Comfort Criteria

Over the years a number of different scales for assessing the acceptability of the pedestrian wind climate have been proposed. For the UK we use the published criteria developed over 30 years by TV Lawson. These 'Lawson Comfort Criteria' have been accepted by most UK authorities, including Westminster City Council and the London Docklands Development Corporation. The Criteria define wind nuisance in terms of percentage of time over certain Beaufort ranges as being:

• Unacceptable (meaning that mitigation is required)
• Tolerable (meaning the nuisance may be tolerated)
• Acceptable (meaning there is no nuisance)

The Lawson criteria are summarised below (where, for example, B5 denotes Beaufort Scale 5).

User Area / Activity	Unacceptable Definition	Tolerable Definition
Roads and Car Parks	6% > B5	2% > B5
Business Walking	2% > B5	2% > B4
Leisure Walking	4% > B4	6% > B3
Standing	6% > B3	6% > B2
Entrances	6% > B3	4% > B2
Sitting Areas	6% > B3	4% > B2

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