OVERSHADOWING ANALYSIS REPORT
Project No: 1172
Project Name: Overshadowing Analysis
Project Address: 5 XXXX Street, Kew VIC 3101
Project Overview
ShadowDiagrams.net.au has been engaged by TXXX SXXX, the owner of 5 XXX Street, Kew VIC, to prepare shadow diagrams and assess the potential impact of the proposed development at 7-9 XXX Street, Kew VIC on his property. This report focuses on evaluating solar access, analysing shadowing effects, and assessing their implications for the amenity and usability of the affected areas.
Regulatory Requirements
This standard safeguards existing private open spaces from overshadowing by new developments.
A17 and B28 - Private Open Space
This standard guarantees that all new dwellings and secondary dwellings offer usable and secluded private open space, easily accessible from living areas. It also enhances the character of residential neighbourhoods.
Where sunlight to the secluded private open space of an existing dwelling or small second dwelling is reduced, at least 75 per cent, or 40 square metres with minimum dimension of 3 metres, whichever is the lesser area, of the secluded private open space should receive a minimum of five hours of sunlight between 9 am and 3 pm on 22 September.
If existing sunlight to the secluded private open space of an existing dwelling or small second dwelling is less than the requirements of this standard, the amount of sunlight should not be further reduced.
Methodology
To ensure an accurate and detailed representation of shadows cast by the existing and proposed buildings, the following methodology was adopted:
Site Analysis
Survey Data Collection: Detailed site plans, including topography, boundaries, and existing structures, were reviewed.
Orientation and Context: The site’s orientation, location, and surrounding environment—including nearby buildings and shadow influences—were analysed using planning application drawings provided by XXXX Architects.
Software and Tools
Simulation Software: Graphisoft Archicad, integrated with geographic and solar data, was utilised for accurate shadow simulations.
Parameter Settings
The site's latitude and longitude were input to ensure precise solar positioning.
Shadows were modelled for 12:00 pm and 4:00 pm on the winter solstice (22 June) and spring equinox (22 September).
True north was referenced from XXXX Architects' drawings, though independent verification was not conducted.
3D Modelling
A 3D model incorporating existing and proposed structures, adjacent buildings, and relevant elements was developed using XXXX Architects’ drawings.
Analysis
Overshadowing differences between the existing and proposed conditions were assessed.
Potential impacts, including overshadowing of private outdoor spaces and windows, were evaluated.
Documentation
Annotations and Legends: Contextual details provided for clarity:
Red Fill – Indicates increased shadowing from the proposed structure at No. 7-9 onto the property at No. 5.
Yellow Fill with Orange Dashed Outline – Represents Secluded Private Open Space (SPOS) in actual use.
Shadow Diagrams
The overshadowing diagrams, illustrating hourly shading at 12:00 pm and 4:00 pm on the winter solstice (22 June) and spring equinox (22 September), are provided in Appendix 1. Earlier time periods have been excluded, as the proposed development at 7-9 does not impact the western and southern SPOS areas of No. 5.
Impact Analysis
The designated secluded private open spaces (POS A, B, C, and D) have been identified for impact assessment, with windows 1 to 8 evaluated for overshadowing, as illustrated in the Appendix 1 diagrams.
The designated Secluded Private Open Space (SPOS) accurately reflects a functional outdoor area seamlessly integrated with the living space of the dwellings, with direct access from the interiors. This space is well-situated with a west and south-facing orientation and is free from pavements, non-trafficable landscaping, or other structures. However, the overshadowing analysis submitted by XXXX Architects inaccurately includes a separate, disconnected area that does not serve as usable private open space. The SPOS identified extends beyond the council's easement for the path, disrupting the direct link to internal living areas. This approach prioritises compliance over practicality, questioning the validity of the analysis. Additionally, the minimum requirement of 40m² (8m x 5m) under Standard B22 should apply only to new developments, not existing ones, as these properties already have functional SPOS areas in place for occupants.
Image 1 An image of the SPOS calculation from XXXX Architects' documentation is presented to illustrate compliance, but it is incorrect as it does not serve the needs of the current occupants.
Image 2 depicts the designated private open spaces currently in use by the occupants, which should be considered when calculating the space for an existing dwelling, shaped by the occupants' usage over many years.
