[单选题]Retrofitting houses to use less energy should be a no-brainer for homeowners.1 time,money spent on ways to reduce heat loss from drauShty houses should produce a 2 return in lower fuel bills.In practice,many are cauLious.Some improvements,such as solid-wall insulation and solar panels,can take over 25 years to 3 their initial cost.Few owners are willing to wait that long:by then many are likely to have.4 and moved on.Several governments have started finance schemes designed t0 5 this problem.Since 2008 PACE programmes have offered American homeowners loans to 6.improvements,repaid through higher local taxes on the property,7 it belongs to.In Brit.ain,Lhe Green Deal offers loans over a 25-year period,with repayments added to energy bills.Countnes including France and Canada have similar 8.In theory,these schemes should boost investment in common energy-saving measures,such as extra insulation and new boilers,9 the first owner does not have to pay all the costs in advance.But enrolment rates have 10,according to Sean Kidney at the Climate Bonds Initiative,a thinktank.In Britain,just 1%of those assessed for the Creen Deal have signed up.In Berkeley,California,home of the first PACE scheme,the 11 rate is similarly low.Homeowners are 12 chiefly because the interest raLes on the loans look high.The Green Deal charges 7%;some PACE schemes a hefty 8%.As these rates are fixed for decades,they will 13 look unattractive when（as now）short-term interest rates are low.Many people als0 14 they will save enough on their energy biUs to cover the repayments.For instance,15 in Britain that installing loft insulation can cut energy bills by 20%have been dented by a government study that found it 16 gas consumption by only 1.7%on average.Others fear that green loans may reduce the value of their home.In America,firms that undewrite mortgages are 17 PACE loans.Green loans have not been a failure everywhere.Around 250,000 households in Germany 18 for them each year.They do so 19 they need pay only 1%interest on them each yeu,thanks to an annual public subsidy of 1.5 billion.Whether that is a（an）20 use of taxpayers'money is another question.12选？
A.unhappy
B.unimpressed
C.unsurprised
D.unsustainable