GODALMING KEY SITE
ENVIRONMENTAL STATEMENT
CHAPTER K:
SUNLIGHT/DAYLIGHT
November 2009
CONTENTS
1.0
INTRODUCTION ............................................................................................................ 1
2.0
POLICY CONTEXT ........................................................................................................ 2
National Planning Policy ................................................................................................. 2
Local Planning Policy ...................................................................................................... 2
BRE Guidelines............................................................................................................... 3
Daylight........................................................................................................................... 3
Sunlight........................................................................................................................... 4
Overshadowing ............................................................................................................... 5
British Standard BS8206 – Lighting for Buildings – Part 2: Code of Practice for
Daylighting 2008 ............................................................................................................. 5
3.0
ASSESSMENT METHODOLOGY .................................................................................. 6
Assessment Methodology ............................................................................................... 6
Sunlight Adequacy to Existing Neighbouring Dwellings................................................... 7
Significance Criteria ........................................................................................................ 8
4.0
BASELINE CONDITIONS............................................................................................. 11
1-12 Wharf Street.......................................................................................................... 11
50-55 Catteshall Lane ................................................................................................... 11
2-28 Victoria Road ........................................................................................................ 12
5.0
PREDICTED IMPACTS ................................................................................................ 13
Demolition and Construction ......................................................................................... 13
Completed Development............................................................................................... 13
1-12 Wharf Street.......................................................................................................... 13
50-55 Catteshall Lane ................................................................................................... 14
2-28 Victoria Road ........................................................................................................ 15
Cumulative Impact ........................................................................................................ 17
6.0
EVALUATION OF SIGNIFICANCE .............................................................................. 18
7.0
OPPORTUNITIES FOR MITIGATION AND ENHANCEMENT ..................................... 19
8.0
RESIDUAL IMPACTS................................................................................................... 20
9.0
SUMMARY AND CONCLUSIONS................................................................................ 21
REFERENCES......................................................................................................................... 23
LIST OF APPENDICES
K.1: Site Plan and 3D Massing Models, Drawing Numbers ROL5877_5_000, 001, 002 and 003.
K.2: Daylight Distribution Contours, Drawing Numbers ROL5877_5_100, 101, 102 and 103.
K.3: Vertical Sky Component Analysis Table.
K.4: Daylight Distribution Analysis Table.
K.5: Overshadowing Analysis Table.
K.6: Overshadowing Analysis, Drawing Number ROL5877_5_200.
K.7. Room Layout and Location Plans for Proposed New Dwellings and Average Daylight Factor
and Sunlight Tables.
K.8. Permanent Overshadowing Analysis, Drawing Number ROL5877_5_305 and Table P6
LIST OF TABLES
K.1: Vertical Sky Component Significance Criteria
K.2: Daylight Distribution Significance Criteria
GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
1.0
INTRODUCTION
1.1
This Chapter assesses the effects of the development with regard to sunlight and
daylight and overshadowing and has been written by Anstey Horne & Company
Limited.
1.2
The Chapter describes the methods used to assess the effects, the baseline daylight
and sunlight conditions currently existing at the site and the sensitive receptors that
are likely to be affected by the development.
1.3
1.4
The following potential effects of the development have been considered:
•
Impact on daylight received by the existing neighbouring residential dwellings
around the site.
•
Impact on the sunlight received by the existing neighbouring residential dwellings
around the site.
•
Impact on the overshadowing of the designated garden areas of those dwelling
houses adjacent to the site.
The proposed development is an entirely “new-build” development of dwellings, and
hence has no existing baseline conditions. An additional part of the assessment has
been to measure and verify the quality and adequacy of sunlight and daylight that will
be enjoyed by those proposed new dwellings.
A representative sample of the
habitable rooms within the proposed new dwellings have therefore been tested for
daylight and sunlight and the proposed new amenity areas, especially the courtyards,
have been tested for the amount of permanent overshadowing in accordance with the
BRE Guidelines.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
2.0
POLICY CONTEXT
National Planning Policy
2.1
There is no current specific national planning policy relating to development and its
potential impacts on daylight and sunlight. The only guidance at national level relates
to tall buildings in guidance produced by English Heritage/The Commission for
Architecture and the Built Environmental (CABE) which recommends that
consideration be given to:
“the effect on the local environment, including microclimates, overshadowing,
night time appearance, vehicle movement and the environment and those in
the vicinity of the building”.
