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Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing 9 Shadowing Chapter Summary Key features A private amenity garden is located to the north of the proposed development which may be affected by shadowing. The car park area (the development site) currently allows sunlight penetration to the area. Impact Construction activities may cause temporary shadowing effects on the gardens. The proposed development overshadows sections of the gardens between 9am and 3pm during the average scenario (in September/ March). There are no areas of the gardens that will be permanently in shadow, therefore the gardens will still be adequately sunlit. There is no impact upon Centenary Square as the proposed Library is to the north. Mitigation Consideration will be given to the placement of construction equipment to ensure no area of the gardens is overshadowed for 100% of the time during the construction phase. No mitigation necessary with the proposed development in place. Residual Effects None Introduction 9.1 This chapter provides an assessment of the consequences of the proposed development on the available daylight and sunlight to the City Centre Gardens to the north of the site. 9.2 Sunlight enhances the appearance of a space, and people expect good levels of natural light when visiting open areas. Sunlight also helps reduce the need for artificial lighting. Conversely, overshadowing may lead to a dull, unattractive appearance, the persistence of frost and may limit plant growth; potentially diminishing amenity use and value. 9.3 The orientation and geometry of surrounding developments are critical to optimising the penetration of sunlight to an open space over the year. Scott Wilson Ltd August 2009 9-1
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing Regulatory / Policy Framework 9.4 The viewpoint of national and local regulatory bodies is that town centres should include positive features such as trees, landscaping and open spaces; and these in return should provide attractive, safe and accessible environments. There is however, no national policy guidance relating to developments and their impact on daylight and sunlight within surroundings areas. Nevertheless, guidance is given in English Heritage (EH)/Commission for Architecture and the Built Environment Guidance (CABE) on Tall Buildings, (July 2007) 1, where paragraph 4.1.9 states that the effect on the local environment, including microclimate, overshadowing, night time appearance, vehicle movements and the environment and amenity of those in the vicinity of the building.. should be fully addressed. 9.5 Policy QE3 of the Regional Spatial Strategy for the West Midlands (January 2008) is concerned with creating a high quality built environment and states that development plans should promote the creation of high quality built environments through the use of architecture, as well as urban and landscape design. Policy QE4 relates to the quality of urban greenspace and its improvement of overall quality especially in city and town centres. 9.6 At a local level, the Birmingham Unitary Development Plan (UDP) 2005 2, states that the quality of the environment is recognised as being crucial, as is the design of new development (paragraphs 3.8, 3.11 and 3.13). New development must also comply with the Council s good design principles, which are concerned with the design and relationship between buildings, streets and squares and other spaces that make up the public domain. Birmingham City Council s Supplementary Planning Guidance document Places for All (p25, November, 2001) 3 states that the design of buildings and spaces should consider the local micro-climate such as ensuring adequate sunlight and shade where required. Methodology Study Area 9.7 The study area is limited to the City Centre Gardens, which is located 20m to the north of the proposed Library site and covers an area of approximately 0.4ha. Consultation 9.8 No consultation on the impacts on City Centre Gardens has been undertaken, although Birmingham City Council stated within the Scoping Opinion that they consider there is a likely impact on the Gardens to the north of the site which requires assessment. Assessment Method 9.9 Using overshadowing images generated for June 21 (summer solstice, from hours 6:00 to 19:00), March 21 (spring / autumn equinox, from hours 9:00 to 18:00) and December 21 (winter solstice, from hours 11:00 to 14:00), the shadowing effects on City Centre Gardens have been examined (see Appendix 8.1 for the simulation results). Following the guidance in Building Research Establishment (BRE) report BR209 4, overshadowing effects are mainly analysed for Scott Wilson Ltd August 2009 9-2
