On average, Vekony, from Greenmatch, a vendor of heat pumps, reports that the cost of a ground-source heat pump in the UK ranges from £2,000 ($2,500) to £6,000 ($7,500), installation costs range between £3,000 ($3,750) to £4,000 ($5,000) and in total, an initial investment of £12,000 ($15000) is required at an exchange rate of £1=$1.25. Despite the high investment, the researcher cites that the GSHP has a payback period of only 4 years while the ASHP requires at least 5 years to payback on the initial investment. Other researchers such as Hanova and Dowlatabadi (2007) have further argued that GSHPs are economically feasible only where the costs of electricity required to operate the heat pumps lead to annual operating savings that are relative to costs of conventional systems. Additionally, the researchers report that although the payback period of GSHPs in residential areas ranges from <10 to 20 years, upon reaching the payback threshold, the GSHPs provide annual operating savings until the end of their lifetimes. Similarly, Hanova and Dowlatabadi (2007), report that once the payback period is reached, GSHPs generate higher returns on investment that exceed the initial investments incurred by the homeowners.