Bangkok City Hall, with Japan's JICA, has started a five-year drainage master plan (first phase three years) targeting 100mm of rain per hour, up from the current design of about 76mm. Proposals under review include at least 50% permeable open space under the Open Space Ratio and possible changes to the Biotope Area Factor, which requires part of a development plot to be ecologically green. For SMEs developing land or buildings in Bangkok, these rules could change site layouts and costs, but no rule is final yet; watch for draft regulations.