West Ryde Railway Station Development Wind Impact, Natural ...

REPORT 10-4961-R2 

Revision 0 

West Ryde Railway Station Development 

Wind Impact, Natural Ventilation Simulation 

and Reflectivity 

PREPARED FOR 

CRI Australia 

Level 2 

72 Berry Street 

NORTH SYDNEY NSW 2060 

22 FEBRUARY 2007


Wind Impact, Natural Ventilation Simulation 

and Reflectivity 

PREPARED BY: 

Heggies Pty Ltd 

ABN 29 001 584 612 

2 Lincoln Street Lane Cove NSW 2066 Australia 

(PO Box 176 Lane Cove NSW 1595 Australia) 

Telephone 61 2 9427 8100 Facsimile 61 2 9427 8200 

Email sydney@heggies.com Web www.heggies.com 

DISCLAIMER 

Reports produced by Heggies Pty Ltd are prepared for a particular Client’s objective and are based on a specific scope, conditions and limitations, as agreed 

between Heggies and the Client. Information and/or report(s) prepared by Heggies may not be suitable for uses other than the original intended objective. No 

parties other than the Client should use any information and/or report(s) without first conferring with Heggies. 

The information and/or report(s) prepared by Heggies should not be reproduced, presented or reviewed except in full. Before passing on to a third party any 

information and/or report(s) prepared by Heggies, the Client is to fully inform the third party of the objective and scope and any limitations and conditions, including 

any other relevant information which applies to the material prepared by Heggies. It is the responsibility of any third party to confirm whether information and/or 

report(s) prepared for others by Heggies are suitable for their specific objectives. 

Heggies Pty Ltd is a Member Firm of the 

Association of Australian Acoustical Consultants. 

Heggies Pty Ltd operates under a Quality System which 

has been certified by Quality Assurance Services Pty 

Limited to comply with all the requirements of 

ISO 9001:2000 "Quality Systems - Model for Quality 

Assurance in Design, Development, Production, 

Installation and Servicing" (Licence No 3236). 

This document has been prepared in accordance with the 

requirements of that System. 

DOCUMENT CONTROL 

Reference Status Date Prepared Checked Authorised 

10-4961-R2 Revision 0 22 February 2007 Matthew Glanville Peter Bourke Matthew Glanville 

10-4961-R1 Revision 0 29 January 2007 Matthew Glanville Peter Bourke Matthew Glanville 


Report Number 10-4961-R2 

Revision 0 


Wind Impact, Natural Ventilation Simulation and Reflectivity 

CRI Australia 

(10-4961R2) 22 February 2007 Page 2

EXECUTIVE SUMMARY 

Heggies Pty Ltd (Heggies) has been engaged by CRI Australia Pty Ltd to conduct a Reflectivity and Wind 

Impact assessment of the proposed West Ryde Railway Station Residential Development, and the 

potential for impact on the surrounding environs. 

In terms of Wind Impact & Natural Ventilation Simulation 

The wind assessment of the proposed West Ryde Railway Station Residential Development has revealed 

the following wind impact considerations. 

In terms of the future wind environment with the proposed development, the following areas are noted as 

being of most significance: 

• Ground Level perimeter footpath areas adjacent the west façade of all Buildings. 

• Level 1 podium terrace between Buildings A, B, C and D. 

Landscaping and other windbreak treatments already included in the proposed development will assist in 

the preservation of wind amenity both at ground level surrounding the site and upper levels of the 

development. Additional recommendations (refer Table 1) have been provided to assist in maintaining 

comfortable conditions at these locations throughout the year. 

It is predicted that, given the above, wind conditions at all public areas 

within and around the development, including street footpaths, should remain 

below the standard council 16 m/sec walking comfort criterion. 

A numerical investigation of a typical single sided apartment within the development has been conducted 

to further investigate the effect of natural ventilation upon cooling loads and potentially the energy 

consumption and star ratings of the apartment. Further comment upon the results described herein is 

contained in a Summary of Expert Opinion relating to Solar Access and Natural Ventilation compliance 

prepared by Steve King 15 th January 2007 also submitted with this Development Application. 

In terms of Reflectivity Impact 

This Reflectivity Analysis of the development shows that there will be no glazing elements within the 

proposed West Ryde Railway Station Residential Development facades which are capable of causing 

adverse glare events at surrounding locations. This is due to the following factors: 

• The development's glazing will have a reflectivity coefficient of less than 15%. 

• The development buildings are of modest height relative to surrounding critical carriageways. 

Building set-backs also assist in limiting glare potential for the site. 

• The facade design overlooking surrounding carriageways involves a mix of glazing forms which 

limit the potential to generate significant glare, eg through recessing within balconies, protection 

by shading elements, location relative to facade indentations, etc. 

In summary, through a combination of choice of glazing, facade design, 

façade orientation and low building height, no facades of the proposed 

West Ryde Railway Station Residential development will produce reflections 

causing either disability glare for passing motorists 

or unacceptable discomfort glare for passing pedestrians. 



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TABLE OF CONTENTS 

1 INTRODUCTION & SITE DESCRIPTION 5 

1.1 Points of Interest with Respect to Wind 5 

1.2 Points of Interest with Respect to Reflectivity 6 

2 WIND CHARACTERISTICS AND CRITERION AFFECTING THE SITE 8 

2.1 Wind Climate 8 

2.2 Pedestrian Wind Acceptability Criteria 8 

3 WIND IMPACT OF THE PROPOSED DEVELOPMENT 9 

3.1 Existing Winds – Wind Impact and Effects 9 

3.2 Future Winds - Predicted Wind Flow Patterns 9 

3.3 Future Winds - Wind Effects and Wind Mitigation Recommendations 10 

4 NUMERICAL ANALYSIS OF NATURAL VENTILATION 13 

5 SUMMARY AND RECOMMENDATIONS 16 

6 REFLECTIVITY IMPACT CONSIDERATIONS 18 

6.1 Glare Characteristics 18 

6.2 Glare Acceptability Criteria 18 

6.3 TI Value Assessment Sites 18 

6.4 Traffic Disability Glare Impact 19 

6.4.1 Reflections Impacting on Ryedale Road 19 

6.4.2 Reflections Impacting on the Northern Railway Line 19 

6.5 Reflectivity Summary 20 

Appendix A Seasonal Wind Roses for Sydney 

Appendix B CFD Modelling 

Appendix C Architectural Drawings 



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1 INTRODUCTION & SITE DESCRIPTION 

Heggies Pty Ltd (Heggies) has been engaged by CRI Australia Pty Ltd to conduct a Reflectivity 

and Wind Impact assessment of the proposed West Ryde Railway Station Residential 

Development, and the potential for impact on the surrounding environs. 

