Worked example of shelter compliance
The above smoking shelter was erected prior to the smoking ban and the owner wished to know whether it complied. The perimeter in this case is set by the roof, which slopes from back to front.
Total area on perimeter (T) = front + back + 2 sides
Front area = 2.2m x 5.1m = 11.22m2
Back area = 3.4m x 5.1m = 17.34m2
Side area (combined) = 2 (2.2 x 2.3) + 1(1.2 x 2.3) = 12.88m2
T = 41.44m2
Total area of solids (X) = front walls + back wall + side walls
Front solid = 1.6m x 1.0m + 1.8m x 1.0m = 3.4m
Back solid = 3.4m x 5.1m = 17.34m2
Sides solid = 2(2.3m x 1.0m) = 4.6 m2
X = 25.34 m2
Totals area of gaps (space) to open air (Y) = T- X = 41.44 m2 - 25.34 m2 = 16.1 m2 Y= 16.1 m2.
Expressed as %, X (solid) is 61 % of the smoking structure and Y (space) is 39%, so Y is not at least 50% of the structure. So the structure is "substantially enclosed" and smoking could not be allowed.
The owner to make the structure comply removed two complete panelled sections from front and side and half of further panelled section of the front. Solid material removed to equivalent of 4.9 m2, so X = 20.44 m2 and Y = 21 m2.
Expressed as %, X (solid) is 49.3 % of the smoking structure and Y (space) is 50.7%, so Y is now at least (exceeds) 50% of the structure. So the structure is not "substantially enclosed" and smoking could be allowed.