daylight and sunlight assessment - essex county council planning/recycling-waste/waste... · ......

Essex County Council

Proposed Waste Transfer Station for Uttlesford District

Daylight and Sunlight Assessment

AMEC Environment & Infrastructure UK Limited

March 2012

© AMEC Environment & Infrastructure UK Limited March 2012 Doc Reg No. 26310cbU022

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Document Revisions

No. Details Date

V1 Reviewed by AC 27/02/2012

V2 Issued to client 28/02/2012

Approved 08/03/2012

Final Issued 09/03/2012

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Executive Summary

Essex County Council is proposing to build a Waste Transfer Station (WTS) for Uttlesford District on land off Chelmsford Road, Great Dunmow, Essex CM6 1LW. The proposed development includes the erection on the site of a main WTS building, two Firewater Sprinkler Tanks and a Pump House, along with other small ancillary buildings and structures.

AMEC has examined the potential of the proposed buildings and structures to impact on the daylight and sunlight that will continue to be received through the windows of the Ambulance Station and received in the gardens of the three residential premises located to the east of the application site. A daylight and sunlight assessment was undertaken for the Ambulance Station building and its western and southern windows. A sunlight assessment was also undertaken for the gardens of the three identified residential premises. The assessments were carried out using the guidance and methodologies in BS8206-2 ‘Lighting for Buildings - Code of Practice for Daylighting’, ‘Site Layout Planning for Daylight and Sunlight– a guide to good practice – second edition’ (BRE 2011), and ‘Application Manual: Window Design’ (CIBSE). The BRE guidance is intended to be used in conjunction with these other documents, and its guidance is intended to fit in with their recommendations.

With regard to the non-residential building at the ambulance station, all three windows/windows group assessed will still receive more than 80% of their current Vertical Sky Component (VSC) values and, hence, the proposals meet the BRE daylight guidelines.

All three ambulance station windows assessed will also still receive more than 80% of their sunlight hours after the WTS development is built and will not lose more than 4% of annual probable sunlight hours and, hence, the proposals meet the BRE sunlight guidelines.

The assessment also found that over half of the garden areas of Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages will continue to receive more than 2 hours of sunlight on the prescribed 21 March date (the equinox) and, hence, the proposals meet the BRE sunlight guidelines.

In summary, the assessments demonstrate that the WTS proposals meet all the BRE daylight and sunlight guidelines. The proposed new development would therefore not have a significant effect on the daylight and sunlight continuing to be received by the surrounding properties, having regard to the official guidelines on the subject. This daylight and sunlight assessment is submitted alongside the planning application.

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Contents

1. Introduction 1

1.1 Purpose of the Assessment 1

1.2 Planning Policy 1

1.3 Relevant Guidelines 1

1.4 The Existing Baseline 2

1.5 The Proposed Development 3

1.6 Scope of the Assessment 4

2. Daylight and Sunlight Assessments 5

2.1 Assessment model and parameters 5

2.2 Potential Receptors 5

2.2.1 Buildings 5

2.2.2 Gardens and Amenity Areas 5

2.3 Potential Factors 5

2.3.1 Trees 5

2.3.2 Fences and Walls 5

2.4 BRE Guidelines Assessment Methodology 6

2.4.1 Daylight 6

2.4.1.1 Existing Buildings 6

2.4.2 Sunlight 6

2.4.2.1 Existing Buildings 6

2.4.2.2 Gardens and Amenity Spaces 6

2.5 Daylight Assessment 7

2.5.1 The Ambulance Station Building 7

2.6 Sunlight Assessment 7

2.6.1 The Ambulance Station Building 7

2.6.2 Gardens of Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages 8

3. Conclusion 9

Appendix A BRE Guidelines – Daylight/Sunlight Appendix B Site Layout Plan Appendix C Daylight Analysis - Brooke Cottage and Hoblongs Cottages Appendix D Built Environment Drawings


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Appendix E Daylight and Sunlight Calculations Appendix F Daylight and Sunlight Drawings


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1. Introduction

1.1 Purpose of the Assessment

The purpose of this assessment is to investigate the effects of the proposed development of the Waste Transfer Station (WTS), located on land off Chelmsford Road, Great Dunmow, in respect of the daylight and sunlight that will continue to be received by surrounding properties.

