Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 Daylighting, Sunlighting and Overshadowing

Document Number: 20643736 Version: 1 Date: 11 August 2011 Amended by: CRB Principal changes: AC Final sign off: AC

1 Introduction............................................................................... 1

2 Executive Summary.................................................................. 2

3 Planning Policy ......................................................................... 3

4 Daylight, Sunlight and Overshadowing Methodology........... 4

5 Surrounding Residential Properties ....................................... 6

6 Assessment Results................................................................. 7

7 Conclusions ............................................................................ 10

8 Appendix A.............................................................................. 11

8.1 Site Plan............................................................................................... 11

9 Appendix B.............................................................................. 12

9.1 VSC, APSH and No-Sky Line Results ................................................. 12

Contents

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 1

1.1 Drivers Jonas Deloitte has been appointed by Land Securities PLC to undertake a daylight, sunlight and overshadowing impact study with regard to the proposed redevelopment of Sussex House, High Street, Crawley, RH10. This report will assess the potential daylight, sunlight and overshadowing impacts to the surrounding residential properties.

1.2 The assessment has been based on the submitted drawings by Lyons+Sleeman+Hoare Architects dated August 2011, drawing numbers P-200, P-201, P-202, P-300.

1.3 In addition to the above, a topographical survey of the site and surrounding area produced by Maltby Land Surveys Ltd has been utilised. Where survey information was not available, the location and size of the surrounding windows have been estimated from site photographs. A 3D model from ZMapping has also been used to assess the positioning and massing of the original buildings that have now been demolished on the site. Research has also been undertaken on the Valuation Office Agency Website to establish which of the surrounding properties are in residential occupation.

1 Introduction

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 2

2.1 Using the Valuation Office Agency website, which lists those properties registered to pay council tax, a number of existing surrounding residential properties have been identified. The potential daylight and sunlight impacts to these properties have been assessed.

2.2 The vertical sky component daylight assessment results show that the vast majority of the surrounding residential windows will continue to receive good levels of daylight in accordance with the BRE Guidelines criteria.

2.3 The sunlight assessment results show that the vast majority of the surrounding habitable rooms that face within 90° of due south will continue to receive good levels of sunlight in accordance with the BRE guidelines.

2.4 Whilst a small number of windows at Oldmeadow House and along Sunnymead are likely to see a reduction in daylight/sunlight levels beyond the BRE Guidelines suggested criteria, the overall daylight penetration to the rooms served by these windows will remain at or above what is considered good for an urban area.

2.5 When taking into account the urban area in which the proposed site is located, and the flexibility that should be applied to the BRE guidelines in such circumstances, the impacts are considered small.

2.6 As there are no existing public or proposed amenity spaces near the development site an overshadowing assessment has not been deemed necessary.

2 Executive Summary

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 3

3.1 The proposed site is within Crawley Borough Council and the proposals have therefore been considered against Crawley’s Local Development Framework (LDF) and the Core Strategy Revision (2008).

3.2 There are key references to protecting the amenity throughout the Core Strategy in particular with reference to policy H3 stating:-

“The council would expect high quality design and layouts to ensure good quality living environments and that there are no significant detrimental impacts on the amenity, character and environmental quality of the surrounding area”.

3.3 The Core Strategy policies on daylight and sunlight have been considered utilising the standards and recommendations set out in the Building Research Establishment (BRE) report:

§ P J Littlefair (1991) “Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice”, Building Research Establishment Report 209. (Referred to in this report as the “BRE Guidelines”).

3.4 Although the BRE guidelines are cited as the principle guidance on this topic, the opening paragraph cautions against strict interpretation of the guidelines, stating:-

“The guide is intended for building designers and their clients, consultants and planning officials. The advice given here is not mandatory and the document should not be seen as an instrument of planning policy. Its aim is to help rather than constrain the designer. Although it gives numerical guidelines, these should be interpreted flexibly because natural lighting is only one of many factors in site layout design. In special circumstances the developer or planning authority may wish to use different target values. For example, in a historic city centre a higher degree of obstruction may be unavoidable if new developments are to match the height and proportions of existing buildings”.

