Guiding principles on ventilation have been incorporated into the Planning Standards & Guidelines, to improve Hong Kong's air circulation, the Planning Department says.

The guidelines are based on the recommendations of the feasibility study for establishing a ventilation assessment system held last year.

Free flow: To avoid airflow obstruction, signboards should be vertical instead of horizontal, especially in areas with high pedestrian activity.

Long-term improvement

For enhanced and long-term improvement to air circulation, it is important to optimise urban design for more wind penetration through the city.

According to the guidelines, sites should be divided into parcels to avoid long and linear site geometry. Breezeways should be provided while amenity areas, building setbacks and non-building areas should be linked to form air paths.

On street orientation, it should be an array of main streets or wide main avenues in parallel or up to 30 degrees to the prevailing wind direction. Streets along the prevailing wind direction should be widened. Building blocks along the waterfront should be of appropriate scale, height and disposition to avoid blockage of sea or land breezes and prevailing winds.

Varying heights

The guidelines also stipulate that varying building heights should be adopted across the district, with heights decreasing towards the prevailing wind direction. Low-rise buildings and open spaces within high-density neighbourhoods should be decentralised to create breathing spaces and congestion of tall buildings should be avoided. Planting in open space and on hillsides should be maximised.

Compact integrated developments and podium structures with full or large ground coverage should be avoided on extensive sites. A terraced podium design is preferred to direct downward airflow to the pedestrian level. Adequate wide gaps should also be provided between building blocks.

To optimise developments' wind capturing potential, the stepping height concept can be considered. The amount and variety of green open space in developments should be maximised.

Cool materials

Projecting obstructions over breezeways or air paths and massive elevated road structures aligned by tall buildings in urban canyons should be avoided. Projecting signboards should be vertical. Developers should also consider using cool materials on pavements, streets and building facades.

The Planning Standards & Guidelines is applied in planning studies, preparation and revision of town plans and development control. The expanded chapter provides guidelines for reference during planning and design stages of projects for the purpose of improving air ventilation at district and site levels.

Reference to an advisory framework for the methodology to undertake air ventilation assessment for developments in Hong Kong is also highlighted. To view the revised chapter click here.