2.2
The current proposals would not be classed as a “tall building” for the purpose of
National Planning Policy
Local Planning Policy
2.3
The relevant Local Plan covering this Application Site is the Waverley Borough
Council Local Plan which was adopted in 2002. Policy D1 states that the Council will
have regard to the environmental implications of development and that it will not be
permitted where it would result in material detriment to the environment by virtue of:
“(c)
Loss of general amenity, including material loss of natural light and
privacy enjoyed by neighbours and disturbance resulting from the
emission of noise, light or vibration.”
2.4
Policy D4 (c) goes on to say that new development should:
“not significantly harm the amenities of occupiers of neighbouring properties by way
of overlooking, loss of daylight or sunlight, overbearing appearance or other adverse
environmental impacts.”
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
BRE Guidelines
2.5
To assess the likely impact objectively, the scientific empirical measurements
contained in the Building Research Establishment (BRE) Guidelines “Site Layout
Planning for Daylight and Sunlight – A Guide to Good Practice” 1991 are the
standards almost universally adopted by Planning Authorities.
Reference is also
made to the British Standard Code of Practice for Daylighting, BS8206 Part 2 2008
and the CIBSE Applications Manual for Window Design, LG10.
2.6
Access to daylight in existing buildings has been assessed in accordance with the
methodology set out in Section 2.2 of the BRE Guidelines. The methodology for
sunlight has been taken from Section 3.2.
Daylight
2.7
2.8
The BRE Guidelines contain two methods for calculating daylight:
•
The Vertical Sky Component (VSC) method.
•
Internal Daylight Distribution by the use of the no skyline contour method.
The VSC method measures the amount of light available on the outside plane at the
centre of the window expressed as a percentage ratio of the amount of total
unobstructed sky visible following the introduction of visible barriers such as buildings,
in comparison to a totally unobstructed outlook. It is a “spot” measurement of daylight
at one given reference point and takes no account of the actual size and use of the
room and the window(s) serving that room.
2.9
The maximum VSC value achievable for a completely unobstructed outlook from a
conventional window in a vertical plane is approximately 40% VSC.
2.10
In its simplest form, VSC can be calculated by using the Skylight Indicator or
Waldram diagrams taken from the Appendices in the BRE Guidelines. These manual
methods do however contain inevitable margins of error and for the present
assessment, specialist daylight software has been used including a 3D massing
model built up from the survey drawings so as to provide a much higher degree of
accuracy.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
2.11
The no skyline contour measures the internal Daylight Distribution within the room
being tested. It divides those areas within the room, measured usually at a horizontal
working plane of 850mm above finished floor level, which can receive direct light from
the sky, from those which cannot. It therefore illustrates the pattern and amount of
daylight penetration within the room being assessed.
Sunlight
2.12
The BRE Guidelines recommend that access to sunlight be assessed for
development proposals. Potential impact on available sunlight is assessed using the
BRE’s Annual Probable Sunlight Hours (APSH) method. This method involves the
prediction of sunlight availability for the main window of each habitable room where
that window faces within 90 degrees of due south. Sunlight availability is measured
for the total year and separately for the winter months. The winter analysis covers the
period between the autumn equinox (21st September) and the spring equinox (21st
March) with the summer period covering the remaining months. The test date for
sunlight is the spring equinox of 21st March on which date the United Kingdom
receives 12 hours of daylight and 12 hours of darkness with sunlight availability
generally being limited to between 0700 and 1700. On that date, sunlight is only
directly incident perpendicular to the plane of a window where that window faces
within 90 degrees of due south. The key receptor for sunlight in a dwelling is the
principal living room.
2.13
For the availability of daylight to existing neighbouring dwellings, the Guidelines
require the measurement of Vertical Sky Component (VSC) which measures the
amount of natural daylight striking the face of the window, followed by the
measurement and plotting of a “no skyline” contour within the room in order to
measure internal Daylight Distribution.
2.14
For sunlight, the Guidelines require the measurement of the total amount of sunlight
received by a window facing within 90 degrees of due south measured on the spring
equinox together with the separate measurement of the availability of winter sunlight.