3.5 It is considered important to note that in inner city centre locations, where townscape issues and urban design dictate the design considerations, a planning balance having regard to daylight and sunlight impacts needs to be found. It is therefore considered sometimes necessary to apply different criteria or recognize that the recommendations in the BRE guidelines should not be strictly applied.

3 Planning Policy

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 4

4.1 The BRE guidelines suggest that only those windows that have a reasonable expectation of daylight or sunlight should be assessed. Commercial properties are not considered to have a reasonable expectation of daylight or sunlight as they are generally designed to rely on electric lighting rather than natural daylight or sunlight. Commercial properties have therefore not been assessed.

4.2 Windows to residential properties which are considered to serve non-habitable rooms, such as entrance ways, landings, garages, bathrooms or store rooms, have also not been assessed.

Daylighting

4.3 Where the internal arrangements are not known, the BRE guidelines set out three methods for assessing the effect of development proposals on the daylighting levels of neighbouring properties. These methods are summarised as follows:-

a) The first method is to strike a line at an angle of 25 degrees (°) from the centre of existing windows. If the profile of the proposed building extends through this angle, then the second method needs to be applied. Drivers Jonas Deloitte has not used the first method, as it does not always reflect the differing heights and layouts of a proposed development. We have therefore gone straight to the second test which is a more accurate method of analysing daylighting levels.

b) The second method calculates the Vertical Sky Component (VSC) at the centre point of each affected window. The VSC is an external daylighting calculation that measures the daylight level to a specific window point on the outside of a property. The calculations fundamentally assess the amount of blue sky that can be seen, converting the result into a percentage. A window looking across an empty field will achieve a maximum value of 40% VSC. The BRE guidelines suggest that 27% VSC is indicative of a ‘good level’ of daylight. If a window does not achieve the 27% VSC, then the third test is considered necessary.

c) The third method involves calculating the VSC of the window in the existing situation prior to re-development. If the VSC, with a development proposal in place, is both less than 27% and less than 0.8 times its former value, then the BRE guidelines suggest that occupants of the existing building are likely to notice the reduction.

4 Daylight, Sunlight and Overshadowing Methodology

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 5

4.4 In conjunction with the VSC test, the BRE guidelines suggests that the distribution of daylight is assessed. This test separates those areas of the working plane (desktop height) that can receive direct skylight and those that cannot. The BRE guidelines suggest that the distribution of daylight is assessed using the No-Sky Line (NSL) test. The BRE guidelines states that:

“If a significant area of the working plane lies beyond the no-sky line (i.e., it receives no direct skylight),then the distribution of daylight in the room will look poor and supplementary electric lighting will be required.”

4.5 The British Standard BS8206-2:2008 suggests that ‘a significant area’ is more than 20%, i.e. 80% of the room area should be in front of the no-sky line. This however is not considered practical for urban areas and large rooms over 4m deep. Taking into account an urban setting it is suggested that ‘a significant area’ should be interpreted as more than 50%, i.e. 50% of a room area should be in front of the no-sky line. This is based on the professional experience and expertise.

4.6 For existing properties the BRE guidelines suggest that if the reduction of the no-sky line area is less than 0.8 times its former value, then the occupants may notice a reduction in the amount of direct daylight.

Sunlighting

4.7 With regard to sunlighting, the BRE guidelines first suggest that the 25° angle test is used in the daylight assessment. If the profile of the proposed building does subtend this angle (i.e. the proposed building passes through this 25° line), then the second method needs to be applied.

4.8 For the second sunlighting test the BRE guidelines suggest using the same skylight indicator and reference point used to assess daylighting to calculate the percentage of Annual Probable Sunlight Hours (APSH). The BRE guidelines state that:

"If this window reference point can receive more than one quarter of annual probable sunlight hours, including at least 5% of annual probable sunlight hours during the winter months between 21st September and 21st March, then the room should still receive enough sunlight".

4.9 The BRE guidelines also note:

“Access to sunlight should be checked for the main window of each room which faces within 90° of due south”.

