Elementary Greenhouse Calculation
For a typical garden greenhouse which could be 4 m long by 3 m wide and 3 m high the glass area will be in the region of A = 43 m2. Glass has a thermal conductivity of σ g = 1.1 W/(m K). The wood frame (σ w = 0.2 W/(m K)) is likely to occupy an area of A f = 2 m2, and have a thickness l w , to give strength, of about 3 cm. To have good thermal properties the glass area will require to be double glazed with say 1 mm glass sheets (l g ) sandwiching a 1 mm layer (l a ) of an inert gas such as argon which has a thermal conductivity σ a = 0.016 W/(m K).