Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to calculate btu per square foot [title] Measure your square footage. [step] Measure the square footage of each room you plan to heat or cool and add them together. If you're installing a furnace or central air conditioning system, this typically includes every room.

Ending1: In some homes, the ducts do not connect to the attic or basement. [substeps] For a rectangular room, multiply the length and width, measured in feet. Ending2: [substeps] Btu equals 3 square feet, so multiply that by 4 to get 3 square feet. [title] Use a sample meter if you want to measure btu per square foot. Ending3: [substeps] This rule is only applicable to rectangular spaces like bathrooms and living rooms. Some websites, like myspace management, allow you to calculate btu per square foot footage by multiplying square footage by 1. Ending4: For heat or cooling, multiply your total square footage by 150 square feet per square foot of space. [substeps] Btu per square foot equals 180 x 2180 square feet.

Answer format: ending1/ending2/ending3/ending4