回本期 meaning in English

payback period
payoff period

In general , the cost - recovery period of an energy - saving installation is about three to five years
一般来说，节能装置的回本期大约为三至五年。
Whether it has worked out the costs incurred by the government departments and public organisations in switching to the use of such installations , their annual savings in energy expenditures and respective cost recovery periods ; if not , the reasons for that ; and
（三）有否计算已转用有关装置的政府部门及公营机构须付出的成本、每年可节省的能源开支及回本期；若否，原因为何；及