daylight sunlight report...3 for planning ca pf pf 25/03/2020 2 for comment ca pf pf 11/03/2020 1...

Daylight Sunlight Report

Crodaun Development

Project No. B949

25th March 2020

O’Connor Sutton Cronin & Associates Daylight & Sunlight Report Multidisciplinary Consulting Engineers Crodaun Development

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Daylight Sunlight Report


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NOTICE

DOCUMENT CONTROL & HISTORY

OCSC

Job No.:

B949

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B949 OCSC XX XX RP YS 0002 S4 P03

Rev. Status Authors Checked Authorised Issue Date

3 For Planning CA PF PF 25/03/2020

2 For Comment CA PF PF 11/03/2020

1 For Comment CA PF PF 30/01/2020

This document has been produced by O’Connor Sutton Cronin & Associates for its

client Crodaun Development Company Ltd. It may not be used for any purpose other

than that specified by any other person without the written permission of the authors.


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DAYLIGHT SUNLIGHT REPORT

INDEX PAGE NO.

1. INTRODUCTION ......................................................................................................... 4

2. SITE DESCRIPTION .................................................................................................... 5

3. PROPOSED BUILDING DESIGN.................................................................................... 7

4. BRE GUIDELINES FOR DAYLIGHT AND SUNLIGHT ........................................................ 8

5. DAYLIGHT LEVELS WITHIN THE PROPOSED DEVELOPMENT ........................................ 9

6. SUNLIGHT ASSESSMENT TO AMENITY SPACES WITHIN THE DEVELOPMENT ............. 18

7. ASSESSING THE IMPACT ON SURROUNDING PROPERTIES ........................................ 20

8. SHADOW ANALYSIS ................................................................................................. 27

9. CONCLUSION .......................................................................................................... 31


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1. INTRODUCTION

OCSC have been appointed to carry out a Daylight / Sunlight study for the proposed Crodaun

development located in Co. Kildare.

The aim of the study is to record and analyse the results for the following:

The expected daylight levels within the living and bedroom areas of each house type and

selected apartments, to give an indication of the expected daylight levels throughout the

proposed development.

The quality of amenity space, being provided as part of the development, in relation to

sunlight.

Any potential overshadowing impact the proposed development may have on properties

adjacent to the site.

The calculation methodology for daylight and sunlight is based on the British Research

Establishments “Site Layout Planning for Daylight and Sunlight: A Good Practice Guide” by PJ

Littlefair, 2011 Second Edition.


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2. SITE DESCRIPTION

Crodaun Development Company Ltd intend to apply to An Bord Pleanála for permission for a

strategic housing development on lands west of the Maynooth Rd (R405) and north of the Kilwoghan

Stream running to the north side of Kilwogan Lane, Celbridge, Co. Kildare (c.12.93Ha).

The development will consist of a residential development consisting of 467 no. dwelling units (216

apartments, 199 houses and 52 duplexes) along with ancillary childcare facility (776sq.m), gym

(320sq.m), café (123sq.m) and retail unit (119sq.m).

The residential units consist of the following:

216 no. apartments (184 no. 2 beds, 32 no. 3 beds) contained in 4 no. blocks to the east side

of the site, (Blocks A, B, C & D), ranging from 5 to 6 storeys high. Blocks A, B & C have

basement car parking. 251 no. houses and duplexes as follows:

20 no. 5 Bed semi-detached 3 storey houses

69 no. 4 Bed semi-detached 2.5 storey houses

23 no. 4 Bed terraced 3 storey houses

38 no. 3 Bed semi-detached 2 storey houses

49 no. 3 Bed terraced 2-storey houses

18 no. 1 Bed apartment units within 2.5 storey duplex blocks

26 no. 2 Bed apartment units within 2.5 storey duplex blocks

8 no. 3 Bed apartment units within 2.5 storey duplex block

The proposed ancillary childcare facility, gym, café and retail unit will all be located on the ground

floor of apartment block D.

The proposed development includes the provision of a landscaped 2.068 ha. public park to the

north.

All associated site and infrastructural works, including open space, landscaping, boundary treatment,

roads, paths, cycle paths, car and cycle parking (including basement parking under the apartment

blocks), foul and surface water drainage, 2 no. substations, 2 no. sub units, and 2 no. vehicular

entrance/egress points off the Maynooth Road.


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Figure 1 – Proposed Site


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3. PROPOSED BUILDING DESIGN

In order to ensure that daylight levels are maximised for Crodaun residential development, a

number of key design issues were analysed during concept design stages.

