Wind Microclimate Assessment RWDI # 1601191-PLW April 21St, 2016

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Bromley-By-Bow South London, United Kingdom

Final Report

Pedestrian Level Wind Microclimate Assessment RWDI # 1601191-PLW April 21st, 2016

SUBMITTED TO SUBMITTED BY

Vanessa Buckland Krishan Jayyaratnam AECOM Environment and Planning Project Engineer St Georges House, [email protected] 5 St Georges Road, Wimbledon, Ender Ozkan London, UK Regional Manager SW19 4DR [email protected]

Stefan Astley [email protected] Project Manager [email protected]

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Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016

TABLE OF CONTENTS

Executive Summary ...... 1 1. Introduction ...... 2 2. Site Description ...... 2 2.1 Site Location and Surroundings ...... 2 2.2 Illustrative Masterplan ...... 3 3. Procedure and Methodology ...... 4 3.1 Simulation of Atmospheric Winds ...... 4 3.2 Measurement Technique ...... 4 3.3 Scaling ...... 4 3.4 Meteorological Data ...... 4 3.5 Pedestrian Comfort ...... 4 3.6 Strong Winds ...... 5 4. Results ...... 5 4.1 Details of the Analysis ...... 5 4.2 Desired Pedestrian Activity around the Illustrative Masterplan ...... 5 4.3 Performance against Criteria ...... 5 4.3.1 Configuration 1: Existing Site with existing surroundings ...... 5 4.3.2 Configuration 2: Illustrative Masterplan with existing surroundings ...... 6 4.3.3 Configuration 3: Illustrative Masterplan with cumulative surroundings ...... 6 4.4 Occurrences of Strong Winds ...... 8 5. Mitigation Measures ...... 9 6. Further Considerations for Detailed Design and Future Planning Applications ...... 10 7. Concluding Remarks ...... 10

Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016

VERSION HISTORY

Index Date Pages Author

A April 18th, 2016 All K. Jayyaratnam

st 1-3, 5-7, 9, B April 21 , 2016 K. Jayyaratnam 10

Checked by:

E. Ozkan

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desired locations highlighted in Configuration 2 remain in Configuration 3; therefore mitigation measures EXECUTIVE SUMMARY described for these locations will remain effective in the cumulative scenario. The objective of this study was to determine the ground, podium and roof terrace level wind environment and Overall, the wind microclimate around the Illustrative Masterplan is largely acceptable for its intended use and assess the acceptability of the wind microclimate around the illustrative masterplan of the Bromley by Bow any windier than desired locations are expected to be mitigated by the measures described in this report. (South) site (‘the Site’) as allocated by the LLDC Local Plan 2015 to 2031, Sub Area 4.1, , in regards to both It is highly recommended that for later detailed design associated with any future planning application for the pedestrian comfort and safety. This report will sit alongside the illustrative masterplan and a suite of Site, or any part thereof, further wind tunnel testing should be undertaken to ensure that the wind microclimate Environmental Impact Topic Reports as the evidence base to a Supplementary Planning Document to be is consistent with the finding of this report and assess balcony locations and any design changes made. adopted by the LLDC, which sets out the maximum parameters for redevelopment of the Site.

This report presents a description of the methodology used and the results of 3 configurations tested in the wind tunnel, namely: • Existing Site with existing surrounding buildings (‘the ‘Baseline’); • Illustrative Masterplan with existing surrounding buildings; and • Illustrative Masterplan with cumulative surrounding buildings Results are presented in terms of the Lawson Comfort Criteria, with the main focus on the windiest (generally winter) and summer season conditions. The existing Site with existing surrounding buildings has conditions acceptable for a range of uses from sitting to leisure walking use. This range of conditions is fairly typical of a predominantly low to mid-rise urban area such as London. In the presence of the Illustrative Masterplan, the wind microclimate in and around the Site is similar to that of the Baseline. Areas close to the taller, southern blocks of the Illustrative Masterplan are windier than areas to the north-east which are sheltered by the Illustrative Masterplan. Overall wind conditions range from acceptable for sitting to leisure walking use during the windiest season except at one location, off-site (east of the No 1 The Plaza development to the south-west of the Site), which observes business walking conditions and occasional strong winds above Beaufort Force 7. In the baseline scenario wind conditions at this location were at the upper end of leisure walking range with Beaufort Force 6 winds. This is mainly due to the aerodynamic effect of the No 1 The Plaza on this area. When the Illustrative Masterplan is in situ, there is a slight increase in wind speeds which causes the conditions at this location to change from leisure walking to business walking in the windiest season, in combination with Beaufort Force 7 winds. In the detailed design stage, adjustments to the Illustrative Masterplan or off-site landscaping will be effective in reducing wind speeds at this location. The majority of thoroughfare locations and entrances experience the desired wind condition for their intended uses during the windiest season. Two building entrances within the Illustrative Masterplan experienced windier than desired wind conditions. Localised landscaping around the entrance (such as small trees, shrubs in planters, porous screens etc.) or recessing the entrance 1.5m will be effective in reducing wind speeds at the entrance to the desired wind condition. Ground level amenity spaces experienced the required wind conditions during the summer season. This is largely as a consequence of the beneficial podium design of the Illustrative Masterplan. The podiums help to ‘catch’ the down-draughting flow from the taller blocks, and prevent it from reaching the ground level. This beneficial design feature should be retained in the detailed design stage. On the other hand, catching the downdrafts the podiums themselves can become windy areas. Localised landscaping within some of the terraces (soft or hard landscaping) will be effective in reducing wind speeds for occupants comfort. Additionally, roof terraces will benefit from a 2m solid balustrade to shelter occupants close to the edges of the roof terraces. With the Bromley-By-Bow North development in place directly north of the Site (Configuration 3), the wind microclimate in and around the Site is largely consistent with Configuration 2. Furthermore the windier than