2.15
For overshadowing, the Guidelines require the measurement of the amount of
permanent overshadowing on the ground measured on the spring equinox.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
Overshadowing
2.16
The BRE overshadowing criteria should be applied to garden areas and designated
amenity spaces such as children’s playgrounds and sitting out areas.
2.17
It measures the amount of permanent overshadowing on the surface of the ground.
For a garden or amenity area to appear to be adequately sunlit, no more than two
fifths and preferably no more than a quarter of that garden or amenity area should be
prevented by buildings from receiving any sun at all on the spring equinox of 21st
March. If as a result of new development an existing garden or amenity area does
not meet these guidelines, and the area which can receive some sun on 21st March is
less than 0.8 times its former value, then the loss of sunlight is likely to be noticeable.
The maximum amount of permanent overshadowing of the proposed gardens should
therefore not exceed 40% but preferably a target of 25% should be achieved.
British Standard BS8206 – Lighting for Buildings – Part 2: Code of Practice for
Daylighting 2008
2.18
BS8206-2 provides guidance and target standards for the measurement and
assessment of daylight and sunlight adequacy within proposed new-build buildings.
The guidance and methodology in BS8206-2 is similar to the guidance and advice
contained in Appendix C of the BRE Guidelines but has been updated to include a
more detailed and representative methodology for measuring Average Daylight
Factors. The target standards for ADF have however remained unchanged and are
the same as those in the BRE Guidelines i.e.:
•
Family kitchens – 2% df.
•
Living rooms – 1.5% df.
•
Bedrooms – 1% df.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
3.0
ASSESSMENT METHODOLOGY
Assessment Methodology
3.1
Daylight and sunlight are two constituents of general “amenity”, the others being
overshadowing, sense of enclosure, privacy and overlooking. The impact on natural
daylight and sunlight to non-domestic and commercial premises is not considered to
be important unless that non-domestic use has a specific requirement for daylight as
part of its normal day to day operations. Suitable examples of where non-domestic
buildings should be included are school classrooms, hospital lying-in wards and
certain other forms of community or recreational buildings such as art galleries or
places of worship. Daylight and sunlight to commercial premises such as offices,
shops and warehouses are not considered to be essential for their use as it is
accepted practice that they usually operate under permanent supplementary artificial
lighting throughout the day. If they are considered at all, they would be classed as a
receptor with very low sensitivity.
3.2
For the purpose of assessing environmental impact, the sensitive receptors are
therefore limited to residential properties and in particular daylight and sunlight to
habitable rooms within those residential properties. A “habitable” room is defined as a
living room, kitchen or bedroom.
Bathrooms, hallways and circulation space are
excluded. It is also generally accepted that a kitchen need only be classed as a
habitable room where it is large enough to accommodate an additional function apart
from food preparation such as dining or as a separate dayroom. For the purpose of
the Building Regulations and Environmental Health Standards, daylight is not a
requirement for a kitchen which is solely used for food preparation provided there is
adequate mechanical ventilation.
3.3
This is normally assessed on the basis of internal area in that for a kitchen to be
classed as a habitable room, the threshold internal area is usually set at 13m²
excluding fixtures and fittings. For example, it is perfectly acceptable to have internal
windowless kitchens provided that they satisfy the Building Regulations in terms of air
changes per hour through mechanical ventilation where a kitchen is solely used for
food preparation and not used as a separate habitable room.
3.4
This principle would also apply to the trend towards open plan living where the “living
room” part of the room is usually located adjacent to the window so as to enjoy the
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
benefit of daylight and sunlight whereas the kitchen area is seen as the subservient
use and usually located at the rear of the room where daylight and sunlight will be
very limited, if received at all.
3.5
Within dwellings, the key habitable room is the living room, which should be classed
as the main sensitive receptor for daylight, as it is the room most likely to be occupied
for the largest part of the day during daylight hours. Kitchens (where they are classed
as habitable rooms – see 3.2 and 3.3 above) are less important, and finally bedrooms
are the least sensitive receptor as they are generally unoccupied during daylight
hours.
