Btu (IT)/square foot Unit Converter

Definition of Btu (IT)/square foot unit

Btu (IT)/square foot is a heat-density unit measuring the amount of heat energy, in International British thermal units, contained, transferred, or applied per square foot of area. It equals 1,055.056 joules per 0.092903 square metre.

History of Btu (IT)/square foot unit

The Btu originated in nineteenth-century English engineering as a practical measure of heat needed to raise one pound of water by one degree Fahrenheit. The International Table (IT) Btu was later standardized at exactly 1,055.056 joules, distinguishing it from older thermochemical and mean Btu definitions. Dividing the IT Btu by a square foot created a convenient area-normalized measure for comparing heat loads, insulation performance, solar gains, and fuel use across differently sized surfaces. It remains common in building and energy engineering.

Applications of Btu (IT)/square foot unit

Today, Btu (IT)/square foot is used to express building heating or cooling intensity, envelope heat loss, solar exposure, and equipment loads relative to floor or surface area. Energy analysts may compare annual consumption in Btu/ft², while engineers use it for duct, roof, wall, and radiant-system evaluations. It also appears in energy codes, benchmarking reports, and real-estate performance studies.

Complete list of Btu (IT)/square foot unit conversion