jtlangevin
commented
8 years ago Retrofit stock is now accounted for in the market microsegment calculations for a measure (see commit 1c6a75e). The revised calculations assume that 2% of the existing stock not up for replacement is retrofitted in each year of the simulation; this figure is based on a widely cited Rocky Mountain Institute report (see commit message for more details). This 2% retrofitted stock is added to the measure's competed stock in each year, which had previously only considered adoptions of equipment for new construction or the replacement of equipment at the end of its useful life.
Initially, it had been assumed that the addition of a retrofit adoption decision type would require adjustments to existing measure market share calculations, as retrofit decisions were considered to differ from the new and replacement decisions already handled by these calculations. Upon further consideration, however, the retrofit decision can be treated as a type of replacement decision in which the replacement simply occurs before the end of the useful life of the equipment, which does not require changes to the existing market share calculations.
It is noted that retrofits are treated as early replacements in the AEO commercial calculations (e.g., see the commercial NEMS documentation, pages 17 and 49). In the AEO case, however, the decision about whether to retrofit existing equipment or not is directly simulated, while Scout imposes this decision through its requirement that 2% of existing stock is retrofitted in each year of the simulation. The imposition of this decision type on the existing stock simplifies Scout calculations and reduces computational requirements, and it also ensures that retrofits are appropriately scaled to real world conditions as part of the Scout analysis engine. Moreover, the 2% figure may be broken out further in the future with the availability of more granular data, to account for differences in retrofit rates by building type or end use, for example.
As retrofits are now represented in baseline stock-and-flow calculations and are appropriately handled by the existing market share calculation framework, this issue can be closed.
Currently, Scout only simulates technology adoption choices in a case where equipment must be purchased for a new building construction, or in a case where existing equipment has reached the end of its life and must be replaced. Retrofit decisions constitute a third possibility. Here, the decision is driven not by the absolute need for a new service or replacement of an existing service, but by an interest in making a cost effective improvement in the energy efficiency and/or operation of one's building, given a certain amount of available capital.
Retrofit decisions could be accounted for in Scout by defining a typical portion of the stock that is retrofitted each year and adding this portion to the 'competed' stock for the measure as appropriate.