@macumber I'll add a EpwDataPoint() constructor that sets the default values. Once we're on C++11, I can go back to being lazy and use chained constructors.

The default values are the "missing" values from the E+ documentation (see the auxiliary programs guide, page 45 in 8.1). Unfortunately, I don't quite have all of the cases handled (see Diffuse Horizontal Radiation, for example). And yes, the dry bulb temperature missing value is 99.9 C.