3.1. BUILDING MATERIAL SELECTION

The selection of materials play an important role in ambient daylight levels. The façade of the

proposed buildings have been carefully selected to promote a sense of brightness and light. The

Crodaun façades are composed of light brick, stone and powder coated aluminum. This will ensure

light is reflected throughout the development. The inclusion of greenery to the amenity spaces will

help to improve the sense of light and brightness within the development.

3.2. GLAZING TO WALL RATIO

The primary function of the glazing to wall ratio is to maximise daylight within the space while

reducing solar gains within the proposed development. The other advantage in conjunction with

appropriate materials is that the more light surfaced, reflective materials used externally, the more

ambient daylight will be reflected to the surrounding areas. Extensive analysis was completed on

Crodaun development to ensure glazed openings were maximised to promote access to daylight

levels. In addition, floor to ceiling heights for apartments of 2.7m and 2.8m further enhance the

opportunity for improved daylight levels. The image below highlights the floor to ceiling height

glazing.

Figure 2 – Apartments Elevation

2.7 m


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4. BRE GUIDELINES FOR DAYLIGHT AND SUNLIGHT

In considering the development potential and the quality of amenity for the new development as

well as for the surrounding properties once the scheme has been implemented, the analysis has

been based on the Building Research Establishment (BRE) guidelines on “Site Layout Planning for

Daylight and Sunlight. A Guide to Good Practice (Building Research Establishment Report, 2011).”

These guidelines provide the criteria and methodology for calculations pertaining to daylight and

sunlight, and is the primary reference for this matter. The guide gives simple rules for analysing sites

where the geometry of the surroundings is straightforward, supplementing them with graphical

methods for complex sites.

However, it is important to note that the performance targets which are included should be used

with a degree of flexibility as per the extract below from the BRE Guide:

“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 numeral

guidelines these should be interpreted flexibly because natural lighting is only one of the many

factors in site layout design.”


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5. DAYLIGHT LEVELS WITHIN THE PROPOSED DEVELOPMENT

5.1. ASSESSMENT CRITERIA – INTERNAL DAYLIGHT

The method of calculation selected for the internal daylight analysis for this development is the

Average Daylight Factor (ADF). This is the most detailed and thus most accurate method which

considers not only the amount of sky visible from the vertical face of the window, but also the

window size, room size and room use.

Architectural plans and elevations provided by Scott Tallon Walker Architects formed the basis for

internal daylight assessment.

In order to quantify the quality of daylight within a space as per BRE Guidelines, the British standards

BS8206 sets out minimum daylight factors to be achieved in new build residential units.

Figure 3 – BS 8206 – Table 2

In order to analyse the ADF within the proposed residential development, simulations have been

completed within the IES VE Software package. A detailed model of the development has been

constructed within the software. The model includes the proposed development as well as the

surrounding buildings adjacent to the site, heights of surrounding buildings have been taken from

survey data.


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5.2. DAYLIGHT RESULTS – INTERNAL DAYLIGHT APARTMENTS

The following section illustrates the apartment units assessed for internal daylight levels for the

proposed Crodaun development. Their subsequent results are shown in the accompanying tables.

In line with standard industry practice, units on ground floor have been selected as ‘worst case’ for

analysis. The theory being that as floor level height increases so too does access to daylight. Block A

has been selected for analysis and is considered to be representative of the units across the site and

therefore results are indicative of daylight levels to be expected across the entire development.

In summary all apartment units not only meet but in the majority of cases exceed the Average

Daylight Factor as outlined within the BRE Guidelines. In all cases generous floor to ceiling heights

have been designed into the project with glazing areas being maximised to amplify the quality of

daylight received. In addition, careful consideration has been given to room layout design

attributing store rooms and circulation areas to the back of rooms and living spaces to the front

where the highest level of daylight is experienced.