The development site is shown in Figure 1 and is located on a narrow north–south site, bounded 

by Ryedale Road to the East, the Main Northern Railway Line to the West and Victoria Road to the 

South. 

Figure 1 

Proposed West Ryde Railway Station Residential Development Site 

The project is a multi-storey residential development constructed on a single level podium. The 

development consists of the following residential components: 

• 2 levels of basement car parking. 

• Single level podium along the entire site including retail commercial space. On top of the 

podium the following residential buildings are proposed. 

• Building A: 11 storeys including one commercial level (10 residential levels) on the 

southern end of the site adjacent to the station. (Building A). 

• Buildings B and C: 8 storeys above the podium including one storey of commercial and 

communal facilities (7 residential levels). 

• Building D: 6 storeys above the podium including one storey with the childcare facility (5 

residential levels) on the northern end of the site. 

The proposed development is a relatively conventional multi-unit residential building, comprising 

a reinforced concrete structure with drywall partitions and masonry external walls. 



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1.1 Points of Interest with Respect to Wind 

Immediately surrounding the site is a mix of retail and residential developments including a 10 

storey residential apartment building on the opposite side of West Ryde Station to the southwest 

of the site and a series of 8-10 storey apartment buildings to the west of the site on the opposite 

side of the Northern Railway Line (see also Figure 3). Low to mid-rise retail and residential 

surround the site in all directions. 

Main public access entries into the building are via ground level lobbies off Ryedale Road. 

Landscaping has been proposed for the Level 1 Podium between the Buildings and around the 

site street perimeter. 

1.2 Points of Interest with Respect to Reflectivity 

Primary façade materials include the following: 

• The glazing chosen for the proposed development will have a reflectivity coefficient of less 

than 15%. 

• The other main façade materials will be rendered / painted concrete with minimal reflectivity. 

The facade design overlooking surrounding carriageways involves a mix of glazing forms which 

limit the potential to generate significant glare, eg through recessing within balconies, protection 

by division screens, location relative to facade indentations, etc. 



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Wind Impact 



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2 WIND CHARACTERISTICS AND CRITERION AFFECTING THE SITE 

2.1 Wind Climate 

In relation to key characteristics of the Sydney Region Wind Climate (Appendix A) relevant to the 

wind impact assessment of the proposed development, we note that Sydney is affected by two 

primary wind seasons: 

• Summer winds occur mainly from the northeast, south and southeast. While northeast winds 

are the more common prevailing wind direction (occurring typically as offshore land-sea 

breezes), southeast and south winds generally provide the strongest gusts during summer. 

• Winter/Early spring winds occur mainly from the west and the south. West quadrant winds 

(southwest to northwest) provide the strongest winds during winter and in fact for the whole 

year. 

2.2 Pedestrian Wind Acceptability Criteria 

The wind impact criteria originally developed by Sydney City Council and used throughout 

Sydney to assess the acceptability of proposed new building developments are as below: 

• The general objective is for annual 3-second gust winds to remain at or below the so-called 

16 m/s “Walking Comfort” criterion. This is a 3 second gust wind speed occurring once per 

year. Whilst this magnitude may appear arbitrary, its value represents a level of wind 

intensity the majority of the population would find unacceptable for comfortable walking on a 

regular basis at any particular location. 

• In many urban locations, either because of exposure to open water conditions or because of 

street “canyon” effects, etc, this level is already currently being exceeded. In such instances 

a new development should not exacerbate existing adverse wind conditions and should 

wherever feasible and reasonable ameliorate such conditions. 



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3 WIND IMPACT OF THE PROPOSED DEVELOPMENT 

3.1 Existing Winds – Wind Impact and Effects 

Existing street level wind conditions in the vicinity of the site are likely to be under the 16 m/sec 

“walking comfort” criterion for most prevailing winds given that the project site is relatively 

protected in a 360 degree pan around the site. In addition there is limited height to existing 

buildings at and near the site with reduced potential to induce channelling and downwash effects 

to wind flow. 

The western end of the site is of most significance for considerations of wind impact as strong 

west quadrant winds prevail during winter/early spring with limited shielding provided by low to 

mid-rise developments upstream. 

Limited shielding is provided to southerly winds by existing developments to the south and the 

downward sloping terrain reaching to the open waters of the Parramatta River approximately 

1500 metres from the site. 

3.2 Future Winds - Predicted Wind Flow Patterns 

Figure 2 provides a graphical representation of the interaction of the proposed development with 

the prevailing local Sydney wind climate and surrounding built environment. These are described 

below as a series of “Wind Actions”. 

Northeasterly Winds 

Northeast winds occur in Sydney mainly during summer. They are typically land-sea breezes and 

tend to be of only moderate strength at the West Ryde site. For the greater part of the time 

during summer these winds will, if anything, provide a desirable cooling effect to the proposed 

development. 

All four buildings have east-facing facades that include apartment living spaces and with exposure 

to these northeast winds and potential to provide natural ventilation to facing apartments (See 

Section 4). The availability of cooler ventilation breezes can provide beneficial cooling during 

summer months 

Westerly (Winter/Early Spring) Winds 

West quadrant winds (southwest to northwest) provide the strongest winds during winter and in 

fact for the whole year. 

Wind Action 1 Westerly winds will approach the site with limited immediate shielding provided 

by the low to mid-rise buildings upstream of the site. The west facades of all Buildings A, B, C 

and D will have a tendency to reduce the horizontal component of wind velocity directly upstream 

of the building producing an increase in positive pressure against the facade. To compensate for 

the reduction in speed against the windward west facade, winds will accelerate to higher 

velocities over the top, around the sides and between the buildings. These higher so-called 

“release” velocities will wrap around building corners and induce high negative pressures against 

the facade (tending to suck air out of the building). 

