What is the cheapest way to improve wall insulation? If a home already has cavity wall insulation, what is the next best way to insulate the walls? Brian Horne, domestic energy expert at the Energy Saving Trust, said: "Once cavity wall insulation is fitted, although it is technically possible to add further external or internal wall insulation, this would be expensive and save very little in energy costs." Therefore, one of the best ways to further insulate your home - in the most cost-efficient manner - would be to add insulation to the loft, roof or floor. Experts say that loft insulation is the most cost-effective way to improve the efficiency of your home. Mr Horne said: "After installing cavity wall insulation, there are other energy efficiency measures that the homeowner could look to install. These mainly include lower-cost measures such as topping up the insulation in the loft (the Energy Saving Trust recommends 270mm of loft insulation), installing draught excluders in doors and windows, gaps around the floor and maybe even up a chimney, and installing or upgrading a set of heating controls on the boiler to control the home temperature. He said: "At the same time if your boiler is over ten years old then it might be worth considering an energy efficient boiler. Replacing an old gas boiler with an A-rated high-efficiency condensing boiler could save you as much as £310 a year. Once you've had any improvements done to the heating system, make sure the engineer explains how the system works and how to set the controls. There are Goverment initiatives in place to encourage homeowners to make energy-saving improvements to their homes or businesses, by providing loans to pay for insulation, double glazing or draught-proofing. The Green Deal scheme, launched in January 2013, provides loans from £5,000 to be paid back over 10 years, up to £10,000 to be paid back between 15 and 25 years. Although the scheme was launched at the beginning of the year, no Green Deal loan providers have made the details of their finance packages public yet. The Green Deal also has a cashback scheme running until 2014. To see if you qualify for the loan, call The Energy Saving Advice Service on 0300 123 1234 (England and Wales) or 0808 808 2282 if in Scotland. The Energy Company Obligation (ECO) programme was also introduced in January 2013 to reduce the country's energy consumption and support the poorest and most vulnerable householders in the UK. Energy suppliers are obligated under the scheme to subsidise the installation of energy efficiency measures in low-income hosueholds. The scheme will run until March 2015, to check if your eligible for the funding, go to gov.uk/energy-company-obligation or call your energy supplier. Some households have complained that too much insulation can cause problems due to the lack of ventilation, although the vast majority of British houses are a long way from such a problem. If you have a question on household bills, email us at moneyexpert@telegraph.co.uk