daylight, sunlight & overshadowing...

DAYLIGHT, SUNLIGHT & OVERSHADOWING ASSESSMENT

HEATHCOTE SECONDARY SCHOOL AND SCIENCE COLLEGE

96 NORMANTON PARK, CHINGFORD, LONDON, E4 6ES

ISSUE REVISION 5 DATE: 16TH OCTOBER 2016

ARTIST HOUSE, 1ST FLOOR, 35 LITTLE RUSSELL ST, LONDON WC1A 2HH

T: 0203 858 0115 E: [email protected]

www.ecostudioxv.com ECO studio Ltd - Registered in England No. 07610136 VAT Number 194867546

Reg. Office 98 Hornchurch Road, Hornchurch, Essex, RM11 1JS

ECOstudio XV LTD is registered with BRE Global no BREC400198, QUIDOS: QUID20110 AND ELMHURST EES/015107

QUALITY CONTROL- First Issue

Created by: Reviewed by: Authorized by:

Stephanie Millan Xavier Valladares Aparna Maladkar

HEATCOTE SECONDARY SCHOOL & SCIENCE COLLEGE

DAYLIGHT SUNLIGHT ASSESSMENT PAGE 2 of 26

REPORT REFFERENCE 462-161016 Heathcote Daylight - Sunlight Rep r5.docx

ECOSTUDIO XV LTD, ARTIST HOUSE, 1ST FLOOR, 35 LITTLE RUSSELL ST, LONDON, WC1A 2HH T: 0203 858 0115

COMPANY REGISTERED IN ENGLAND NUMBER 7610136 VAT NUMBER 194 867 546

CLIENT: HEATHCOTE SECONDARY SCHOOL

ARCHITECT: NPS Group

PROJECT TITLE:

Heathcote Secondary School and Science College, 96 Normanton

Park, Chingford, London, E4 6ES

REPORT: Daylight Sunlight & Overshadowing Assessment

AUTHOR: Stephanie Millan

REVIEWER: Xavier Valladares

AUTHORIZED: Aparna Maladkar

TYPE: For comment

FIRST ISSUE DATED: 14TH December 2016

REVISIONS: Date: REASON

REVISION 1- DRAFT 12TH OCTOBER 2016 MORE DETAILED ADDED TO MASSING AT

12NO BRITISH LEGION ROAD.

REVISOIN 2- DRAFT 12TH OCTOBER 2016 UPDATED SITE PLAN FOR 12NO BRITISH

LEGION ROAD.

REVISION 3- DRAFT 13TH OCTOBER 2016 MODEL AND ANALYSIS UPDATED BASED

ON TOPOGRAPHICAL SURVEY.

REVISION 4- DRAFT 13TH OCTOBER 2016 SECTION X-X’ ADDED

REVISION 5 16TH OCTOBER 2016 UPDATED BASED ON DETAILED

TOPOGRAPHICAL SURVEY






INDEX

1.0 EXECUTIVE SUMMARY .......................................................................................................................... 4

2.0 INTRODUCTION ..................................................................................................................................... 6

3.0 THE NATURE AND EFFECT OF DAYLIGHT AND SUNLIGHT ............................................................... 7

4.0 ASSESSMENT OF THE EFFECT ON DAYLIGHT – SUNLIGHT ............................................................... 8

5.0 ASSESSMENT CRITERIA ON DAYLIGHT – GENERAL .......................................................................... 9

6.0 ASSESSMENT CRITERIA ON SUNLIGHT AND OVERSHADOWING.................................................12

7.0 DATA .....................................................................................................................................................13

8.0 ANGLE TO SKY FROM HORIZONTAL ................................................................................................14

9.0 DAYLIGHT SUNLIGHT & OVERSHADOWING ASSESSMENT RESULTS ...............................................19

12. CONCLUSION ..........................................................................................................................................26

FIGURE 01 – MASSING OF THE ADJOINING HOUSES “AS EXISTING” IN LIGHT GREY AND

BUILDING “AS PROPOSED” IN ORANGE- PERSPECTIVE VIEW.






