Do Shadow Diagrams Need to Show Neighbouring Properties?

Shadow Diagrams

When a modelled shadow extends towards or beyond the subject site boundary, the surrounding property context can become important to understanding the drawing. Shadow diagrams do not necessarily need to show every neighbouring property in the same level of detail, but they should provide enough relevant context to establish where the shadow falls and meet the requirements applying to the project.

In Brief

Shadow diagrams may show neighbouring properties where surrounding context is needed to understand the shadow extent or satisfy the relevant documentation requirements. This can include property boundaries, neighbouring buildings and other relevant site information. The appropriate extent of that context depends on the project, the modelled shadow and the purpose of the assessment.

Do Shadow Diagrams need to show neighbouring properties?

Not every shadow diagram needs to show every neighbouring property. The amount of surrounding information required depends on what the shadow assessment needs to communicate and the documentation requirements applying to the development.

Where the modelled shadow remains within the subject site, extensive surrounding detail may not always be necessary to understand the shadow condition. Where shadow extends beyond the site boundary, neighbouring context can become more important because the reader needs to see where that shadow falls.

Property boundaries, neighbouring building outlines and other relevant contextual information can provide that spatial reference. They turn an isolated shadow shape into a drawing that can be understood in relation to the actual site and surrounding development.

The appropriate extent of neighbouring information should therefore be determined by the project rather than by assuming that every surrounding property must always be represented in the same way.

Why is neighbouring context shown on a Shadow Diagram?

Neighbouring context helps locate the modelled shadow. Without surrounding boundaries or built form, a shaded area extending away from the proposed development can be difficult to interpret spatially.

Showing the subject site together with relevant adjoining land allows the reader to establish where the site ends and where the surrounding properties begin. Neighbouring building outlines can provide another reference point for understanding the position and extent of the shadow.

This context is particularly useful where the shadow crosses a property boundary or where the relationship between the proposed development and surrounding built form is important to the documentation.

The purpose is not simply to make the drawing more detailed. Surrounding information should help explain the shadow condition being represented.

Neighbouring context is shown to locate the shadow, not simply to add detail. The relevant question is whether the drawing provides enough surrounding information to understand where the modelled shadow falls.

Does every neighbouring property need to be shown?

No. A shadow assessment does not automatically require an extensive model of the entire surrounding neighbourhood.

The surrounding area represented should be relevant to the shadow condition and the purpose of the documentation. If a property or building has no meaningful relationship to the shadow being shown, adding it may provide little additional information.

Conversely, where the shadow extends across adjoining land or where surrounding built form is necessary to understand the drawing, omitting that context can make the assessment harder to interpret.

The scope should therefore be sufficient to communicate the relevant shadow relationship while also responding to any specific drawing or assessment requirements that apply to the project.

What neighbouring information may be relevant?

The neighbouring information represented on a shadow diagram can vary according to the assessment. Property boundaries are often an important starting point because they establish the relationship between the subject site and adjoining land.

Neighbouring building footprints or other relevant built form may also be shown where they help explain the site context or are necessary for the shadow model. This can make it easier to understand how the proposed development sits within the surrounding built environment.

Other site information may be included where it is relevant to the purpose of the assessment or specifically required by the applicable documentation requirements.

The appropriate information is therefore project-specific. A useful drawing includes the surrounding context needed to understand the modelled shadow without assuming that every feature beyond the site boundary needs to be reproduced.

What if the shadow crosses the property boundary?

When a modelled shadow crosses the subject site boundary, surrounding context becomes particularly useful. The drawing needs enough spatial information for the reader to identify where the shadow extends once it leaves the site.

Showing the adjoining property boundary and relevant built form can help establish that relationship. A sequence of diagrams at different times may then show how the position and extent of the shadow beyond the boundary changes during the nominated assessment period.

A shadow crossing a property boundary does not, by itself, determine whether the development satisfies or fails a planning requirement. It establishes where the modelled shadow falls.

Any assessment of what that shadow means for solar access or planning performance requires the relevant project criteria to be considered separately.

Do neighbouring buildings affect the Shadow Diagram itself?

Neighbouring buildings can be relevant to both the context shown on the drawing and the geometry represented within the shadow model. Their role depends on the scope and purpose of the assessment.

Where existing surrounding buildings contribute to the shadow condition being represented, their geometry may be relevant to establishing the existing baseline. Where they primarily provide spatial context, their representation may help the reader understand the relationship between the proposed development and surrounding built form.

The information available about surrounding properties can therefore influence the level of detail that can reasonably be represented. Survey information, architectural documentation and other project material may contribute to the model depending on what is available and required.

For a broader explanation of the source information used to prepare the assessment, see What Information Is Needed to Prepare Shadow Diagrams?

How accurate does neighbouring information need to be?

Where neighbouring geometry is relevant to the shadow assessment, the reliability of that information affects what the model can represent.

A neighbouring building shown only as general context does not necessarily serve the same modelling purpose as geometry being relied upon to establish a specific shadow condition. The required level of information should therefore reflect how that neighbouring element is being used within the assessment.

Where important surrounding geometry is based on incomplete or approximate information, the limitations of that information can affect the reliability of the resulting representation.

This forms part of the wider relationship between model inputs and output reliability discussed in How Accurate Are Shadow Diagrams?

Are neighbouring windows and private open space always shown?

Not necessarily. There is no single assumption that every shadow diagram must identify every neighbouring window, outdoor area or other property feature.

Specific areas or building elements may become relevant where the applicable planning requirements require them to be considered. In those circumstances, the documentation may need sufficient information to identify the relevant relationship between the modelled shadow and the area being assessed.

That should be determined from the requirements applying to the particular development rather than from a generic assumption about what every shadow diagram must contain.

The shadow drawing establishes the spatial condition. Where specific solar access criteria apply to neighbouring areas, those criteria form part of the relevant planning or solar access assessment.

Does showing shadow on a neighbouring property mean there is a planning problem?

No. A shadow diagram showing shadow on neighbouring land does not, by itself, establish that there is a planning problem.

The drawing records a geometric condition: where the modelled shadow falls at the nominated date and time. It may also show how that condition changes between existing and proposed development scenarios or across several assessment times.

Whether that shadow is relevant to a particular planning control depends on the requirements applying to the project. Those requirements may consider specific locations, periods or other criteria that cannot be determined from the presence of shadow alone.

This distinction keeps the role of the shadow diagram clear: it shows the modelled shadow condition, while the applicable planning assessment determines what that condition means.

How much surrounding context is enough?

Enough surrounding context should be shown to make the relevant shadow condition understandable and to meet the documentation requirements applying to the project.

Too little context can make it difficult to identify where the shadow falls once it extends beyond the subject site. Too much unrelated information can make the drawing unnecessarily complex without improving the assessment.

The useful extent is therefore defined by relevance. The drawing should include the surrounding properties, boundaries, built form or other features needed to locate and understand the shadow being assessed.

This is part of the wider documentation question explored in What Should a Shadow Diagram Show?

Neighbouring context within the wider shadow assessment

The subject site provides the primary reference for a shadow diagram, while neighbouring context helps establish what lies beyond that boundary and where the modelled shadow falls in relation to surrounding development.

The amount of surrounding information required depends on the project. Where adjoining properties are relevant to the shadow condition, their boundaries, built form or other necessary features can provide important spatial context.

That context should remain purposeful. The objective is not to reproduce the entire neighbourhood, but to provide enough information for the relevant shadow relationship to be understood clearly.

The shadow diagram then establishes where the modelled shadow falls. Where further assessment of solar access or planning performance is required, the applicable project criteria determine how that shadow condition is evaluated.