4 minute read
Lockdown has changed the way we view daylight and sunlight within our homes
NUMEROUS studies demonstrate the positive impact natural light has on both our physical and mental health and, with recent reports on the effects vitamin D and UV light have on the Covid-19 virus, general awareness of natural light is rising. Toby Rogan-Lyons, Planning Director, Neighbourly Matters at Lichfields, explains...
Previous work and schooling practices meant that most people would have only a limited time in their homes during the day. However, the present restrictions have led to a dramatic increase in this, and increased levels of home-working are likely to feature for some time.
All this is leading to an upsurge in awareness of the impact our home environment has on us as individuals, with natural light forming a significant element of that.
This, coupled with the good weather experienced across the UK during lockdown - May saw record sunlight hours - will have instilled occupants with a, perhaps elevated, expectation of light within their homes.
However, expressing this understanding in a measurable way will always be problematic; terms such as ‘light’ and ‘airy’ are subjective. When undertaking studies to assess the effects a proposed development may have on the natural light amenity of both neighbouring properties and future residents, the guidance given in Building Research Establishment document 209 (Site Layout Planning for Daylight and Sunlight, a guide to good practice, 2011, BRE Report) is most often used, and reports based on this guidance are expected by most planning authorities for new developments.
The BRE Report
The BRE Report provides numerous tests used to assess daylight and sunlight striking windows and the penetration of daylight within spaces.
These tests provide absolute and comparative numerical results and are used by consultants and planning officers to judge a development’s impacts on natural light.
Sunlight penetration at 4 pm
BS EN 17037 view analysis
However, there is endless debate on the interpretation of these results when it comes to effects on peoples’ lives. Daylight and sunlight consultants will often discuss the appropriateness of the targets provided in the BRE Report.
The daylight targets within the BRE Report are based on what proportion of the sky is visible to a test point and not on the quality of the light experienced within a space.
In urban areas the proportion of sky visible from within buildings is often restricted and the targets provided in the BRE Report are difficult to achieve.
Whilst this urban area disparity is discussed in the BRE Report alternative absolute targets are not provided and it is left to Planning Authorities and officers to interpret, or accept, what is appropriate.
Heated debates
All of this often leaves any interested parties baffled and confused, leading to heated debates at public consultations and planning committees.
It is difficult to convince a neighbouring occupier or Committee member that the proposed 20-storey tower, to be built close to a property, will leave that property with appropriate levels of daylight and sunlight when the building will form a major part of residents’ outlook.
In June of last year the British Standard (BS 8206 part 2) which provided the basis for the guidance contained in the BRE Report was superseded by a new standard (BS 17037).
This standard introduces a number of new tests and definitions to the current daylight and sunlight testing practices.
Revised methodologies
The revised methodologies are significantly different from the previous testing approach and are based on
providing a more accurate assessment of natural light within buildings.
The move away from the previous simplified calculations has been brought about by the advances in simulation technology and the need to provide practical guidance for natural light in urban areas.
It is hoped that use of the revised testing methods will provide clarity, at least for proposed accommodation, as the tests are predominantly based on the intensity and duration of natural light within a room.
With occupiers having a greater perception of natural light, increased interaction with their immediate community and the likelihood that they will be spending a greater amount of time at home, awareness of events that effect community and property is likely to rise.
Increased awareness and scrutiny
It is expected that more people and community groups will scrutinise planning applications and be driven to comment. As such, local planning officers are likely to call for clarity in natural light testing.
When providing daylight and sunlight analysis, consultants will need to be aware of the rise in public awareness and tailor their reports to be more accessible, or face criticisms of trying to bamboozle committees and the public.
As an industry we will need to simplify the results of detailed analysis and express them in ways that relate to perceptions of light, perhaps providing some form of standardised terminology - dim, pleasant, well-lit, bright, glaring - relating to result values.
