Looking to enhance your planning prospects, our daylight, sunlight and overshadowing assessments will increase your prospects by ensuring that you follow the Buildings Research Establishment (BRE) guidance with regards to daylight, sunlight and overshadowing implications of your development.

DSO Assessments are becoming much more commonly required, particularly in built-up urban areas to accompany planning applications and without due consideration can lead to a planning application being refused.

As highly experienced specialist daylight consultants, all our work is carried out in line with the BRE Guidance Report – ‘Site layout planning for daylight and sunlight – a guide to good practice’ , and using state of the art Dynamic Simulation Modelling software you can be assured your planning application requirements will be in good hands with the planning team here at Melin.

We also offer Internal Daylight Assessments, for proposed developments with restricted daylight and sunlight availability such as basement dwellings.  Please click here for further information.

What are DSO Assessments?

A DSO Assessment analyses the amount of natural sunlight and daylight received directly within a proposed building development, as well as determining the impact of any reduction in daylight and sunlight for existing buildings surrounding it due to overshadowing.

When is a DSO Assessment required?

An assessment is required when a new building or extension has the potential to affect residences and office spaces in those buildings surrounding it.  The assessment may also have to consider the impact upon adjoining parks and gardens when applicable. 

Our dynamic simulation software has the capability to model the effects upon of all these critical considerations so you know the impact of your proposed development, and crucially be able to make informed design decisions that will streamline the planning process.

How is a DSO Assessment carried out? – Some bedtime reading!

When carrying out a Daylight, sunlight and Overshadowing assessment we have to be aware of the following key definitions as they form the basis of any report we produce;

• Skylight – the proportion of the sky an observer can see from an opening.
• Sunlight – the proportion of annual probable sunlight hours (APSH) predicted to fall upon a window.
• Overshadowing – the effect upon skylight and sunlight at an observers location, from neighbouring buildings or obstructions.

The term daylight is used to refer to all visible parts of global solar radiation. Ie skylight and sunlight.

Where the new building has the potential to block daylight to existing residencies or offices within its surrounding area, an assessment of the ‘Vertical Sky Component’ is required to give a ‘before and after’ assessment to ensure minimum standards are maintained within the existing buildings, as well as the new building itself. The ‘Vertical Sky Component’ is a measure of the amount of daylight reaching a window.

Overshadowing, or loss of sunlight to existing properties, is assessed using annual probable sunlight hours (APSH). This is a measure of how much sunlight a window can receive before and after the new building development is constructed.

The Building Research Establishment (BRE) has developed a guidance document with recommendations on how daylight standards should be assessed. The BRE guidance states that any DSO assessment should consider the effect upon residential properties within the proposed and existing buildings. The rooms that should be assessed include the living rooms, kitchens, and bedrooms, but there is no requirement to consider the effect upon bathrooms, staircases or corridors. As well as residential properties, BRE recommends the assessment of offices in both the proposed and existing buildings. 

All our in house planning stage team have years of experience producing DSO Assessments from sites of one house to large housing and commercial office developments for national clients, If you are looking for a DSO Assessment for your proposed building development please get in touch here.

Internal Daylight Assessments

In proposed dwellings with restricted daylight and sunlight availability such as basement dwellings, based on the plans of the proposed development, we are able to determine both the amount of daylight and its distribution within the rooms in order to determine whether it is deemed adequately lit to the BRE good practice guidelines.

Based on the results of our daylight assessments, we can help the architect to alter the design, where necessary to increase daylight availability. This could include advising on window sizes and room layouts to maximize daylight and sunlight. Furthermore, our internal daylight assessments are often conducted alongside daylight impact assessments which helps our clients achieve planning consents. We can also assist with prior approval applications for permitted developments.