AMI = Area Median Income; FPL = Federal Poverty Level DEPRECATION WARNING: Choices "other housing unit above" and "other housing unit below" will be deprecated in the future. Enumerations from http://www.fsec.ucf.edu/en/publications/pdf/FSEC-DN-7-84.pdf Gives compass direction a surface (window, wall) is facing. Measured in degrees clockwise from North. MBtu refers to million Btu. A fraction that has to be between 0 and 1 inclusive A fraction that can be greater than one (ie 110%) By leaving this field empty, the weather station is assumed used for all functions such as utility bill regression analysis and energy model simulations. If different weather stations are used for the different functions, use this field to specify the usage of each weather station. The North American Fenestration Standard/Specification for windows, doors and, skylights provides a method for rating the structural performance, water resistance and air leakage of fenestration products.