19 JANUARY 2008, Page 55

Dear Mary

Q. Now that eco-issues are so fashionable my husband has come out as a militant meanie on energy conservation. Meanwhile our three teenage daughters use absurd amounts of hot water each day and leave their laptops and televisions on. They also prance about in the skimpiest clothes imaginable, which means they always want the heating on full blast. Mary, how can I tackle these incompatibilities so that I can conserve some of my own energy and not have to dissipate it all on resolving domestic disputes?

A.B., Pencaitland, East Lothian A. Stimulate your daughters’ own interest in conserving energy with the purchase of a Wattson O1 energy monitor. (£149.50 from www.electricity-monitor.com). This minimalist, packet-of-butter-sized device is easily fitted to your mains cable. Henceforth it will reveal, on an attractive LED display, exactly how much wattage is being consumed by the household at any one time. The whole family will soon be transfixed as the display changes from red (bad) through violet (average) to cool blue (good). Your daughters will swiftly become addicted to the ‘reward fix’ of seeing the numbers tumble to a desirable target of less than a thousand watts (blue) as they rush about the house turning things off. You will soon see them clad in sensible woollies to achieve this aim.