Daylighting Calculations

Good levels of daylighting are crucial to occupant comfort in new buildings.

Daylighting calculations can help designers to mitigate against the risk of poor natural light and also provide credits against environmental assessments like The Home Quality Mark, Code for Sustainable Homes and BREEAM.

Developing in high density urban, built up areas can often lead to poor light levels in some dwellings. Daylighting calculations take account of a number of factors including ‘view of the sky’, and whether there is enough light at a working  plane (desk) level within the dwelling. This will very much depend on orientation, elevation and surrounding buildings – for example on a block of apartments, some units may be impacted much more than others.

Why Do I Need Daylighting Calculations?

Daylighting analysis is commonly required:

Daylighting is not a mandatory issue in HQM or Code Assessments, but most of our clients find it a relatively inexpensive and effective means of gaining extra credits.

BREEAM also offers credits in it’s Health & Wellbeing / Visual Comfort category.

In both instances the assessor will need to see compliant daylighting calculations. For example, Code Assessments will need to demonstrate that daylighting factors achieve 1% in bedrooms, 1.5% for living rooms, and 2% for kitchens.

Working plane calculations need to show that 80% of the working plane in a room receives direct light from the sky.

What Makes a Compliant Daylighting Calculation?

Several key standards exist to provide guidance:

  • BS 8206-2:2008 Lighting for Building – Part 2 Code of Practice for Daylighting
  • CIBSE Lighting Guide LG10:1999 – Daylighting & Window Design
  • Communities & Local Government Code for Sustainable Homes Technical Guide Nov 2010

Daylighting CalculationsDaylighting Calculations may be performed manually using the above standards, guidance and formulae.

They may also be carried out using Dynamic Simulation Modelling (DSM) software packages such as those provided by Designbuilder, IES and TAS. These allow for much more sophisticated 3D modelling and analysis.

Build Energy can provide daylighting analysis across a multitude of buildings, from one-off self builds to very large and complex mixed use schemes, using DSM technology. We can create bespoke reports tailored to your requirements, and find solutions to any issues.

Would you like to discuss your project?

Call us for a chat on 01202 280062 or email

"Build Energy supported our new build project in Parkstone, Poole. From the initial SAP assessment, through technical build queries, to onsite air pressure and noise testing, the process was very smooth and easy to navigate. Build Energy help you conserve your energy for other building projects! We look forward to working with Build Energy on future projects."

Ben Baker

Baker Home Developments