Assumptions
Every figure on the case study comes from these.
The representative home
One home stands for the county: Mitchell County's median build year is 1957, and 58 percent of its homes were built before 1960. The engine starts from that vintage.
- Before
- 2,000 sq ft, one storey, two occupants, 70F setpoint, R-7 attic, R-4 walls, 18 ACH50, SEER2 10 heat pump.
- After
- R-38 attic, R-13 walls, 7 ACH50, SEER2 16 and HSPF2 8.8, plus a setback thermostat.
- Climate
- IECC zone 3B, climate pack Texas TRM weather zone 2 (Dallas-Fort Worth, station 722590), the Texas TRM 12.0 weather zone assignment for the county.
- Heating fuel
- ACS 2022 five year puts county heating at 51 percent electric, 37 percent gas and 12 percent other, most of that propane. The modelled home heats electrically, and no fuel switching is modelled.
- Retail rate
- 14.94 cents per kWh, used for the household's own bill.
What the fund claims
Capacity is claimed pro rata to what the fund paid. A fund covering a third of a job claims a third of the kilowatts, and the household's share stays with the household.
Where $5,200 comes from
The default price is what a flat kilowatt of supply costs the campus. ERCOT settles this site in the West load zone, and at 2025 prices that kilowatt costs:
- Energy
- About $369 per kW-year. A flat kilowatt runs all 8,760 hours, measured from the 2025 settlement point price file.
- Transmission
- About $68 per kW-year through 4CP, charged on a customer's own demand at the four system peaks.
- Ancillaries and fees
- About $16 per kW-year, estimated.
- 20 years
- $453 per kW-year discounted at 6 percent is about $5,196 per kW, rounded to $5,200. That is what a kilowatt of supply costs them, not an avoided cost.
The 20 year horizon is the site's contracted term. On 25 September 2026 Cipher Digital announced (GlobeNewswire, SEC 8-K) that the contracted lease term at its Barber Lake site in Colorado City was extended from 10 to 20 years: an amendment to Cipher's existing lease with Fluidstack, plus a binding commitment from a second tenant to lease the facility for a further 10 years after the Fluidstack lease ends.
At this rate the rebate reaches the full $15,580 cost of the modelled five upgrade job, so the household pays nothing for that package.
The campus side assumes spot exposure and a flat 300 MW load. A hedged supply contract would be flatter and probably higher. Source: ERCOT historical settlement point prices.