1.0 EXECUTIVE SUMMARY

DAYLIGHT, SUNLIGHT AND OVERSHADOWING TO NEIGHBOURS

The assessment undertaken in this report demonstrates that properties at 9, 10, 11 & 12 British Legion Road, would

not notice a reduction in their current Daylight and Sunlight levels if the proposed development at Heathcote

Secondary School goes ahead as currently proposed. This revision includes, a more detailed model has been

done for the property at 12 British Legion Road.

The angle to sky from horizontal has been calculated between the proposed development and the adjoining

properties at 9, 10, 11 and 12 British Legion Road. This can be seen in figures 12 to 15 below.

The analysis demonstrates that the proposed development subtends an angle well below the 25° rule. Therefore,

the proposed development will not impact the current daylight conditions, as it subtends an angle of between 7°

to 21° to the horizontal, under the worst case conditions.

An additional section X-X’ has been drawn perpendicular to the closest window at 12no British Legion Road

towards the school. This section shows an angle of only 13° to horizontal. Therefore, the proposed development

complies well within the BRE guidelines for daylight access.

The Annual Probable Sunlight Hours (APSH) and Winter Probable Sunlight Hours (WPSH) analysis has been carried

to the south facing façade and 1no worst case window at 12 British Legion Road. The sunlight conditions, even

with the proposed building, would receive more than the minimum 392 Annual Probable Sunlight Hours (APSH)

and 72 Winter Probable Sunlight Hours (WPSH).

The difference between the existing and proposed conditions is well below the maximum 20% allowed by the BRE

Guidelines for both the façade and the worst case window. The APSH for the façade has a 5.58% change (from

2,832 hrs. to 2,674 hrs.). The façade has 11.31% difference in WPSH (from 1,256 hrs. to 1,114 hrs.).

The worst case window has 7% change in APSH (from 3,026 hrs to 2,804 hrs.) and a 15% change in WPSH (from

1,319hrs to 1,116hrs). Therefore, the scheme complies well with the BRE Guidelines for Sunlight access to neighbours.

See Tables 3no and 4no for further details.

For a garden or an open space to appear adequately sunlit throughout the year, the BRE Guidelines recommend

that at least half of a garden or amenity area should receive at least 2 hours of sunlight on 21st March. In terms of

Sunlight and Overshadowing.

Results show that more than half of the garden at 12 British Legion Road, under the proposed conditions, receives

2no hours of sunlight. The existing conditions have an average value of 5.90 probable sunlight hours (PSH) and 5.30

PSH with the proposed scheme. The change is only 10.16% which is within accepted parameters. Therefore, the

scheme complies with the BRE Guidelines in terms of Sunlight and Overshadowing for gardens and open spaces.

Therefore, the scheme complies with the BRE Guidelines in terms of Daylight, Sunlight, and Overshadowing for

gardens and open spaces.

FIGURE 02 – MASSING OF THE ADJOINING HOUSES IN GREY WITH THE PROPOSED

DEVELOPMENT IN ORANGE.

FIGURE 03 – MASSING OF THE SITE AS EXISTING WITH THE ADJOINING BUILDINGS

IN GREY.






FIGURE 04 – SITE PLAN AS PROPOSED SHOWN IN SOLID GREY HATCH






2.0 INTRODUCTION

The Building Research Establishment (BRE) has set out in their handbook Site Layout Planning for Daylight and

Sunlight a Guide to Good Practice (2011), guidelines and methodology for the measurement and assessment of

daylight and sunlight within proposed buildings. This document states that it is also intended to be used in

conjunction with the interior daylight recommendations found within the British Standard BS8206-2:2008 and the

Applications Manual on Window Design of the Chartered Institution of Buildings Services Engineers (CIBSE).

The guide also provides advice on site layout planning to determine the quality of daylight and sunlight within

open spaces between buildings.

