A garment (700, 1000, 1200) comprising: a first garment portion formed of a first material having a first surface and a second surface, the first material formed using at least: a first yarn that is dimensionally stable upon exposure to a physical stimulus, a second yarn that exhibits a dimensional transformation upon exposure to the physical stimulus, the second yarn plated with the first yarn such that the first yarn generally forms the first surface of the first material and the second yarn is generally positioned under the first yarn, a third yarn forming the second surface of the first material, the third yarn mechanically manipulated to form a plurality of projections that extend from the second surface, each of the plurality of projections having a terminal end located opposite the first material,wherein the first material comprises a knitted material, and wherein the first surface of the first material comprises an outer-facing surface of the garment and wherein the second surface of the first material comprises an inner-facing surface of the garment; and characterised in that the first garment portion exhibits a first air permeability when unexposed to the physical stimulus and wherein the first garment portion exhibits a second air permeability when exposed to the physical stimulus, the first air permeability being less than the second air permeability. a first garment portion formed of a first material having a first surface and a second surface, the first material formed using at least: a first yarn that is dimensionally stable upon exposure to a physical stimulus, a second yarn that exhibits a dimensional transformation upon exposure to the physical stimulus, the second yarn plated with the first yarn such that the first yarn generally forms the first surface of the first material and the second yarn is generally positioned under the first yarn, a third yarn forming the second surface of the first material, the third yarn mechanically manipulated to form a plurality of projections that extend from the second surface, each of the plurality of projections having a terminal end located opposite the first material,wherein the first material comprises a knitted material, and wherein the first surface of the first material comprises an outer-facing surface of the garment and wherein the second surface of the first material comprises an inner-facing surface of the garment; and characterised in that the first garment portion exhibits a first air permeability when unexposed to the physical stimulus and wherein the first garment portion exhibits a second air permeability when exposed to the physical stimulus, the first air permeability being less than the second air permeability. a first yarn that is dimensionally stable upon exposure to a physical stimulus, a second yarn that exhibits a dimensional transformation upon exposure to the physical stimulus, the second yarn plated with the first yarn such that the first yarn generally forms the first surface of the first material and the second yarn is generally positioned under the first yarn, a third yarn forming the second surface of the first material, the third yarn mechanically manipulated to form a plurality of projections that extend from the second surface, each of the plurality of projections having a terminal end located opposite the first material,wherein the first material comprises a knitted material, and wherein the first surface of the first material comprises an outer-facing surface of the garment and wherein the second surface of the first material comprises an inner-facing surface of the garment; and characterised in that the first garment portion exhibits a first air permeability when unexposed to the physical stimulus and wherein the first garment portion exhibits a second air permeability when exposed to the physical stimulus, the first air permeability being less than the second air permeability.