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1. INTRODUCTION 2. SITE DESCRIPTION

RWDI have been instructed by Danescroft Land Ltd, on behalf of the group of landowners (Danescroft Land Ltd, 2.1 Site Location and Surroundings Lindhill Properties Ltd, British Land PLC, Vastint Holding B.V, Southern Housing Group, LLDC), to undertake a Pedestrian Level Wind Microclimate Assessment in relation to the redevelopment of the Bromley by Bow (South) The Site is located in the London Borough of Tower Hamlets, UK. The Site is bounded by railway lines to the site (herein referred to as ‘the Site’), allocated as Sub Area 4.1 of the London Legacy Development Corporation south, the A12 road to the west, River Lea to the east and parts of the Bromley-By-Bow North/Bow River Village (LLDC) Local Plan 2015 to 2031. The Site is located with the London Borough of Tower Hamlets (LBTH) and development (planning ref. PA/11/02423) which are already in construction to the north. falls under the planning jurisdiction of the LLDC. The immediate surrounding area consists of a mixture of low to mid-rise suburban residential and commercial It is the intention of the landowners to submit an Illustrative Masterplan (being produced by Karacusevic Carso developments with a few high-rise buildings. Architects (KCA)) to the Planning and Policy Decisions Team (PPDT) of the LLDC. This illustrative masterplan No 1 The Plaza is the tallest building within the immediate surrounding area, with an approximate height of 85m has been subject to environmental testing, and this report forms part of a series of Environmental Impact Topic and is located approximately 100m to the south-west of the Site. Due to the prevailing winds from the south- Reports which have been produced to form a separate evidence base identifying any potential significant west and the Site location (in the wake of No 1 The Plaza from prevailing winds), it is expected that there will be environmental effects of the operation of the maximum extents/parameters of the illustrative masterplan, and some impact on the wind microclimate around the Illustrative Masterplan. As a result of the expected impact of where further work might be required to support a planning application for development of the Site, or any part the No 1 The Plaza, this development has been included in our wind tunnel model. thereof. Generally there are many low to medium rise buildings to the south-west with a fairly open terrain (due to the Both the Illustrative Masterplan and Environmental Impact Topic Reports will provide the basis upon which a cleared site for the future Strand East development) to the north-east. As a result winds from the south-west will series of redevelopment parameters and design guidelines will be developed for the Site. These parameters have a high turbulence with a low mean wind speed, i.e. increased ‘gustiness’; whereas winds from the north- and guidelines will be adopted as a Supplementary Planning Document (SPD) for the Site. Both the Illustrative east will have lower turbulence with a higher mean wind speed. Masterplan and Environmental Impact Topic Reports (including this Pedestrian Level Wind Microclimate Assessment) will be appended to the SPD. Figure 1 shows an aerial view of the site and surroundings, with the approximate site location highlighted in yellow. Wind tunnel tests were conducted on a 1:300 scale model of the KCA Illustrative Masterplan. The investigation quantifies the wind conditions within and around the Site, by comparing the measured wind speed and frequency of occurrence with the well-established Lawson Comfort Criteria. Meteorological data for London has been combined, analysed and adjusted to the site conditions by modelling the effect of terrain roughness on the N wind speeds approaching the site. Measurements were taken at up to 223 locations for 36 wind directions, in 10 degree intervals. The measurements covered ground level locations along the building facades and at corners, near main entrances, within open amenity spaces and on pedestrian routes within and around the Site. In addition, measurements on podiums and roof top terraces were taken. Analysis was conducted on a seasonal basis but the report focuses on the windiest season results (i.e. winter) and those for the summer season, when pedestrian activity generally requires calmer conditions. Three configurations of the wind tunnel model were tested, as follows: • Configuration 1: Existing site with existing surrounding buildings (‘Baseline); • Configuration 2: Illustrative Masterplan with existing surrounding buildings; and • Configuration 3: Illustrative Masterplan with cumulative surrounding buildings. Results are presented in a series of ‘dot-plots’ which indicate the measured comfort criteria for the windiest and summer seasons for each configuration.

Figure 1: Aerial Photograph of the Existing site (approx. site highlighted in yellow)

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2.2 Illustrative Masterplan

Figure 3 below shows a 3D model view (view from the south-east) of the Illustrative Masterplan, identified by the blue buildings. The Illustrative Masterplan will be a masterplan development and will compromise several

buildings of up to 25 storeys (with a maximum height of approximately 92 metres AOD as shown in Figure 3). The intended uses of the Illustrative Masterplan will be a mix of commercial, residential, academic, community and public amenity use. Amenity areas are to be provided throughout the Illustrative Masterplan. There will be public and residential amenity spaces provided at ground, podium and roof top level locations.