The proposed development includes, of particular relevance to this assessment, a main WTS building, two Firewater Sprinkler Tanks and a Pump House. Other relatively small ancillary buildings and structures areas are also proposed on the application site, but are located further away from the surrounding properties that are likely to be affected. The WTS building is located towards the eastern side of the site with a hardstanding to the south, whilst the two tanks and the pump house are located in the north-eastern part of the site, adjacent to the ambulance station building (see the planning application drawing 26310-GD-A-CVD-010-E)

1.2 Planning Policy

Policy GEN2 of the Uttlesford Local Plan (2005) states, amongst other things, that ‘development will not be permitted unless it would not have a materially adverse effect on the reasonable occupation and enjoyment of a residential or other sensitive property, as a result of loss of privacy, loss of daylight, overbearing impact or overshadowing’.

There are no policies directly relating to daylight and sunlight in the Essex and Southend Waste Local Plan (WLP) or Planning Policy Statement 1 (PPS1) (the latter addresses design issues in new development but does not make specific reference to daylight and sunlight requirements).

1.3 Relevant Guidelines

With regard to daylight and sunlight, there are three main guidance documents. The primary document is the Building Research Establishment (BRE) Guidelines “Site Layout Planning for Daylight and Sunlight– a guide to good practice – second edition” (BRE 2011). The guidance provides criteria that apply to dwellings and non-domestic buildings that would expect to have a requirement for sunlight.

The other documents, which are referred to within the BRE Guidelines, are the British Standards “Lighting for Buildings: Code of Practice for Daylighting” (BS 8206) and the Chartered Institute of Building Services Engineers (CIBSE) “Application Manual: Window Design”. The BRE guidelines are intended to be used in conjunction with the BS and CIBSE advice. The BRE guidelines state that:

“1.6 The guide is intended for building designers and their clients, consultants and planning officials. The advice given here is not mandatory and this 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

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guidelines, these should be interpreted flexibly because natural lighting is only one of many factors in site layout design.”

The BRE guidance provides methods of measurement that are set out in full at Appendix A.

The three main methods predominantly used to calculate daylight are those involving the measurement of the total amount of skylight available:

Vertical Sky Component (VSC);

No Sky Contours (NSC); and

Average Daylight Factor (ADF).

In relation to sunlight, the criteria given in the BRE Guidelines calculates the annual probable sunlight hours (APSH), having regard to the amount of sun available in both the summer and winter for each window facing within 90° of due south and the amount of sunlight available on the 21 March for gardens and amenity areas.

The following extracts from the BRE guidance are relevant.

“The guidelines given are intended for use with adjoining dwellings and any existing non-domestic buildings where the occupants have a reasonable expectation of daylight; this would normally include schools, hospitals, hotels and hostels, small workshops and most offices.” (Chapter 2 ‘Light from the sky’)

“The British Standard is intended to give good access to sunlight for amenity purposes in a range of situations. However, in some circumstances, the designer, or planning authority, may wish to choose a different target value for hours of sunlight. If, in a particular development, sunlight is deemed to be less important, but still worth checking for, a lower value could be used……In certain situations care needs to be taken in applying these guidelines. For example, if the existing building stands unusually close to the common boundary with the new development, then a greater reduction in sunlight access might be unavoidable.” (Chapter 3 ‘Sunlight’)

1.4 The Existing Baseline

The application site extends to 0.84 hectares in area and is located on previously developed derelict and degraded land to the rear of the Ambulance Station, off Chelmsford Road, Great Dunmow. The application site is currently vacant and contains no buildings. Vehicular access to the site is gained via a shared access road off Chelmsford Road, which is accessed from the B184.

