Ballpark Lab

Data Sources and Model Assumptions

Published datasets and model assumptions are different things. We identify both so you can decide how much confidence to place in an estimate and which parts to check in a local quote.

Maintained by the Ballpark Lab Research Team. Read the calculation methodology or send a correction. A source name is not an endorsement of Ballpark Lab or proof that every displayed value came from that source.

Which prices remain model assumptions?

Installed-price bands, construction feature allowances, sitework adjustments and regional multipliers are stored model inputs. Earlier descriptions cited general industry surveys, but a complete record tying each value to a dated source, sample and scope has not yet been published. Do not interpret these inputs as measured local bids, a representative state survey or an official labor index.

An EIA energy price does not validate the installation allowance beside it. A professional association's construction guidance does not establish our shell-price inputs. Published CSV reports compare calculated scenarios, not individual transactions or independently collected quotes.

For a price input to be independently verifiable, its record needs the exact source, observation period, location and scope, plus any transformation used. Where that record is missing, we identify the number as a model assumption rather than inventing a citation. Get comparable written quotes before committing to work.

Dataset and reference inventory

We combine published energy and product datasets with curated references and Ballpark Lab pricing assumptions. A named source supports only the fields described below; it does not validate every price or local multiplier. Data dates describe the stored snapshot, not a promise of automatic refresh.

Dataset snapshots and API integrations

  • U.S. EIA API v2 — Residential electricity and natural-gas price snapshots; energy-price refresh scripts calculate trailing 12-month averages
  • OpenEI Utility Rate Database (URDB) — Utility tariff lookup used by the paid roof-report workflow; tariff applicability must still be checked against the customer's bill
  • Google Solar API — Roof geometry, solar production estimates and imagery for the paid roof analysis
  • NREL PVWatts v8 — Modeled solar production profiles, not measurements of output at the user's property
  • ENERGY STAR certified products — Certified heat-pump and pool-pump model and efficiency data; not installation-price surveys

References and model assumptions

  • NREL — Solar-resource reference values used in state-level estimates
  • DSIRE + state programs — Curated incentive and net-metering references; verify current eligibility with the program administrator
  • IRS / federal policy — Tax-policy reference; verify applicable dates and eligibility with the IRS rather than treating a calculator as tax advice
  • Ballpark Lab pricing assumptions — Installed-price bands, feature allowances and regional factors. Earlier notes cited general industry surveys, but a complete source-to-value record is not yet published; these are not verified local bid statistics

Pricing provenance and known limitations: publication dates, automated refresh schedules and data validation are separate checks.

The energy snapshot currently extends through April 2026. A refresh script being available is not proof that it ran recently; check the stored dates. Missing local values may fall back to a national or default value according to the individual calculator.

Source links and their actual role

U.S. EIA Open Data

Energy-price datasets. The refresh scripts use residential electricity and natural-gas series; they do not supply pool, siding or HVAC installation prices.

OpenEI Utility Rate Database

Utility tariff reference for roof-report modeling. The selected tariff still needs to be checked against the property's actual service and bill.

Google Solar API documentation

Roof geometry, imagery and solar production estimates in the paid report workflow, not a physical roof inspection.

NREL PVWatts

Solar energy modeling; simulated production is not measured generation at an individual property.

DSIRE

Incentive and policy research. Stored summaries are not automatic confirmation that a household is eligible.

IRS credits and deductions

Tax-policy verification. Check applicable dates and conditions with the IRS; calculators are not tax advice.

ENERGY STAR data

Certified-product model and efficiency records, not installer quotes or verification of our cost assumptions.

ENERGY STAR pool efficiency guidance

General pool equipment and cover guidance. Published potential savings are separate from our fixed heating-model discount.

Pool heating: allowances versus evidence

The calculator uses installation allowances of $2,500–$4,000 for gas, $3,500–$6,000 for a heat pump, and $3,000–$7,000 for solar. Confirm equipment, connections and site-specific work in a written local quote.

This calculator applies a fixed 45% reduction to its modeled operating allowance when a cover is selected. That is a planning assumption, not a guaranteed saving for your pool or every heater. Actual savings depend on cover use, weather, water temperature and equipment; the solar circulation allowance is simplified too.

This is an area, energy-price and season-based budget model, not a heat-loss simulation or equipment-sizing calculation. It does not calculate target water temperature, hourly weather, wind, humidity, heater output or heat-pump COP. Installation ranges are fixed model allowances, not live local bids.

See the shared reference scenarios in the heating calculator. Local planning references for the reviewed Maine siding page are linked beside the relevant guidance; they do not validate its price ranges.

Stored pricing-data dates

Solar: June 30, 2026. Pool: June 30, 2026. Fence: July 1, 2026. Driveway: July 6, 2026. Siding: July 6, 2026. HVAC: July 10, 2026.

An editorial review does not update these dataset dates or imply a new survey. This page's provenance wording was reviewed September 18, 2026.