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing the spring /autumn equinox (21 st March or September). Therefore the spring equinox images generated for the scheme have been used for the analysis. 9.10 At present, there are no mandatory requirements for daylight and overshadowing, although the following offer advice for examining the effects of buildings on daylight: Code for Sustainable Homes Technical Guide (Hea 1: Daylighting) 5 ; Ecohomes 2006, credit HW1 (Health and Wellbeing-Daylighting) 6. CIBSE Lighting Guide 10:1999 7, British Standard (BS) 8206, Part 2: 2008 8, BRE report BR209, 2005 4. 9.11 These guidelines are based on average (Autumn/Spring) scenarios and therefore must be used with discretion, and applied with consideration made to the site specific environment. In Autumn/Spring the sun is at an intermediary position in the sky (neither too high nor too low in the sky). Therefore, where overshadowing is above the indicative threshold for the average scenario, then a higher performance would occur during the summer months, with reduced and / or no overshadowing throughout. 9.12 BRE report BR209 4 provides guidelines on the significance of overshadowing of gardens, courtyards and open spaces, stating the following: For it to appear adequately sunlit throughout the year, no more than two-fifths and preferably no more than a quarter of any garden or amenity area should be prevented by buildings from receiving any sun at all on 21 March. And if the area which can receive some sun on 21 March is less than 0.8 times its former value, then the loss of sunlight is likely to be noticeable. For open areas, no more than 40%, and preferably no more than 25%, of any of the open spaces should be prevented from receiving any sunlight on 21 March / September by the proposed development (sunlight at an altitude of 10% or less is excluded). It is suggested that, for it to appear adequately sunlit throughout the year, no more that two-fifths and preferably no more than a quarter of any garden or amenity area should be prevented from receiving any sun at all on 21 March. If, as a result of new development, an existing garden or amenity area does not meet these guidelines, and the area that receives direct sunlight on 21 March / September must not be reduced to less than 0.8 times its former value, as a result of the proposed development. It is also important to note that this percent area based guideline is very much a minimum standard and will not guarantee large quantities of sunlight in summer and/or winter. 9.13 Should the overshadowed area be less than the recommended maximum of 40% (and preferably less than the ideal 25%) of the total open space area, then the impact of overshadowing can be considered insignificant. Scott Wilson Ltd August 2009 9-3
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing Existing Conditions 9.14 The current overshadowing of the City Centre Garden has been assessed by examining the shadowing images of the proposed development and estimating the area of shadow cast without the development (see Appendix 9.1 for all overshadowing images). 9.15 Images show that during the early morning hours in the spring equinox (March), Baskerville House casts a shadow over the western section of the gardens for a short time. The REP also appears to overshadow south eastern areas of the gardens between 10:00 and 11:00 am, although it is difficult to establish the extent of existing shadow for The REP from the proposed development images. The images also show that the existing gap between The REP and Baskerville House (i.e. the site of the proposed development) currently allows sunlight to penetrate into the central areas of the gardens in late morning to early afternoon. Later in the day in March (17:00) the residential towers create a shadow over the northern sections of the gardens. 9.16 During the early morning hours in June (6:00-7:00am) the multi-storey car park overshadows a small area of the western section of the gardens. Later in the day during the June scenario, between 17:00 and 19:00 the gardens are partially overshadowed by the residential towers to the north. 9.17 In December, sections of the garden receive some sun in the morning but the gardens become almost completely shaded by The REP and the ICC (International Convention Centre) by early afternoon (13:00). 9.18 In summary, the City Centre Gardens currently appear to receive sunlight for most of the scenarios for which images have been generated, although for a few hours, mainly early in the morning or late in the afternoon, some areas of the garden are shaded due to existing surrounding buildings. Effects of the Development During Construction 9.19 During the construction phase cranes would be used, including two tower cranes (to be permanently erected for 66 weeks and 74 weeks), and mobile cranes at varying times during the construction programme. These cranes may cause some intermittent overshadowing of the gardens, although the lattice structured tower cranes are unlikely to cast any significant shadow. 9.20 The location and height of material storage areas, site offices and compounds are not currently known, thus any impact on the gardens cannot be determined. During Operation 9.21 The overshadowing images for March 21 from 09:00 to 17:00 show that the proposed development overshadows different sections of the City Centre Gardens between 09:00 and 15:00. Between 9:00 and 10:00 approximately 75% of the garden is in shadow (because of the proposed development), see image 9.1 below (reproduced from the images in Appendix 9.1). Scott Wilson Ltd August 2009 9-4
