Category Archives: Sunlight and Daylight

Equivalent First Zone – Right to Light

Equivalent First Zone – Daylight Assessment

For many years we have been using the old paper and pen method to calculate VSC (Vertical Sky Component) and APSH (Annual Probable Sunlight Hours) and for many sites it is still possible to use this method.

However, the new BRE 209 guide has migrated from ADF values to far more complex calculation requirements, which are now only possible to do with a computer model.

Equivalent First Zone

For a long term client we have also offered to calculate Equivalent First Zone values for Existing vs Proposed Site Layout. This has been a steep learning curve for us, but we have managed to produce several sets of Equivalent First Zone calculations that indicate the maximum building possible to achieve, without compromising right to light.

So time moves on we miss our pens and our paper, but it is plain to see that the computer model does an extortionary volume of calculations in no time at all, and can derive values for very complex layouts where we mat have struggled in the past, and Equivalent First Zone Calculations they can carry out a days worth of calculations in just a few seconds.


Daylighting Study – Lambeth – London

Daylighting Study – Lambeth – London 

Acting on instructions from a much valued repeat client, Southwest Environmental Limited have conducted a Sunlight and Daylight Study in Lambeth, London.  

The scope of the study includes for ADF value calculation and a Sun-on-the-Ground calculation, these are explained further below:
ADF- This is used to estimate the level of lighting inside the development prior to construction. In its most basic form it is a measure of window size to room size. i.e. is the window big enough for the room. Other factors also go in to the calculation such as quality of the glass, and whether daylight can reach the window i.e. is the window darkened by near by tall buildings. 
Sun-on-the-Ground – A shady cold cool garden can be nice in the summer, but in spring and autumn it can be gloomy. We can work out whether an outdoor area you have proposed will be bright or gloomy. We do this using the BR209 method, which is verging on witchcraft. 
Very happy to talk about any of the above so please ring for a discussion about it. 

Daylight Study – Gloucester

Southwest Environmental Limited have recently completed a Daylight Study for a site in Gloucester. The study included for an assessment of daylighting impact from a proposed development, on existing neighbouring sites as part of the planning application.

The VSC calculations were carried out, and it was shown the the proposed building did not cause more than the recommended 20% reduction in VSC at assessed windows.

If you would like to discussing daylighting please call the office, we can talk for free or provide a quote for a formal study.

Sunlight Daylight Assessment Cornwall

Sunlight Daylight Assessment Cornwall 

Acting on instruction from a client in Exeter, Southwest Environmental Limited have prepared a Sunlight and Daylight Assessment for a Site in Bude, Cornwall.

The report was to check impacts on an existing property. SWEL used the well established (and normally applied) BR209 assessment method to derive VSC and Daylight Values for neighboring windows.

All was found to be well and good. And the design was considering applicable given the context of sunlight and daylight.

The proposed building was 3 stories in height and was set back approximately 20 meters from the existing building which was though worst affected. The worst affected window experienced a 12% drop in day light, with the guide allowing for 20%.

ADF Daylight Assessment – Lambeth SW4

ADF Daylight Assessment – Lambeth SW4

Southwest Environmental Limited have recently issued a ADF Daylight Assessment Report for a project in Lambeth.

The design of the project was most unusual. It consisted of a dwelling being built in a gap in a row of terraced houses. Instead of using the full available height to match the existing houses, the development makes use of a basement and a ground floor level only. As such is fairly unique in appearance certainly when considering the immediate vicinity.

Basement & Ground Floor Only Design

This low level construction obviously aided in the minimisation of any day lighting or sun lighting issues, and the dwelling met all criteria relating to external impacts as described in BR209. Interior lighting was found to be excellent throughout with ADF values exceeding guide minimum values by some margin.

SWEL regulatory carry out Sunlight and Daylight Assessments across the Greater London Area. Our reports are well received and we pride our selves on a quick turnaround, often in 5 working days or less.

The above image is reproduced courtesy of Tekton Design & Build SW18.

Sunlight and Daylight Assessment – Lambeth SW16

Sunlight and Daylight Assessment – Lambeth SW16

Acting on instruction from a repeat client Southwest Environmental Limited have carried out a daylighting assessment for a mews style development in Lambeth, London.
The concern here was not impact on existing neighbours but the provision of adequate light for future occupants. 
Sky Angel has a Strong Effect on ADF Values
An ADF value was calculated for each room with all assessed rooms demonstrating adequate lighting. 
There are a number of factors which effect the ADF value of a room, but the most important ones are window size relative to window size. 
Southwest Environmental carry out around 20 sunlight and daylight studies in London every year. If the design does not produce adequate light or excessive impact then we can offer design advice, which will normally rectify the problem. 

Sunlight Daylight Assessment

Sunlight & Daylight Assessment – Epsom

Acting on instruction from a repeat client in the Epsom area, Southwest Environmental Limited are undertaking a Sunlight and Daylight Assessment for a prestige development of 2 no. 6 bedroom houses, which occupy the plot of a single smaller dwelling.

The scheme makes very good use of the space available, but unfortunately in the first instance the height of the buildings was a little too great, as it caused loss of daylight to a neighbouring kitchen window that was beyond the loss allowable under BRE 209.

Recommendations were made that involved altering the pitch of the roof, and allowing for a flat roof area, where it would not impact of the character of the property. This reduced overshadowing to the point where, the scheme became acceptable.

The reduction in height did not result in any loss of usable internal space, although it did result in some loss of loft space, which may have been suitable for conversion in the future.

Environmental Consultants London

Sunlight Daylight Assessment

Southwest Environmental are Environmental Consultants who regularly undertake Sunlight and Daylight Assessments in London, in this case this Assessment took place in Tottenham (N17).

The original plan was for the building to have 5 stories with an extra penthouse single unit on the fitth floor. This was a problematic layout owing to there being very little over shadowing pre-development.

Southwest Environmental were able to inform our client of the maximum possible building height based on the bRE 209 reduction criteria which was around 12 meters in this instance. Th height would change dependent of the scale and distance of the building in relationship to the affected window.

After redcuing the building height to 4 stories the calculations were acceptable, and the rpeort was issued in support of the application.

This report may be used in the appeal process to prove that 4 stories does not create adverse overshadowing conditions.

Environmental Consultants London

Sunlight Daylight Assessment – Lambeth, London, SE27

Sunlight Daylight Assessment – Lambeth, London, SE27

The Sunlight Daylight study has been carried out in accordance with  the recommendations of the Building  Research Establishment Report “Site Layout Planning for Daylight & Sunlight 1991”. This is the  standard adopted by a wide range of District and Borough Councils across the UK.

 The scheme was already sympathetically design by the architects in question when plans were forwarded to SWEL for assessment.

Calculations were carried out to assess impacts. The scheme showed at worst VSC and Sunlight at 84% of their former value and as such the reports recommendation as that the scheme was allowed to proceed.

Sunlight and Daylight Assessment Reports London

Sunlight & Daylight Assessment – Hackney (N1)

Sunlight & Daylight Assessment – Hackney

SWEl have just sucessfull completed a sunlight & daylight assessment for an unusual retrofit project in Cazenove (Hackney) London.

The project invloves the install of a further two stories on top of an existing building the design is modern and well considered to reduce daylighting impacts, with a tiered design with width decreasing upwards.

The surrounding buildings were subject to considerable overshadowing prior to the development, and as such only minimal reductions in enjoyed light were acceptable.

Sunlight & Daylight reduction post project were within limits set in the relavent guidance, and as such the project with minor alterations was recommended to proceed.

Sunlight and Daylight Assessment