Westerly winds impacting with the western facade will accelerate to higher velocities over the top 

and around the sides of the building. These higher release velocities will accelerate through 

corner balconies inducing higher wind conditions at these locations. 



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Figure 2 Westerly Windflow Movement through the site 

Wind Action 2 



Wind Action 2 For westerly winds the stagnation of wind flow against upper levels of the west 

facades of Buildings A, B, C and D will be drawn towards ground level in the form of vertical 

“downwash” flow. The downwash effect from upper levels will have some impact at ground level 

locations adjacent the Northern Railway line. Downwash will continue to flow beneath the 

apartment blocks at podium level where openings exist. 

Southeast (Summer) and South (All Year Round) Winds 

South and southeast winds occur in Sydney throughout the year generally providing the strongest 

gusts during summer. There exists limited shielding upstream to the south of the site providing 

limited protection from the impacts of southerly winds at ground level. Furthermore, there will be 

some acceleration of southerly winds toward the site over the upstream topography rising from 

the open waters of the Parramatta River. There will be a channelling effect along Ryedale Road 

(Wind Action 3) on the western and eastern sides of Buildings A, B, C and D at ground level. 

3.3 Future Winds - Wind Effects and Wind Mitigation Recommendations 

Table 1 summarises the potential wind effects resulting from these wind actions at pedestrian 

locations throughout the site and, where required, possible windbreak amelioration needed to 

reduce winds to more acceptable levels in terms of human comfort. 

Additional treatments are recommended where new or improved windbreaks are required beyond 

those already shown in existing architectural drawings; eg street trees, trellis screens, etc. 



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Table 1 

Wind Impact and Recommended Windbreak Treatments 

Location of 

Interest 

Potential Magnitude 

of Wind Impact 

Explanation of Wind Impact 

Additional Windbreak Treatment / 

Recommendations 

Street Perimeter 

Footpaths on 

Ryedale Road. 

Moderate 

Winds approaching the 

16 m/s walking criterion 

Channelling of southerly winds along the 

Ryedale Road perimeter of the site (Wind 

Action 3). 

Trees proposed along Ryedale Road and throughout the 

Level 1 podium should also serve to disperse the 

channelling effect. Tree planting shown on current 

architectural drawings will serve to disperse channelling 

winds over a wider area with reduced intensity. 

Level 1 Podium 

Moderate to High 

Winds at the 

16 m/s walking criterion 

The potential impact of wind flow upon 

the Level 1 podium terrace and wind 

channelling between Buildings A, B, C 

and D is described by Wind Action 1. 

Downwash generated against the west 

facade spilling onto the podium (Wind 

Action 3). Wind Actions 1 and 3 will 

combine to produce strong wind 

conditions in the gaps between Buildings 

A, B, C and D. 

Current architectural drawings indicate podium planting 

will be included in the gaps between the podium 

buildings. Dense planting achieving heights of 4 metres 

or more should be encouraged throughout these building 

gap locations to deflect and disperse winds above 

walkway level. Alternatively a series of porous screens 

(50% porosity) of similar size could be used. 

Buildings A, B, C and D west façades will divert flow 

toward ground level in the form of downwash. Given the 

height of the building winds at ground level could be 

approaching the16 m/s walking criterion. 

Residential 

Building Entrance 

Lobbies. 

Low to Moderate 

Winds likely below the 

16 m/s walking criterion. 

Lobby entrances will receive 

considerable wind shielding from the 

Wind Actions described above by the 

podium set-back and Rdale Street 

awnings. 

As an optional measure, shrubs, planter boxes, etc, 

could be added outside the building entry points to 

assist in breaking up winds. Such wind measures also 

serve as windicators” which would not only help 

ameliorate higher strength winds but, more importantly, 

give users of the development warning of uncomfortable 

wind conditions when entering and leaving the building. 

Upper Level 

Balconies 

High Wind Actions 1. Wrap around corner balconies will experience the 

strongest winds. Non-porous side walls have been 

included on corner balconies to prevent winds 

accelerating through these spaces. 


West Ryde Railway Station Development Wind Impact, Natural Ventilation Simulation and Reflectivity 

Report Number 10-4961-R2 CRI Australia 

Revision 0 (10-4961R2) 22 February 2007 Page 11

Location of 

Interest 

Potential Magnitude 

of Wind Impact 

Explanation of Wind Impact 

Additional Windbreak Treatment / 

Recommendations 

Internal winds 

through “dual 

frontage” 

Residential 

Apartments 

Moderate 

External doors and windows 

may become difficult to 

operate. 

Potential for internal door 

slamming, paper blown off 

tables, strong internal 

breezes. 

Wind Action 1. 

Residential apartments at the northern 

and southern most ends of each block 

have a multiple aspect or “dual frontage” 

to enable cross-flow from opposite 

facades, thereby encouraging natural 

ventilation under most prevailing wind 

conditions. 

However, during stronger winds high 

internal flows could be established 

through the apartments driven by 

pressure differentials across the building 

envelope. 

Minor Technical Considerations Required 

Risk of apartment opening during extreme wind events 

to be considered during detailed design. Possible 

solutions include: 

• Full/partial seal of facades facing prevailing wind 

directions and at critical corner locations. 

• Implement strata management plans requiring 

tenants to close all doors and windows when the 

apartments are unoccupied. 

Central Apartments in each block include single loaded 

corridors to the west, serving as the acoustic ‘buffer’, 

with all habitable rooms generally oriented to the east 

away from the railway noise. These single sided 

apartments will not experience the same level of cross 

flow experienced by the dual frontage apartments with 

reduced potential for adverse wind impact. Section 4 

below outlines the potential for cooling breezes to 

penetrate the single sided apartment. 


West Ryde Railway Station Development Wind Impact, Natural Ventilation Simulation and Reflectivity 

Report Number 10-4961-R2 CRI Australia 

Revision 0 (10-4961R2) 22 February 2007 Page 12

4 NUMERICAL ANALYSIS OF NATURAL VENTILATION 

Aspects of residential apartment amenity have acquired a new importance in NSW, due to the 

influence of State Environmental Planning Policy 65 - Design of Residential Flat Buildings. Whilst 

SEPP 65, Principle 7 - Amenity - refers to “natural ventilation”, supporting documents specify or 

describe “cross ventilation”. Little if any attention is being paid to the often acceptable ventilation 

performance of single sided units. 