The Illustrative Masterplan consists of several buildings that will be taller in comparison to their immediate surrounding buildings. These buildings will present a large surface area to high level prevailing winds from the southwest sector; therefore we expect winds to be forced downwards leading to windy conditions at ground

level. Acceleration of flow around building corners is another aerodynamic effect that is likely to occur, and in this particular case channelling of wind between adjacent buildings. The prevailing south-westerly winds are expected to be channelled throughout the development between the proposed buildings resulting in constriction and acceleration of the flow.

Figure 2: Illustrative Masterplan (blue buildings) view from south-east

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3. PROCEDURE AND METHODOLOGY 3.4 Meteorological Data

Wind tunnel testing is the most established and robust means of assessing the pedestrian wind microclimate Combined meteorological data derived from the meteorological stations of the major London airports (Heathrow, with the Illustrative Masterplan in place. It enables the turbulent wind conditions at the Site to be quantified and Gatwick and Stansted) have been corrected to standard conditions of 10m above open flat level country terrain. classified in accordance with the Lawson Comfort Criteria (hereafter referred to as ‘the Criteria’). The meteorological station data are then adjusted to the Site conditions using the methodology implemented in the BREVe3 software package. To produce the results within the tunnel, a 1:300 scale model of the existing buildings at the Site and the surrounding area within a 360 metre (m) radius of the centre of the Site was constructed. Approximately 30 years of meteorological data for London was used in this report and is presented in Appendix B as wind roses by season (refer to Figure 23, Appendix B) with the wind speed divided into Beaufort Force The basic methodology for quantifying the pedestrian level wind environment is outlined below: ranges (see Table 4, Appendix C). The radial axis indicates the cumulative number of hours per season that • Measure the wind speeds at pedestrian level in the wind tunnel relative to a reference wind speed; the wind speed exceeds the particular Beaufort Force. The seasons are defined as spring (March, April and May), summer (June, July and August), autumn (September, October and November) and winter (December, • Adjust standard meteorological data to account for conditions at the site; January and February). • Combine these to obtain the expected frequency and magnitude of wind speeds at pedestrian level; The meteorological data indicate that the prevailing wind direction throughout the year is from the south-west. and This is typical for many areas of southern England. There is a secondary peak from north-easterly winds, • Compare the results with the Lawson Comfort Criteria to ‘grade’ conditions around the site; especially during the spring, and these tend to be cold winds. The combination of meteorological data, Site altitude and velocity ratios permits the percentage of time that 3.1 Simulation of Atmospheric Winds wind speeds are exceeded at ground level on the Site to be evaluated. The locations can then be assessed using the Criteria, as described below. The wind is turbulent, or gusty, and this turbulence varies depending upon the site and elevation. It is necessary to reflect these differences in the wind tunnel test. In addition, the atmospheric boundary layer is a shear flow The meteorological data indicate that the prevailing wind direction throughout the year is from the south-west. which means that the mean wind speed increases with height. Modelling these effects is achieved by a There is a secondary peak from north-easterly winds, especially during the spring, and these tend to be cold combination of spire and floor roughness elements to create a naturally-grown boundary layer that is winds. representative of urban or open country conditions, as appropriate. The detailed contoured proximity model The combination of meteorological data and velocity ratios permits the percentage of time that wind speeds are around the site is used to fine-tune the flow and create conditions similar to those expected at full scale. exceeded on the site to be evaluated. The locations can then be assessed using ‘comfort criteria’, as described below. 3.2 Measurement Technique

Wind speed measurements were made using Irwin probes. For pedestrian comfort studies, both the mean wind 3.5 Pedestrian Comfort speed and the peak wind speed are measured at each location at a scaled height of 1.5m above ground level. The assessment of the wind conditions requires a standard against which the measurements can be compared. The typical equivalent full scale time period for measuring the mean wind speed is around 90 minutes, whereas This report uses the Lawson Comfort Criteria, which have been established for over thirty years. The comfort the peak wind speed is taken as the wind speed exceeded for 1% of the time. criteria, which seek to define the reaction of an average pedestrian to the wind, are described in Table 1 and Wind speeds at each location were measured for 36 wind directions with 0° representing a wind blowing from illustrated in Figure 24. If the measured wind conditions exceed the threshold then they are unacceptable for the North and 90° a wind blowing from the East. the stated pedestrian activity and the expectation is that there may be complaints of nuisance or people will not use the area for its intended purpose. 3.3 Scaling The criteria set out six pedestrian activities and reflect the fact that less active pursuits require more benign wind conditions. The six categories are sitting, standing/entering/leaving a building, leisure walking, business The length scale of the model was 1:300 and the velocity scale was approximately 1:2 for strong winds. The walking and roadway/car-park, in ascending order of activity level. In other words, the wind conditions in an model was built based on the illustrative floor plans produced by KCA (KCA drawings 266-A-D-100-00, 266-A- area for sitting need to be calmer than a location that people merely walk past. The distinction between leisure D-100-05 and 266-A-D-100-Roof). Consequently the time scale for the tests was 1:150, or in other words 1 walking and business walking is that in the business scenario, where pedestrians are on Site because their second in the wind tunnel is equivalent to 150 seconds at full scale. livelihood depends upon it, they will be more tolerant of stronger winds. The criteria are derived for open air conditions and assume that pedestrians will be suitably dressed for the season. The coloured key in Table 1 below corresponds to the presentation of wind tunnel test results described in Section 4 of this report.

