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.
The inputs may be accessed within the operational and control technologies section of the ventilation inputs screen. A number of technology and control parameters are available for each. A two-position or continuously modulated damper is required for some of these options.
The air leakage into a building is determined from the inferred or user-specified infiltration rate. The infiltration rate is the amount of outside air entering the building during periods when the ventilation system is either not operating or not supplying outside air (i.e., times when building is not under a positive pressure).
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.
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 ventilation end use inputs screen contains very basic information on the ventilation motors (total capacity and efficiency). The fan motors button simply enables a user to specify more detailed motor parameters by accessing the underlying fan motor inputs screen. From here, information, such as speed, enclosure type, voltage, vintage, and number of motors can be specified. It is important to realize that if any of this information has been entered, the fan motor inputs on the main ventilation screen will be inaccessible without first deleting the more detailed inputs.
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.