Prices must be provided for all fuels being used in the buildings being modeled. In addition, prices may also be provided for fuels not currently being used for FEDS to consider those fuels in its economic calculations (e.g., to consider fuel-switching opportunities).
TIP—Watch units required for fuel price parameters! Electric energy prices are requested in ¢/kWh, while demand charges are in $/kW.
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.
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.
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.
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).
Typically, the "Other" fuel type represents liquid propane gas (LPG) or propane fuel. However, if you use another fuel type that is not listed (e.g., wood chips), you may use "Other" to represent this fuel type.
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.
A minimum or contract demand is included in some commercial and industrial electricity tariffs. It specifies the minimum billing demand that will be charged each month. This is important to understand because implementing energy efficiency projects that reduce the site’s monthly peak demand below the contract demand will have limited return, as no additional savings in demand charges will accrue once the actual monthly demand falls below the minimum contract value. If that is possible for your site, it is best to review this with your utility and negotiate a lower contract demand.
A demand ratchet is a billing method commonly imposed by electric utilities on large commercial or industrial customers. It specifies that the billed demand level in kW be the larger of the actual peak demand for the billing period, or a percentage of the highest peak reached during the previous X months. A typical demand ratchet uses 80% of the peak demand occurring during the previous 11 months as the comparison point. Under this scenario, if your facility experiences a peak demand of 1,000 kW for one hour (or 15 minute interval) you will be billed for a minimum of 800 kW during the next 11 months, even if your actual demand is much lower. Demand ratchets are generally used by utilities to reduce the risks of serving certain types of customers who have potentially large swings in demand during the year—making them pay for the assurance of having the high capacity available when needed.
A marginal price is the price paid for the last increment of energy purchased. This should, therefore, exclude all fixed charges (e.g., the monthly customer or meter charge) and focus only on the costs that vary based on the amount of energy used. Some rate structures are more complex and require some analysis. For example, in a block electric rate structure where users pay a certain amount depending on how much electricity used during the month, the value of electricity would be the price corresponding to the amount the building generally consumes in a month (rather than the average cost over all kWh's used). The marginal rate is the value of a unit of energy saved (i.e., the value of a kWh saved by an efficiency measure).
Providing detailed marginal prices for electricity (including any time-of-day or seasonal variations, and the impact of demand charges and ratchets) is important as it can have a huge impact on the types and cost effectiveness of recommended efficiency measures, as compared with applying basic melded average rates.
Distillate oil is light fuel oil that has been further refined than heavier oils. Examples include #2 fuel oil and diesel fuel. Residual oil, as its name suggests, is the oil residue that remains after distilling out the lighter grade components. It is generally designated as #4, #5, or #6 fuel oil, is much more viscous than ordinary oils, and must be heated to allow it to flow and be burned.
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 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.
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.
Most fuels are valued in FEDS as delivered to the building or end-use. However, the value for district fuels at the building or end-use level are determined somewhat differently. For self-generated fuel types (e.g., central steam, hot water, or chilled water) FEDS calculates the value of the fuel from the inputs in the central plants and thermal loops module. For example, the average value of self-generated steam is calculated based on the energy price of the fuel consumed by the boiler at the central plant along with its conversion efficiency, value of auxiliary energy and chemicals and labor to operate the plant, plus thermal and leakage losses in the thermal loops that distribute the steam to the building. If the central steam plant has multiple distribution loops, the losses may be different and therefore each steam loop can have its own average value for the steam it delivers. For purchased central fuel types (purchased steam, hot water, or chilled water) the value of the fuel delivered to the installation boundary is entered on the "Non-Electric Energy Prices" screen, and then FEDS applies information on the efficiency of each distribution loop to determine the average value of the steam at the building level as delivered by each loop. Marginal values do not consider fixed O&M costs (i.e., those that do not vary with the quantity of central fuel produced/delivered) or distribution losses (which are fixed and do not vary with the amount of energy delivered). Marginal values are used to determine the value of each increment of energy consumed or saved.
No. Given the importance of energy prices on the analysis, as well as the significant variation in rates available within a given region, there are no default or inferred electric or non-electric fuel price data. Users should enter the value of all fuels available.