Tools
Nine calculators for scoping a hospital decarbonization case, built on published US DOE, EPA, ENERGY STAR, NIST and NREL methods. They run in your browser and send nothing anywhere.
Jump to: Carbon footprint, Equivalencies, EUI benchmark, Chilled water, Life-cycle cost, Solar PV, Refrigerants, Anesthetic gases, and the Scope 2 estimator on the home page.
About this tool
What it does: Adds up carbon from purchased electricity (Scope 2) and on-site fuels (Scope 1).
Background: Uses EPA eGRID subregion rates and EPA fuel factors, following the GHG Protocol.
Benefit: Shows where your footprint comes from and whether to start with power or fuel.
Scope 2 = kWh ÷ 1,000 × lb/MWh ÷ 2,204.62 ÷ (1 − loss). Scope 1 = therms × 0.005291 t, diesel gal × 0.01018 t, gasoline gal × 0.008887 t. Sources: EPA eGRID2023, EPA equivalencies factors. Excludes refrigerants, anesthetic gases, CH₄ and N₂O from fuels.
About this tool
What it does: Translates tonnes of CO2e into familiar equivalents such as cars, homes and trees.
Background: Uses the EPA Greenhouse Gas Equivalencies methodology.
Benefit: Helps communicate scale to boards and staff.
Equivalents = tCO₂e ÷ EPA factor (passenger vehicle 4.29 t/yr, home energy 7.45 t/yr, 0.060 t per urban seedling grown 10 years). Source: EPA Greenhouse Gas Equivalencies Calculator factors, page updated August 2026.
About this tool
What it does: Calculates energy use intensity in kBtu per ft2 and compares it with the ENERGY STAR hospital median.
Background: EUI is the standard building energy benchmark in the U.S.
Benefit: Shows how efficient the hospital is and what a target saves.
Site EUI = (kWh × 3.412 + therms × 100 + other kBtu) ÷ gross floor area. Median for general medical and surgical hospitals: site 234.3, source 426.9 kBtu/ft² (ENERGY STAR). Weather, services and bed mix change the fair comparison.
About this tool
What it does: Calculates plant kW per ton, COP and EER from power, flow and delta-T.
Background: Whole-plant efficiency includes chillers, pumps and towers.
Benefit: Spots poor chilled-water performance and the value of fixing it.
Tons = GPM × ΔT ÷ 24. kW/ton = kW ÷ tons. COP = 3.517 ÷ (kW/ton). EER = 12 ÷ (kW/ton). Measure kW and flow at the same time and use a meaningful load point. Whole-plant kW/ton includes pumps and towers; chiller-only figures will read lower.
About this tool
What it does: Calculates NPV, payback, savings-to-investment ratio and IRR for an efficiency project.
Background: Uses the FEMP and NIST life-cycle cost method.
Benefit: Tells you whether a project pays back before you commit funds.
NPV = savings × UPV* − O&M × UPV − initial cost. SIR = PV savings ÷ (initial cost + PV O&M). Real IRR from the same cash flows. Method: NIST IR 85-3273-40 (Annual Supplement to NIST Handbook 135, August 2025) under 10 CFR 436A. Excludes taxes, incentives and replacement costs.
About this tool
What it does: Estimates solar output, bill savings and carbon avoided against hospital demand.
Background: Uses a specific yield (kWh per kWdc) with annual degradation.
Benefit: Shows whether a system is sensibly sized for the hospital.
Year-t energy = kWdc × yield × (1 − degradation)^(t−1). Offset assumes all PV output is used on site. Yield source: NREL PVWatts. Not a design or interconnection study.
About this tool
What it does: Converts refrigerant charge and leak rate into lost gas, cost and CO2e.
Background: Refrigerant leaks are Scope 1 and use IPCC GWP values.
Benefit: Makes the cost of leaks visible.
Leaked lb = charge × rate. tCO₂e = lb × 0.45359 ÷ 1,000 × GWP. GWPs are IPCC AR5 100-year values with blends computed from component fractions. Confirm which assessment report your reporting program requires (AR4, AR5 or AR6).
About this tool
What it does: Converts anaesthetic agent and nitrous oxide use into CO2e.
Background: Uses GWP100 values and liquid densities for each agent.
Benefit: Identifies the highest-impact agent to review with clinicians.
Edit GWP and density assumptions
tCO₂e = mL × density × GWP ÷ 1,000,000 (agents); kg × GWP ÷ 1,000 (N₂O). Assumes purchased volume is eventually emitted. Published GWPs vary: sevoflurane 130–210, isoflurane 510–565, desflurane 1,620–2,720, N₂O 265–298 across sources (compiled in the MPOG sustainability toolkit). Densities are typical label values; check your product.
Where the numbers come from
| Input | Source to use |
|---|---|
| Electricity and fuel | Twelve months of utility bills or revenue-meter and fuel-delivery records |
| Grid factor | EPA eGRID subregion (US), or your regulator or utility elsewhere. Hourly intensity from a dataset such as Electricity Maps |
| Savings and demand reduction | An audited estimate (ASHRAE Level 2 or 3), not a target |
| Solar yield | NREL PVWatts for your location, tilt and azimuth, or a full yield study |
| Discount rate | DOE FEMP annual rate for federal analyses; your own hurdle rate for private investment |
Limits
- Scope 1 and 2 on a CO₂ basis. Methane and nitrous oxide from fuel combustion are small and not included.
- Scope 3 (procurement, waste, travel) is not included.
- Results are planning estimates, not a verified inventory, an audit or a net-zero claim.
- Full formulas, constants and sources are on the methods and reference data pages.
Need more depth? The engineering toolkit has 42 linked worksheets (chillers, AHUs, pumps, motors, boilers, waste, finance, dashboard and roadmap). Need another calculator? Tell me which one.