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Don't Block Out The Sun

Posted in Education on Sep 06, 2023.

We've recently had an increase in requests for Daylight and Sunlight Assessments so we wanted to take a moment to explain what they are why you might need one.

What's the difference between Daylight and Sunlight?

Firstly, lets define the difference between daylight and sunlight. Daylight is identified as being the amount of natural light that enters a building to provide acceptable illumination of internal accommodation between sunrise and sunset. Whereas sunlight refers to direct sunshine which can impact overshadowing.

We helped our client that needed a daylight and sunlight assessment to check whether their proposed extension would cast a shadow on their neighbours solar panels.

What is a Daylight and Sunlight Assessment?

A Daylight and Sunlight Assessment is a technical analysis which assesses the possible impact on daylight, sunlight and overshadowing by a new development or extension.

Let's say that you want to add a 2 storey extension to the side of your property. A daylight and sunlight assessment would identify how the shadow caused by your new extension would impact your own property and your neighbours. It would also identify if your windows and doors allowed for adequate amounts of natural light inside the property.

As part of our assessment, we will create a digital 3D model of your property (including the surrounding buildings and structures) and simulate the amount of daylight and sunlight your property facades would receive. We will prepare a report with the results and details of what impact the new development or extension will have. 

When is it needed?

Some local authorities will ask for a Daylight and Sunlight Assessment when you seek planning permission. This is usually the case for proposed developments or extensions which could potentially have a damaging impact on the current levels of daylight and sunlight on surrounding areas.

However, it can be a good idea to have an assessment carried out at the very early design stage as it helps to give a rough idea if the mass and scale of a development’s design will be suitable at the desired location. It can also be a useful tool to ensure that your design makes best use of the light available in your properties location.

Does the assessment just evaluate surrounding properties?

No. Whether you are looking to build a new building(s) or add an extension, the assessment will not only assess the neighbouring properties, but your own too, as your extension could affect your own daylight and sunlight levels.

Can my planning application be refused without an assessment?

Yes, if the local authority has requested an assessment as part of your application, then yes. It's also worth noting that it doesn’t necessarily mean that if you obtain a daylight and sunlight assessment, your application will be granted, this isn't the case.

If the result from the assessment shows a negative impact to the surrounding residential properties, this could reduce your chances of gaining approval.

Who can carry out Daylight and Sunlight Assessments?

We can! All of our consultants are fully qualified and have the required software and knowledge to carry out the assessment and much more. Please get in touch if you would like a quote or if you have any queries.