Home improvements can often focus on changing appliances like sinks and taps, but homeowners have been urged to cut their energy inefficiency and heating bills by improving their household insulation as well.The National Insulation Association (NIA) has said that the onset of winter made now the perfect time for making the change especially while energy suppliers offer subsidies for the procedure.Over 13 million homes in the UK have inadequate insulation, according to the group, with total annual savings of 650 million on energy bills possible should homeowners carry out the necessary improvements.Neil Marshall, chief executive of the NIA, refuted the ideas that it was too late in the year to make the change, explaining Were really moving into the heavy quarters in terms of energy bills the heavy period is really October to February.I would argue that the quicker you get insulation installed, the quicker you can make savings on the bills that are going to be coming through next year. While some would argue that winter weather makes home improvements like cavity wall insulation more difficult, the NIA insisted that heavy work especially in lofts - could be very unpleasant in the summer heat, making the current season a preferable time.