Sunlight Adequacy to Existing Neighbouring Dwellings
3.6
For sunlight, the BRE Guidelines recommend that access to sunlight be assessed for
development proposals. Potential impact on available sunlight is assessed using the
BRE’s Annual Probable Sunlight Hours (APSH) method. This method involves the
prediction of sunlight availability for the main window of each habitable room where
that window faces within 90 degrees of due south. Sunlight availability is measured
for the total year and separately for the winter months. The winter analysis covers the
period between the autumn equinox (21st September) and the spring equinox (21st
March) with the summer period covering the remaining months. The test date for
sunlight is the spring equinox of 21st March on which date the United Kingdom
received 12 hours of daylight and 12 hours of darkness with sunlight availability
generally being limited to between 0700 and 1700. On that date, sunlight is only
directly incident perpendicular to the plane of a window where that window faces
within 90 degrees of due south. The key receptor for sunlight in a dwelling is the
principal living room. That room should therefore be treated as a sensitive receptor.
Kitchens and bedrooms are low receptors.
3.7
Each of the methods of measurement described above have been applied in this
assessment with calculations being undertaken using specialist computer software
applied to three dimensional autocad models of the existing surrounding properties
and the Proposed Development. The computer software is based on the Waldram
method to establish VSC, and uses the room layouts and window dimensions derived
from the accurate survey information produced by Michael Gallie & Partners Land
Surveyors supplemented by historical survey information supplied by Scott Wilson
Limited and Z-Mapping.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
3.8
The existing surrounding buildings have been modelled using the site survey together
with research of the historical archives for as many of the neighbouring buildings as
possible. Where detailed drawings have not been available, floor heights and room
layouts have been estimated from window locations and the characteristics of the
buildings in question. The only existing designated amenity areas under present
conditions adjacent to the site which could fall within the BRE overshadowing criteria
are the rear gardens of 2-28 Victoria Road (even numbers).
Significance Criteria
3.9
The criteria given in the BRE Guidelines have been used as a basis to assess the
Proposed Development’s potential impact. The significance criteria for each of the
methods of measurement is summarised below.
3.10
The VSC method measures daylight in two ways:
•
First, on an absolute scale based on the actual VSC value measured on the
face of the window being tested; and
•
Second, on a comparative scale based on the light received expressed as a
percentage of the original value.
3.11
A Significance Criteria therefore needs to incorporate both scales of measurement.
3.12
To satisfy the initial test in the Guidelines, the Vertical Sky Component measured on
the face of the window should not fall below a target value of 27% VSC. Provided
that a window will continue to receive more than 27% VSC, it will receive an adequate
amount of daylight for all conventional habitable uses. It is however recognised that
this target standard has been derived using a low density suburban housing model
and that with existing buildings in a relatively densely built-up historic urban
environment, especially for windows in lightwells, the magnitude of such levels of
daylight is often unachievable. Where the VSC value is below 27% under existing
conditions, it becomes necessary to assess the percentage reduction.
From the
research undertaken by the BRE, they have found that it is acceptable to reduce
existing daylight (and sunlight) levels by a factor of 0.2 (20%) before that loss of light
becomes materially noticeable.
3.13
The no skyline test is an area-based test and is measured in terms of a percentage
reduction in the amount of the working plane that has direct sky visibility. If, following
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
the construction of a new development, the no skyline contour moves so that the area
of the existing room that does not receive direct sky light is reduced by more than 0.2
(20%) times its former value, then this will be noticeable to the occupants and more of
the room will appear poorly lit.
3.14
The methods of testing and units of measurement for daylight (and sunlight) do not
lend themselves very easily to the ranking system adopted in the conventional
“Significance Criteria” generally followed in Environmental Statements, as they are
often used in a “pass” and “fail” manner rather than on a sliding ranking scale.
However, in the tables below, each table represents the Significance Criteria adopted
for each of the daylight methodologies.
Table K.1:Vertical Sky Component (VSC)
Quantitative Reduction
Significance
VSC between 25% and 27% or loss less than
20% of present value.
Negligible
VSC between 20% and 24.99% or loss
between 20% and 29.9% of present
value.
Minor Adverse
VSC between 10% and 19.99% or loss
between 30% and 39% of present
value.
Moderate Adverse
VSC below 10% or loss greater than 40% of
present value.
Substantial Adverse
Table K.2: Daylight Distribution
3.15
Quantitative Reduction
Significance
Loss less then 20%.
Negligible
Loss between 20% and 29.9%.
Minor Adverse
Loss between 30% and 39.9%.
Moderate Adverse
Loss over 40%.
