Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area PLANNING DEPARTMENT Term Consultancy for Air Ventilation Assessment Services Cat A – Term Consultancy for Expert Evaluation and Advisory Services on Air Ventilation Assessment (PLNQ 37/2007) Quarry Bay Area Professor Edmund Choi City University Professional Services Limited July 2008 1 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area Contents Page 1 Introduction 1 2 Objective of the Study 1 2.1 Materials for study 1 2.2 Site visit 1 3 Study Scope 2 4 Study Area 2 4.1 Site boundary and coverage 2 4.2 Site characteristic 4 5 Wind Availability 8 5.1 Wind data from MM5 simulation result and site wind availability 9 6 Flow Evaluation 15 6.1 Topographic effect 15 6.2 Effect of greenery and open space 17 6.3 Effect of building lay-out and street pattern 18 6.3.1 Existing condition 18 6.4 Evaluation of air ventilation conditions for Proposed Height Restrictions and Potential Redevelopments 23 7 Problematic areas and Mitigation 25 7.1 Problematic areas 25 7.2 Mitigation measures 25 8 Future Studies 30 9 Acknowledgement 30 Annex I – Site photographs of Quarry Bay area 31 2 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area 1 Introduction In the Team Clean report published in August 2003, the Government undertook to examine the practicality of stipulating Air Ventilation Assessment (AVA) as one of the considerations for all major development or redevelopment proposals and in future plan making. Subsequently, a strategic objective to promote sustainable urban planning and design practices has been set out. One of the objectives is to look at issues such as buildings restricting air flow. 2 Objective of the Study To facilitate better planning control, it is helpful to have a better understanding on the air ventilation characteristics of the Study Area (the Area), namely the area of the Quarry Bay “Outline Zoning Plan No. S/H/21/24”. The objective of this assignment is to carry out an expert evaluation (EE) to assess the likely impact of the proposed building height restrictions of the development/redevelopment sites within the study area on the pedestrian wind environment and compared to the existing condition. This expert evaluation is carried out based on the Air Ventilation Assessment framework as set out in the Housing, Planning and Lands Bureau, and Transport and Works Bureau Technical Circular No. 1/06 and its Annex A – Technical Guide for Air Ventilation Assessment for Development in Hong Kong. 2.1 Materials for study This expert evaluation report is based on the materials supplied by the Planning Department to the Consultant on 30th May 2008, listed as follows: Aerial photo Existing and committed building height profile Planned building height profile Existing building height restrictions Proposed building height restrictions Postulated podium & building footprint Summary of development parameters Existing scenario - Spot height & No. of storeys Existing scenario - Spot height & No. of storeys for podium Planned Scenario - Spot height & No. of storeys Planned Scenario - Spot height & No. of storeys for podium Location & view points of site photo Site photos MM5 wind data over site 2.2 Site visit The consultant visited the Area and carried out site inspections between 31st May 2008 and 6th June 2008. Special features of the site are referred to and photographs are given in the later part of the report. 1 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area 3 Study Scope The scope of work includes the tasks as follows. • To identify good building design features; • To identify any key ventilation corridors; • To identify any potential problem areas; • To provide recommendation for mitigation measures; and • To advise if any further detailed study is required and the scope of the detailed study required. 4 Study Area 4.1 Site boundary and coverage The Study Area covers the Quarry Bay area of Hong Kong Island with a total area of about 207 hectares. It is bounded by the Victoria Harbour to the north; Lei King Wan to the east; Hoi Chak Street, Java Road and Mansion Street to the West; and the Tai Tam Country Park to the south. The Area is primarily a mixed residential and commercial area. There are a number of large-scale private residential developments to the north of King’s Road extending towards the Harbour Waterfront/Quarry Bay Park (i.e. Taikoo Shing and Lei King Wan), and on the uphill towards the south (i.e. Kornhill and Nam Fung Sun Chuen). Higher density and comparatively smaller-scale residential developments are mainly found along King’s Road. Major commercial activities are concentrated in Taikoo Place, along King’s Road and at Cityplaza. Majority of buildings (commercial and residential) is medium-rise at about 100mPD, except the more recent residential development at north- east of the area (Grand Promenade of about 219mPD) and the office development at Taikoo Place (One Island East of about 301mPD). A map of the Area is given in Figure 4.1. 2 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area X Position of Wind-A X Position of Wind-B Figure 4.1 Map of Study Area 3 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area 4.2 Site characteristics Topography: As mentioned, the site is bounded on the north by the Victoria Harbour and on the south by the Tai Tam Country Park. Therefore, the northern part of the site is at about 4mPD whereas the southern end of the site is at about 200mPD (Figure 4.2). The buildings at the southern part of Hong Shing Street have a site level of about 65-70mPD. However if we go further south, there is the Mount Parker (532m high) and the Siu Ma Shan (about 410m high) respectively on the SSE and SSW of the Area (Figure 4.3). The general site of the Area lies at the lower part of a valley stretching from south to north. Area north of the King’s Road is relatively flat. From King’s Road southwards, the land gradually slopes upwards. Victoria Harbour Tai Tam Country Park Figure 4.2 Contour map of the area (source from Google Map) 4 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area Study area Siu Ma Shan Mount Parker Figure 4.3 Tall mountains further south of the Study Area Figure 4.4 Mountain, wooded and greenery areas (from Google map) 5 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area Greenery and open space: The southern part of the Area is part of the Tai Tam Country Park (P1) which evidently provides plenty of trees and greenery. The Area is also surrounded by greenery on its east and west. On the east, it covers about one half of the length of the site boundary, and on the west about three quarters of the site boundary (Figure 4.4). Other than this natural greenery area, the largest greenery and open space is the long stretch of parks and sport grounds along the waterfront next to the Island Eastern Corridor. From the east end, there is the Lei King Wan Park, and the Quarry Bay Park which extends almost the entire length of the northern border of the site (P2, P3). There are areas for sports (e.g. soccer field, tennis courts & etc.) at about the centre of the park (P4). Towards the west is a relatively open space formed by the big round-about of the Island Eastern Corridor. At the western end of the park (next to Hoi Chak Street) there are also areas for sports (P5). From this description, it can be seen that there are some form of greenery or open space on almost all sides of the study area. Other than these larger open spaces, there are some smaller green areas dotted here and there in the Area: (The major greenery areas are high-lighted in Figure 4.5) • A rectangular patch of green area north of Taikoo Shing Road next to One Island East, this area is relatively big at more than 3000m2. • The strip of land running north-south along One Island East, Oxford House and Dah Chong Hong, to the understanding of the consultant, this strip of land is being developed into an open greenery space (P6). • Strip of tree-lined green area along Hong Yue street and Hong Pak Path and areas along hillside between building developments in the northern sector of the Area (P7). • There are also a few small open spaces, e.g. badminton court, pedestrian sitting area, dotted around the area (P8). • On the roof of podium of many building complexes, there is some form of roof garden with trees and open space (P9). Note: Photographs of the areas described are given in the Photograph Section at Annex I. 6 Term Consultancy for Air Ventilation Assessment Expert Evaluation on Quarry Bay Area Figure 4.5 Greenery and open space Layout of building development and street pattern: Overall, layout of building developments within the Area can broadly be classified into three types: 1) Building complex with several tall towers and large podium of rectangular or near rectangular shapes. The various phases of Taikoo Shing north of King’s Road belong to this type of development (P10). As such, the street layout around these developments are of rectangular grid pattern. Nam Fung Sun Chuen on the southern portion of the study area also has such rectangular pattern. 2) Building development where groups of tall towers (with or without podium) are constructed along a curve.