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.
No. FEDS infers parameters based on the most likely current condition of a building and its equipment. Inferences for an 1820 vintage building will reflect the typical improvements and upgrades that have occurred over time.
During a month that has been identified as seasonally unoccupied (also referred to as non-operating), FEDS assumes zero occupancy, all lights are off (except exit signs), and the cooling system is shut down. Heating is operated at a reduced level generally for the purpose of preventing the pipes from freezing (temperature kept at low setpoint specified by the unoccupied season thermostat setting). General plug loads are assumed to be non-operational, as are most motors (although this may be overridden by specifying monthly motor load factors).
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.
Unoccupied hours or day types of occupied months are those periods during which there is reduced occupancy of the building. These are referred to as low occupancy periods in FEDS. For a typical commercial facility this might occur during the night and on weekends. A small number of occupants might be present (though less than during normal operating hours), and all energy systems remain active although they may operate at reduced levels. The operation of HVAC, lighting, plug loads, and motors are all controlled by inputs such as thermostat setpoints (enabling temperature setback), ventilation control mode, and utilization/load factors.
Full 24-hour occupancy can be specified for any day type by entering the same start and end hours (except 0 and 2400). For unoccupied day types enter 0 for both start and end times (or leave them blank). Note: if you do not specify occupancy hours, they will remain blank and FEDS will model the buildings as though they are unoccupied (reduced occupancy). Shortcut buttons are available on the standard occupancy inputs screen to make specifying continuously occupied and unoccupied day types easier.
If the building is newer than the rated life of the equipment in question, then the remaining life is equal to the difference of rated life and building age. If the building is older than the equipment's rated life, FEDS assumes that on average, equipment will be halfway through their life (but users can override this assumption and specify actual equipment vintage). Rated lives vary by equipment technology. Some examples of rated lives used in FEDS are:
envelope components (windows, insulation, etc.) – 40 years
lights – typically 25 years (Although the cost of replacing lamps and ballasts is figured into the analysis based on specific replacement intervals and hours of operation)
boilers – 40 years
furnaces – 20 years
chillers – 20 years
package AC units – 15 years
heat pumps – Air Source/15 years, Ground-Coupled/20 years
motors – 15 years
hot water heaters – electric, 12 years; gas, 10 years; distributed heat pump, 12 years; central heat pump, 15 years
FEDS contains a built-in database of building survey data and is able to infer a number of building parameters based on the small set of required inputs provided by the user. For example, FEDS uses information such as building type, location, floor area, and vintage to determine the most likely construction type and geometry. It uses similar information along with heating fuel type and cooling equipment, to determine the most likely heating technology and ventilation system parameters for a building. All inferences enable a user to model buildings without having intimate knowledge of the detailed engineering parameters. The resulting building prototype parameter values are statistically the most likely values based on the limited set of information provided. Of course, all inferred data may be easily overwritten by simply entering (locking) a value in the user interface screens.
FEDS draws upon a number of sources to determine inferable parameter values. Major sources include national building energy consumption surveys such as the Commercial Buildings Energy Consumption, Residential Energy Consumption Survey, large end-use studies such as the End-Use Load and Consumer Assessment Program, ASHRAE handbooks, building and equipment codes and standards, and manufacturers' data and extensive building audit and evaluation experience.
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.
A locked value, in terms of FEDS inputs, is one that the user has entered for an inferable parameter. This indicates to the model that this is a user-entered value and should not be updated (inferred). Clicking on the lock symbol can also lock a currently inferred value. When a value is locked, the lock icon will appear as a latched or closed lock. To unlock a value, simply click the icon again, changing it to an open or unlatched lock. This value will now be inferred the next time inferences are run.
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.
FEDS project costing algorithms account for any materials, taxes, and labor costs applicable to a given retrofit measure. Additionally, 15% contractor overhead, 10% design cost, and 6% site level supervisory, inspection and overhead factors are applied, along with any multipliers specified on the regional costs screen under the financial options. Note that many of the cost factors reflect real regional variation, including labor rates, materials cost multipliers, and sales tax rates—with differentiation driven by the specified zip code. Each of these parameters are also able to be modified by the user, if appropriate.
