Daylight / Sunlight modelling
IN2 Engineering provides technical daylight, sunlight, and overshadowing assessments to support planning applications for commercial, residential, and mixed-use developments
Daylight modelling for planning applications
Our building physics team uses 3D dynamic simulation to evaluate schemes against BRE 209 and EN 17037, helping project teams demonstrate compliance, protect neighbouring amenity, and secure planning permission without compromising design quality.
Why daylight modelling is critical for planning approval
Local authorities and An Bord Pleanála increasingly expect detailed daylight and sunlight assessments as part of valid planning submissions. High-density urban infill, tight site boundaries, and adjacent residential properties create immediate friction around site layout, massing, and overshadowing.
Failing to evaluate daylight early risks planning delays, formal objections from neighbours, or costly redesign requests after a submission is made. An accurate daylight model establishes clear baseline metrics for your site. It identifies potential daylight deficits or overshadowing impacts on surrounding properties while the design is still fluid, giving planning officers the technical evidence required to approve a scheme.
What standards are used for daylight and sunlight planning assessments?
Our engineering team models developments in full compliance with current Irish planning frameworks and industry design guidance.
- BRE 209 (Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice): Widely used by Irish planning authorities to assess impact on neighbouring buildings (Vertical Sky Component, Daylight Distribution) and sunlight access to surrounding gardens or public amenities.
- EN 17037 (Daylight in Buildings): The European standard evaluating interior daylight provision within proposed developments. We assess Target Illuminance () across specified fraction thresholds to confirm internal space compliance.
- Climate-Based Daylight Modelling (CBDM): Advanced annual simulation using location-specific climate data. We calculate spatial Daylight Autonomy (sDA) to measure adequate daylight levels over the year and Annual Sunlight Exposure (ASE) to control potential glare and overheating risk.
What does our daylight and sunlight analysis cover?
We carry out a complete physical and environmental analysis of your site using 3D dynamic simulation tools.
- Internal daylight provision: Quantifying daylight levels across all habitable or commercial spaces using EN 17037 target illuminance levels and CBDM metrics.
- Impact on neighbouring properties, daylight: Assessing reductions in Vertical Sky Component (VSC) and daylight distribution (No Sky Line) for surrounding residential windows to ensure neighbouring amenities remain protected.
- Impact on neighbouring properties, sunlight: Calculating annual and winter probable sunlight hours (APSH/WPSH) for adjacent properties, along with sunlight hours on outdoor courtyards, gardens, and public realm spaces on March 21st (BRE 209 criteria).
- Overshadowing and solar access: Mapping transient shadows cast across adjacent sites throughout the year to demonstrate minimal adverse impact on surrounding land.
What technical deliverables do you receive for your planning application?
When you engage IN2, we deliver a comprehensive, planning-ready technical package designed for immediate review by planning officers, consultants, and legal teams.
- Planning-compliant daylight and sunlight report: A clear, rigorous technical document containing executive summaries, methodology descriptions, compliance tables, and direct comparisons against BRE and EN thresholds.
- False-colour daylight maps and visual diagrams: High-resolution floor plan overlays illustrating daylight factor contours, spatial Daylight Autonomy, and sunlight exposure across every floor plate.
- Transient overshadowing animations: Hourly shadow plots illustrating solar access across site boundaries for spring and autumn equinoxes.
- Targeted mitigation strategies: Practical architectural recommendations, such as glazing adjustments, window repositioning, or revised balcony depth, where baseline schemes show marginal compliance.
How we integrate daylight analysis into early-stage design
Treating daylight modelling as a post-design “tick-box” exercise often leads to emergency design revisions when a scheme fails compliance late in the process.
IN2 works directly with architects and design teams from concept massing through to final submission. By testing early geometric concepts using our simulation software, we identify potential daylight issues while massing, window-to-wall ratios, and floor heights are still adjustable. This iterative approach allows us to optimise building geometry to pass planning gates comfortably, protecting both internal light levels and surrounding neighbour access, without compromising your overall architectural vision.
Related projects
Why work with IN2 Engineering?
- We have maintained 100% success rate on achieving planning
- Our analysis and reporting adhere to the BRE Guidelines, 2008 British standard, EN standards and The National Annex
- We have substantial experience in this relatively new area of planning in a wide range of sectors