Daylight and Sunlight Assessments

Daylight and Sunlight Assessments for Planning and Design Teams

KJ Tait provides daylight and sunlight assessments to support planning applications, design development and environmental performance analysis across the UK. Our work helps project teams understand how proposed developments may affect neighbouring amenity, internal daylight quality and sunlight access, allowing informed decisions to be made before planning submissions are finalised.

We support architects, planning consultants, developers and asset managers with technical daylight modelling, BRE-based daylight and sunlight analysis and practical design advice for residential, commercial and mixed-use developments.

Our assessments help project teams understand planning risk, identify opportunities for design refinement and provide robust technical evidence to support planning and development objectives.

BRE Daylight and Sunlight Assessments

Our daylight and sunlight assessments are typically undertaken in accordance with recognised industry guidance, including Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice. We assess the likely impact of proposed developments on neighbouring properties and internal spaces using established methodologies and digital modelling tools.

Typical BRE Daylight Analysis Includes:

• Vertical Sky Component (VSC)
• No Sky Line (NSL)
• Average Daylight Factor (ADF)
• Daylight Distribution Analysis
• Overshadowing Assessments
• Sunlight Availability to Amenity Spaces
• Annual Probable Sunlight Hours (APSH)

Our reports are developed to align with planning authority requirements while remaining technically robust and commercially practical. We aim to identify risks early and provide clear recommendations where daylight or sunlight performance may become constrained.

Understanding the Key Daylight and Sunlight Metrics

Vertical Sky Component (VSC)

Vertical Sky Component measures the amount of visible sky available from a window. It is commonly used to assess the effect a proposed development may have on neighbouring properties and forms a key part of many daylight impact assessments.

No Sky Line (NSL)

No Sky Line analysis considers how effectively daylight is distributed within an existing room. Rather than simply assessing light at a window, NSL helps evaluate the usable area of a space that continues to receive direct skylight.

Average Daylight Factor (ADF)

Average Daylight Factor is commonly used to assess the daylight performance of proposed accommodation. It helps determine whether residential, educational, office or other occupied spaces achieve appropriate internal daylight levels.

Annual Probable Sunlight Hours (APSH)

APSH analysis evaluates the amount of direct sunlight received by a window throughout the year. This metric is often used where developments may influence sunlight access to neighbouring residential properties.

Overshadowing and Amenity Space Analysis

Where developments may affect gardens, courtyards, roof terraces or external amenity areas, overshadowing assessments can help understand how sunlight access may change throughout the year and whether potential planning concerns could arise.

Daylight Impact Assessments

KJ Tait undertakes daylight impact assessments for planning applications across the UK. A daylight impact assessment evaluates how a proposed development may affect daylight availability, sunlight access and neighbouring amenity, helping project teams understand potential planning risks before projects progress.

Daylight impact assessments are commonly required for residential developments, mixed-use schemes, urban infill sites and commercial projects where new buildings may influence the daylight and sunlight received by neighbouring properties or external amenity spaces.

Using recognised methodologies and digital modelling techniques, we assess daylight and sunlight performance and provide reporting suitable for planning submissions. Our assessments help architects, planning consultants and developers make informed decisions that balance planning compliance, development viability and building performance objectives.

Planning Support and Design Stage Daylighting Analysis

Daylight and sunlight performance can significantly influence planning outcomes, particularly on constrained urban sites or where developments interface closely with neighbouring buildings. Early stage daylight analysis can help design teams understand potential planning risks before layouts are fixed.

KJ Tait works alongside planning consultants, architects and wider design teams to provide technical modelling and support throughout the planning process. This includes feasibility studies, massing reviews, planning submission reports and responses to planning comments relating to daylight and sunlight access.

We focus on providing commercially realistic advice that balances planning compliance, development viability and building performance outcomes.

What a Daylight and Sunlight Assessment Can Include

Depending on the project requirements, a daylight and sunlight assessment may include:

• Review of planning requirements and project constraints.
• Development of a digital model of the proposed scheme and surrounding context.
• Assessment of impacts on neighbouring properties.
• Internal daylight analysis for proposed accommodation.
• Sunlight and overshadowing assessments for windows and amenity spaces.
• Daylight and sunlight calculations using recognised methodologies.
• Identification of potential planning risks and opportunities for design refinement.
• Technical reporting suitable for planning submission.
• Support during planning review and design development where required.

No two projects are identical and the scope of assessment should reflect the scale, complexity and planning context of the development.

Our Daylight and Sunlight Assessment Process

We work closely with architects, planning consultants and developers throughout the planning and design process. Our assessments are tailored to the specific requirements of each project while providing clear technical evidence to support planning submissions and design development.

1. Initial Project Review

We review available drawings, project requirements, planning considerations and surrounding context to establish the scope of assessment.

2. Digital Model Development

Our team develops a digital model of the proposed development and surrounding environment to allow detailed daylight and sunlight analysis.

3. Daylight and Sunlight Assessment

We undertake the appropriate assessments using recognised methodologies, including analysis of daylight availability, sunlight access and amenity impacts where required.

4. Review of Potential Planning Risks

Results are reviewed to identify planning risks, opportunities for design refinement and areas requiring further consideration.