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Table 1: Lawson Comfort Criteria 4. Results Key Comfort Category Threshold Description 4.1 Details of the Analysis Light breezes desired for outdoor restaurants and seating areas Sitting 1% > B3 where one can read a paper or comfortably sit for long periods To account for the difference in height and terrain roughness between meteorological conditions at the airports and the Site, it is necessary to apply adjustment factors to the wind tunnel velocity ratios. Adjustment factors Gentle breezes acceptable for main building entrances, pick- Standing/Entrance Use 6% > B3 (mean factors) were computed for wind directions from 0° through to 360°. The reference height in the wind up/drop-off points, bus stops and window shopping tunnel was at the equivalent full-scale height of 120 metres. Table 2 presents the mean factors for the Site. The higher mean factors indicate terrain that is more open; this is as a result of the cleared Site to the north- Moderate breezes that would be appropriate strolling along a Leisure Walking 4% > B4 city/town centre street, plaza or park east. Table 2: BREVe3 mean factors at 120m above ground level Relatively high speeds that can be tolerated if one’s objective is to Business Walking 2% > B5 walk, run or cycle without lingering Wind Direction 0° 30° 60° 90° 120° 150° 180° 210° 240° 270° 300° 330°

Winds of this magnitude are considered a nuisance for most Roadway/Car-park 6% > B5 activities, and wind mitigation is typically recommended Mean Factor at 120m 1.41 1.44 1.44 1.46 1.39 1.36 1.44 1.44 1.39 1.35 1.36 1.38

3.6 Strong Winds 4.2 Desired Pedestrian Activity around the Illustrative Masterplan

1 Lawson also specified a lower limit strong wind threshold when winds exceed Beaufort Force 6. Exceedance Generally, for a mixed-use development, the target conditions are: of this threshold may indicate a need for remedial measures or a careful assessment of the expected use of • Leisure walking during the windiest season on pedestrian thoroughfares; that location; e.g. is it reasonable to expect elderly or very young pedestrians to be present at the location on the windiest day of the year? • Standing/entrance conditions at main entrances, drop off areas or taxi ranks, and bus stops throughout Typically, stronger winds are associated with areas which would be classified as acceptable for business the year; and walking or roadway use. In a mixed-use, urban development scheme, business walking and roadway • Sitting conditions at outdoor seating and amenity areas during the summer season when these areas conditions would not usually form part of the ‘target’ wind environment and would usually require mitigation due are more likely to be frequently used by pedestrians. to pedestrian comfort considerations. This mitigation would also reduce the frequency of, or even eliminate, any strong winds. The business walking and roadway classifications are usually avoided because of their association with occasional strong winds unless they are on a minor pedestrian route or a route where pedestrian access could For locations on a pedestrian thoroughfare, where the wind speed occasionally exceeds Beaufort Force 6, the be controlled in the event of strong winds. wind is unlikely to generate nuisance to pedestrians. However, we would expect pedestrians to experience difficulty in walking when the wind speed exceeds Beaufort Force 7 or 8. Achieving a sitting classification in the summer usually means that same receptor would be acceptable for standing in the windiest season because winds are stronger at this time. This is considered acceptable for the If the wind speed exceeds B6 wind speed threshold in a proposed amenity space or outside an entrance, these majority of external amenity spaces because other factors such as air temperature and precipitation influence conditions would be unacceptable and would require mitigation. However, in such cases the area is likely to be people’s perceptions about the ‘need’ to use seating in the middle of winter. classified as acceptable for leisure walking, business walking or roadway use and so would require mitigation to satisfy the Lawson Comfort Criteria in any case. 4.3 Performance against Criteria It is RWDI’s practice to report incidences when the Beaufort Force 6, Beaufort Force 7 and Beaufort Force 8 The wind microclimate within and around the site has been assessed and classified using the Lawson Comfort thresholds are exceeded for more than 1 hour per annum. The results for this study are presented in Table 3, Criteria defined in Table 1. The results of the assessment for each configuration are described below and which also shows the wind direction that contributes most to the strong winds. presented graphically in Figures 9-16.

4.3.1 Configuration 1: Existing Site with existing surroundings

The discussion of the wind microclimate in the Baseline configuration is based on the results shown in Figure 9 and Figure 10 for the windiest and summer season respectively. The Baseline Configuration consisted of the existing Site with existing surrounding buildings.

