The lack of legislation against advertising the gross floor area of new flats means the market is continuing to see extreme examples of efficiency ratios.
Just compare two examples of flats put on the market recently by the Housing Society and the Urban Renewal Authority.
The Housing Society has launched the sale of 327 flats at Heya Green, Cheung Sha Wan, with a high efficiency rating of 80 per cent.
Such a high ratio has rarely been seen in new private residential projects in recent years.
The society, a statutory body and the developer of the project, has not included the clubhouse in the gross floor area of the flats now on sale.
Also taken out of the calculation were other items usually included in the gross floor area by private developers, including lift shafts, electrical meter rooms and the main lobbies.
Daniel Mak Yiu-man, assistant general manager of the society's marketing division, said: 'This is aimed at letting buyers have a better idea how much they are paying for their actual living space.