The site slopes gently from 53m above ordnance datum (AOD) in the west to 48m AOD in the east at the access road entrance. Adjacent and surrounding properties and land uses comprise:

To the north, Hoblong’s Brook, a Travelodge hotel, Hoblong’s Industrial Estate and Langley’s Lodge;

To the west, the remainder of the former contractor’s compound, beyond which lies farm-land and the A120(T);


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To the south, the A120(T) dual carriageway, its slip-road and verges, with agricultural land beyond; and

To the east, three existing residential dwellings which front onto the now truncated section of Chelmsford Road, plus a site which was first granted planning permission for a dwelling in 2007 (Ref: UTT/1750/07/FUL) and subsequently for two flats in 2008 (Ref: UTT/1531/08/FUL), together with an existing ambulance station. To the immediate east of these properties is the B1256 main road which connects to the A120(T) dual carriageway via the roundabout junction.

Adjacent to the north-eastern boundary of the proposed WTS site is a single-storey Ambulance Station building that has windows facing the proposed Firewater Sprinkler Tanks and the Pump House. A detached two-storey house, Brooke Cottage, is located to the immediate east of the Ambulance Station site. Two semi-detached two-storey residential premises, known as Nos. 2 and 3 Hoblongs Cottages, adjoin the eastern boundary of the application site. No.2 Hoblongs Cottage is the site of the two planning permissions mentioned above,

Three windows in the Ambulance Station building face within the 90 degrees of due south1 – one on the western façade of the building and two on the southern façade. The window on the western façade sits approximately 1000mm from ground level and is heavily frosted. The penetration of daylight and sunlight through this window is therefore already limited. A clear glass window on the southern façade of the building sits at a similar height to the one on the western façade. A further clear glass full-length bay window (with three faces) exists on the south-facing wall at ground level, looking out onto an external patio seating area. The internal layout of the building and the precise usage of the rooms are unknown. The above elements are illustrated on the drawing 26310-GD-A-DAY-002-A at Appendix B.

Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages also have windows facing within 90 degrees of due south. A boundary hedge, approximately 2.5m to 3m high and approximately 2m wide, runs along the western boundary of the Ambulance Station and hedging and other vegetation exists along parts of the western boundaries and gardens of Nos. 2 and 3 Hoblongs Cottages.

1.5 The Proposed Development

The layout of the proposed development is shown on the planning application drawing 26310/GD/A/CVD/010/E. The proposed height of the main WTS building is 9.76 metres to the ridge and 8.45 metres to the eaves (on the eastern and western elevations of the building), whilst the height of the Firewater Sprinkler Tanks is 4.5 metres and the height of the Pump House 3.0 metres. Other buildings and structures proposed on the application site are of smaller scale and are located away from the surrounding properties and their buildings. These other buildings and structures will therefore not give rise to any impact on the daylight or sunlight received by the surrounding properties.

1 Windows within 90 degrees of South tend to have better sunlight and daylight and are therefore more sensitive to any decrease.

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1.6 Scope of the Assessment

This assessment will identify whether the proposed WTS development will affect the adjacent occupiers, and if so, will quantify any change in daylight or sunlight provision. The Ambulance Station building is located adjacent to the proposed Firewater Sprinkler Tanks and the Pump House, whilst Nos. 2 and 3 Hoblongs Cottages adjoin the application site separated by their gardens.

The BRE guidelines suggested that “loss of daylight and sunlight to existing windows need not be analysed if the

distance of each part of the new development from the existing window is three or more times its height above the centre of the existing window”. The three residential premises of Brooke Cottage and Nos 2 and 3 Hoblongs Cottages are located outside of this criterion and therefore have not been assessed further. (see Appendix C for the details of this assessment).

The Ambulance Station building is however relatively close to the proposed Firewater Sprinkler Tank and Pump House and falls within the above BRE guidance. The BRE guidelines also state that, ”if any part of a new

building, or extension, measured in a vertical section perpendicular to a main window wall of an existing building, from the centre of the lowest window, subtends an angle of more than 25 degrees to the horizontal”, a more detailed check is needed to find the loss of daylight and sunlight, and this situation applies to the Ambulance Station building.