The table below compares solar access to windows and secluded private open space (SPOS) under existing and proposed conditions on 22 June and 22 September. Percentages reflect the proportion of glazing in windows and doors exposed to sunlight, as well as the solar exposure of the designated SPOS. Dashed orange lines with a yellow fill delineate the SPOS boundary, while red fill indicates additional shadows cast on property number 5 by the proposed development at 7-9, as shown in the overshadowing diagrams in Appendix 1. Any significant reductions in solar access are highlighted in red text below the table.
June 22 - Solar Access - Existing
12pm 1pm 2pm 3pm 4pm
Window 1 0% 0% 0% 9% 24%
Window 2 25% 32% 22% 62% 51%
Window 3 0% 0% 2% 35% 46%
Window 4 0% 23% 29% 63% 47%
Window 5 50% 42% 53% 54% 53%
Window 6 60% 60% 58% 44% 46%
Window 7 0% 0% 0% 18% 53%
Window 8 0% 4% 19% 56% 61%
POS.A 28% 29% 27% 7% 0%
POS.B 45% 61% 48% 18% 0%
POS.C 19% 44% 41% 11% 0%
POS.D 0% 3% 19% 33% 0%
June 22 - Solar Access - Proposed
12pm 1pm 2pm 3pm 4pm
Window 1 0% 0% 0% 0% 0%
Window 2 25% 32% 2% 0% 0%
Window 3 0% 0% 0% 0% 0%
Window 4 0% 23% 0% 0% 0%
Window 5 50% 42% 0% 0% 0%
Window 6 60% 60% 0% 0% 0%
Window 7 0% 0% 0% 0% 0%
Window 8 0% 4% 4% 0% 0%
POS.A 28% 25% 0% 0% 0%
POS.B 45% 46% 0% 0% 0%
POS.C 19% 35% 0% 0% 0%
POS.D 0% 3% 0% 0% 0%
September 22 - Solar Access - Existing
12pm 1pm 2pm 3pm 4pm
Window 1 0% 0% 2% 3% 41%
Window 2 22% 31% 27% 19% 27%
Window 3 0% 0% 0% 3% 46%
Window 4 0% 12% 27% 26% 26%
Window 5 56% 27% 24% 29% 12%
Window 6 60% 60% 60% 58% 47%
Window 7 0% 0% 0% 3% 37%
Window 8 0% 3% 24% 2% 23%
POS.A 46% 55% 55% 31% 17%
POS.B 61% 74% 67% 66% 26%
POS.C 54% 72% 72% 38% 22%
POS.D 9% 28% 38% 52% 69%
September 22 - Solar Access - Proposed
12pm 1pm 2pm 3pm 4pm
Window 1 0% 0% 0% 0% 0%
Window 2 22% 31% 27% 18% 0%
Window 3 0% 0% 0% 1% 0%
Window 4 0% 12% 27% 0% 0%
Window 5 56% 27% 24% 0% 0%
Window 6 60% 60% 42% 0% 0%
Window 7 0% 0% 0% 0% 0%
Window 8 0% 3% 24% 0% 0%
POS.A 46% 55% 19% 0% 0%
POS.B 61% 74% 26% 0% 0%
POS.C 54% 72% 32% 0% 0%
POS.D 9% 28% 38% 14% 13%
Compliance Statement and Recommendation
June 22:
Solar access to the secluded private open spaces and windows starts to decrease after 1pm, with no sunlight reaching these areas from 2pm onwards.
September 22:
Solar access to the secluded private open spaces and windows begins to diminish from 2pm, with no sunlight reaching these areas after 3pm.
While solar access at 4pm is not a minimum requirement, it has been incorporated due to the property's north-facing frontage, which offers very limited solar access. As such, 4pm solar access is considered crucial, particularly during winter months.
In accordance with the regulatory requirements outlined above, each private open space is less than 40sqm, with a minimum dimension of under 3m. Collectively, these spaces fail to achieve the required 5 hours of solar access between 9am and 3pm under current conditions. The proposed development at 7-9 further exacerbates this non-compliance, reducing solar access to near nonexistence by 2pm. Given that these areas receive no direct sunlight before midday due to their orientation, it is essential that existing solar access is not further compromised. The development should therefore be redesigned to reduce bulk and scale while increasing setbacks to prevent further deterioration of the already insufficient solar access. Additionally, the second-storey apartments directly overlook these private open spaces, eliminating any sense of seclusion and compromising privacy, which must be addressed separately.