of new gas boilers by 2035, as part of its strategy to tackle climate change. from next april households in england and wales will be offered grants of £5,000 to install air source heat pumps, or other green heating. £ 450million will be spent on the boiler upgrade scheme, which will run for three years. around 20 percent of uk emissions are from heating buildings, according to officialfigures, so there is pressure on the heat and buildings strategy to deliver effective reductions. 90 thousand replaced boilers critics describe the scheme as "unambitious". 0ur consumer affairs correspondent colletta smith has this report. it came down there, into that corner. there is a secret lying under richard's garden. the heat for his home is absorbed by an underground network of pipes.