Stackable energy transfer core spacer

A unitary stackable energy transfer core spacer comprising a peripheral frame member,

• said peripheral frame member extending about and defining a framed core opening,
• said peripheral frame member having a pair of opposed major sides,
• said peripheral frame member comprising
• a pair of side opening components and
• a pair of side wall components,
• each side opening component comprising a framed side opening in air communication with said framed core opening,
• each side wall component respectively interconnecting said side opening components,
• said spacer being configured such that said spacer may be oriented and stacked, major side to major side, on top of a second like spacer, with an intermediate air to air energy transfer sheet extending across the framed core openings and being sandwiched between the frame members of both spacers so that the spacers and the energy transfer sheet define a pair of transversely oriented air paths on opposite sides of the energy transfer sheet, each air path extending from one respective framed side opening through a respective framed core opening to the other respective framed side opening of a respective spacer and
• wherein each side opening component comprises a first frame element and a second frame element, said first frame element and said second frame element being associated with a respective major side of the frame member, being spaced apart by a respective framed side opening and being offset with respect to each other such that one frame element does not overly the other frame element.