All single sided residential apartments within the West Ryde Development are elevated and will 

have exposure to prevailing breezes as discussed in Section 3.2 of this report. The availability of 

breezes provides a heat purge mechanism for the apartments and a highly effective means for 

reducing cooling loads in summer. Heat build up of the apartment air volume during the summer 

months can be quickly displaced through window/door opening and cross ventilation. 

A numerical investigation of a typical single sided apartment within the development has been 

conducted to further investigate the effect of natural ventilation upon cooling loads and potentially 

the energy consumption and star ratings of the apartment. 

A simplified 3D model was created using Computational Fluid Dynamics (CFD) software. A 

typical single sided apartment in Building C was modelled at the location shown in Figure 3 on 

the east side of the building and with immediately surrounding developments modelled. The 

building was subjected to north easterly wind flow and the resulting effect on ventilation within the 

apartment investigated. The model was run for a time dependant ventilation scenario where all 

doors were open, along with all internal bedroom doors. The average magnitude of wind flow was 

assumed to be 1 m/s conservatively approximating a typical afternoon breeze. With an initial 

internal temperature of 30ºC, the apartment was exposed to the breeze at 22ºC. 

Figure 3 CFD Model of the built environment surrounding the test apartment. 

Test 

Apartment 



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The following figures show the static temperature of the apartment 1.5 meters above the ground, 

in one minute intervals after exposure. Slight pressure differentials between openings produce 

weak breezes through the apartment, which effectively purge the unwanted heat. This analysis 

shows that despite the apartment only having single sided openings, opening the two balcony 

doors produced airflow resulting in an efficient purging of the internal heat load. 

Figure 4 Static temperature contours of the Single Sided Apartment over 6 minutes 

Time = 30 seconds 

Time = 1 min 

Time = 2 minutes 



Time = 1 hour 



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It can be seen from the figures that in only 10 minutes the internal temperature has dropped 

significantly, with the majority of the apartment being within 2ºC of the ambient temperature. 

The total time needed to purge heat from the single opening space is in the order of half an hour 

and needs to be considered in a practical context. Most cooling breezes will persist for at least 

this order of time providing ample opportunity to displace the internal volume of heated apartment 

air. 

Further comment upon the results described above is contained in a Summary of Expert Opinion 

relating to Solar Access and Natural Ventilation compliance prepared by Steve King 15 th January 

2007 also submitted with this Development Application. 



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5 SUMMARY AND RECOMMENDATIONS 

The wind assessment of the proposed West Ryde Railway Station Residential Development has 

revealed the following wind impact considerations. 

In terms of the future wind environment with the proposed development, the following areas are 

noted as being of most significance: 

• Ground Level perimeter footpath areas adjacent the west façade of all Buildings. 

• Level 1 podium terrace between Buildings A, B, C and D. 

Landscaping and other windbreak treatments already included in the proposed development will 

assist in the preservation of wind amenity both at ground level surrounding the site and upper 

levels of the development. Additional recommendations (refer Table 1) have been provided to 

assist in maintaining comfortable conditions at these locations throughout the year. 

It is predicted that, given the above, wind conditions at all public areas 

within and around the development, including street footpaths, should remain 

below the standard council 16 m/sec walking comfort criterion. 

A numerical investigation of a typical single sided apartment within the development has been 

conducted to further investigate the effect of natural ventilation upon cooling loads and potentially 

the energy consumption and star ratings of the apartment. Further comment upon the results 

described herein is contained in a Summary of Expert Opinion relating to Solar Access and 

Natural Ventilation compliance prepared by Steve King 15 th January 2007 also submitted with this 

Development Application. 



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Reflectivity Impact 



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6 REFLECTIVITY IMPACT CONSIDERATIONS 

6.1 Glare Characteristics 

With respect to the reflectivity impact of the proposed development, the following issues are 

relevant: 

• At large incident angles (typically greater than 70 o ), the reflectivity of all glazing types 

increases dramatically. Thus, regardless of the glazing type, the potential for glare increases 

significantly when incoming solar rays can impact on a building close to parallel to the plane 

of the glazing. 

• On a practical level, incoming solar rays with an altitude angle greater than 20 o are 

intersected and obstructed by a typical windscreen roof-line. In this Report, it is assumed 

that the sun altitude angle must be less than 25 o to have the potential to produce a traffic 

disability glare event. 

• Pedestrian discomfort glare can occur when the sun altitude is greater than 25 o . However, in 

most such instances, a pedestrian has the ability to adjust his/her line of sight to a more 

horizontal view away from the glare source. 

• It is assumed that glare events can only occur when the solar altitude is greater than about 

3 o , enabling the entire solar disc to be visible. 

6.2 Glare Acceptability Criteria 

The criteria used within this Report to assess the acceptability or otherwise of glare events is 

through the so-called “Threshold Increment Value”, or TI Value, of the reflection condition. 

• In assessing traffic disability glare, the TI value should remain 

• below 10 for major roads and 

• below 20 for minor roads. 

• In assessing pedestrian discomfort glare, TI values should remain 

• below 2 at pedestrian crossings and 

• below 3 for other footpath locations. 

6.3 TI Value Assessment Sites 

All surrounding traffic areas were examined for disability and discomfort glare including Ryedale 

Road, Victoria Road and the Northern Railway Line. The relatively modest height of the 

development’s buildings precludes the possibility of reflected glare on streets further a field. 

In relation to reflectivity, the local built-up environment comprises mainly medium-rise residential 

buildings with limited capacity to provide solar shielding to the site. 



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6.4 Traffic Disability Glare Impact 

6.4.1 Reflections Impacting on Ryedale Road 

Reflection conditions associated with the development’s eastern façades (overlooking Ryedale 

Road) that have been examined are: 

• Mid to late morning winter rays striking the eastern façade of all Buildings from the north with 

reflections towards the south along Ryedale Road. 

We note firstly that the development's glazing will have a reflectivity coefficient of less than 15%. 