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4.3.1.1 Pedestrian Comfort Amenity Spaces – Ground Level (Figure 12) There are several amenity spaces at ground level, shown in Figure 7; the majority of these spaces experience In the baseline scenario, the built out section of Bromley-By-Bow North and an in-construction building along the desired sitting wind conditions during the summer season as a result of the podium design of the Illustrative William Guy Gardens were included in the wind tunnel model. The existing Site and nearby surrounding area Masterplan. This beneficial design feature prevents down-draughting flow from reaching the ground level; experiences a range of conditions acceptable from sitting to leisure walking use during the windiest season. All however increase the wind speeds on podium (discussed below). The southern part of the canal-side park and of the locations have wind conditions acceptable for their current use. Leisure walking conditions are located in the pocket park large square experience isolated occurrences of standing wind conditions; however as the two isolated areas: close to the No1 The Plaza, due to down-draughting of prevailing south-westerly flows majority of these areas observe sitting wind conditions this is deemed acceptable for their intended amenity use. channelling between the south-easterly corner of the development and the building to the south-east; and towards the north of the Site where prevailing south-westerly winds accelerate between the construction of the Amenity Spaces – Podium and Roof Terraces (Figure 13) northern parts of the Bromley-By-Bow development and the warehouse to the south. The podium level amenity spaces are shown in Figure 8; the majority of which experience the desired sitting During the summer season, wind conditions are calmer with the majority of locations observing sitting or wind condition during the summer season. Podium-level receptors were located in frequently used central parts standing wind conditions. of each terrace. It is noted that the corners of the taller blocks at podium level will likely observe leisure walking conditions, but these areas are generally used for walking and not for amenity purposes. 4.3.1.2 Strong Winds The podium areas to the south of the Illustrative Masterplan (receptors 202-204, 207, 210, 211, 215, 216 and This section refers to data in Table 3. There were two occurrences of strong winds during the baseline 218) observed standing conditions as a result of being exposed to the prevailing south-westerly winds. configuration exceeding Beaufort Force 6. These exceedances were measured at receptors 49 and 50 for up Depending on the use of these amenity spaces, for example if long term seating is not intended, a mix of sitting to 5.4hours per year and are along the thoroughfare to the south-east of the No 1 The Plaza. and standing conditions is acceptable. Wind conditions were measured at several roof terraces; the majority of which observed the desired sitting wind 4.3.2 Configuration 2: Illustrative Masterplan with existing surroundings conditions during the summer season. The three tallest towers (receptors 194, 197 and 209) observed standing conditions as they are exposed to wind conditions from all angles. Roof terrace receptors 164, 170, The discussion of the wind microclimate for the Illustrative Masterplan with existing surrounding buildings is 217 and 220 observe standing wind conditions which are caused by their exposure to the prevailing south- based on results shown in Figure 11 for the windiest season at ground level, and Figures 12 and 13 for the westerly winds in combination with being located further away from the taller towers which would provide summer season, for ground and podium/roof terrace levels respectively. beneficial shelter. Receptor 200 experienced leisure walking conditions as this terrace, although a low level roof terrace is located in the adjacent to one of the tallest towers of the Illustrative Masterplan. Prevailing south- 4.3.2.1 Pedestrian Comfort westerly winds will accelerate around the tall tower and into the terrace, creating windier than desired conditions. Generally the wind conditions around the Site with the Illustrative Masterplan in place are one or two categories windier than the baseline. The results range from acceptable for sitting to business walking use throughout the 4.3.2.2 Strong Winds year. This section refers to the data in Table 3. There were nine occurrences of strong winds: • Thoroughfares (Figure 11) Beaufort Force 6 was exceeded at receptors 19, 27, 83 and 144 for up to 4.3 hours per annum. Since this is a minor exceedance of the B6 criterion occurring on thoroughfare locations, this is not expected All thoroughfare locations in and around the Illustrative Masterplan achieve acceptable wind conditions during to cause a nuisance to pedestrians. the windiest season. There was one location which observes business walking conditions in Configuration 2, at receptor 49. This location is windier than in the baseline scenario and as a result has exceeded the lower • Receptor 49 is located to the east of the No 1 The Plaza development to the south-west of the threshold of the business walking criterion. Illustrative Masterplan and observed strong winds exceeding Beaufort Force 7 for 1.4 hours per annum. Typically, strong winds exceeding B7 would be unacceptable along a thoroughfare. Entrances (Figure 11) • Beaufort Force 6 was exceeded at receptors 200, 209, 215 and 220 for up to 4.2hours per annum and There are several main building entrances around the Illustrative Masterplan; the majority of these entrances are located in amenity spaces/roof terraces of the Illustrative Masterplan. These locations will require are located in areas experiencing the required standing or calmer wind conditions. There are two entrances mitigation in order to eliminate occurrence of strong winds. which observed windier than desired conditions, receptor 17 and receptor 145. Receptor 17, a northern entrance to the northern business space of the Illustrative Masterplan, observed leisure 4.3.3 Configuration 3: Illustrative Masterplan with cumulative surroundings walking conditions. This is due to the channelling effects between the Illustrative Masterplan and the under construction northern parts of the Bromley-By-Bow North development. The discussion of the wind microclimate for the Illustrative Masterplan with cumulative surrounding buildings is based on results shown in Figure 14 for the windiest season at ground and podium level, and Figures 15 and Centrally, between the blocks of the Illustrative Masterplan, receptor 145, a southern entrance to the food store 16 for the summer season, for ground and podium/roof terrace levels respectively. of the Illustrative Masterplan, observes leisure walking wind conditions. The orientation of the blocks of the Illustrative Masterplan presents a restriction to the oncoming flow and therefore there is a localised acceleration For the cumulative configuration, the rest of the Bromley-By-Bow North development (further north of the Site of winds. than the completed section of this development included in Configuration 1) was included in the wind tunnel model. This consisted of several blocks to the north of the Site.