ECOstudio XV has been commissioned to undertake the following studies of the adjoining property 12 British Legion

Road in relation to the proposed development at Heathcote Secondary School:

o Create a 3D computer model of the proposal based upon drawings prepared by the design team.

o Carry out the following assessments:

o Daylight, sunlight and overshadowing assessment to neighbours using the methodologies set out in

the BRE guidelines for Angle to Sky from Horizontal, PSH, APSH & WPSH. These were based on design

proposals developed by the design team.

o Prepare a report setting out the analysis and our findings.

FIGURE 05 – PROBABLE SUNLIGHT HOURS OF THE DEVELOPMENT “AS PROPOSED”

TOWARDS THE GARDEN AT 12no. BRITISH LEGION ROAD.






3.0 THE NATURE AND EFFECT OF DAYLIGHT AND SUNLIGHT

The provision of daylight is as important as ensuring low levels of noise, or low levels of odour, in maintaining the

enjoyment of one’s property. Adequate levels of daylight are important not only to light and heat the home, but

also for an occupant’s emotional well-being. Daylight is widely accepted to have a positive psychological effect

on human beings and there is a great deal of evidence to suggest that people who are deprived of daylight are

more susceptible to depression and mood swings. This is common in northern countries, such as Norway, Iceland

and Canada where daylight is scarce during the winter months.

When assessing the effects of proposed building projects on the potential to cause issues relating to light, it is

important to recognize the distinction between daylight and sunlight. Daylight is the combination of all direct and

indirect sunlight during the daytime, whereas sunlight comprises only the direct elements of sunlight. On a cloudy

or overcast day diffused daylight still shines through windows, even when sunlight is absent.

Care should also be taken when the development is situated to the south of existing buildings, as in the northern

hemisphere the majority of the sunlight comes from the south. In the UK (and other northern hemisphere countries)

south- facing facades will, in general, receive most sunlight, while north facing facades will receive sunlight few

hours during summer months, specifically early mornings and late evenings.






4.0 ASSESSMENT OF THE EFFECT ON DAYLIGHT – SUNLIGHT The Department for Communities and Local Government (DCLG) sets national planning policy. Their document

“The Planning System: General Principles (2005)”, published in conjunction with Planning Policy Statement 1:

Delivering Sustainable Development, discusses the need to protect amenities in the effects of overshadowing, and

does not have target, criteria or relevant planning guidance, in the way it has for other environmental impacts

such as noise, landscape or air quality.

Reference is made to the Building Research Establishment (BRE) report, “Site Layout Planning for daylight and

sunlight- a guide to good practice” by P J Littlefair, 2011.

FIGURE 06 – ANNUAL SUN PATH WITH MASSING OF THE DEVELOPMENT “AS

PROPOSED” - PERSPECTIVE VIEW






5.0 ASSESSMENT CRITERIA ON DAYLIGHT – GENERAL

When assessing the effects of proposed building projects on the potential to cause issues relating to light, it is

important to recognize the distinction between daylight and sunlight. Daylight is the combination of all direct and

indirect sunlight during the daytime, whereas sunlight comprises only the direct elements of sunlight. On a cloudy

or overcast day diffused daylight still shines through windows, even when sunlight is absent.

Care should also be taken when the development is situated to the south of existing buildings, as in the northern

hemisphere the majority of the sunlight comes from the south. In the UK (and other northern hemisphere countries)

south- facing facades will, in general, receive most sunlight, while north facing facades will receive sunlight few

hours during summer months, specifically early mornings and late evenings.

5.1 ASSESSMENT CRITERIA ON DAYLIGHT – IMPACT TO NEIGHBOURS

Reference is made to the Building Research Establishment (BRE) report, “Site Layout planning for daylight and

sunlight- a guide to good practice” by P J Little fair.

The BRE document looks at three separate areas when considering the impacts of a new development on an

existing property:

1. – Daylight - The impacts of all direct and indirect sunlight during daytime.

2. – Sunlight - The impacts of only the direct sunlight; and overshadowing of garden and open spaces.

3. – Overshadowing of Gardens and Open spaces

The BRE report provides guidelines for when the obstruction to sunlight may become an issue:

- If the proposed or existing development has a window that faces within 90° of due south, and

- On this window wall, all points on a line 2m above ground level are within 4m (measured sideways) of a point

which receives at least a 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.