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing Image 9.1: Illustration of the extent of Shadowing on the 21 st March at 10:00am 9.22 By mid-day it is estimated that more than 50% of the gardens would receive sunlight. The images show that beyond 15:00 on this day in March, there is no shadow cast onto the gardens (see image 9.2 below). Image 9.2: Illustration of the extent of Shadowing on the 21 st March at 15:00pm 9.23 All areas of the gardens would receive sunlight at some point during the day during the March equinox. Therefore according to the recommendations in BRE BR209, the City Centre Gardens will still be adequately sunlit with the proposed development, because there are no areas of the gardens that will be permanently in shadow. Scott Wilson Ltd August 2009 9-5
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing 9.24 As described above, where overshadowing is above the indicative threshold for the average scenario, then a higher performance would occur during the summer months, with reduced and / or no overshadowing throughout. The images generated for the June period illustrate that the City Centre Garden will receive better sunlight penetration during summer periods when the sun s altitude angle is greater, creating shorter shadows of the surrounding buildings. 9.25 The shadowcast images produced for June show that between 7:00 and 14:00 the proposed development is likely to create a shadow on sections of the southern areas of the gardens, with approximately 20% of the gardens being in shadow at 9:00 as a worst case (see image 9.3 below). Image 9.3: Illustration of the extent of Shadowing on the 21 st June at 09:00am 9.26 By 14:00, the gardens receive 100% sunlight (see image 9.4 below). 9.27 In conclusion, although the proposed development overshadows some areas of City Centre Gardens, at no point during the peak hours of the day is the entire Garden under shadow: there is always access to direct sunlight within the Garden area. 9.28 There is no impact upon the sunlight available within Centenary Square as the proposed development is to the north of the square and therefore would not cast a shadow onto the square. Scott Wilson Ltd August 2009 9-6
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing Image 9.4: Illustration of the extent of Shadowing on the 21 st June at 14:00pm Cumulative Impacts 9.29 There may be possible additional shadowing effects resulting from the V building associated with the Arena Central development, located to the south of Centenary Square. The proposed V building would be 50 storeys high, over the double the height of the existing adjacent Alpha Tower. 9.30 Analysis of the shadowing images produced for the proposed development show the shadow cast by Alpha Tower in the morning in March (see image 9.1 and the shadow occurring at the bottom of the image) is directed towards the gardens and may shadow the gardens in the early hours. The adjacent V tower, being taller and in the same locality as Alpha Tower, may therefore also shadow the gardens to the north of the proposed development and probably later into the morning. 9.31 This is for the average scenario however, and because no areas of the garden are likely to be permanently in shade with both developments in place, the cumulative impact is not considered to be significant. 9.32 Broad Street Tower is located some distance away, so would not affect shading within the gardens. Mitigation Measures 9.33 Consideration will be given to the placement of construction compounds, material storage and site offices on and near the site to ensure that no part of the gardens would be totally overshadowed throughout the day. Scott Wilson Ltd August 2009 9-7
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing 9.34 No mitigation measures are recommended with the proposed development in place as there would be adequate sunlight available to the City Centre Gardens. Scott Wilson Ltd August 2009 9-8
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing References 1. English Heritage (EH)/Commission for Architecture and the Built Environment Guidance (CABE) on Tall Buildings, (July 2007). 2. The Birmingham Plan, Birmingham Unitary Development Plan 2005, Birmingham City Council, Incorporating alterations; October 2005. 3. Birmingham City Council s Supplementary Planning Guidance document Places for All. November, 2001. 4. BRE report BR209: Site layout planning for daylight and sunlight: A guide to good practice. P Littlefair, 2005. 5. Code for Sustainable Homes Technical Guide (Hea 1: Daylighting), Version 2, May 2009, Communities and Local Government (CLG); 6. Ecohomes 2006, credit HW1 (Health and Wellbeing-Daylighting), BRE 2006. 7. Daylight and Window Design, CIBSE Lighting Guide 10:1999. 8. BS8206:2:2008, British Standard 8206: Part 2: 1992. Lighting for Buildings Code of Practice for Daylighting. Scott Wilson Ltd August 2009 9-9
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Chapter 9 Shadowing CHAPTER 9 APPENDIX Scott Wilson Ltd August 2009
Birmingham City Council Library of Birmingham integrated with The REP Environmental Statement Appendix 9.1 Shadowing APPENDIX 9.1 SHADOWING IMAGES Scott Wilson Ltd August 2009