Property experts have claimed that people looking into green home design could be thwarted by the age of their property.Construction trade group the Home Builders Federation (HBF) indicated that energy efficiency was a more difficult and more costly goal to strive for in older properties.Claims have been made that the green standards imposed on current government house-building schemes will entail an additional 60 per cent in costs, meaning that for older houses the struggle to attain energy efficiency is even tougher.John Slaughter, spokesperson for the HBF, said If you compared a house built today with one built 100 years ago it might be four to six times more energy efficient overall. So there are factors like that which will mean that a newly built home will be less expensive to run than an older property.Green home design can often focus on big energy consumption areas like the kitchen, where changes like the installation of wall insulation, double glazing and sink waste disposal units can cut energy and waste levels.