Table 03 summarises the criteria used to assess the impacts from new development on the daylight reaching

existing properties.

5.2 ANGLE TO SKY FROM HORIZONTAL- IMPACT TO NEIGHBOURS

In general, a building will retain the potential for good interior diffuse day lighting provided that on all its main

faces:

a) No obstruction, measured in a vertical section perpendicular to the main face, from a point 2m above

ground or first level, subtends an angle of 25 ° to the horizontal or less. See Figure 06 for further details. OR If (a) is not satisfied, then all points on the main face on a line 2m above ground or first level are within 4m

(measured sideways) of a point which has a vertical sky component of 27% or less.

TABLE 01 – SUMMARY CRITERIA FROM BRE REPORT TO ASSESS THE IMPACT OF THE

PROPOSED DEVELOPMENT

PARAMETER

BRE REPORT

REFERENCE

CRITERIA

ACCEPTABILITY

CRITERIA

Daylight

Section 2.2

Any part of the new

building measured in a

vertical section

perpendicular to a main

window wall subtends an

angle of less than 25° to

the horizontal

Any part of the new

building measured in a

vertical section

perpendicular to a main

window wall subtends an

angle of less than 25° to the

horizontal.

Vertical Sky Component

(VSC)

Reduction from existing not

more than 20% its former

value if VSC is lower than

27%.






b) If (a) is not satisfied, then all points on the main face on a line 2m above ground or first level are within 4m

(measured sideways) of a point which has a vertical sky component of 27% or less.

5.3 VERTICAL SKY COMPONENT (VSC) CRITERIA

When the angle to sky from horizontal criteria is not met, of there is a complex geometry in the surrounding buildings

a more detailed assessment needs to be carried out. This detailed assessment is called Vertical Sky Component

(VSC).

This analysis will quantify the amount of sky falling on the reference windows for a daylight calculation).

FIGURE 07 - SECTION SHOWING THE ANGLE TO SKY FROM HORIZONTAL CRITERIA FOR DIFFUSE

DAYLIGHTING






When undertaking a daylight assessment, the BRE report recommends a VSC of 27% or more should be achieved

if a room is to be adequately day lit. It is also suggested that when existing levels of daylight are below 27% VSC,

a reduction of more than 20% from the existing level.

FIGURE 08 – STEREOGRAPHIC DIAGRAM FOR CALCULATING THE VSC






6.0 ASSESSMENT CRITERIA ON SUNLIGHT AND OVERSHADOWING

6.1 SUNLIGHT – THE IMPACTS DIRECT SUNLIGHT

The methodologies and criteria to assess the impact of Direct Sunlight. Table 05 summarises the criteria used to

assess the impact from a new development on the sunlight reaching existing properties. Further details can be

found at Appendix 1 of the BRE Report,

6.2 ASSESSMENT CRITERIA ON SUNLIGHT AND OVERSHADOWING TO GARDENS, PARKS AND OPEN SPACES

According to Paul Littlefair’s “Site Layout Planning for Daylight and Sunlight” if a building is to be constructed

near an open space such as:

Gardens

Parks

Children Playgrounds

Outdoor swimming pools

Monuments or fountains.

A Sunlight analysis should be carried out in order to prove that, at least half of the garden or open space

receives 2 hours of sunlight on 21st March. In addition, the reduction between the exiting and proposed

conditions should not be more than 20% reduction or 0.8 times its former value.

FIGURE 09 – INSERT REFERENCE IMAGE SUNLIGHT TO GARDEN, OPEN SPACES

TABLE 02 – SUMMARY CRITERIA FROM BRE REPORT TO ASSESS THE IMPACT OF PROPOSED

DEVELOPMENTS

PARAMETER

BRE REPORT

REFERENCE

CRITERIA

ACCEPTABILITY

CRITERIA

Sunlight &

Overshadowing

Section 3.1

Annual Probable Sunlight

Hours. (APSH)

Winter Probable Sunlight

Hours. (WPSH)

Reduction from existing not

more than 20%

AND

Not less than 75 for WPSH

and 392 for APSH






7.0 DATA All of the information has been taken directly from digital files provided by NPS. The height of the obstructions has

been taken from survey data and OS Maps.