In relation to reflections off the eastern facade, a number of factors contribute towards TI values 

being minimal or non-existent for all of the examined conditions, in particular: 

• The design of the eastern side of all buildings incorporates an articulated facade with 

recessed glazing which limits the potential for this façade to create reflections. Reflections 

off the protruding masonry sections and other non-glazed façade elements (such as balcony 

privacy screens) will produce diffuse type reflections without potential to generate specular 

glare reflections. 

• If aluminium louvres are used for window shading these should have a matt sheen and be of 

darker colouring to minimise potential for specular reflections. 

• The provision of street trees on the footpath of Ryedale Road will provide some limited 

blockage to incoming solar rays and potential reflections. 

• The facade areas of interest are of relatively modest height (compared to high-rise 

developments) thereby limiting the potential angles able to create potential reflections which 

can impact at far field locations. 

As a consequence, our calculations at all relevant locations yield negligible TI values. 

6.4.2 Reflections Impacting on the Northern Railway Line 

Reflection conditions associated with the development’s west façade that have been examined 

are: 

• Midday and early afternoon winter rays striking the western façades of all Buildings from the 

north with reflections towards the south along the train line. 

For the reasons described above for the Ryedale Road façade, reflected solar rays from the west 

facade are expected to produce TI values being minimal or non-existent. 



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6.5 Reflectivity Summary 

This Reflectivity Analysis of the development shows that there will be no glazing elements within 

the proposed West Ryde Railway Station Residential Development facades which are capable of 

causing adverse glare events at surrounding locations. This is due to the following factors: 

• The development's glazing will have a reflectivity coefficient of less than 15%. 

• The development buildings are of modest height relative to surrounding critical carriageways. 

Building set-backs also assist in limiting glare potential for the site. 

• The facade design overlooking surrounding carriageways involves a mix of glazing forms 

which limit the potential to generate significant glare, eg through recessing within balconies, 

protection by shading elements, location relative to facade indentations, etc. 

In summary, through a combination of choice of glazing, facade design, 

façade orientation and low building height, no facades of the proposed 

West Ryde Railway Station Residential development will produce reflections 

causing either disability glare for passing motorists 

or unacceptable discomfort glare for passing pedestrians. 



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Appendix A 

Report 10-4961-R2 

Page 1 of 1 

SEASONAL WIND ROSES FOR SYDNEY 

Spring 

Summer 

Autumn 

Winter 

Wind Speed (m/s) 

>= 9.5 

7.5 – 9.5 

5.5 – 7.5 

3.5 – 5.5 

1.5 – 3.5 

0.5 – 1.5 

*data obtained from BOM Sydney Airport Monitoring Station 

(10-4961R2) 

Heggies Pty Ltd

Appendix B 

Report 10-4961-R2 

Page 1 of 1 

CFD MODELLING 

Numerical Modelling Assumptions 

The CFD model used for this study was prepared using GAMBIT software and processed using 

FLUENT finite element software. The package was used to solve the Navier-Stokes conservation 

equations for continuity, momentum and energy in the computational domain, to predict the 

transient distribution of airflow and energy. An iterative procedure was used to solve the 

governing equations in the computational domain. 

Geometry and Mesh 

A geometrically representative 3-dimensional model of the Residential Buildings and the existing 

surrounding developments was constructed. 

The geometry was created using GAMBIT software. The computational domain was covered by a 

mesh of approximately 1,500,000 tetrahedral elements and 2,000,000 nodes with seven degrees 

of freedom (p,u,v,w,k,ε,energy). 

Additionally a 2D mesh with increased levels of mesh discretion was created to aid the basic wind 

impact assessment. This was also created in Gambit using a mesh of approximately 295955 quad 

and tri elements. This mesh also included a boundary layer mesh on the walls of the building. 

Boundary conditions 

A profiled velocity inlet was modelled 300 metres upstream to the north east of the tower and 300 

metres downstream to the east. An average velocity of 5m/s was used with the randomly varying 

between 4 and 6 m/s with varying degrees of yaw and turbulence kinetic energy. An outflow 

boundary condition was modelled downstream of the building as well as to either side and above. 

Turbulence specification k- standard model (kinetic energy and dissipation rate) were calculated 

from empirical relationships 

(10-4961R2) 

Heggies Pty Ltd

Appendix C 

Report 10-4961-R2 

Page 1 of 1 

ARCHITECTURAL DRAWINGS 

The environmental impact assessment carried out in this report was based on the following 

architectural drawings supplied by Cox Richardson Architects 11 December 2006: 

• DA-A-204_01 

• DA-A-102_01 

• DA-A-107_01 

• DA-A-108_01 

• DA-A-109_01 

• DA-A-110_01 

• DA-A-111_01 

• DA-A-112_01 

• DA-A-113_01 

• DA-A-114_01 

• DA-A-201_01 

• DA-A-202_01 

(10-4961R2) 

Heggies Pty Ltd

S T E V E K I N G 

C O N S U L T A N T A R C H I T E C T 

A B N 3 1 3 8 8 3 8 0 5 5 7 

1 1 C L O V E L L Y R O A D R A N D W I C K N S W 2 0 3 1 

M o b . 0 4 1 4 3 8 5 4 8 5 P h o n e / F a x 0 2 9 3 9 8 6 3 7 6 

F A C U L T Y O F T H E B U I L T E N V I R O N M E N T U N I V E R S I T Y O F N E W S O U T H W A L E S 

P h o n e 0 2 9 3 8 5 4 8 5 1 F a x 0 2 9 3 8 5 4 5 0 7 e – m a i l : s t e v e k @ u n s w . e d u . a u 

SUMMARY EXPERT OPINION 

SOLAR ACCESS 

AND 

NATURAL VENTILATION COMPLIANCE 

WEST RYDE RAILWAY STATION RESIDENTIAL DEVELOPMENT 

1.0 PRELIMINARIES 

15 January 2007 

1.1 I provide this summary report as an expert opinion, relating to solar access and 

natural ventilation compliance of apartments on the above site, under the applicable DCP and 

SEPP65. 