A daylight and sunlight assessment has therefore been undertaken for the Ambulance Station building and its western and southern windows. A sunlight assessment has also been undertaken for the gardens of the three identified residential premises, in accordance with the methodology provided in the BRE guidance.

The following baseline data sources have been consulted:

Ordnance Survey maps of the area;

Site layout drawings, baseline position and proposed, and elevations of the proposed development, in CAD format (*.dwg) indicating proposed heights of building from datum level;

Aerial photography;

Stereographic diagram and weather data from IES-VE Suncast; and

BRE Digest 209, ‘Site Layout Planning for Daylight and Sunlight: a guide to good practice – second edition’ (2011).

In addition to the above data, a site visit was undertaken in November 2011.


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2. Daylight and Sunlight Assessments

2.1 Assessment model and parameters

In order to provide a sound basis for modelling the effects of the proposed development, a 3-D model of the built environment was created using the Integrated Environmental Solutions (IES) software in order to illustrate the following situations (see drawing 26310/GD/A/DAY/003/A at Appendix D):

The baseline position; and

The location and scale of the proposed main WTS building, the two Firewater Sprinkler Tanks, and the Pump House.

2.2 Potential Receptors

2.2.1 Buildings

One building, the Ambulance Station, was identified which has windows facing within 90° of due south.

2.2.2 Gardens and Amenity Areas

Three gardens of the three residential premises of Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages were identified.

2.3 Potential Factors

2.3.1 Trees

The proposed landscaping to the immediate rear of the main WTS building has not been taken into account in this study because, as stated in the BRE guidance, the shapes of trees are almost impossible to predict and because the dappled shade of a tree can be considered more pleasant than the ‘solid’ shadowing of a building. The landscaping proposed would also take many years to mature to a height that would start to overtake the height of the main WTS building.

2.3.2 Fences and Walls

There is some existing fencing along the eastern boundary, but, notwithstanding this, a new section of close-boarded fencing 2.5 metres in height is proposed along the eastern boundary of the application site where it adjoins Nos. 2 and 3 Hoblongs Cottages.


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2.4 BRE Guidelines Assessment Methodology

The BRE guidelines give guidance on the criteria and the calculation of loss of daylight and sunlight (See Appendix A for more details).

2.4.1 Daylight

Daylight is measured of the total amount of light from the sky available to a window of a room.

2.4.1.1 Existing Buildings

The BRE guidelines advise that the diffuse daylight of an existing building may be adversely affected if its Vertical Sky Components (VSC), measured at the centre of an existing main window, is less than 27% and less than 0.8 times the amount previously received. (The measurement of VSC is used in this study because the precise room layouts of the identified residential receptors are unknown and, hence, the other two daylight tests, as explained in Appendix A, could not be applied.)

2.4.2 Sunlight

Sunlight is measured in terms of how many hours of sun a window, or a garden/amenity area, will receive over the course of a year.

2.4.2.1 Existing Buildings

The BRE sunlight tests are only applied to windows that face within 90 degrees of due south, as these window openings benefit from the highest levels of sunlight and, therefore, any loss of sunlight is more noticeable. The BRE guidance advises that main windows should receive at least 25% of the total annual probable sunlight hours, including at least 5% of the annual probable sunlight hours in the winter months between 21 September and 21 March. Sunlight availability will be adversely affected if the total number of sunlight hours is also less than 0.8 times the amount previously received, or if the reduction in sunlight lost over the whole year is greater than 4% of annual probable sunlight hours.

2.4.2.2 Gardens and Amenity Spaces

The BRE guidelines recommend that at least half of the particular receptor (a garden or amenity area) should receive at least two hours of sunlight on the 21 March date each year. If, as a result of new development, an existing garden or amenity receiving two hours or less of sunlight on the 21 March also experiences less than 0.8 times its former value, then the loss of sunlight is likely to be noticeable.

