Layer R-Value Comparison
Compare nominal resistance of layers in series.
Formula: Series-layer R = R1 + R2; U ≈ 1 ÷ R.
Whole-wall R differs because of framing bridges, air films and installation defects. Use consistent US R-value units.
Layer R-Value Comparison
Compare nominal resistance of layers in series.
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Calculator reference
Understanding AC and ductwork estimates
A whole-house square-foot estimate is a starting scenario. Climate, insulation, air leakage, windows, solar exposure, people and duct location can materially change the actual cooling requirement. A large unit can cool the air before removing enough moisture.
Manual J calculates sensible and latent loads. Manual S selects equipment using performance data. Manual D designs the duct system using room airflow, the blower’s pressure capability and the losses of ducts, fittings and components. Velocity-only duct dimensions do not complete that design.
One ton of cooling equals 12,000 BTU per hour. Thermal cooling kW describes heat removed; electrical input kW describes power consumed. Room/window AC estimates use the ENERGY STAR room table separately from the whole-house scenarios.
For heat pumps, cooling results alone cannot select the system: heating output at winter design temperature and backup heat need a separate evaluation. Material calculators estimate quantities; they do not size structural members or establish electrical or plumbing code compliance.