Sunlight Indicator Test

[Temp]

Our council is consulting on new Planning Application validation check lists. I see that for all Full Planning Applications..

 

"where there is a potential adverse impact upon the current levels of sunlight/daylight of adjoining properties and/or of future occupiers of the proposed development"

 

...you must provide a "Sunlight Indicator Test". They provide a link to this page at the BRE and a £55 book...

 

https://www.bregroup.com/services/testing/indoor-environment-testing/natural-light/

 

I think a significant percentage of new houses/self builds have some potential to impact "current levels of sunlight/daylight of adjoining properties". In the past Planning Officers would assess an application and request more information, reports or studies. Now it seems you have to do one for even minor adverse impacts that do not come close to affecting someones right to light.

 

Searching the BRE website for  "Sunlight Indicator Test" finds no matches. Google isn't much more helpful. 

 

Anyone know if this is a simple exercise that you can complete yourself or a massive bill from a consultant? 

 

 

 

[Jeremy Harris]

In principle it sounds like a good idea, to try to quantify the impact of any development on light at any existing dwelling.  I suspect that it will turn into yet another excuse to charge exorbitant fees, though.

[ProDave]

£55 for an 84 page book actually makes the wiring regs book sound like good value.

 

When I needed is similarly expensive but even shorter BRE book, I went to our local library and borrowed it on an inter library loan, it cost me just over £1 in postage costs to do so.  That would be my advice for something you only want once.

[Temp]

Hopefully I'll never need it.

 

I'm on the mailing list of people that have commented on local plans in the past so they notify me of all policies out for public consultation. They invariably ignore all comments but it forces them to at least write a reply.

 

Today I noticed it's not a requirement for a householder application so not needed for extensions.

[MintSprint]

PM me if you would like a copy of the book in PDF format (on the understanding that you will not further distribute it).

 

The process is somewhat long-winded, but not beyond the realms of the amateur. The usual question is what value you put on your own time: unless it is very little, you're better off paying a professional to do it, rather than spending a long time researching how to do it yourself, for a one-off application.

 

It's much easier, these days (the book was written some time ago) if you use a 3D model in a program like SketchUp, which can generate accurate, geographically located sun path and shadows based upon it.

 

As you say, it won't be a validation requirement for a householder (or, indeed any) planning application, but in lieu of one, they'll apply the basic '45  degree rule'. A sunlight analysis, on the other hand, can very frequently prove that the design is acceptable even where it fails the 45 degree rule.

[Temp]

Thanks @MintSprint. Hopefully I'll never need to do one. Any idea how much a professional would charge?  

[MintSprint]

21 minutes ago, Temp said:

Any idea how much a professional would charge?  

 

It depends whether you have a 3D CAD model they can use; as above, if one is available, it's actually a pretty quick and simple process, these days - certainly no more than a £few hundred.

 

If you have to do the background work to support it, it'd be a bit more - a high 3-figure or very low 4-figure sum.

[Mr Punter]

I have only had 2 of these done - one cost £2000 and the other £720.  They model the impact of the scheme on the windows of the adjacent properties.  I think they may be even cheaper now.

 

Often not needed if it complies with the 45 and 25 degree rules.

[MintSprint]

5 minutes ago, Mr Punter said:

Often not needed if it complies with the 45 and 25 degree rules.

 

Yeah, if you comply with the 45 and 25 degree rules, they're redundant (in fact the methodology in the document we're talking about basically says that if you comply with the 25/45 degree rules, you don't need to go any further)

 

In fact, you've got to be doing something completely horrendous to fail the full analysis; the standard they set isn't terribly high.

[Mr Punter]

1 minute ago, MintSprint said:

In fact, you've got to be doing something completely horrendous to fail the full analysis; the standard they set isn't terribly high.

 

It is easily done in higher density settings, though.  I am not sure how much discretion can be allowed but have seem some schemes where multiple ground floor windows fail but the scheme gets consent.

[MintSprint]

1 hour ago, Mr Punter said:

... have seem some schemes where multiple ground floor windows fail but the scheme gets consent.

 

New development is treated differently (less stringently) than impact on existing development.

[Temp]

Our planners are changing the validation checklist for Full Planning Applications to add the following:

 

Daylight/sunlight assessment

Required where there is a potential adverse impact upon the current levels of sunlight/daylight of adjoining properties and/or of future occupiers of the proposed development

A sunlight indicator test using the British Research Establishment’s ‘Site layout planning for daylight and sunlight – A guide to good practice.’

Edited March 19, 2020 by Temp