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Enter LCC inputs

The LCC Engine (Tab 3) runs the 30-year lifecycle cost calculation. It turns the energy savings and the up-front costs of the proposed improvements into dollar figures using the PNNL (Pacific Northwest National Laboratory) method. Staff and external reviewers can both edit this tab.

1. Compute the energy delta

First, tell the tool which two models to compare:

  1. Pick the baseline rating and the proposed rating from the loaded models.
  2. The tool reads each model's annual energy use and computes the energy delta — how much electricity (kWh), gas (therms), and propane (gallons) the proposed home saves compared with the baseline.

These savings drive the dollar savings in every year of the calculation.

2. Enter the measure inputs

Provide the cost side of the comparison:

  • Net Measure Cost — the added up-front cost of the proposed improvements over the baseline. You can enter this directly, or build it up from the Cost Bridge Table and apply the result here.
  • Replacement cost and replacement year(s) — if a piece of equipment will be replaced during the 30-year period, enter its replacement cost and the year(s) it happens.
  • Maintenance cost change — any change in annual maintenance cost.

3. (Optional) Adjust PNNL parameters

The calculation ships with the PNNL reference assumptions — fuel prices, fuel-price escalation rates, inflation, mortgage assumptions, and the discount rates. You can override individual parameters when a project calls for it, and lock a parameter so a later change elsewhere does not overwrite your value. Leave these at their defaults unless you have a specific reason to change them.

4. Calculate LCC

Select Calculate LCC. The tool builds a 31-row cash-flow table — a base year (year 0) plus the following 30 years — and reports:

  • Net present value at 3% and net present value at 7%. A positive value means the package is cost-effective under that discount-rate assumption.
  • Simple payback in years.
  • Year-one energy savings and the full cash-flow table.

For how these figures are derived, see the staff algorithm reference for the Ohio IECC cost analysis.

The $/SF cost and savings summary

Tab 3 also shows a builder-facing $/SF Cost & Savings Summary: the incremental Net Measure Cost expressed as a one-time construction cost per square foot, and an annual operating-cost table (baseline, proposed, and savings per square foot per year) for each energy component. It refreshes automatically when you change the Net Measure Cost or a model slot.

Next step

Review the combined output on the Results Dashboard. To build up the Net Measure Cost from priced equipment, use the Cost Bridge Table.