Figure 4 – Ground Floor Block A Assessed Units

Unit ADF required (%) ADF results (%) Meets minimum ADF required

A Living 1.5 1.6 Y

B Bedroom 1.0 3.2 Y

C Living 1.5 1.6 Y

D Bedroom 1.0 3.2 Y

E Living 1.5 1.7 Y

F Bedroom 1.0 4.5 Y

G Living 1.5 1.6 Y

H Bedroom 1.0 3.2 Y

I Bedroom 1.0 3.3 Y

J Bedroom 1.0 3.2 Y

K Living 1.5 1.6 Y

Table 1 – Average Daylight Factor Results - Block A Ground Floor

A

B

C

D

E F

I H G K

J


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5.3. DAYLIGHT RESULTS – INTERNAL DAYLIGHT HOUSES

The following section outlines the expected internal daylight levels for the houses within the

proposed Crodaun development. A selection of typical house types considered to be representative

of the development have been selected for analysis. The results presented are considered to be

indicative of the daylight levels to be expected across the site. All of the houses meet the minimum

daylight levels in accordance with BRE Guidelines.

Figure 5 – Site Layout Highlighting in Red Assessed Houses


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Figure 6 – Houses Type


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Figure 7 – Type A House Layout


Ground Floor Din/ Kit 2.0 4.5 Y

Sitting Area 1.5 3.3 Y

1st Floor Bedroom 1 1.0 2.8 Y

Bedroom 2 1.0 3.5 Y

Bedroom 3 1.0 3.5 Y

2nd Floor Bedroom 4 1.0 3.7 Y

Bedroom 5 1.0 4.0 Y

Table 2 – Average Daylight Factor Results – Type A House

Ground Floor First Floor Second Floor

Second Floor

First Floor

Kit/Din

Sitting Room Bed 1

Bed 4

Bed 2

Bed 3

Bed 5


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Figure 8 – Type B House Layout





Bedroom 2 1.0 3.2 Y

Bedroom 3 1.0 3.5 Y


Table 3 – Average Daylight Factor Results – Type B House


Second Floor

First Floor

Sitting Room

Kit/Din

Bed 3

Bed 1

Bed 2

Bed 4

Bed 3


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Figure 9 – Type C House Layout





Bedroom 2 1.0 3.5 Y

Bedroom 3 1.0 2.8 Y

Table 4 – Average Daylight Factor Results – Type C House

Ground Floor First Floor

Kit/Din

Sitting Area

Bed 1

Bed 2

Bed 3


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Figure 10 – Type F House Layout


Ground Floor Kit/Din/ Liv 2.0 4.5 Y

Bedroom 1.0 3.3 Y

1st Floor Kit/Din/ Liv 2.0 4.1 Y

Bedroom 1 1.0 3.2 Y


Table 5 – Average Daylight Factor Results – Type F House


Kit/Din/Liv Kit/Din/Liv

Bed

Bed 1

Bed 2


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Figure 11 – Type H House Layout


Ground Floor Kit/Din/ Liv 2.0 3.4 Y

1st Floor Lounge 1.5 5.0 Y

Bedroom 1 1.0 3.2 Y

Bedroom 2 1.0 3.5 Y


Bedroom 4 1.0 4.1 Y

Table 6 – Average Daylight Factor Results – Type H House


Lounge

Bed 1

Bed 2 Bed 3

Bed 4

Kit/Din/Liv


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6. SUNLIGHT ASSESSMENT TO AMENITY SPACES WITHIN THE

DEVELOPMENT

BRE Guidelines recommend that for external amenity spaces to appear adequately sunlit throughout

the year, at least half of the garden or amenity space should receive at least two hours of sunlight on

March 21st.

The image below outlines the communal amenity spaces provided within the development, which

have been analysed.

Figure 12 – Communal Amenity Spaces


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The red squares in the image below mark the areas that are receiving a minimum of 2 hours of

sunlight on the 21st of March. It can be seen that almost all the open spaces easily achieve 2 hours of

direct sunlight, and therefore the amenity spaces within the development are in line with the BRE

recommendations for sunlight to amenity space.

Figure 13 – Communal Amenity Space - Hours of Sunlight on March 21st


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7. ASSESSING THE IMPACT ON SURROUNDING PROPERTIES

7.1. DAYLIGHT & SUNLIGHT IMPACT METHODOLOGY

As per the BRE Guidelines it is important to safeguard the daylight to nearby buildings, from a

proposed development, where a reasonable expectation of daylight is required. The flow matrix

below outlines the criteria to be assessed, as per the BRE Guidelines, in order to ascertain any

potential impact to adjacent buildings from the proposed development.

Figure 14 – Steps on the criteria of compliance

STEP 1

STEP 2

STEP 3

STEP 4


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As per the flow matrix, the BRE and BS8206 guidelines provide four main methods for assessing

daylight availability.