Substantial Adverse
For the measurement of daylight, sunlight and overshadowing of the proposed new
dwellings, as there are no existing baseline conditions, there can of course be no
measureable “impact” by measuring and comparing the difference between an
“existing” and “proposed” set of conditions. The significance criteria for the proposed
new dwellings and amenity areas should therefore be measured against the absolute
design standards contained within the BRE Guidelines and British Standard Code of
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
Practice for Daylighting. This will be assessed on a “pass” or “fail” basis and if any of
the sample Receptors do not meet the target design standards, the amount by which
they fail to meet that standard is then the material consideration in assessing
“impact”.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
4.0
BASELINE CONDITIONS
4.1
The site is presently made up of several parts which vary in age, use and nature of
existing buildings ranging from a Police Station, occupied and derelict light industrial
units and areas of cleared land. There is no single coherent or uniform type or scale
of building on the site.
4.2
The site itself is approximately triangular in shape being bordered by Wharf Street to
the north west and Catteshall Lane along the south with the north eastern boundary
of the “triangle” being formed by the rear terrace houses at 2-28 Victoria Road and
the adjoining land owned by the Council (presently used as an open surface level car
park).
4.3
The sensitive receptors to daylight and sunlight are the windows serving habitable
rooms in the existing neighbouring residential properties.
4.4
A review of the site and its surroundings has identified the following sensitive
receptors:
•
The dwellings in 1-12 Wharf Street.
•
The habitable rooms in the dwelling houses in 50-55 Catteshall Lane.
•
The habitable rooms in 2-28 Victoria Road (even numbers).
1-12 Wharf Street
4.5
This property appears to be a block of flats and lies adjacent to the western apex of
the triangular site at the junction of Wharf Street and Catteshall Lane. The principal
receptors, i.e. the front elevation windows, face south west and face onto Hambledon
House. Those windows do not have a direct outlook onto the Site but do receive
daylight and sunlight from an oblique angle and could therefore experience an impact.
50-55 Catteshall Lane
4.6
There is a considerable difference in finished ground level between the site and the
houses that we have identified as 50-55 Catteshall Lane.
Those houses stand
considerably higher than the level of the site itself. Each house has a number of
north facing windows which have a direct outlook onto the site and those windows
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
appear to serve habitable rooms. They are therefore sensitive receptors in respect of
daylight. Sunlight does not apply to these properties as the windows do not face
within 90 degrees of due south and therefore do not fall within the BRE sunlight
criteria, nor will there be any overshadowing of the existing gardens that serve these
properties.
2-28 Victoria Road
4.7
These are a row of relatively small terraced houses with single storey rear extensions.
The terrace has a slight curve to the effect that some of the windows face within 90
degrees of due south and therefore fall within the BRE sunlight criteria.
4.8
At ground floor level, some of the windows have been enclosed by extensions to the
original rear extensions and where the ground floor rear facing windows have not
been enclosed, they suffer from the “tunnel effect” created by the pattern of
consecutive rear extensions side by side. This arrangement therefore prejudices the
availability of daylight and sunlight under baseline conditions and any future
conditions and the impact on these particular windows should therefore be taken in
this context.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
5.0
PREDICTED IMPACTS
Demolition and Construction
5.1
The level of impact in relation to daylight and sunlight to the surrounding properties
will vary throughout the demolition and construction phases depending on the level of
obstruction caused. There will be a brief and temporary improvement in daylight
levels during the demolition phase when the existing buildings are demolished and
the site is cleared. However, as the existing and proposed buildings are constructed,
including the necessary Temporary Works that will be required such as scaffolding,
debris netting and site hoardings and other forms of Temporary Works, there will be a
temporary loss of daylight which will go beyond the impact of the completed building
as the temporary “massing” created by scaffolding and other temporary works will be
marginally larger than the completed building. Those temporary works are however
necessary for the construction of the development to some extent for Health & Safety
but as they will be in place for a relatively short period during the course of
construction their effect will be of negligible significance.
Completed Development
5.2
As the proposed new buildings are of greater “massing” in comparison to the existing
buildings, the levels of natural light received by the receptors in 1-12 Wharf Street,
50-55 Catteshall Lane and 2-28 Victoria Road will be reduced. Annexed at Appendix
K.1 is a copy of drawing numbers ROL5877_5_000, 001, 002 and 003 which
comprise the site plan and images of the 3D massing models of the existing and
proposed buildings.
