Room-by-Room Mini-Split & Heat Pump BTU Zoning Calculator
Calculate exact heating and cooling BTU loads, condenser tonnage, and room-by-room ductless mini-split air handler head sizes based on IECC climate zone, ceiling height, and spray foam vs. fiberglass insulation.
Every HoolieHaus floor plan includes pre-calculated HVAC tonnage and spray foam board-foot schedules.
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
How many BTUs per square foot do I need for a spray-foamed barndominium or ADU?
While older unsealed homes often used a crude 30 BTU/sq ft rule of thumb, a tight envelope insulated with closed-cell spray foam (R-21 walls / R-49 roof) typically requires only 18 to 24 BTU/sq ft depending on climate zone and glazing. Oversizing an HVAC unit in a spray-foamed home causes short-cycling and poor humidity control.
Should an attached garage or workshop share the main house ductwork?
Never. Residential building codes (IRC R302.5.2) strictly prohibit connecting ductwork between a garage/shop and living quarters to prevent carbon monoxide and chemical fumes from entering bedrooms. Always use a dedicated ductless mini-split head for a conditioned workshop bay.