Computer modelling techniques have been applied to trace the path of the sun through the sky. The final result is an accurate assessment of the number of sunlight hours a particular window will receive, both before and after the development, including diagrams to show the location of shadows at different times of the day on the 21 March.


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The results of each assessment have been assessed against the criteria set out in the BRE guidance. In practice, BRE Guidelines should be used flexibly and not as an instrument of planning policy, as they are not mandatory, but are intended to help the designer and planning authority to balance their judgement against other material considerations. The assessment methodology is set out in full at Appendix E.

2.5 Daylight Assessment

2.5.1 The Ambulance Station Building

Following development, window group C of the ambulance station building (See Appendix F for window group illustrations) is predicted to have a Vertical Sky Component (VSC), measured at the centre of each existing window, higher than 27%. Windows A & B have VSC values less than 27% in both their existing and proposed situation. However, following development, the VSC of these two windows is no less than 0.8 of their former values. The existing boundary hedge (which is about 2.5m tall) close to the window is likely to block out much of the existing daylight and sunlight. This window is also frosted, which restricts daylight and sunlight.

All three windows/windows group receive more than 0.8 times their former VSC values and, hence, the proposals meet the BRE daylight guidelines. More details to the calculations can be found in Appendix E.

2.6 Sunlight Assessment

2.6.1 The Ambulance Station Building

Two out of three identified windows (Window B and Window group C - see Appendix F) of the Ambulance Station building will receive more than 25% of annual probable sunlight hours (APSH) following the development, including 5% of APSH between 21 September and 21 March (the winter months).

The third window (Window A) does not satisfy the 25% of APSH test in both its existing situation and following development (i.e. pre- and post-development). This window will continue to receive, however, the same percentage of APSH (17.11%) after the development is built. As there is no change of sunlight received by this particular window, the proposals meet the BRE sunlight guidelines.

All three windows in the ambulance station building will still receive more than 0.8 times their sunlight hours after the development and will not lose more than 4% of the annual probable sunlight hours (APSH) to be received over the whole year.

The proposed development will therefore satisfy the BRE sunlight to windows guidelines and more details of the calculations can be found in Appendix D.


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2.6.2 Gardens of Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages

The assessment found that over half of the garden areas of Brooke Cottage and Nos. 2 and 3 Hoblongs Cottages will continue to receive more than 2 hours of sunlight on 21 March (see drawing 26310-GD-A-DAY-004-A at Appendix F). In practice, due to the existing houses, hedges and trees on the properties, the proposed WTS building will only make a marginal impact in terms of sunlight shadowing.

The proposed development therefore meets the BRE sunlight guidelines and more details to the calculations can be found in Appendix E.


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3. Conclusion

This assessment has investigated the effects of the proposed development of the Waste Transfer Station (WTS), located on land off Chelmsford Road, Great Dunmow, in respect of the daylight and sunlight that will continue to be received by surrounding properties.

The potential receptors are the ambulance station, the two adjoining cottages and their gardens, although the cottages have not been assessed in detail as they are located sufficiently far from the proposed development not to be significantly affected2. This is illustrated in the drawings in Appendices C and F.

There are three potential methodologies for undertaking daylight and sunlight assessments, with the Vertical Sky Component (VSC) methodology adopted for this assessment on the basis that the other two methodologies would require information on the internal dimensions of rooms which was not available.

In terms of daylight, the ambulance station has been assessed and two of the windows have been found to have a VSC of less than 27% in their existing state, showing that they do not currently receive good levels of daylight. The BRE guidance suggests that if a window in this situation receives less than 80% of its existing daylight as a result of the proposed development, then it will be adversely affected. The assessment shows, however, that the ambulance station windows will still receive over 98% of their current daylight even after the proposed development is built. The proposals therefore achieve the BRE recommendations on daylight.