This is followed at Appendix K.2 by drawing numbers
ROL5877_5_100, 101, 102 and 103 which illustrate the Daylight Distribution no
skyline contour analysis for each of the sensitive receptors and also provide the
location references for the windows and rooms tested in the analysis.
Those
references should be cross referenced with the room and window locations referred
to in the tabulated numerical results tables for the daylight and sunlight analyses
annexed at Appendices K.3, K.4 and K.5.
1-12 Wharf Street
5.3
On the basis of the VSC method of measurement, out of the seventeen sensitive
receptors, one first floor window (window W2/11) will experience a moderate
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
adverse impact and the remaining sixteen will experience a negligible impact. It
should however be noted that window W2/11 is in fact a small secondary window
forming part of a larger bay window (see drawing number ROL5877_5_100 annexed
at Appendix K.2). From the plan, it can be seen that room R1/11 is served by a bay
window comprising three separate windows of which window W2/11 is part. The
remaining two windows, including the principal window (W3/11) comfortably satisfy
the BRE Guidelines. As the bay window serves one single room, these three results
should be taken together which then shows that the availability of daylight to this
room will remain very good indeed. In fact, fourteen of the windows do not even
register on the scale of impact as they will all continue to receive in excess of 27%
VSC and therefore fully satisfy the target design standards of the BRE Guidelines in
any event.
5.4
Using the alternative Daylight Distribution method of measurement, there are fifteen
sensitive receptors as Daylight Distribution applies to “rooms” rather than “ windows”
and out of those fifteen sensitive receptors, all fifteen will experience a negligible
impact with ten out of the fifteen experiencing no measurable loss of internal Daylight
Distribution at all.
5.5
The tests show that there will be no material loss of direct daylight from the sky which
will be noticeable in terms of the outlook from the windows and that there also will be
no noticeable or material loss of internal Daylight Distribution.
5.6
The results of the sunlight analysis show that there will be no material loss of winter
or annual sunlight and that these receptors will all comfortably satisfy the BRE target
standards. The impact on sunlight will therefore be negligible.
50-55 Catteshall Lane
5.7
All of the receptors in 50-55 Catteshall Lane comfortably satisfy the VSC and Daylight
Distribution target guidelines. In terms of VSC, all of the residual values will be in
excess of 27% VSC and none of the rooms in question will experience any loss of
internal Daylight Distribution at all. The impact is therefore negligible.
5.8
The BRE sunlight criteria does not apply to these receptors as they do not face within
90 degrees of due south and as the proposed development lies to the north of the
existing gardens, there will be no additional permanent overshadowing of those
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
gardens as a result of the development and therefore neither sunlight nor
overshadowing needs to be tested.
2-28 Victoria Road
5.9
Out of the thirty six sensitive receptors identified for these properties, all thirty six will
fall within the negligible significance criteria with many of those receptors not only
comfortably satisfying the BRE Guidelines but achieving a target VSC value in excess
of 27%. Likewise, the results of the internal Daylight Distribution analysis show that
all of the rooms will not only fall within the negligible significant criteria for Daylight
Distribution, the vast majority (almost two thirds) will experience no measureable loss
of internal Daylight Distribution at all, and even where there is a numerical loss, the
quantum of loss is so small as to be imperceptible.
5.10
In terms of sunlight, it is only 10-28 Victoria Road that marginally face within 90
degrees of due south and hence fall within the BRE sunlight criteria. Those receptors
generally face west and therefore even if they were totally unobstructed, are only
capable of receiving approximately half of the total available sunlight hours on the
spring equinox in comparison to a window facing due south. As the orientation of
these receptors is such that they are only capable of receiving half of the available
sunlight on the spring equinox, the targets and significance criteria should be applied
accordingly and requires a certain amount of judgement and interpretation.
The
numerical results of the sunlight analysis sets the overall impact in the negligible
category.
5.11
Annexed at Appendix K.6 is drawing number ROL5877_5_300 and Table P4 which
illustrates the extent of permanent overshadowing under “existing” and “proposed”
conditions. The green circular hatching indicates the amount of existing permanent
shadow and the extra amount of permanent overshadowing is illustrated by the red
circular hatching.