4.10 Therefore, any windows facing 90° of due north need not be analysed as they have no expectation of sunlight.

4.11 If the suggested APSH levels are not achieved the BRE guidelines suggest that the occupants are likely to notice an effect if the reduction in APSH at the given point is less than 0.8 times its former value in either the total sunlight hours percentage or those received in the winter months.

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 6

5.1 Using the Valuation Office Agency website we have identified which properties are registered as paying council tax and therefore in residential occupation. The following properties have been identified and assessed for daylight impacts.

§ Oldmeadow House

§ 55-71 Sunnymead

§ 73-89 Sunnymead;

§ 91-107 Sunnymead;

§ 98 High Street (1st Floor only);

§ 101 High Street (1st Floor only);

5.2 A site plan highlighting the location of the above residential properties is given at Appendix A.

5.3 As there are no existing public or proposed amenity spaces near the development site an overshadowing assessment has not been deemed necessary.

5 Surrounding Residential Properties

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 7

Daylight and Sunlight

6.1 A full set of the VSC and APSH results are given at Appendix B.

Oldmeadow House

6.2 We have analysed all windows that face the development site at ground, first, second and third floor levels.

6.3 The VSC daylight results show that 8 of the 16 windows assessed will meet or exceed the BRE guidelines suggested criteria. 8 windows at ground and first floor level will experience reductions slightly beyond those recommended by the BRE guidelines.

6.4 The results for the 8 windows that do not meet the BRE guidelines are only marginally below the suggested criteria with ratio reductions between 0.77 and 0.65. However, the VSC results in the proposed scenario are all above or very close to 20% VSC which we consider to be good for an urban area.

6.5 To fully understand the impacts to Oldmeadow House, No-Sky Line tests have also been carried out. From plans downloaded from Crawley Borough Council’s planning website a room depth of 3.5m has been used at each floor level.

6.6 The No-Sky Line results show that the ground and 1st and floor rooms will still retain full direct daylight distribution to the entire room area.

6.7 The APSH sunlight results show that each window will continue to exceed the BRE Guidelines suggested criteria with a total APSH above 25%, of which at least 5% are in the winter months.

6.8 Overall the daylight impacts to Oldmeadow House are considered to be minor when considering that these windows will still continue to receive a VSC of around 20% or above in the proposed condition. In addition, when taking into consideration the existing undeveloped site, which is an unusual starting point for a central urban area , the impacts are considered acceptable in the context of the local planning policies.

55-71 Sunnymead

6.9 We have analysed all windows that face towards the development site at ground, first and second floor levels.

6 Assessment Results

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 8

6.10 The VSC daylight results show that each window will experience a negligible reduction of daylight well within the BRE guidelines suggested criteria.

6.11 The APSH sunlight results show that each window will continue to exceed the BRE Guidelines suggested criteria with a total APSH above 25%, of which at least 5% are in the winter months.

73-89 Sunnymead

6.12 We have analysed all windows that face the development site at ground, first and second floor levels.

6.13 The VSC daylight results show that 23 of the 33 windows assessed will meet or exceed the BRE guidelines criteria. 10 windows will therefore experience reductions slightly beyond those recommended by the BRE guidelines.

6.14 The results for the 10 windows that do not meet the BRE guidelines are only marginally below the BRE Guidelines with ratio reductions between 0.79 and 0.71 which we consider to be negligible in light of the urban nature of the site.

6.15 The APSH sunlight results show that 20 of the 27 windows assessed will meet the BRE guidelines criteria. 7 windows will experience reductions slightly beyond those recommended by the BRE guidelines.

6.16 As no information was available from Crawley Borough Councils planning website regarding the internal layouts of these properties we have analysed all the windows that face towards development site. It should however be noted that some of these windows may not serve habitable rooms and therefore could be excluded from the analysis.

91-107 Sunnymead

6.17 We have analysed all windows that face the development site at ground, first and second floor levels.

6.18 The VSC daylight results show that 32 of the 33 windows assessed will meet the BRE guidelines criteria. 1 window at ground floor level will experience reductions marginally beyond those recommended by the BRE guidelines.

