FEDS that are within 10-15% of actual values suggests a reasonably accurate model. An experienced user who is knowledgeable about building energy systems and their interactions can successfully calibrate to a much tighter tolerance.
Refer to Appendix G of the FEDS User's Guide. Ex: FL 2x4 4F40T12 STD2 = a 2-foot by 4-foot fluorescent fixture, with four 40 watt T12 (1.5 inch diameter) lamps, operated by two standard magnetic ballasts (designed to operate two lamps each).
A useful rule of thumb is that a full FEDS optimization run will take a couple minutes per building set. However, run-time depends on a number of factors, including computing resources, processor speed, size, and complexity of the case. The more buildings, use areas, and technologies being analyzed, the longer the FEDS run will take. Additionally, the presence and number of central energy plants and thermal loops will also impact run-time.
Conversely, a calibration run of the same case and computer takes only a few seconds (with additional time to generate the reports). This is because all building sets are excluded from optimization to help focus on the baseline energy results and aid in focusing on model quality assurance and calibration processes.
Installing FEDS will require approximately 1.7 GB of hard disk space. It is also important to have enough free disk space for case files. We recommend another 10-30 MB for this depending on the number and size of site models.
The blue arrows indicate inputs that are required for FEDS to run. If any of these cells do not have a value provided, FEDS will not be able to run and will produce an alert either upon saving a screen or updating inferences. Once a valid input value has been provided and saved, the blue arrow will disappear.
The lock symbol that appears next to many of the input cells indicates the value is inferable by FEDS and does not require an input. An open lock icon means the value is not locked and may be changed by FEDS when inferences are updated. The closed lock symbol represents inputs whose value is locked and protected from being changed when inferences are updated. A user may lock a value by either entering a value into one of these cells, or by clicking on an open lock symbol to lock the value that is currently present in the cell.
Input cells that do not have an icon next to them are for values not absolutely required for FEDS to run but are highly recommended. Values, such as the fuel price data and occupancy hours are extremely important (yet a value may not be required for each fuel or day type). Others, such as the energy consumption inputs and building/technology identifications, are not used by FEDS except for reporting and aiding the user in understanding the output.
The utilization factors for lighting represent the portion of time particular lights are on, on average, over the building set. They are expressed as a fraction of the maximum possible load (i.e., 100% of the lights are on 100% of the time) for a given time period. FEDS infers the occupied and unoccupied period utilization factors based on what is typical on average for the lighting technology and use-area type. FEDS typically assumes that some lights are on even during unoccupied times for security, safety, or cleaning staff, or simply because lights were left on. During seasonally unoccupied months and other periods defined as non-operating, utilization factors are set to 0 for all lighting records except for exit lights, which are assumed to operate constantly.
Attractive NPVs, payback periods, and SIRs typically fall within certain ranges, which should always be positive. However, negative values are possible in a couple of instances and do not necessarily indicate an error. The first possibility is that the project is recommended for a technology or building component you identified as "replacement required". As such, FEDS will recommend the most cost-effective replacement option, but not require that it be cost effective. So, while it may be the best replacement option, it may exhibit seemingly nonsensical economic figures of merit. Similarly, if a building retrofit occurs due to central plant or thermal loop abandonment, it may also exhibit negative savings criteria. That simply means that the retrofit (e.g., replacing central steam service with an in-building boiler) was not cost effective when looking just at the building energy use and costs. But the value of abandoning the central plant and/or distribution loop (due to the accompanying reductions in thermal losses and O&M costs) provided a net positive gain when added to the negative savings at the building level. Thus, at the site level, taking the central plant and thermal loop savings into account, the net benefit is positive—but purely from the building perspective (reflected in the TXD and CSV reports) the change from steam to dedicated boiler was not cost effective. Reviewing the central plant and thermal loops section of the TXS report and looking for a positive abandonment value will provide additional detail on just how much of a net positive gain accrues do the abandoning the plant and/or loop.
In FEDS MBtu signifies Million British Thermal Units. Throughout the program, the 'M' prefix represents million or 106 (MW, MBtu), while 'k' represents thousand or 103 (kWh, kBtu).
The index code in following the existing technology description for a heating or cooling technology represents the technology record number. For example,{H2} indicates a heating technology is actually heating record #2 (as input in the user interface). This information can be valuable when dealing with heat/cool pairs with several heating and cooling records in a single building set.
Section 432 of the Energy Independence and Security Act of 2007 (EISA 432) requires U.S. federal agencies to perform energy and water evaluations of their covered facilities on a recurring basis and report their performance via the Compliance Tracking System (CTS). The FEDS CTS report is provided to help agencies compile and format results from their FEDS analyses to facilitate this reporting requirement. Measures identified with buildings modeled in FEDS are categorized and summarized into the CTS Evaluation Upload Template (in an Excel spreadsheet format).
The Energy Resilience and Conservation Investment Program (ERCIP) report (*.ecp, otherwise known as the DD 1391) is a special form required by certain U.S. Department of Defense agencies in order to submit projects for ERCIP funding. The ERCIP report is designed to facilitate the form preparation and submittal process.
The [Heating/Cooling] end use designation is used for existing heat pumps or heat/cool pairs. Because such technologies provide both heating and cooling, two rows are needed to describe them on the *.csv report. [HEATING/Cooling] indicates that the data on that row pertain to the heating technology (and overall economic impacts) while [Heating/COOLING] indicates that the data describes the cooling portion of the equipment (and no overall energy and economic data are shown).
The lighting use-area fixture density is the inferred fixtures per square foot and is based on typical lumen levels for different use-area types. It represents the average fixtures per square foot over the entire use-area (or building for single use-area buildings). Typically, the user will know the total number of fixtures in a use-area and can enter this and allow the software to calculate the fixtures per square foot.
For heat/cool pairs (separate heating and cooling technologies), information may be listed for both retrofits to new, more efficient equipment and to a heat pump. In some cases, it may be cost effective to replace the heating equipment (or cooling only, or both) with a newer unit of similar type, as well as replace both heat and cool simultaneously with a heat pump system. All cost-effective options will appear on the *.csv report. The best option can be determined by comparing the sum of the individual heat and cool annualized total life-cycle costing savings with that of the combined heat/cool system (i.e., heat pump).
The installed capital cost listed at the very bottom of the *.txd report represents the actual total cost including materials, labor, taxes, and overhead. It is the actual cost that would be paid to complete a project. The installed cost value listed under the life-cycle costs savings section displays both the present and annualized values of the installed cost as used in the life-cycle cost analysis. The present value of the installed cost may be less than the installed capital cost if the study period for the analysis is less than the life of the new equipment. This can occur when the remaining life of the existing technology is less than the life of the retrofit technology. In this case, the cost of the retrofit technology is annualized over its full rated life, but only the annualized costs occurring during the remaining life of the existing equipment is discounted back to the analysis year and used for a fair cost/benefit comparison.
No. At this time FEDS considers only fixture per fixture replacements that provide similar light output. However, the energy impact of correcting an over/under lit condition could be analyzed comparing by two consecutive FEDS baseline runs (by running without optimization).