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4.3.3.1 Pedestrian Comfort

Generally the wind conditions around the Illustrative Masterplan are largely consistent with Configuration 2 with all locations observing conditions acceptable for sitting to business walking use. There remain localised areas of leisure walking conditions at some block corners and where several blocks meet, such as the central area. Additionally there are several locations to the north-east of the Illustrative Masterplan where sitting conditions are measured. In Configuration 2 these locations observed standing conditions and the reduction in wind speeds experienced in Configuration 3 in this area is due to the ‘blockage’ effect created by the wider Bromley- By-Bow development. As a result, the oncoming winds are presented by a larger massing of buildings and therefore travel around the wider development rather than through it, as shown below.

Prevailing south-westerly winds

Figure 4: General wind flow in Configuration 3

All thoroughfare locations remained acceptable for their intended use and all entrance remained consistent with Configuration 2; entrances at receptors 17 and 145 remained experiencing leisure walking conditions (Figure 14). During the summer season wind conditions are generally one category calmer than the windiest season and Prevailing are consistent with Configuration 2. Additionally receptors 204 and 218 observed wind conditions acceptable south-westerly for sitting use, one category calmer than in Configuration 2, during the summer seasons at the podium level winds (Figure 15). All other podium and roof terrace level wind conditions remained consistent with Configuration 2 with the majority of southern amenity spaces experiencing standing conditions (Figure 16) Figure 3: General wind flow in Configuration 2 4.3.3.2 Strong Winds This section refers to the data in Table 3. There were eight occurrences of strong winds: • Beaufort Force 6 was exceeded at receptors 5, 83 and 144 for up to 1.6 hours per annum. Since these are infrequent exceedances of the B6 criterion, occurring on thoroughfares, they are not expected to cause a nuisance to pedestrians. • Receptor 49 is located to the east of the No 1 The Plaza development (south-west of the Illustrative Masterplan) and observed strong winds exceeding Beaufort Force 7 for 1.2 hours per annum. • Beaufort Force 6 was exceeded at receptors 200, 209, 215 and 220 for up to 4.1 hours per annum and are located in amenity spaces/roof terraces of the Illustrative Masterplan. These locations will require mitigation in order to eliminate occurrence of strong winds.

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4.4 Occurrences of Strong Winds Areas with occasional strong winds exceeding Beaufort Force 6, 7 or 8 are listed in Table 3 together with the primary wind direction and the number of hours per annum for which the threshold wind speed is exceeded. Table 3: Configuration Annual Exceedance of Strong Winds

Location Beaufort Force Exceedence Wind Direction Hours per Annum Configuration 1: Baseline (existing Site with existing surrounding buildings)

49 B6 210 5.4 50 B6 350 1.5 Configuration 2: Illustrative Masterplan with existing surrounding buildings

19 B6 230 1.5 49 B7 220 1.4 83 B6 290 1.1 144 B6 240 3.1 200 B6 240 4.2 209 B6 290 1.3 215 B6 230 2.3 220 B6 30 1.1 Configuration 3: Illustrative Masterplan with cumulative surrounding buildings 5 B6 220 1.1 49 B7 210 1.2 83 B6 270 1.1 144 B6 240 1.6 200 B6 240 4.1 209 B6 290 1.3 215 B6 220 2.5 220 B6 60 1.0

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5. MITIGATION MEASURES

The wind tunnel tests were conducted on models where no landscaping was included. This was done to generate a conservative (i.e. a relatively windy) worst-case scenario. The test results showed that although the Site was generally windier in the presence of the Illustrative Masterplan most receptors had a wind microclimate that was acceptable for the desired pedestrian activity. The majority of thoroughfare locations observed the desired leisure walking or calmer conditions except at receptor 49. This is an off-site location and is noted to be close to the lower threshold of the business walking criterion in the existing scenario (Configuration 1). During the detailed design stage, this location can be mitigated with changes to the block on the southwest corner of the Illustrative Masterplan or localised landscaping features off-site at this location.

All but two building entrances of the Illustrative Masterplan observe the desired standing or calmer wind Figure 5: Examples of localised landscaping around entrances conditions. Entrances at receptors 17 and 145 experience leisure walking wind conditions during the windiest season and will require mitigation measures in order to reduce winds locally. This can be readily achieved by adding localised hard/soft landscaping (Figure 5) around the entrance (for example small trees, shrubs in planters, porous screens etc.). Additionally, recessing these entrances by 1.5 will provide a ‘buffer’ zone for pedestrians/occupants as they ingress/egress. Ground level amenity spaces observed the required sitting wind conditions during the summer season and therefore are acceptable for their intended use. Podium locations with windier than desired conditions (receptors 202-204, 207, 210, 211, 215, 216 and 218) require mitigation measures depending on their intended use. If these amenity spaces (towards the south of the Illustrative Masterplan) are intended for long term seating, localised screening and planting (Figure 6) will be required to reduce wind conditions to a sitting classification. There were several roof terraces which will require mitigation if intended for amenity uses. Roof terraces are generally windier than other amenity spaces as they are relatively exposed to winds from many directions. For the Illustrative Masterplan, roof terraces at receptors 164, 170, 186, 194, 197, 209, 217 and 220, observed standing wind conditions and the roof terrace located at receptor 200 observed leisure walking conditions during the summer season. Similar mitigation measures as described for podium level amenity spaces will be effective for roof terraces in order to break up the winds flowing through the terrace and protect occupants. Additionally adding a 2m balustrade will help to shelter areas at the edges of the terraces. Several amenity spaces measured strong winds exceeding B6 (receptors 200, 209, 215 and 220); however as these locations also require mitigation to achieve comfort conditions, such mitigation measures are expected to eliminate the occurrences of B6 strong winds. Figure 6: Examples of localised landscaping within a terrace/balcony With the described mitigation measures in place, it is expected that all locations in and around the Illustrative

Masterplan will be acceptable for their intended uses.

Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016 Page 10

6. FURTHER CONSIDERATIONS FOR DETAILED DESIGN AND 7. CONCLUDING REMARKS FUTURE PLANNING APPLICATIONS In conclusion: This wind tunnel testing was conducted on the Illustrative Masterplan and therefore only considered the overall 1. The meteorological data for the site indicate prevailing winds from the south-west quadrant throughout massing and main entrances. Certain assumptions were made such as a standard 1.2m balustrade added at the year with secondary winds from the north-easterly direction, particularly during spring. all roof terraces and along some sides at the podium level. During the detailed design phase as part of a planning application for the Site or any part thereof, the façade articulation, details of entrances, balcony 2. In the Baseline Scenario (Configuration 1) the majority of the Site observed conditions ranging from locations and uses of amenity spaces will be better defined. At the detailed stage of the design process, the sitting to leisure walking use throughout the year. Illustrative Masterplan should be wind tunnel tested again to accurately assess the wind microclimate in and 3. In the presence of the Illustrative Masterplan (Configuration 2), the microclimate around the Site is around the Illustrative Masterplan as there will be localised differences in the massing. Additionally susceptible similar to the Baseline. The majority of conditions remained acceptable for their intended use. balcony locations can be instrumented in order to asses wind conditions experienced by the occupants within them. 4. All thoroughfare locations experienced the desired wind conditions except one off-site location, east of No 1 The Plaza. This location is windy in the Baseline scenario, and has business walking conditions and strong winds in excess of B7 when the Illustrative Masterplan is in place. Mitigation measures can be developed during detailed design stages, either by minor changes to the southwest block on the site or through off-site landscaping at this location. 5. The majority of building entrances around the Illustrative Masterplan are acceptable for their intended use; however two entrances would require mitigation measures to reduce wind speeds locally. Recommended mitigation measures include soft or hard landscaping either side of these entrances of recessing the entrance 1.5m. 6. There are several ground level amenity spaces which all experienced the desired wind conditions as a result of the podiums of the Illustrative Masterplan; a beneficial design feature which should be retained in the detailed design stage. Additionally some of the podium level amenity spaces also observed the desired wind conditions; however podium amenity spaces towards the south of the Illustrative Masterplan observed standing conditions and would require soft/hard landscaping to reduce wind speeds. 7. Roof terraces are generally windier than required due to their exposed nature to most wind angles. As a result roof terraces, if intended for amenity use, will require a 2m solid balustrade with landscaping within. 8. There were several instances of strong winds exceeding B6 and one instance of strong winds exceeding B7. The majority of B6 exceedances are located on thoroughfares where infrequent winds of this magnitude are unlikely to cause a nuisance. The other B6 exceedances are expected to be eliminated as these locations also require mitigation to achieve comfort conditions. The exceedance of B7 is expected to be reduced after considering the present hard and soft landscaping around the No 1 The Plaza development. 9. In Configuration 3, with the wider Bromley-By-Bow development constructed, the wind conditions remain largely consistent with Configuration 2. Therefore with the implementation of the mitigation measures described for Configuration 2, all locations in and around the Illustrative Masterplan are expected to be acceptable for their intended uses. 10. Overall, the majority of locations in and around the Illustrative Masterplan are acceptable for their intended use and isolated locations experiencing windier than desired conditions may be mitigated with the measures suggested within this report. 11. It is recommended that at the detailed design phase, the Illustrative Masterplan should be wind tunnel tested to ensure that the wind microclimate is consistent with the finding of this report and assess balcony locations and any design changes made.

Pocket Park

Canal Side Park

Towpath Environment

School Playground

Proposed Ground Level amenity spaces True North Drawn by: SM Figure: 7

Date Revised: Apr. 20, 2016 Bromley by Bow - London (UK) Project #1601191 Proposed Podium Level amenity spaces True North Drawn by: SM Figure: 8

Date Revised: Apr. 20, 2016 Bromley by Bow - London (UK) Project #1601191 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71

80 69 38 70 77 72 79 68 78 56 40 76 74 73 57 59

41 55 58 65 54 64

42 53 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 40 80m

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 9 C1 Ground Floor - Existing Site with existing surrounding buildings Windiest Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71

80 69 38 70 77 72 79 68 78 56 40 76 74 73 57 59

41 55 58 65 54 64

42 53 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 40 80m

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 10 C1 Ground Floor - Existing Site with existing surrounding buildings Summer Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71 88 80 69 38 70 77 72 79 68 78 56 40 76 67 74 73 57 66 59