In terms of sunlight, two of the windows in the ambulance station will continue to receive good levels of direct sunlight, whilst the third window currently receives poor levels of sunlight, and this will be unchanged by the proposed WTS development. BRE recommends that gardens receive at least two hours of sunshine on 21 March (the equinox) in order to be considered appropriately sunlit. Both cottage gardens will continue to comply with this guidance, as the proposed WTS development will only have a marginal effect on these properties. The proposed development therefore achieves the BRE recommendations for sunlight.

As all of the assessments have shown that the proposed development complies with BS8206-2 and the BRE guidance, no other calculation methodologies are necessary.

2 As stated in ‘Site layout planning for daylight and sunlight; A guide to good practice’ (BRE)

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© AMEC Environment & Infrastructure UK Limited

Appendix A BRE Guidelines – Daylight/Sunlight


Daylight

In the first instance, if a proposed development falls beneath a 25° angle taken from a point two metres above ground level, then the BRE say that no further analysis is required as there will be adequate skylight (i.e. sky visibility) availability.

The three methods for calculating daylight are explained in the box below.

Vertical Sky Component (VSC)

The principal method of assessing this is a measure of the amount of sky visible from the window of an affected room. This assessment component is called the Vertical Sky Component (VSC). For a window of a room to be adversely affected under the BRE guidance, the window must have a view of less than 27% of the 'dome of the sky' (a VSC of less than 27%) and the VSC must be less than 0.8 times its previous value. The Vertical Sky Component is an externally assessed calculation and does not require room use or sizing.

No Sky Contours (NSC)

The no sky-contours is a measure of those parts of the room which have no view at all of the sky at all. It is similar to the VSC approach in that a reduction of 0.8 times in the area of sky visibility at the working plane may be deemed to adversely affect daylight. It is however, very dependent upon knowing the actual room layouts or having a reasonable understanding of the likely layouts.

Average Daylight Factor (ADF)

A further more detailed assessment is called the Average Daylight Factor. This is a measure of the actual likely natural diffuse daylight in a room taking account of various matters influencing this such as the actual room layouts, reflectivity of surfaces and the glazing in the window.

All of the above measures can be used to contribute to a full assessment of the adequacy of the natural diffuse daylight in a room and the significance of any loss of natural daylight in a room.

In conjunction with the BS and CIBSE, the guidance provides a further method in Appendix C of the guidelines, which outlines criteria, based on the average daylight factor, room depth, and the position of ‘no-sky’ contours.

Sunlight

In relation to sunlight, the criteria given in the BRE Guidelines calculates the annual probable sunlight hours (APSH) having regard to the amount of sun available in both the summer and winter for each given window facing within 90° of due south. Summer is considered to be the six months between March 21st and September 21st and winter the remaining months.

The BRE give criteria (based on British Standard) and method for calculating sunlight and applies as follows:

In general, a dwelling or non-domestic building which has a particular requirement for sunlight, will appear reasonably sunlit provided that:

at least one main window wall faces within 90° of due south; and

on this window wall, all points on a line 2m above ground level are within 4 m (measured sideways) of a point which receives at least a quarter of annual probable sunlight hours, including at least 5% of annual probable sunlight hour during the winter months, between 21 September and 21 March.


Appendix B Site Layout Plan

Essex CC Waste Planning Great Dunmow Waste Transfer StationDaylight and Sunlight Assessment

Site Layout Plan

February 201226310/GD/A/DAY/002/A.indd squij


Appendix C Daylight Analysis - Brooke Cottage and Hoblongs Cottages


The BRE guidelines state that daylight assessment is applied to those rooms in adjoining dwellings where daylight is required, such as living rooms, kitchens and bedrooms. The loss of light to existing windows need not be analysed if the distance of each part of the new development from the existing window is 3 or more times its height above the centre of the existing window. In this case of the proposed WTS building, the building height is 9.76metres at its highest and for existing building, the typical existing ground floor window height is 1.5metres above ground level, the effect on existing buildings more than 3 x (9.76-1.5) = 24.78metres away need not be analysed (refer to the grey zone and the text on drawing 26310/GD/A/DAY/001/A below). Nos.2 and 3 Hoblongs Cottages are the nearest residential properties to the proposed main WTS building.

