Payback time! 1

Lesson objectives  understand methods to reduce energy loss from the home.  understand how these methods work (the keyfacts).  understand and calculate ‘payback time’.  begin to understand ‘cost effectiveness’. 2

Heat loss from the home This is a thermal image of a typical home. Red areas are hot and show where heat energy is escaping from. Yellow areas also show heat loss. Briefly discuss the areas where most heat is being lost. 3

So what can be done? 4 roof windows walls draughts floor Where does the heat escape from? next

Loft insulation 5 A thick layer of insulation of the loft floor. It works because it’s a poor conductor and traps air, stopping convection. Cost - £450 Saves - £150 every year. Return to home

Cavity wall insulation 6 Insulation placed in the cavity of the walls It works because it’s a poor conductor and traps air, stopping convection. Cost - £500 Saves - £100 every year. Return to home

Draught excluders 7 Brushes and seals on doors. Prevents warm air escaping from the home. Cost - £30 Saves - £20 every year. Return to home

Double glazing 8 Windows and doors with 2 planes of glass with air trapped in between. Air is a poor conductor and there is no convection because the air is trapped. Cost - £3000 Saves - £100 every year. Return to home

Floor insulation 9 An insulation layer under the floor Prevents heat loss because it is a poor conductor. Cost - £300 Saves - £20 every year. Return to home

Other methods Hot water JacketRadiator control valves 10 An insulating jacket around the hot water tank. Costs - £20 Saves - £40 a year Not very common now because few homes have a hot water tank. Valves to control the temperature in each room. Costs - £200 Saves - £40 a year

Payback time Which method would you choose to do first? Each method has a different cost and saving, so we calculate ‘payback time’. This is the time it takes to save what you spent. 11

Payback time Use this equation to determine the payback time of each method. Then decide which method you would decide to do first. 12

Cost effectiveness The difference between cost and savings over a period of time. If savings are bigger than costs then the method is cost effective and worth doing. 13

Review of Lesson objectives Can you: 1.Name several methods to reduce energy loss from the home? 2. Calculate ‘payback time’? 3. Determine whether a energy saving method is cost effective? 14

A well insulated house… 15