My research from online and factory brochures showed casements superior
in air infiltration to sliders and double hung, only fixed units can
surpass a casement, as I previously noted you pull a casement into its
weather stripping, sliders also wear the gasket, test are on new units.
For high wind areas casements cant be beat, and considering slide type
seals that wear out and the fact that 50% of heat loss can be air
infiltration in old units casements win every time