Section Remapping Potential
About Subscript Elements and Remapping  
Power Plant Types good
Industries impossible
Industrial Process Emissions Policies very limited
Cash Flow Entities impossible
Building Type good
Building Component limited
Vehicle Type and Cargo Type good
Fuels very limited
Hydrogen Production Pathway good
Land Use Policy good

About Subscript Elements and Remapping

The Energy Policy Simulator (EPS) uses subscripts (array dimensions) to manage data. Examples of subscripts include “Industry Category,” “Building Type,” “Electricity Source,” and so forth. Each subscript contains various elements. For example, the “Building Type” subscript contains three elements: urban residential, rural residential, and commercial. All subscripts and their elements can be viewed by downloading the model, opening it in Vensim Model Reader, and clicking the “Subscripts” button.

When adapting the EPS to a new geography, we are sometimes asked if we can add additional elements to a subscript or modify the elements that are inside a subscript, in order to better match the available subscript elements to the particularities of that geography. Extending a subscript (adding additional elements) requires a structural edit to the core EPS executable (EPS.mdl, EPS.vpmx) and can be tedious, due to the careful connections that must be made throughout the model to ensure all calculations are completed and the new elements are added to the appropriate output graphs. On the other hand, changing the meaning of an existing subscript element can be done entirely in input data (e.g. by modifying the Excel and CSV input data files). We call this “remapping” a subscript element.

Remapping a subscript is possible, but caution must be taken. In some cases, the model structure treats certain elements differently from others, based on the model’s understanding of what those subscript elements mean. This can make certain output graphs inaccurate if remapping is done inappropriately. This documentation page aims to help clarify which subscript elements may be remapped and under what constraints.

Power Plant Types

The 16 elements of the “Electricity Source” subscript are: hard coal, natural gas nonpeaker, nuclear, hydro, onshore wind, solar PV, solar thermal, biomass, geothermal, petroleum, natural gas peaker, lignite, offshore wind, crude oil, heavy or residual fuel oil, and municipal solid waste. (This does not include distributed generation, which is handled in the Buildings sector and is not part of this subscript.) Remapping of power plant types is possible given the following constraints:

Remember that when remapping, you likely will need to update not only a variety of variables within the electricity sector (e.g. start year capacity, heat rate, expected capacity factors, etc.) but also pollutant emissions intensities and pollutant emissions intensity improvement rates (in the Fuels section).


The 8 elements of the “Industry Category” subscript are: cement and other carbonates, natural gas and petroleum systems, iron and steel, chemicals, coal mining, waste management, agriculture, other industries.

Industrial Process Emissions Policies

The nine industrial process emissions policies are a subset of the “Policy” subscript and also are used in the “Industry by Process Emissions Policy” subscript The nine elements are: methane capture, methane destruction, f gas substitution, f gas destruction, f gas recovery, f gas inspct maint retrofit, cropland and rice measures, livestock measures, and cement measures. Each policy lever represents a “bucket” of different technical strategies (summed up from a major EPA report, for non-CO2 gases), and the exact composition of those buckets can change, as long as the following guidelines are respected:

For example, you could remap the “cement clinker substitution” policy to “cement measures” and add data about the cost and reduction potential of alternative cement chemistries to the existing data on clinker substitution in PERAC, so this lever represents doing both of these technical measures (depending on the lever’s setting). You could also consolidate all F-gas measures into a smaller number of levers (by default, four levers), or remap “Crop and Rice Measures” to a different policy that affects methane and nitrous oxide in the agriculture industry.

Cash Flow Entities

The nine cash flow entities (entities to whom the EPS can assign positive and negative cash flows) are: government, nonenergy industries, labor and consumers, foreign entities, electricity suppliers, coal suppliers, natural gas and petroleum suppliers, biomass and biofuel suppliers, and other energy suppliers.

Building Type

The three elements of the “Building Type” subscript are: urban residential, rural residential, and commercial.

Building Component

The six elements of the “Building Component” subscript are: heating, cooling and ventilation, envelope, lighting, appliances, and other components.

Vehicle Type and Cargo Type

The six elements of the “Vehicle Type” subscript are: LDVs, HDVs, aircraft, rail, ships, and motorbikes. The two elements of the cargo type subscript are: passenger and freight.


Fuels appear in a variety of subscripts, including “All Fuels” and sector-specific fuel subscripts, such as “Industrial Fuel” or “Transportation Fuel.”

Hydrogen Production Pathway

The hydrogen production pathway subscript includes five pathways: electrolysis, natural gas reforming, coal gasification, biomass gasification, and thermochemical water splitting.

Land Use Policy

The six land use policies are a subset of the “Policy” subscript and also are used in the “Land Use Policy” subscript The elements are: forest set asides, afforestation and reforestation, forest management, avoid deforestation, peatland restoration, and forest restoration.