This tool illustrates the physics of Reflectivity vs. Emissivity. It demonstrates why a thin sheet of shiny foil can stop 97% of radiant solar heat from entering your tiny house, but only if installed correctly with a dedicated air gap.
It features a “Heat Ray Visualizer” that shows solar radiation penetrating standard roofing materials versus bouncing off a radiant barrier, and calculates the potential AC energy savings for hot climates like Texas and Florida.
Radiant Barrier Simulator
Reflect solar heat and reduce AC bills in hot climates.
1. Roof Configuration
The Physics of Foil
This is the #1 mistake. Radiant heat must travel through air to be reflected. If you sandwich foil directly between roof sheathing and insulation, heat simply conducts through the foil like a frying pan. You typically need at least 3/4″ air space facing the shiny side.
Standard building materials absorb ~90% of solar heat (Emissivity 0.9). Aluminum foil emits only ~3-5% (Emissivity 0.03). In a tiny house where the roof is just inches from your head, this can drop ceiling temperatures by 20-30°F in summer.