2.0 DOCUMENTS 

2.1 Preliminary DA drawings issued by Cox Richardson Architects 11 December 2006: 

• DA-A-204_01 

• DA-A-102_01 

• DA-A-107_01 

• DA-A-108_01 

• DA-A-109_01 

• DA-A-110_01 

• DA-A-111_01 

• DA-A-112_01 

• DA-A-113_01 

• DA-A-114_01 

• DA-A-201_01 

• DA-A-202_01 

• DA-A-203_01 

2.2 Preliminary CFD analysis of natural ventilation by Heggies (Draft Report 10-4961-R1 

dated 15 January 2007). 

3.0 GENERAL APPRAISAL OF THE PROPOSED DEVELOPMENT 

3.1 Massing and site layout 

The site is bounded to the west by the railway line and south and east by the public 

roadways. The extreme narrow land dimension and the similarly extreme external noise 

mitigation required are the major planning constraints, determining the general form of the 

complex as a series of ‘slab’ blocks. 

The apartment planning is the logical response of single loaded corridors to the west, serving 

as the acoustic ‘buffer’, with all habitable rooms generally oriented to the east away from the 

railway noise, and forming the civic façade of the buildings. 

The easterly outlook provides a high degree of amenity with uninterrupted views for all 

apartments. This orientation also has the additional benefit of unobstructed solar access from 

Page 1 of 9

shortly after sunrise throughout the year, including mid-winter, and unobstructed access to 

the all of the summer cooling breezes from the south to the north-east. 

In my considered opinion, the general planning and site layout strategy is the only sensible 

response to the site. The detailed disposition of apartments, and in particular the method of 

articulation of the façade then become critical in achieving both solar access compliance and 

maximising the benefit of natural ventilation. 

4.0 SOLAR ACCESS COMPLIANCE 

4.1 Methodology 

The assessment technique relies on a fully developed 3D computer model, with manual count 

of half hourly or more closely spaced time intervals of sun exposure on the relevant facades. 

The projection used is known as ‘View from the Sun’. Technically the views are true 

perspective from the apparent position and distance of the Sun. The critical utility of Views 

from the Sun is that the technique allows direct and precise quantification of solar access for 

individual apartments, because: 

• all sunlit faces are shown; 

• all surfaces in shadow are hidden by the objects that overshadow them. 

It is important to note that by definition, therefore, the views show no shadows. 

In my considered opinion therefore on a site of this complexity no other technique is suitable 

for an appropriately detailed solar access and overshadowing assessment. 

4.2 Assessment Criteria 

4.2.1 Time of exposure to solar access 

Given that actual effective sun access is being examined, I consider it legitimate to take 

account of solar access outside the hours of 9 a.m. to 3 p.m. 

The conventional limitation of effective sunlight to between those hours normally reflects 

uncertainty as to whether lower sun angles may be obstructed by unknown features remote 

from the site. Where that uncertainty is not relevant, both early morning and late afternoon 

winter sun are demonstrably of high amenity value for private outdoor space and especially 

glazing oriented in appropriate directions, as is the case on this site. 

Explanation 

The basis of the preferred time period for the consideration of effective 

sunlight being 9a.m. to 3p.m. is historical. When there were no means to 

accurately examine actual sunlight available to complex buildings, it was 

reasonably assumed that a conservative estimate of achieved solar 

access for generally northerly glazing could only be obtained if there was 

a high degree of certainty that sun would be available from a particular 

portion of the sky. 

A more careful examination of the actual sunlight penetration for glazing 

of different orientations makes clear that for easterly oriented glazing 

early morning sun is highly effective. It is near normal to the glazing 

surface, and is likely to penetrate deeply into the interior of the habitable 

room of which the glazing is part. 

With comprehensive computer model simulation including the 

surrounding topography of the built form, it is possible to establish 

whether or not the relatively low altitude sun is likely to remain 

unalienated in the long term. On this site, that is clearly the case. 

In short, by excluding morning and afternoon sun, solar access rules as 

currently applied have the effect of actually excluding some of the more 

SUMMARY EXPERT OPINION: SOLAR ACCESS AND NATURAL VENTILATION 

WEST RYDE RAILWAY STATION RESIDENTIAL DEVELOPMENT Page 2 of 9

effective likely sunlight penetration of interiors. The underlying 

performance objectives of both energy-based and amenity oriented solar 

access requirements are better met if the qualifying time period during 

the mid-winter day is not limited ⎯ other than excluding perhaps the 

first and last half hour of the day. 

4.2.2 Angles of incidence to facades 

I have also conformed with the principles set out by Roseth, SC of the Land and Environment 

Court of NSW in Parsonage vs Ku-rin-gai, for what might be called ‘effective solar access’. 

Eplanation 

In qualifying effective sun access, there are three reasons to limit the 

acceptable angle of incidence of solar radiation to the glass: 

• At large angles of incidence, the proportion of radiation falling on 

the glass actually transmitted rapidly diminishes, and the 

proportion externally reflected rapidly increases. This is simply 

an optical quality of the glass itself, and a suitable threshold 

angle has to be nominated. When sunlight is very acute to the 

plane of the glass, it is also highly likely to be obstructed by 

normal amounts of reveal associated with the window framing. 

• Sunlight falling on an opening at an acute angle achieves very 

small slivers of sunlight in the occupied space of which that 

glazing is part. 

Different authorities nominate different assumed angles, but the 22.5° nominated in Technical 

Bulletin 13 is a reasonable conservative threshold. In reality, the angle of incidence should 

be imposed in both plan and section. Here I estimate the angle of incidence in the 3D views, 

and exclude sun which will not create a distinct and usable sun patch. 

4.2.3 The proportion of glazing to be accepted as complying 

I apply the ‘50% rule’ from in Parsonage vs Ku-rin-gai, and count as complying only where a 

minimum of 50% of relevant glazing is sunlit. 

4.3 Quantification of solar access 

The plans are not labelled with unique identifiers of the 181 individual apartments. I therefore 

provide the quantification in summary form in Table 1, referenced to the four individual 

buildings within the development. 

With the given plan arrangements, in general the terraces and verandahs receive as long as, 

or longer sun exposure than the adjacent glazing. Therefore, I do not distinguish in the table 

between designated living area glazing and private open space on terraces or verandahs. 