5. Technical Reporting

We prepare clear reports suitable for planning applications, planning submissions and stakeholder review.

6. Ongoing Design and Planning Support

Where required, we provide support during planning determination, design development and responses to planning queries relating to daylight and sunlight performance.

BREEAM Daylight Assessments

We also undertake daylight assessments in support of BREEAM certification and wider sustainability objectives. Daylighting performance can contribute to occupant wellbeing, visual comfort and energy efficiency while supporting environmental assessment frameworks.

Our BREEAM daylight modelling services assess internal daylight performance against the relevant requirements of the applicable BREEAM scheme. This may include daylight illuminance analysis, glare considerations and spatial daylight performance depending on project requirements.

Daylighting should not be considered in isolation. Solar gains, overheating risk, façade design, operational energy performance and occupant comfort often interact with daylight strategies. KJ Tait's wider experience in thermal modelling, building performance and sustainability consultancy allows these factors to be considered together rather than as separate exercises.

Digital Daylight Modelling and Building Performance Analysis

Our team uses advanced digital modelling techniques to assess daylight and sunlight performance across a range of building typologies and project stages.

We understand that daylight performance does not sit in isolation. Daylighting strategies often interact with overheating risk, façade design, operational energy use and occupant comfort. Our wider building physics and sustainability expertise allows us to consider daylighting within the context of overall building performance.

Why Teams Appoint KJ Tait for Daylight and Sunlight Consultancy

• Clear and technically robust reporting
• Commercially focused planning support
• Experience supporting complex urban developments
• Integrated sustainability and building performance expertise
• Collaborative support for architects and planning consultants
• Early-stage feasibility and massing analysis
• UK-wide project support

Unlike many specialist daylight consultants, KJ Tait combines daylight expertise with wider building performance, sustainability and MEP engineering knowledge. This enables us to consider daylight performance alongside overheating risk, energy performance, occupant wellbeing and wider environmental objectives.

Relevant Project Experience

KJ Tait has supported architects, planning consultants, developers and asset managers on a wide range of daylight and sunlight assessment projects. Our experience includes urban residential developments, mixed-use schemes, commercial refurbishments and hospitality projects where balancing development aspirations and neighbouring amenity is a key consideration.

Our wider experience in sustainability, building performance, thermal modelling and environmental design allows daylighting considerations to be assessed within the context of overall building performance rather than as a standalone planning exercise.

Frequently Asked Questions

What is a daylight and sunlight assessment?

A daylight and sunlight assessment evaluates how a proposed development may affect daylight levels, sunlight access and neighbouring amenity. Assessments are commonly prepared in support of planning applications where new development could influence surrounding buildings, external amenity spaces or the quality of daylight within proposed accommodation.

When is a daylight and sunlight assessment required?

Planning authorities may request a daylight and sunlight assessment where a development could affect neighbouring properties, internal daylight levels or external amenity spaces. Assessments are commonly required for urban infill developments, taller buildings, residential schemes, mixed-use developments and sites where buildings are located in close proximity to one another.

What is a daylight impact assessment?

A daylight impact assessment examines the effect a proposed development may have on daylight and sunlight received by neighbouring properties and amenity spaces. It is typically undertaken to support planning applications and to help identify potential planning risks during design development.

What is the difference between a daylight and sunlight assessment and a rights of light assessment?

A daylight and sunlight assessment considers planning and environmental impacts using recognised technical methodologies. A rights of light assessment is a separate legal exercise that considers private property rights rather than planning policy. The two assessments address different issues and are often commissioned for different purposes.

What are VSC, NSL, ADF and APSH?

These are commonly used daylight and sunlight metrics. Vertical Sky Component (VSC) assesses visible sky at a window, No Sky Line (NSL) evaluates daylight distribution within an existing room, Average Daylight Factor (ADF) assesses internal daylight levels and Annual Probable Sunlight Hours (APSH) measures direct sunlight availability throughout the year.

Do local planning authorities require daylight and sunlight assessments?

Many planning authorities require daylight and sunlight assessments where developments may affect neighbouring amenity, internal daylight provision or external spaces. Requirements vary depending on the scale, location and nature of the proposed development.

Can daylight modelling help identify planning risks before submission?

Yes. Early-stage daylight modelling can highlight potential issues relating to neighbouring amenity, building massing, façade design and internal daylight quality before planning layouts are fixed. This can help reduce planning risk and support more informed design decisions.

Do you undertake BREEAM daylight assessments?

Yes. KJ Tait undertakes daylight modelling in support of BREEAM assessments and wider sustainability objectives. Daylighting performance can contribute to occupant wellbeing, visual comfort and environmental assessment outcomes depending on the project requirements and applicable scheme.

Can daylight assessments support design development as well as planning applications?

Yes. Daylight modelling can be undertaken at concept, planning and technical design stages. Early-stage analysis can help assess building form, glazing strategies and internal layouts before detailed design has progressed too far.

How does daylighting relate to wider building performance?

Daylighting strategies often interact with solar gains, overheating risk, façade design, occupant comfort and operational energy performance. Considering daylight within the wider context of building performance can help project teams make more balanced design decisions.