7.1.1 25O LINE CRITERIA

In the first instance, if a proposed development falls beneath a 25⁰ angle taken from a point 1.6

metres above ground level from any adjacent properties, then the BRE say that no further analysis is

required in relation to impact on surrounding properties as adequate skylight will still be available. In

the case of the Crodaun development, this method was used to analyse the daylight impact on the

surrounding properties once the development is in place. The analysis has shown all adjacent

properties, with the exception of some of the South and Southeast houses fall below the 25⁰ line.

Therefore it can be stated that no impact is perceived to any other surrounding properties and only

the properties mentioned above must be selected for further analysis to determine any potential

impact.

7.1.2 VISIBLE SKY COMPONENT

The second method is known as the Vertical Sky Component (VSC). The VSC calculation is the ratio of

the direct sky illuminance falling on the outside of a window, to the simultaneous horizontal

illuminance under an unobstructed sky. The BRE Guide sets out two guidelines for the VSC:

If the VSC at the centre of the existing window exceeds 27% with the new development in

place, then enough sky light should still be reaching the existing window.

If the VSC with the new development in place is both less than 27% and less than 80% its

former value, then the reduction in light to the window is likely to be noticeable.

This means that even if the VSC is less than 27%, as long as the VSC value is still greater than

80% of its former value, this would be acceptable and thus the impact would be considered

negligible.

It is important to note that the VSC is a simple geometrical calculation which provides an early

indication of the potential for daylight entering the space. However, it does not assess or quantify

the actual daylight levels inside the rooms. If the VSC standard is not met on any window, a more

detailed assessment based on the Average Daylight Factor should be undertaken.

A number of properties located at No. 70, 75, 76, 81 & 82 Crodaun Forest Park Properties, No. 9

Castle Village Ave and No. 36 Kilwogan Ln to the South and Southeast of the proposed development

fall within the 25⁰ line (Step 1) and they have been selected for VSC analysis.


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7.1.3 NO SKY LINE

The third method is the No Sky Line or Daylight Distribution Method. This method assesses the

change in position of the No Sky Line between the existing and proposed situations. It does take into

account the number and size of windows to a room, but still does not give any qualitative or

quantitative assessment of the light in the room, only where sky can or cannot be seen. Thus, as this

method is limited, it was not used as part of the analysis.

7.1.4 AVERAGE DAYLIGHT FACTOR

The final method of calculation is the Average Daylight Factor (ADF). This is a more detailed and thus

more accurate method which considers not only the amount of sky visible from the vertical face of

the window, but also the window size, room size and room use. Where dimensions for the room to

be assessed are available, this is the best method of assessment, but even where they are not, it

provides a very informative result. It gives guidance as to the qualitative and quantitative change in

daylight and is related to the British Standard BS 8206 Part II.

This step is only utilised for assessing the impact to adjacent properties where compliance is not

achieved using the VSC analysis. The properties selected for VSC have shown compliance under the

VSC method and therefore this step was not required.

Sections 7.2 and 7.3 on the following pages outline the details of the analysis undertaken.


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7.2. IDENTIFYING SENSITIVE RECEPTORS

In order to undertake the assessment, prior to following the flow matrix, first the key sensitive

receptors around the site need to be identified. According to the BRE Guide sensitive receptors are

described as:

Habitable rooms in residential buildings, where the occupants have a reasonable

expectation of daylight.

Other sensitive receptors are gardens and open spaces on adjacent properties to the new

scheme, excluding public footpaths, front gardens and car parks. In accordance with the BRE

Guide, windows are selected as sensitive receptors on the basis of being a habitable room

facing the proposed development.

Similarly, amenities and open spaces are selected on the basis of being in the immediate vicinity of

the proposed development. A primary purpose of a daylight, sunlight and overshadowing

assessment is to determine the likely loss of light to adjacent buildings resulting from the

construction of the proposed development.

Therefore, in this case, the proposed development is identified as the potential source of impact.

The sensitive receptors identified for this study are windows of habitable rooms facing the site

where the occupants have a reasonable expectation of daylight. Table 7 below identifies all sensitive

receptors analysed, whilst Figure 15 identifies their location.

