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ADORB Concepts

The A.D.O.R.B. cost (Annualized De-carbonization Of Retrofitted Buildings) is a lifecycle cost metric that captures the true cost of building ownership by including externalities that conventional cost analyses ignore — primarily carbon emissions and grid infrastructure investment.

The Five Cost Components

Each year of the analysis period produces five cost categories. All are discounted to present value (PV) before summing.

1. Direct Energy Cost (pv_direct_energy)

Annual electricity and gas purchase costs, including:

  • Purchased electricity (kWh x purchase price)
  • Sold electricity / net metering credits (kWh x sale price)
  • Annual base / connection charges for each fuel

Discount rate: 2%

2. Operational Carbon Cost (pv_operational_CO2)

The cost of CO2 emissions from building operations:

  • Electricity CO2 — hourly purchased electricity multiplied by hourly grid emissions factors from NREL Cambium data, projected forward for each future year. This captures grid decarbonization over time.
  • Gas CO2 — total gas consumption converted to therms, multiplied by a fixed emission factor (12.7 tons CO2 per therm).
  • Both are multiplied by the price of carbon (default: $0.25/kgCO2).

Discount rate: 7.5%

3. Maintenance & Replacement Cost (pv_direct_MR)

The direct dollar cost of installing and periodically replacing:

  • Constructions (walls, floors, roofs, windows) — replaced at their lifetime_years interval
  • Equipment (HVAC, lighting, appliances, PV) — replaced at their lifetime_years interval
  • CO2 reduction measures — one-time costs at their specified year

Each item’s full cost (labor + material) is charged at year 0 and again at each replacement cycle within the analysis duration.

Discount rate: 2%

4. Embodied Carbon Cost (pv_embodied_CO2)

The carbon cost of manufacturing the materials used in constructions, equipment, and CO2 measures:

  • Material cost (total cost x material fraction) is converted to kgCO2 using the national emissions intensity factor (kg_CO2_per_USD from PhAdorbNationalEmissions).
  • The resulting kgCO2 is multiplied by the price of carbon.
  • A 0.75 adjustment factor is applied.
  • Like direct costs, embodied CO2 recurs at each replacement cycle.

Discount rate: 0% (no discounting — embodied carbon is treated at face value)

5. Grid Transition Cost (pv_e_trans)

The building’s share of national renewable energy infrastructure investment:

  • The USA national transition cost ($4.5 trillion) is spread over 1,600 GW of new nameplate capacity, yielding a cost per Watt.
  • This is amortized linearly over 30 years.
  • Each year, the building’s peak electrical demand (W) is multiplied by the annual per-Watt transition cost.
  • After year 30, the transition cost drops to zero.

Discount rate: 2%

Present Value Discounting

All costs are converted to present value using:

PV = nominal_cost / (1 + discount_rate)^(year + 1)

Different cost categories use different discount rates (see above) to reflect different risk profiles and time preferences.

Analysis Duration

The analysis duration (typically 50–100 years) determines how many years of costs are computed. Longer durations capture more replacement cycles and show the long-term benefit of durable, low-carbon designs.

Grid Region (Cambium Data)

The PhAdorbGridRegion holds hourly CO2 emissions factors for each year from 2023 through 2111 (89 years), sourced from NREL Cambium. These factors reflect projected grid decarbonization and vary by region (27 US regions).

The hourly granularity matters: a building that consumes electricity during peak-carbon hours will have higher operational CO2 costs than one that shifts load to cleaner hours.

National Emissions Intensity

The PhAdorbNationalEmissions factor (kg_CO2_per_USD) converts material dollar costs to embodied kgCO2 using a country-level economic input-output approach. This is a simplified proxy for full lifecycle assessment (LCA) of each material.

Labor vs. Material Fractions

Each construction and equipment item has a labor_fraction (0.0–1.0). Only the material fraction (1 - labor_fraction) contributes to embodied CO2, since labor does not carry upstream manufacturing emissions.