Earliest sun 

exposure Still in sun at 

Number of 

apartments 

07.30 10.00 10.30 

≥2.5 

hours 

≥3 

hours Complying 

Total 

apartments 

Block A 48 16 32 16 48 54 

Block B 38 9 29 9 38 50 

Block C 42 10 32 10 32 50 

Block D 23 8 15 8 23 27 

TOTAL 108 43 141 181 

% 78% 

Table 1: Summary of complying sun access at mid-winter June 21 

The relevant views ‘views from the sun’ are attached as Appendix B of this Opinion. 



5.0 NATURAL VENTILATION COMPLIANCE 

5.1 Performance Objectives 

The RFDC also gives a quantified recommendation for interpreting SEPP 65 with respect to 

natural ventilation: 

• Building depths, which support natural ventilation typically range from 10 to 18 

metres. 

• Sixty percent (60%) of residential units should be naturally cross ventilated. 

• Twenty five percent (25%) of kitchens within a development should have access to 

natural ventilation. 

• Developments, which seek to vary from the minimum standards, must demonstrate 

how natural ventilation can be satisfactorily achieved, particularly in relation to 

habitable rooms. 

(Rules of Thumb: Natural Ventilation p.87) 

SEPP65 itself does not refer to prescribed quantitative standards, but may be regarded as a 

performance based regulatory instrument. Proper reading of the Residential Flat Design 

Code as it interprets SEPP65 similarly makes clear the performance based approach of the 

Code. 

However, the control of energy efficiency and energy use for assuring thermal comfort is now 

vested exclusively in SEPP BASIX. It would therefore be reasonable to assume that specific 

performance measures for buildings designed in compliance with SEPP65 would be 

scrutinized in light of a more general energy conservation objective, with emphasis on the 

issue of ventilation for general amenity. 

5.2 Natural ventilation/cross ventilation 

So-called ‘cross-ventilation’ is a simplistic expedient for checking the likely contribution of 

natural ventilation to projected comfort conditions. ‘Cross-ventilation’ describes the condition 

where a dwelling has operable openings to two or more distinctly different orientations, thus 

making likely that in any conditions of breeze, relative pressure differentials will assure some 

air movement through connected spaces in the dwelling. The Rules of Thumb in the 

Residential Flat Design Code give a quantified recommendation for interpreting SEPP65 with 

respect only to cross ventilation, relating to the overall proportion of complying dwellings, but 

not to the expected performance for any one dwelling. 

The simple definition of cross ventilation is met by all ‘end’ apartments in the complex. In 

addition, another group of apartments are designed with cantilevered portions of the main 

living area, assuring that openings are available in adjacent parts of the façade ⎯ of 

sufficient separation and sufficiently different wind pressure under all likely conditions, as to 

be safely classified as also cross-ventilated. Finally, the top floor duplex apartments are 

provided with skylights that can be assumed to be reliable means of assuring exhaust 

ventilation to the low pressure zone of the roof for all wind directions, and therefore to enable 

cross ventilation of those apartments. 

In Table 3 summarising the ventilation compliance, all such apartments are classified as 

cross-ventilated without further discussion here. 

5.3 Enhanced single sided natural ventilation 

As a consequence of the acoustic protection measures adopted in the planning, the majority 

of apartments in the proposed development are single sided. 

I have previously demonstrated that natural ventilation compliance under the RFDC is 

achievable by suitably designed single sided apartments with reliable exposure to the 

prevalent summer cooling breezes in Sydney. The fundamental attribute for achieving this 

condition is the degree of ‘relief’ in the dominant windward façade ⎯ by use of protruding 

elements and recessed balconies, as notably employed in this design. The ventilation 

potential of single sided units is further significantly enhanced by some design attributes: 

• ‘Shallow’ plan dimensions measured from the façade; 



• Detailing of façade elements that is likely to create and enhance local pressure 

differentials between adjacent rooms and/or openings to the same room. 

• Internal layout that is relatively ‘clean’, i.e. minimizes obstructions to air movement; 

• Internal openings of significant area provided to bedrooms, assuring least loss of 

momentum for the air stream where air movement between living and sleeping zones 

is envisaged; 

• Window sizes and operable sash areas in excess of industry average provisions; 

• Physical protection of principal openings to assure shelter in conditions of wind driven 

rain. 

5.4 Cooling wind and breeze exposure 

Figure 1 illustrates the relative distribution of frequency and velocity of summer winds for 

Sydney, based on the Reference Meteorological Year. 

Figure 1: Summer wind velocities and frequencies, Sydney. 

The chart shows relative frequencies for the whole day. It may be noted that the most 

frequent winds suitable for general cooling are the sea breezes from just east of north to 

south-east. Southerly ‘busters’ can achieve rapid cooling, often accompanied by rapid 

temperature drops and higher wind speeds. These also occur with useful frequency. 

All apartments in the subject development have a favourable exposure to the above wind 

orientations. 

5.5 Validation study by Heggies 

Heggies have undertaken CFD validation of the likely velocities and air exchange patterns 

with relation to a ‘worst case’ typical apartment plan in this development. The results of the 

CFD simulations for this project confirm that the single sided ventilation effects are sufficiently 

reliable under the influence of Sydney’s prevailing wind regime. 



It is therefore confidently predicted that ventilation for mass heat flow (ie. removal of excess 

heat from the air volume and building fabric at appropriate times) will be sufficient to ensure 

adequate cooling performance. 

5.6 Quantification of ventilation compliance 

For units located on lower floors of the proposed development, likely air change rates will 

cope quite adequately with so-called mass heat flow effects, as necessary to achieve 

appropriate summer cooling. Upper levels that are subject to unobstructed higher wind 

velocities are likely be more concerned with restricting the potential air exchange, and are in 

my view unlikely to try to take advantage of all available operable sashes provided. 

m/s 

km/h 

Still 0.0 0.0 

Not Noticeable 0.1 0.4 

Barely Noticeable 0.3 1.0 

Pleasant Breeze 0.5 1.8 

Light Breeze 0.7 2.5 

Hair and Papers Move 1.0 4.0 

Noticeably Draughty 1.4 5.0 

Unpleasant Breeze 1.7 6.0 

Gusting Breeze 2.0+ 6.5+ 

Table 2: Effect of air velocities on perceived comfort 

Table 2 above indicates general responses to different air speeds. Note that air velocities in 

excess of 1.4m/s (corresponding to winds in excess of 5km/h) will be considered of nuisance 

value. Thus, assuming a very conservative scenario that internal air velocity one meter from 

the window is no more than 30% of available wind speed, winds of over 15km/hr are likely to 

be excluded more than encouraged. 