41 55 58 65 54 64 52 42 53 43 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 40 80m

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 11 C2 Ground Floor - Illustrative Masterplan with existing surrounding buildings Windiest Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71 88 80 69 38 70 77 72 79 68 78 56 40 76 67 74 73 57 66 59

41 55 58 65 54 64 52 42 53 43 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 40 80m

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 12 C2 Ground Floor - Illustrative Masterplan with existing surrounding buildings Summer Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 30 60m

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 13 C2 Podium and Roof - Illustrative Masterplan with existing surrounding buildings Summer Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71 88 80 69 38 70 77 72 79 68 78 56 40 76 67 74 73 57 66 59

41 55 58 65 54 64 52 42 53 43 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 30 60m

Preliminary Sensor Plan: True North Drawn by: ME Figure: 14 C3 Ground Floor - Illustrative Masterplan with existing surrounding buildings Windiest Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016 10 13

1 11 12

2 9

3 4 7 14

5 15 75 16 6 17

18 20 19

23 24

29 30 32

97 31 33 98 96 34 94 93 95 37 35 92 99 36 91 90 82 84 81 83 89 39 85 86 87 71 88 80 69 38 70 77 72 79 68 78 56 40 76 67 74 73 57 66 59

41 55 58 65 54 64 52 42 53 43 60

45 61 46 63

47 48 62

50 51

LEGEND: LAWSON COMFORT CRITERIA: SENSOR LOCATION: Sitting Grade Level Standing/Entrance Podium Level Leisure Walking Terrace/Balcony Business Walking Level Carpark/Roadway 0 30 60m

Preliminary Sensor Plan: True North Drawn by: ME Figure: 15 C3 Ground Floor - Illustrative Masterplan with existing surrounding buildings Summer Season Approx. Scale: 1:2000

Pedestrian Wind Comfort Conditions: True North Drawn by: ME Figure: 16 C3 Podium and Roof - Illustrative Masterplan with existing surrounding buildings Summer Season Approx. Scale: 1:2000

Bromley by Bow - London, United Kingdom Project #1601191 Date Revised: Apr. 08, 2016

Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016

APPENDIX A: PHOTOGRAPHS OF THE WIND TUNNEL MODEL

` Figure 19:Illustrative Masterplan with existing surrounds (Configuration 2) – View in the Wind Tunnel (from the South) Figure 17:Existing Site with existing surrounds (Configuration 1) – View in the Wind Tunnel (from the South)

Figure 18:Existing Site with existing surrounds (Configuration 1) – View in the Wind Tunnel (from the East, overhead) Figure 20:Illustrative Masterplan with existing surrounds (Configuration 2) – View in the Wind Tunnel (from the South, overhead)

Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016

Figure 21:Illustrative Masterplan with cumulative surrounds (Configuration 3) – View in the Wind Tunnel (from the South)

Figure 22:Illustrative Masterplan with Cumulative Surrounds (Configuration 3) – View in the Wind Tunnel (from the South, overhead)

Bromley-By-Bow – London, United Kingdom Pedestrian Level Wind Microclimate Assessment RWDI#1601191 April 21st, 2016

APPENDIX B: METEOROLOGICAL DATA APPENDIX C: LAWSON COMFORT CRITERIA

London (combined) - Spring meteorological data London (combined)- Summer meteorological data 0 0 400 400 330 30 330 30 300 300

300 200 60 300 200 60

100 100

270 0 90 270 0 90

240 120 240 120

B0 210 150 B1 210 150 B2 180 180 B3

London (combined)-Autumn meteorological data B4 London (combined) -Winter meteorological data 0 0 B5 400 400 330 30 B6 330 30 300 300

300 200 60 300 200 60

100 100

270 0 90 270 0 90

Figure 24:Graphical representation of the Lawson Comfort Criteria

Beaufort Hourly Average 240 120 240 120 Description of Wind Noticeable Wind Effect Force Wind Speed (m/s) 0 < 0.45 Calm Smoke rises vertically. 210 150 210 150 180 180 1 0.45 – 1.55 Light Air Direction shown by smoke drift but not by vanes. 2 1.55 – 3.35 Gentle Breeze Wind felt on face; leaves rustle; wind vane moves. Figure 23:Seasonal wind roses for London (in Beaufort Force) (Radial axis indicates the hours for which the stated Beaufort Range is exceeded) 3 3.35 – 5.60 Light Breeze Leaves & twigs in motion; wind extends a flag.

4 5.60 – 8.25 Moderate Breeze Raises dust and loose paper; small branches move.

5 8.25 – 10.95 Fresh Breeze Small trees, in leaf, sway.

6 10.95 – 14.10 Strong Breeze Large branches begin to move; telephone wires whistle.

7 14.10 – 17.20 Near Gale Whole trees in motion.

8 17.20 – 20.80 Gale Twigs break off; personal progress impeded.

9 20.80 – 24.35 Strong Gale Slight structural damage; chimney pots removed.

10 24.35 – 28.40 Storm Trees uprooted; considerable structural damage.

11 28.40 – 32.40 Violent Storm Damage is widespread; unusual in the U.K. Countryside is devastated; only occurs in tropical 12 > 32.40 Hurricane countries.

Table 4: Beaufort Land Scale