Figure 11 shows the site plan as proposed with 4no sections taken to analyse the Angle to Sky from Horizontal.

FIGURE 11 – SITE LOCATION SHOWING THE PROPOSED SITE IN LIGHT ORANGE AND EXISTING HOUSES IN BROWN






8.0 ANGLE TO SKY FROM HORIZONTAL The angle to sky from horizontal has been calculated between the proposed development and the adjoining

properties at 12, 11, 10 and 9no British Legion Road. This can be seen in figures 12 to 16 below.

The below figures demonstrates that the proposed development subtends an angle well below the 25° rule.

Therefore, the proposed development will not impact the current daylight conditions, as it subtends an angle of

between 7° to 21° to the horizontal on the worst case conditions.


towards the school. This section shows an angle of only 13° to horizontal.

FIGURE 12 – SECTION A-A´ SHOWING ANGLE TO SKY FROM HORIZONTAL FOR 12 BRITISH LEGION ROAD- WORST CASE CONDITION FROM WINDOW TO SCHOOL.






FIGURE 13 – SECTION B-B´ SHOWING ANGLE TO SKY FROM HORIZONTAL FOR 11 BRITISH LEGION ROAD.






FIGURE 14 – SECTION C-C´ SHOWING ANGLE TO SKY FROM HORIZONTAL FOR 10 BRITISH LEGION ROAD.






FIGURE 15 – SECTION D-D´ SHOWING ANGLE TO SKY FROM HORIZONTAL FOR 9 BRITISH LEGION ROAD.






FIGURE 16 – SECTION X-X´ SHOWING ANGLE TO SKY FROM HORIZONTAL FOR 12 BRITISH LEGION ROAD.






9.0 DAYLIGHT SUNLIGHT & OVERSHADOWING ASSESSMENT RESULTS

SUNLIGHT ASSESSMENT RESULTS

The proposed development orientation, located at 96 Normanton Park, London, E4 6ES can be seen on Figure 16.

According to the BRE Guidelines any window should be assessed against the WPSH and APSH if they face 90°

degrees due south. This in relation to the proposed development and the existing conditions.


to the south facing façade and worst case window at 12 British Legion Road. The sunlight conditions, even with

the proposed building, would receive more than the minimum 392 Annual Probable Sunlight Hours (APSH) and 72

Winter Probable Sunlight Hours (WPSH).







FIGURE 17 - SITE PLAN SHOWING THE SITE IN SOLID GREY “AS PROPOSED”






9.1 GARDEN AND OPEN SPACES

According to Littlefair’s “Site Layout Planning for Daylight and Sunlight” if a building is to be constructed near an

open space such as:

Gardens.

Parks.

Children Playgrounds.

Outdoor swimming pools.

Monuments or fountains.

Daylight analysis should be carried out in order to prove that, at least, half of the garden or open space receives

2 hours of sunlight on 21st March. F






PSH with the proposed scheme. The change is only 10.16% which is within accepted parameters.

Therefore, the scheme complies with the BRE Guidelines in terms of Sunlight and Overshadowing for gardens and

open spaces.






TABLE 03 – APSH & WPSH 12no BRITISH LEGION ROAD

SITE ADDRESS

CONDITION

ANALYZED

MINIMUM

APSH AS PER

BRE

GUIDELINES

APSH

REDUCTION

PERCENTAGE

(MAXIMUM 20% IF

BELOW 392 APSH)

MINIMUM

WPSH AS PER

BRE

GUIDELINES

WPSH

REDUCTION

PERCENTAGE

(MAXIMUM 20% IF

BELOW 72 WPSH)

COMPLIES WITH

BRE GUIDELINES?

