Installing heavy curtains or reflective film on windows, sealing window and door cracks, and properly sealing a chimney are good ways to insulate a house. Have a professional install attic insulation.
Heavy, dark-colored curtains help prevent air and light from leaking through windows, which keeps a house cooler during the summer and warmer in the winter. Windows and doors can develop cracks around the edges. Seal these cracks with strip insulation or caulk, depending on the location. Reflective film, foil film or double-paned windows can also help reduce heat transfer through windows, though double-paned windows are expensive to install. Films are less effective, but cheaper and easier to install.