So-called comfort ventilation, which relies on adequate air velocities, can therefore be 

expected to be adequate for all units in the development at most times. Again, I would expect 

that upper floors are likely to need to restrict openings more often than to maximize them. 

Cross 

ventilated 

Reliable enhanced 

single sided Complying 

Total 

apartments 

Block A 29 25 54 54 

Block B 26 24 50 50 

Block C 24 26 50 50 

Block D 15 12 27 27 

TOTAL 94 87 181 181 

% 54% 46% 100% 

Table 3: Natural ventilation compliance 

The addition of acoustically baffled ducts connecting the living area of some apartments to 

the western façade above ceiling level, is an additional enhancement of the likely ventilation 

performance. I note that the potential enhanced ventilation effect of such ducts is not 

incorporated in the Heggies worst case configuration model. In my view, detailed accounting 

for the contribution of such ducts to the characterisation of natural ventilation compliance is 

not necessary in this instance, as the otherwise enhanced single sided ventilation itself may 

be safely characterised as complying with the performance requirements of the RFDC. 



6.0 CONCLUSIONS 

6.1 Site constraints 

The site is bounded to the west by the railway line. The extreme narrow land dimension and 

the external noise mitigation required from the railway determine the general form of the 

complex, as a series of ‘slab’ blocks of single loaded corridors to the west serving as the 

acoustic ‘buffer’, with all habitable rooms generally oriented to the east. 

It is reasonable to acknowledge that the site conditions of this development give rise to a 

severely constrained design response for both solar access and natural ventilation 

compliance. 

6.2 Solar access 

The easterly orientation is shown by comprehensive 3D modelling to achieve unobstructed 

solar access from shortly after sunrise throughout the year, including mid-winter. 

This easterly low sun is safely categorized as ‘effective sunlight’ in accordance with the 

principles laid down by the Land and Environment Court in its interpretation of compliance. 

Counting sun access from that time, most apartments relying only on the easterly façade 

achieve variously a minimum of 2.5 or 3 hours of sun to both living area glazing and private 

open space. Approximately a quarter of the apartments achieve additional afternoon sun to 

living spaces or other rooms. The morning sun can be regarded as achieving a high degree 

of amenity for the relevant apartments, providing suitable winter warm-up early in the day, 

while avoiding adverse westerly afternoon sun exposure in summer. 

On that basis, the proportion of apartments characterised as complying is 141 from a total of 

181, being 78%. This complies with the RFDC Rules of Thumb. 

6.3 Natural ventilation 

The easterly orientation of the long facades of the slab blocks gives unobstructed access to 

the all of the summer cooling breezes from the south to the north-east. 

The distribution of apartments between ‘end’ conditions, cantilevered corner conditions for 

living rooms, and two storey duplex apartments with skylights, achieves cross ventilation for 

54% of the dwellings, without serious conflict with acoustic considerations. 

The detailed disposition of apartments, and in particular the method of articulation of the 

façade is critical in achieving a reliable regime of natural ventilation for the remaining single 

aspect units. Quantitative analysis of the likely single sided ventilation undertaken by 

Heggies suggests that the worst case apartments may be safely characterised as complying 

with the performance requirements of the RFDC. Combined with the favourable orientation to 

minimise summer afternoon heat loads, the natural cooling performance of all the dwellings is 

likely to be better than average. 

In my considered opinion, on that basis the development may be considered fully compliant 

for natural ventilation under the Residential Flat Design Code. 

Steve King 



A.0 CREDENTIALS 

I have been teaching architectural design, thermal comfort and building services at the 

Universities of Sydney, Canberra and New South Wales since 1971. Since 1992, I have 

been a Research Project Leader in SOLARCH, the National Solar Architecture Research Unit 

at the University of NSW. Until its disestablishment in December 2006 I was the Associate 

Director, Centre for Sustainable Built Environments, UNSW. 

My research and consultancy includes work in solar access, energy simulation and 

assessment for houses and multi-dwelling developments. I am the principal author of SITE 

PLANNING IN AUSTRALIA: Strategies for energy efficient residential planning, published by 

AGPS, and of the BDP Environment Design Guides on the same topic. Through 

UNISEARCH and NEERG Seminars, I conduct training in solar access and overshadowing 

assessment for Local Councils. I have delivered professional development courses on topics 

relating to energy efficient design both in Australia and internationally. 

Of relevance to this matter, SOLARCH/UNISEARCH were the contractors to SEDA NSW for 

the administration of the House Energy Rating Management Body (HMB), which accredits 

assessors under the Nationwide House Energy Rating Scheme (NatHERS), NSW. I was the 

technical supervisor of the HMB, with a broad overview of the dwelling thermal performance 

assessments carried out in NSW over the first five years of the scheme. I have been a 

member of the NSW BRAC Energy Subcommittee, and also a member of the AGO Technical 

Advisory Committee on the implementation of the new mandated software tool under 

NatHERS. 

I teach the wind and ventilation components of environmental control in the undergraduate 

course in architecture at UNSW, and am the author of internationally referenced, web 

accessed coursework materials on the subject. 

Of particular relevance, over the last three years I have delivered the key papers in the 

general area of assessment of ventilation and solar access performance and compliance, 

including most recently Solar Access and Ventilation: Reflections on Parsonage at the 

NEERG Seminar on 27 July 2005, cited by Commissioner Moore in the LEC the following 

day. 

I am a Registered Architect and maintain a specialist consultancy practice in Sydney and 

Canberra. I regularly assist the Land and Environment Court as an expert witness in related 

matters. 



B.0 VIEWS FROM THE SUN JUNE 21 

The views appended are half hourly from sunrise to 11am, when the majority of apartments 

cease to have solar access to relevant glazing or private open space.

West Ryde Railway Station Development Wind Impact, Natural ...

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