Double-pane, gas-filled, low-emittance windows sound quite sporty, and they do wonders to improve insulation and resale value.
Less sophisticated windows may also seal well. But to qualify for Energy Star status, they've got to block at least 70 percent of the sun's heat and reflect heat indoors. They also reduce the likelihood of condensation, and some employ coatings to block ultraviolet light to prevent fading.
Carpets, consider that last one a win.
Pat Greenhouse/Globe Staff