6.19 The APSH sunlight results show that 24 of the 27 windows assessed will meet or exceed the BRE guidelines criteria. 5 windows will experience reductions slightly beyond those recommended by the BRE guidelines. Of those 5 windows 2 will experience reductions in the winter months only.

6.20 The results for the 3 windows that do not meet the BRE guidelines are only marginally below the BRE Guidelines with ratio reductions between 0.79 and 0.76.

6.21 As no information was available from Crawley Borough Councils planning website regarding the internal layouts of these properties we have analysed all the windows that face towards development site. It should however be noted that some of these windows may not serve habitable rooms and therefore could be excluded from the analysis.

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 9

All Sunnymead Properties

6.22 It should be noted that all of the properties along Sunnymead are heavily obscured from the development site due to the dense vegetation that runs along the west of Pegler Way and therefore it is likely that these properties will not see the development site at all. The daylight and sunlight analysis conducted to these properties does not take into account this obstruction and therefore some flexibility should be applied to the results for these properties.

98 High Street

6.23 Following a site visit to this property we have found only the windows at first floor level facing towards the rear of the property serve habitable rooms.

6.24 The VSC daylight results show that each window will exceed the BRE guidelines suggested criteria.

6.25 As these windows face within 90° of due north a sunlight assessment to these window has not been necessary.

101 High Street

6.26 Based on information collected during our site visit it was noted that only the windows at first floor level may be residential with the ground floor windows serving the Public House.

6.27 The VSC daylight results show that each window will exceed the BRE guidelines suggested criteria.

6.28 As these windows face within 90° of due north a sunlight assessment to these windows has not been necessary.

Overshadowing

6.29 As there are no existing public or proposed amenity spaces near the development site an overshadowing assessment has not been deemed necessary.

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 10

7.1 The vertical sky component daylight assessment results show that the vast majority of the surrounding residential windows will continue to receive good levels of daylight in accordance with the BRE Guidelines criteria.

7.2 The sunlight assessment results show that the vast majority of the surrounding habitable rooms that face within 90° of due south will continue to receive good levels of sunlight in accordance with the BRE guidelines.

7.3 Whilst a small number of windows at Oldmeadow House and along Sunnymead are likely to see a reduction in daylight/sunlight levels beyond the BRE Guidelines suggested criteria, the overall daylight penetration to the rooms served by these windows will remain at or above what is considered good for an urban area.

7.4 The more significant impacts will occur to the ground and first floor windows of these properties however it is worth noting that in the case of Oldmeadow House many of the rooms served by the windows analysed are in fact dual aspect and the No-Sky line results confirm that any reductions will be only marginally beyond those recommended by the BRE guidelines.

7.5 It should also be noted that the adjoining properties along Sunnymead are heavily obscured from the development site due to the dense vegetation that runs along the west of Pegler Way. The vegetation has been ignored for the purposes of this report but if it was included the occupants are unlikely to be able to see the development site at all. As suggested in the BRE guidelines it is therefore considered that some flexibility should be applied to the results for these properties.

7.6 When taking into account the urban area in which the proposed site is located, and the flexibility that should be applied to the BRE guidelines in such circumstances, the impacts are considered small.

7.7 As there are no existing public or proposed amenity spaces near the development site an overshadowing assessment has not been deemed necessary.

7.8 Overall, any daylight and sunlight impacts to the existing surrounding residential properties are considered small and adhere to the local planning policies.

7 Conclusions

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 11

8.1 Site Plan

8 Appendix A

Oldmeadow House55-71 Sunnymead

73-89 Sunnymead

91-107 Sunnymead

101 High Street

98 High Street

Athene Place, 66 Shoe Lane, London EC4A 3BQ

Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 12

9.1 VSC, APSH and No-Sky Line Results

9 Appendix B

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Daylighting, Sunlighting and Overshadowing Proposed Redevelopment of Sussex House, High Street, Crawley, RH10 13

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