5.12
The BRE Guidelines permit the extent of overshadowing to be increased by a factor
of 20%.
5.13
From the results of the technical analysis, the extent of additional permanent
overshadowing will be limited to six out of the twelve gardens and the extent of that
permanent overshadowing will not only be well within the BRE Guidelines but will be
so small as to be imperceptible. The impact is therefore negligible.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
Daylight, Sunlight and Overshadowing of Completed Development
5.14
The drawings and tables in Appendix K7 illustrate the location of a sample of
habitable rooms at ground, first and second floor levels where the availability of
daylight and sunlight has been tested. These rooms have been selected as they are
located in those parts of the proposed development where daylight and sunlight is
likely to be at its lowest levels, e.g. in the corners of the courtyards or where some
rooms are served by windows that are recessed within private amenity balconies or
have projecting private amenity balconies over them which results in the “canopy
effect”. The room and window location references on the drawings should be cross
referenced with the room and window location references used in the corresponding
daylight and sunlight tables within the same appendices.
5.15
From the results of the ADF analysis, four rooms were found not to achieve the target
design standard. These were rooms R1/900, R2/910, R5/601 and R4/902. The
reason why all four of these rooms fall short of the target design standard is a result
of the “canopy effect” of either recessed or projecting balconies. Rooms R1/900,
R2/910 and R4/902 have windows that are partially recessed whereas room R5/602
has a private amenity balcony above it. All four windows therefore experience the
“canopy effect” of the projections above the windows and it is therefore unrealistic to
expect to achieve the target daylight (and sunlight) standards in such circumstances.
5.16
Likewise, when the results of the Annual Probable Sunlight Hours and winter sunlight
hours tests are reviewed, there is a parallel correlation in that those windows which
are flush with the external wall of the buildings record very good levels of annual and
winter sunlight and the only marginal shortfalls are where the windows are either
recessed or have projecting private amenity balconies above them.
5.17
Taken on the whole, the daylight and sunlight results that have been obtained are
very good and the overall design performs very well. Where there are a very small
number of shortfalls in daylight or sunlight, that shortfall arises due to the external
private amenity space in front of each of the windows and the positive benefit of
providing amenity space should be balanced against the resulting lighting conditions.
With such a small number of very minor transgressions, the overall impact is
considered to be negligible.
5.18
Appendix K8 summarises the results of the permanent overshadowing analysis of the
amenity areas within the proposed development.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
5.19
The results of the technical analysis show that the extent of permanent
overshadowing of the proposed amenity areas will be comfortably within the BRE
Guidelines. Although the proposed design meets the target design standards, there
will be some parts of the amenity space that will be in permanent shadow on the
spring equinox and the impact is therefore to be classed as negligible.
Cumulative Impact
5.20
There will be no cumulative impacts on the identified sensitive receptors as a result of
other neighbouring development other than the proposed development itself.
Although other developments in reasonably close proximity of the Site have been
identified, none of those developments will have any impact at all on the availability of
daylight or sunlight nor will they affect the amount of overshadowing of existing
neighbouring amenity space. Taking all of these factors into account, the receptors
that fall within the testing criteria will not be affected by any other development
beyond the Site itself, both now and in the foreseeable future and there therefore are
no reasonably foreseeable cumulative effects that would give rise to any further
impacts than those identified within the present analysis.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
6.0
EVALUATION OF SIGNIFICANCE
6.1
The impacts measured for the daylight, sunlight and overshadowing that will be
experienced by the existing neighbouring dwellings will all be within the negligible
significance criteria. In the vast majority of tests undertaken, the results show that
there will be no material impact at all on the neighbouring dwellings in that the
receptors will comfortably satisfy the target design standards even before any
reduction ratio is applied.
6.2
No single neighbouring dwelling or collection of dwellings as a whole, will experience
any material detrimental or adverse impact as a result of the proposed development
either in terms of daylight, sunlight or overshadowing, as the proposed development
comfortably satisfies all of the relevant standards within the BRE Guidelines and
British Standard Code of Practice for Daylighting. For the proposed new dwellings,
there are no baseline conditions and there therefore is no “impact” to be measured.