Development name Primary activity

70, 75, 76, 81 & 82 Crodaun Forest Park Properties Residential

9 Castle Village Ave Residential

36 Kilwogan Ln Residential

Table 7 – Sensitive Receptors surrounding Crodaun Development


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Figure 15 - Location of Sensitive Receptors (Image from Google Maps)

Proposed development

25o line perimeter

Identified buildings (VSC Applied)


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7.3. DAYLIGHT IMPACT ON SURROUNDING PROPERTIES ANALYSIS

Step 1 → 25⁰ line criteria

As outlined previously, if a proposed development falls beneath a 25⁰ angle taken from a point 1.6

metres above ground level from any adjacent properties, then the BRE states that no further analysis

is required in relation to impact on surrounding properties as adequate skylight will still be available.

In order to analyse any potential impact on the properties adjacent to the proposed Crodaun

development, a perimeter line has been created around the development which is reflective of a 25⁰

taken from a horizontal level to the highest point on the proposed structures. Figures 16 below

depicts the 25⁰ perimeter line.

From Figures 16 below it can be clearly seen that all surrounding properties fall outside of the 25⁰

angle except for properties located at No. 70, 75, 76, 81 & 82 Crodaun Forest Park Properties, No. 9

Castle Village Ave and No. 36 Kilwogan Ln to the South and Southeast of the proposed development.

Therefore, they have been selected for VSC analysis, while it can be stated that for the remaining

adjacent properties no impact is perceived in relation to daylight from the proposed development.

Figure 16 – Proposed Site Plan identifying 25⁰ line criteria

Properties selected for VSC

Perimeter to identify skylight obstructed


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Step 2 → VSC criteria

In order to analyse the daylight impact to the properties falling inside the25⁰ perimeter line, a

window at lower level of No. 70, 75, 76, 81 & 82 Crodaun Forest Park Properties, No. 9 Castle Village

Ave and No. 36 Kilwogan Ln has been modelled.

The VSC levels received by these properties once the proposed development is constructed will

exceed 27%, therefore in compliance with BRE Guidelines. It can be stated that excellent levels of

daylight will still be received and negligible impact will be perceived to any of the adjacent

properties.


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8. SHADOW ANALYSIS

The overshadowing impact on the surrounding buildings has been analysed for the proposed

development. The overshadowing images illustrate the overshadowing impact on March 21st at 10

a.m., 12 p.m., 2 p.m. and 4 p.m. The analysis confirms that overshadowing to the east properties

would start being perceivable after 4 p.m., therefore it can be outline that negligible overshadowing

impact will be perceived to any of the surrounding properties.

Figure 17 – Overshadowing 21st March 10:00

N


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N


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N


30


N


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9. CONCLUSION

The proposed Crodaun development has been evaluated and analysed in order to determine the

following:

The expected daylight levels within the living and bedroom areas of selected house type and

apartments, to give an indication of the expected daylight levels throughout the proposed

development.

The quality of amenity space, being provided as part of the development, in relation to

sunlight.

Any potential overshadowing impact the proposed development may have on properties

adjacent to the site.

Calculations and methodology used are in accordance with BRE Guidelines for daylight and sunlight

and based on the British Research Establishments “Site Layout Planning for Daylight and Sunlight: A

Good Practice Guide” by PJ Littlefair, 2011 Second Edition, however, the following should be

reiterated as previously outlines;

“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 that constrain the designer. Although it gives numeral

guidelines these should be interpreted flexibly because natural lighting is only one of the many

factors in site layout design”

Internal Daylight

The analysis confirms that excellent levels of internal daylight will be received across the

development. All analysed rooms meet and greatly exceed the recommendations outlined within

the BRE guidelines in relation to internal daylight levels.

In all cases generous floor to ceiling heights have been designed into the project with glazing areas

being maximised to amplify the quality of daylight received. In addition, careful consideration has

been given to room layout design attributing store rooms and circulation areas to the back of rooms

and living spaces to the front where the highest level of daylight is experienced.


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Sunlight Analysis

The analysis undertaken has shown that the majority of the amenity spaces receive at least two

hours of sunlight on March 21st, exceeding the minimum requirement of two hours of sunlight on

more than the 50% of the amenity space on March 21st and showing compliance with the BRE

Guidance.

Impact to Surrounding Properties

Analysis has confirmed that the proposed development is in compliance with the BRE Guidelines in

relation to daylight impact to surrounding properties. The analysis has also confirmed that the only

perceivable overshadowing would be to the east properties after 4 p.m., therefore it can be outline

that negligible overshadowing impact will be perceived and excellent levels of sunlight will still being

achieved by all surrounding properties once the proposed development is constructed.


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daylight sunlight report...3 for planning ca pf pf 25/03/2020 2 for comment ca pf pf 11/03/2020 1...

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