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.
Generally, it is best to specify the original purpose of the building as the building type, and then modify the use-area type to reflect its current use. Select building type = "Education", use-area type = "Office." The building's construction characteristics are inferred based on building type, while usage parameters (including occupancy, lighting and equipment use, and hot water demand) are based on the use-area type.
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
There is effectively no limit to the number of building sets allowed in a single case if there is enough hard drive space. Currently, each building set occupies approximately 4.3 megabytes of space across all file types. Given adequate storage space, FEDS can be—and has been—used to model an entire community, city, or utility service area.
There is no real limit to the number of buildings that can be modeled in a building set. However, building sets are designed to model buildings that share similar characteristics. The more similar buildings are within a given building set, the more accurate the results will be.
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.
Use the building type or use-area designation that best fits regardless of which list it is on. The building set classes were grouped this way to aid in the selection of common types, but either list may be selected.
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.