Instead, the quality of daylight, sunlight and overshadowing needs to be measured on
the absolute scales within the Guidelines. The receptors chosen for the analysis
were a sample of those habitable rooms that are likely to experience the lowest levels
of natural daylight and sunlight.
All of the rooms which have conventional flush
windows will comfortably satisfy the target design standards but four rooms in the
sample fell below that target standard as a result of the windows being recessed or
where they were set below a projecting private amenity balcony. The number of
windows which did not meet the target design standard, coupled with the quantum by
which there was a shortfall of ADF and/or APSH will be relatively small and should be
balanced against the benefit of private amenity space provided by the balconies.
That benefit offsets the relatively small shortfall in lighting conditions and in view of
the very small number of receptors that fall within this category, the impact is
considered to be negligible.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
7.0
OPPORTUNITIES FOR MITIGATION AND ENHANCEMENT
7.1
Throughout the design process, the scale and “massing” of the proposed buildings
has been influenced by the previous proposals for the Site, townscape issues and
input from Anstey Horne & Company Limited to ensure that the proposed new
buildings would not result in any material or unreasonable impact on existing
neighbouring amenity. The principal mitigating measure in this regard has therefore
been the development of the design itself to ensure that the final product satisfies the
Council’s policy objectives.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
8.0
RESIDUAL IMPACTS
8.1
There will be no residual impact as no mitigation measures are required.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
9.0
SUMMARY AND CONCLUSIONS
9.1
For the purpose of this Environmental Statement, the recognised standards to be
adopted for assessing the impact of the proposals on existing neighbouring dwellings
are the Building Research Establishment Guidelines “Site Layout Planning for
Daylight and Sunlight – A Guide to Good Practice” 1991, and the British Standard
Code of Practice for Daylighting, BS8206 Part 2, 2008. These standards limit the
sensitive receptors windows and rooms within residential properties around the Site
that have the potential to be affected.
9.2
Following a detailed site appraisal, these sensitive receptors have been identified as
1-12 Wharf Street, 50-55 Catteshall Lane and 2-28 Victoria Road. The results of the
technical analysis demonstrate that the proposed development will practically fully
satisfy the BRE Guidelines in terms of impact on daylight, sunlight and
overshadowing. For the vast majority of the receptors, the impacts that have been
measured will fall within the negligible significance criteria and for the very small
number of receptors which do not fully satisfy the BRE Guideline standards, the
impact will only be minor adverse and also be influenced by valid mitigating factors
such as windows serving non-habitable rooms or secondary windows where other
primary windows remain unaffected.
9.3
The impact on sunlight and overshadowing will also be negligible.
9.4
Although there will be a measurable loss of direct daylight and sunlight which will be
noticeable in terms of the outlook from the receptors, the loss of light will be
negligible and the amount of light that will remain will be more than adequate for
each of the design uses for the rooms served by each of the receptors. The amenity
enjoyed by the neighbouring dwellings will therefore not be affected.
9.5
In overall conclusion, the proposed development will not give rise to any material
deterioration to the amenity enjoyed by the existing neighbouring buildings as
demonstrated by the numerical results and it should therefore follow that the Council’s
policy objectives have been satisfied.
Chapter K: Sunlight/Daylight
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GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
9.6
A summary of the potential impact of the proposed development is set out in the table
below.
Description of
Impact
Description of
Significance
Description of
Residual Impact
Description of
Significant of
Residual
Impact
Loss of daylight
to 1-12 Wharf
Street
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Loss of sunlight
to 1-12 Wharf
Road
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Loss of daylight
to 50-55
Catteshall Lane
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Loss of daylight
to 2-28 Victoria
Road
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Loss of sunlight
to 2-28 Victoria
Road
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Overshadowing
of rear gardens of
2-28 Victoria
Road
Negative, direct
permanent and
negligible.
Daylight levels to
habitable rooms will be
reduced but will remain
above the recognised
target design standards.
Negative,
direct
permanent and
negligible.
Chapter K: Sunlight/Daylight
22
GODALMING KEY SITE PHASE II: ENVIRONMENTAL STATEMENT
REFERENCES
Building Research Establishment (BRE) Guidelines “Site Layout Planning for Daylight and
Sunlight – A Guide to Good Practice” 1991.
British Standard BS8206-2; 2008, Lighting for Buildings – Code of Practice for Daylighting.
Chapter K: Sunlight/Daylight
23