a recent report by a group of yale university researchers calculated that polyester/cotton garments (e. g. , shirts) containing 50 polyester should use 30 less energy for their manufacture and maintenance than comparable cotton garments. this value includes the projected energy demands for production or growth of the respective fibers through yarn spinning, fabric and garment manufacture and finally maintenance of the garment through repeated wearing, washing, cleaning and drying cycles. in the reported study, a series of key cotton spun knit fabrics from key fibers and fiber blends were prepared and tested in finishing, laundering and drying operations it is demonstrated that in home laundering and drying, the combined energy demand for 100 cotton fabrics is about 2. 0-2. 5 times higher than for 100 polyester and blends having a high polyester content industrial finishing operations (e. g. , bleaching, dyeing) are more complex but also favor polyester and specific polyester/acrylic blends over cotton and cotton-rich blends by factors of 2. 7 to 3. 2 in terms of water consumption and 2. 2 to 2. 5 in terms of energy demand. extensive data are tabulated. 24 refs