12NO BRITISH

LEGION ROAD

AS EXISTING

392 2,832

5.58 %

72 1,256

11.31 %

YES

AS PROPOSED

392 2,674 72 1,114 YES

FIGURE 18 – APSH– DEVELOPMENT “AS EXISTING” – 12 BRITISH LEGION RD 2,832 HRS

FIGURE 19 – APSH– DEVELOPMENT “AS PROPOSED” – 12 BRITISH LEGION RD 2,674 HRS






FIGURE 20 – WPSH– DEVELOPMENT “AS EXISTING” –– 12 BRITISH LEGION RD 1.256 HRS

FIGURE 21 –WPSH– DEVELOPMENT “AS PROPOSED” – 12 BRITISH LEGION RD- 1,114HRS






TABLE 04 – APSH & WPSH 12no BRITISH LEGION ROAD- WORST CASE WINDOW

SITE ADDRESS

CONDITION

ANALYSED

MINIMUM

APSH

AS PER BRE

GUIDELINES

APSH

REDUCTION

PERCENTAGE

(MAXIMUM 20% IF

BELOW 392 APSH)

MINIMUM

WPSH AS PER

BRE

GUIDELINES

WPSH

REDUCTION

PERCENTAGE

(MAXIMUM 20% IF

BELOW 72 WPSH)

COMPLIES WITH

BRE GUIDELINES?

12NO BRITISH

LEGION ROAD

WORST CASE

WINDOW

AS EXISTING

392 3,026

7.0%

72 1,319

15.0 %

YES

AS PROPOSED

392 2,804 72 1,116 YES

FIGURE 22 – APSH– DEVELOPMENT “AS EXISTING” – 12 BRITISH LEGION RD-WORST CASE

WINDOWS = 3,026 HRS

FIGURE 23 – APSH– DEVELOPMENT “AS PROPOSED” – 12 BRITISH LEGION RD =2,804

HRS






FIGURE 24 – WPSH– DEVELOPMENT “AS EXISTING” –– 12 BRITISH LEGION RD 1,319 HRS

FIGURE 25 –WPSH– DEVELOPMENT “AS PROPOSED” – 12 BRITISH LEGION RD 1,116 HRS






FIGURE 26 – PSH– DEVELOPMENT “AS EXISTING” – 21ST MARCH –AVERAGE 5.90 HRS

FIGURE 27 –PSH– DEVELOPMENT “AS PROPOSED” – 21ST MARCH- AVERAGE 5.30 HRS






10. CONCLUSION

DAYLIGHT SUNLIGHT AND OVERSHADOWING- TO NEIGHBOURS

The assessment undertaken in this report demonstrates that properties at 9, 10, 11 & 12 British Legion Road, would

not notice a reduction in their current Daylight and Sunlight levels if the proposed development at Heathcote

Secondary School goes ahead as currently proposed. This revision includes, a more detailed model has been

done for the property at 12 British Legion Road.

The angle to sky from horizontal has been calculated between the proposed development and the adjoining

properties at 9, 10, 11 and 12 British Legion Road. This can be seen in figures 12 to 15 above.

The analysis demonstrates that the proposed development subtends an angle well below the 25° rule. Therefore,

the proposed development will not impact the current daylight conditions, as it subtends an angle of between 7°

to 21° to the horizontal, under the worst case conditions.


towards the school. This section shows an angle of only 13° to horizontal. Therefore, the proposed development

complies well within the BRE guidelines for daylight access.


to the south facing façade and 1no worst case window at 12 British Legion Road. The sunlight conditions, even

with the proposed building, would receive more than the minimum 392 Annual Probable Sunlight Hours (APSH)

and 72 Winter Probable Sunlight Hours (WPSH).












PSH with the proposed scheme. The change is only 10.16% which is within accepted parameters. Therefore, the

scheme complies with the BRE Guidelines in terms of Sunlight and Overshadowing for gardens and open spaces.

Therefore, the scheme complies with the BRE Guidelines in terms of Daylight, Sunlight, and Overshadowing for

gardens and open spaces.

FIGURE 28 –BUILDING “AS PROPOSED” IN SOLID ORANGE AND CONTEXT IN LIGHT

GREY.

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