The non-annual maintenance cost is used by FEDS to account for costs recurring on a non-annual basis, such as incremental equipment replacements and replacing failed lamps and ballasts. For example, the present value of the non-annual maintenance cost for lighting represents the present value of the total cost (including materials and labor) to replace the burned-out lamps and ballasts of a particular lighting technology over the course of the study period (generally 25 years).
Variable occupancy is an improved approach to the seasonal occupancy option which allows users to specify that certain months are non-operating (e.g., schools may be shut down over summer break). Variable occupancy also offers greater flexibility by allowing users to specify the percent of days within specific months which follow the general occupancy and operation schedule defined in the standard occupancy inputs. One hundred percent indicates the building or use area operates all days of that type during the month according the standard schedule. Zero percent indicates the building (use area) is either non-operating (shut down) or in a low occupancy state (occupied at the low occupancy and equipment use level) for all days of that type during the month. For any value between 0% and 100%, FEDS will multiply that value by the actual number of days of that type in the month and model the resulting number of days (rounded to the nearest whole day) as operating according to the standard schedule. The remainder of the days of that type in the month will be deemed either non-operating or at low occupancy (depending on the selection of non-operating period status type). As a convention, FEDS will model the first X days in the month as occupied and operating to the standard schedule, and the remaining days of that type in the month as non-operating or at low occupancy. The variable occupancy capability provides significant modeling flexibility and is particularly useful in modeling occupancy and building operation that varies within the course of a month, such as for National Guard or Reserve buildings that may only be heavily occupied on certain weekends through much of the year.
Another option for even greater control over building and use-area operation and occupancy (for each hour of the year) is also available. Contact FEDS Support for more information if interested in using this approach.
FEDS employs the same standard life-cycle costing methodology and algorithms as the building life-cycle costing computer program developed by the National Institute of Standards and Technology.
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 discount rate is the factor used to adjust (discount) future sums of money into the equivalent current year dollar amount. It can also be thought of as the interest rate or hurdle rate (i.e., the rate of return required by a company for it to undertake a project). FEDS uses the real discount rate, which has the effect of inflation removed. FEDS provides the current Federal real discount rate as the default, but the user may enter any discount rate appropriate for their projects. Energy service companies performing shared energy savings contracts typically require real rates of return in the neighborhood of 10 to 20%.
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 global cost multiplier is an overall cost multiplier applied to the total project cost (including all materials, labor, taxes, overhead). It can be used to adjust all of the total project costs used in FEDS economic calculations. This could be used for such purposes as to account for special cost-impacting requirements of working at a facility with stringent security requirements or health and safety risks, or to assess the impact of varying costs on project economics.
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).
On the bottom right of some input screens (windows, lighting, heating, cooling, hot water, and motors) is a check box labeled "replacement required". The purpose of this selection is to tell FEDS that this particular building component or technology must be replaced. Whether it has failed (for example, windows are broken, or the furnace has stopped working), or a replacement or upgrade is planned, checking this box will force a replacement to be evaluated and selected when the FEDS optimization analysis is run. If a replacement option is cost effective, FEDS will work as normal; however, if one is not, FEDS will still provide the recommendation even though it may not be otherwise cost effective. FEDS will still report the most cost-effective option and all of the standard details to help users make informed decisions. This option is also known as replace on failure economics.
FEDS project costs are based on industry averages and may not match the exact costs you will be charged. The end-use and technology multipliers are intended to enable the user to adjust for these discrepancies so that the costs used in the FEDS analyses are as close to actual as possible. The recommended approach would be to first enter any known cost data (such as, labor rates, tax rate, discount rate, etc.), and then run FEDS, generate reports, and see what types of projects are coming up. Compare the project costs to actual known costs or bids for similar projects of that type. If any of the technology costs are grossly high or low, adjust them appropriately with a technology multiplier. Rerun FEDS to see if the same technology is being selected, and make sure that the costs more closely represent what the anticipated cost to complete the project. Because of the complex nature of the FEDS cost data, this iterative multiplier approach is the best way for users to modify project costs.
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. All occupancy hours must be specified by the user. Failing to do so will indicate to the model that the building is operating in the unoccupied mode each day during the week.