BRE guidelines also suggest that if the angle from the centre of a window to the horizontal subtended by the proposed development at its highest point (i.e. the main WTS building in this case) is less than 25 degrees, then it is likely to have a substantial effect on the diffuse skylight enjoyed by the existing building. The proposed main WTS building will not be within the 25 degree arc as measured from Nos. 2 and 3 Hoblongs Cottages.


Appendix D Built Environment Drawings


Existing Built Environment andProposed Development

Existing Built Environment

Proposed DevelopmentFebruary 2012

26310/GD/A/DAY/003/A.indd squij


Appendix E Daylight and Sunlight Calculations


Table E1 Vertical Sky Components results – A comparison of ‘Existing Site’ and ‘Proposed Development’

Windows Baseline position Proposed Development

Comparison of daylight received under the existing and the proposed scheme

A 6.2 6.1 98.3% (pass)

B 19.1 19.4 101.6% (pass)

Group C 27.6 27.5 99.6% (pass)

Table E2 Percentage of sunlight the main windows of the Ambulance Station received during summer months (22 March to 20 September) and winter months (21 September to 21 March) and in a year round with current site conditions

Windows Summer Winter Annual

No. of sunlight hours Percentage



A 169.1 11.38% 85.1 5.73% 254.2 17.11%

B 541.8 36.46% 213.6 14.29% 755.4 50.75%

Group C 405.4 27.28% 175.7 11.82% 581.1 39.10%

Table E3 Percentage of sunlight the main windows of the Ambulance Station received during summer months (22 March to 20 September) and winter months (21 September to 21 March) and in a year round with proposed development

Windows Summer Winter Annual




A 169.1 11.38% 85.1 5.73% (pass) 254.2 17.11% (fail)

B 541.8 36.46% 212.3 14.29% (pass) 754.1 50.75% (pass)

Group C 422.43 28.43% 168.5 11.34% (pass) 591.0 39.77% (pass)

The BRE guidance recommends at least 25% of the main windows should receive at least 25% of the total annual probable sunlight hours, including at least 5% of the annual probable sunlight hours in the winter months between 21st September and 21st March.

Table E4 Comparison of sunlight received under the existing and the proposed scheme

Annual Probable Sunlight Hours

Windows Baseline position Proposed development

Comparison of sunlight received under the existing and the proposed scheme

A 254.2 254.2 100% (pass)

B 755.4 754.1 99.8% (pass)

Group C 581.1 591.0 102% (pass)

The BRE guidelines suggest that the if the total number of sunlight hours falls below these targets and is less than 0.8 times the amount prior to the development, sunlight availability may be adversely affected.



Appendix F Daylight and Sunlight Drawings


Daylight Analysis

February 201226310/GD/A/DAY/005/A.indd chans

Window A (with existing site conditions)

Window B and Windows Group C (with existing site conditions)

Window A (with proposed development)

Window B and Windows Group C (with proposed development)


Sunlight Analysis - Gardens of Brooke Cottage & Hoblong’s Cottages

February 201226310/GD/A/DAY/004/A.indd squij

21st March 07:00

2 0 M a r 0 7 : 0 0 2 0 M a r 0 8 : 0 0 2 0 M a r 0 9 : 0 0 2 0 M a r 1 0 : 0 0

21st March 08:00 21st March 09:00 21st March 10:00

21st March 15:00

2 0 M a r 1 5 : 0 0 2 0 M a r 1 6 : 0 0 2 0 M a r 1 7 : 0 0 2 0 M a r 1 8 : 0 0


21st March 11:00

2 0 M a r 1 1 : 0 0 2 0 M a r 1 2 : 0 0 2 0 M a r 1 3 : 0 0 2 0 M a r 1 4 : 0 0


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