You are a historian who is compiling information on the changing materials used in a product in one of the categories listed below. Choose a product that uses a variety of materials that have been discussed in this lesson (for example, a car or a tennis racket). Using online or library resources, research past materials used to create the product. Be sure to discuss the materials currently being used for the design and include information on the sustainability of these resources. Your research must also explain why the materials changes were made (for example, safety, cost, or weight). Keep track of your references so that you can document all of the resources used for your report.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c