Glossary
Baseline model
The reference home built to the 2019 Ohio Residential Code. Every comparison has exactly one baseline. Savings and cost are always measured against it.
Proposed model
A home that adds 2024 IECC efficiency improvements. An analysis can hold up to six proposed models, each representing one packaged set of improvements to evaluate.
R408 credits
Points earned under the 2024 IECC additional-efficiency-credit pathway (section R408). The proposed home must earn enough credits to comply — 10 for a small home (under 5,000 square feet) or 15 for a large home (5,000 square feet or more).
Climate Zone 4 and Climate Zone 5 (CZ4 / CZ5)
The two climate zones that cover Ohio. A measure can be worth different credits in each zone, so the tool tracks compliance in both at once.
Net Measure Cost
The added up-front cost of the proposed improvements compared with the baseline. It is the main cost input to the lifecycle cost calculation.
Replacement cost
The cost of replacing a piece of equipment during the 30-year analysis period, applied in the replacement year(s) you specify.
Net present value (NPV) at 3% and 7%
The sum of the proposed package's discounted future cash flows over 30 years. The tool reports it at both a 3% and a 7% discount rate. A positive value means the package is cost-effective under that assumption.
Payback
The simple payback period in years — roughly how long the energy savings take to recover the net measure cost. It is undiscounted, so it does not change with the discount rate.
$/SF (cost per square foot)
A per-square-foot view of the numbers: the one-time construction cost per square foot, and annual operating costs per square foot per year. It makes the result easier to compare across homes of different sizes.
ERI pathway
The Energy Rating Index compliance pathway. When a proposed home uses it, the Cost Bridge Table can include the associated rating fee via a per-slot toggle.
Cost Bridge Table
The section of the LCC tab that prices the proposed improvements by matching a model's equipment against a reviewed cost catalog, then totals the incremental cost.
PNNL parameters
The financial assumptions behind the lifecycle cost calculation — fuel prices, fuel-price escalation, inflation, mortgage terms, and discount rates — taken from the Pacific Northwest National Laboratory reference method.
Ekotrope
The third-party energy modeling software and API that supplies the model data loaded into the Model Library.