Housing Secretary Winnie Ho on Sunday said about 7,000 flats under the Home Ownership Scheme (HOS) will be rolled out each year in the next five years.

The government said it is trying to assist families that exceed public housing income and asset limits to buy a home.

"When the interest rates remain low and citizens find prices in the private market hard to afford, they opt for public housing instead because they could not find a middle option," Ho told a television programme.

"We are trying to expand the middle area...and the continuous supply of HOS flats will allow such families to own a place for themselves," Ho added.

She also said that the administration will consider ways to improve the balloting mechanism.

"We've heard a lot of opinions on the balloting mechanism through political parties and different organisations, and we will announce the changes to the public when we have a comprehensive plan," she said.

Meanwhile, Ho said the well-being design guide, unveiled last week, will not be mandatory for public housing estates.

She said some elderly-friendly designs, such as placing hooks on the tops of letter boxes for hanging bags and installing handrails in building lobbies, can be classified as standard guidelines.