Planning matters

The publication of the revised BRE Report (BR 209) in June 2022 caught most planning authorities by surprise and highlighted a need for guidance and training on daylight and sunlight matters amongst Planning Officers. Lichfields received requests for, and provided, CPD sessions to Planning Officers within Local Planning Authorities across the UK, the Greater London Authority and the Planning Inspectorate along, alongside requests from architects and developers. These sessions, particularly those with Planning Officers, created opportunities to discuss the practical application of the new guidance. Outside of the need to understand the revisions, CPD sessions allowed officers to voice their frequent concerns regarding reliance on reports supporting developments. These concerns were in some instances drawn with reference to the ‘Rainbird’ ([2018] EWHC 657) and ‘Guerry’ ([2018] EWHC 2899) cases, where planning permission was quashed by the courts due to errors and misleading statements within the daylight and sunlight reporting. What was clear was a need to be able to provide clear and robust guidance for committee members that Planning Officers had confidence in presenting. Amongst Planning Officers and committee members there can be a distrust of daylight and sunlight reports, particularly where they contain little interpretation of data or discussion where transgressions are noted other than assurances that these are ‘typical’. The revisions created significant confusion within a field that was already seen on the whole as a bit of a ‘dark art’. The realisation that the revisions did not impact on the tests applied to neighbouring properties was mostly treated with relief. However, the changes regarding how proposed dwellings should be tested emphasised the many misconceptions and preconceptions held by those required to draw conclusions from analysis undertaken by others. Discussions on the new methodologies highlighted the limitations vertical sky component and no sky line testing pose in judging perceived daylight within rooms with the general refrain being ‘but what does it mean?’ Discussions on the new assessment methods centred on which of the new daylight tests (Daylight Factor and Spatial Daylight Autonomy - Illuminance) is the preferred test and confusion over whether both are required. It was clear that, if presented correctly, the illuminance method was more relatable to personal experience than the daylight factor method. There were also concerns and misconceptions that the daylight factor method was the same as the average daylight factor method previously used. The new guidance also introduces the UK Annex, a new testing metric for ‘hard to light’ dwellings. This element of BS EN 17037 introduces UK only daylight targets which are aimed at properties where daylight access is restricted due to location and external limiting factors such as existing tree cover or within basement rooms. There is confusion over the use of the UK Annex and the alternative targets given. The BRE Report states that the UK Annex gives minimum recommendations for habitable rooms in the UK but also states the targets are intended for ‘hard to light’ dwellings. As such, reliance on the UK annex targets was not considered to be appropriate in all cases - can rooms at the upper stories of proposed tall buildings really be considered as ‘hard to light’. Reliance on the UK Annex alone, without justification, was seen as another element that generated distrust of daylight and sunlight reports. Looking back through discussion notes the received commentary can be summarised as follows: Are the new standards harder to achieve? Concern over manipulation of the results and how they are presented, How do the new methodologies tally with ‘appropriate’ daylight and sunlight arguments? What factors are in the control of officers to improve results? Is the UK Annex an appropriate target? The need to present all results clearly with supporting justification where necessary. Overall, the changes, once understood, were welcomed. There is a need to ensure that all analysis is presented clearly and, where necessary, relevant justification for deviations is discussed. There is an element of distrust of daylight and sunlight reports and more planning authorities will be seeking third party reviews of submitted analysis. The Lichfields team is being approached far more frequently than previously by planning officers to undertake such reviews. The revisions to the BRE Report present an opportunity to provide greater design input as schemes progress. There is an opportunity to tie assessments into other design concerns such as overheating and sustainability and a greater co-operation between consultants should become the norm. Again, the opportunity for early daylight and sunlight analysis to inform the design process and a more collaborative cross-disciplinary approach to natural light and other disciplines is to be welcomed. It is also clear that, while the testing of impacts on neighbours has not changed, there needs to be greater clarity and justification when presenting effects to assist Planning Officers and Committee Members. Use of illuminance and the revised sunlighting testing provides analysis results and imagery that are more easily grasped by the lay person. They show that there needs to be an educational element to reports and liaison with officers if support for a scheme is to be obtained. The Lichfields Neighbourly Matters team has become adept at running the new testing methods, informing the design process and presenting results in a clear and accessible manner. We strongly advocate early inclusion of daylight and sunlight testing in the design and pre-application processes to help de-risk projects. Taking design teams and Planning Officers through the testing journey, explaining the new guidance and interpreting daylight and sunlight results with clarity promotes assurance in the final design, secures trust from Officers and allows schemes to be presented confidently at committee.

The BRE Daylight and Sunlight Report (Site Layout Planning for Daylight and Sunlight: a guide to good practice) has been revised. The guidance contained in the Report has been updated to reflect the changes in the British Standard. It will fundamentally change the way applicants are required to assess natural light conditions for all residential planning applications. It also introduces a requirement to assess other non-residential uses.  The revised BRE Report is a guidance document giving advice on the interpretation of the recommendations given in both British Standard BS EN 17037 and CIBSE guide LG10. The previous British Standard (BS 8206 part 2) was replaced in June 2019 by BS EN 17037. BS EN 17037 introduces a number of new tests and definitions to the current daylight and sunlight testing practices. The most notable changes are: The Average Daylight Factor (ADF) and No Sky Line/Daylight Distribution (DD) tests for proposed accommodation are deleted and replaced.  Daylight in proposed buildings is to be assessed with reference to the area of the room achieving target daylight factors. An alternative test using target Lux value is also discussed. Both are valid and either can be used by an applicant. The tests introduce the effects of internally and externally reflected light into the daylight evaluation. Target illuminance testing also introduces time criterion.  Further qualitative tests for View, Sunlight Exposure and Glare are introduced.  The current documents (BRE Report, BS 8206 part 2 and LG10) discuss daylight and sunlight within homes, schools, hotels and hospitals but do not apply guidance to workspace. The new standard applies to the above buildings and additionally, provides guidance for workspaces. As anticipated the revised BRE Report leaves the current recommendations for effects on neighbouring properties and open spaces untouched. The major changes will be to assessment of proposed developments with the current daylight (VSC, ADF, DD) and sunlight (APSH) tests being superseded by the new tests. The changes will have a profound effect on the way daylight and sunlight within new development is assessed. Developers, architects and local planning authorities should be aware of the changes and the implications they will have during the design process and in the determination of planning applications. Daylight within proposed accommodation The previous BRE Report recommended that daylight within proposed accommodation was tested using the Average Daylight Factor (ADF), Room Depth and No-Sky Line or ‘Daylight Distribution’ (DD) tests. These tests are deleted and replaced with daylight provision which will now be tested through either of two tests. The new tests are undertaken with reference to minimum, medium and high target illuminance values. The first suggested test assesses daylight factors[1] across a reference plane at 850mm above floor level covering the whole room area. The plane should see the target daylight factor (DTM) achieved across at least 50% of the test plane. For the United Kingdom the target minimum, medium and high daylight factor (D) values are set at 2.1%, 3.5% and 5.0% respectively. For example, as a minimum, rooms should see D values of 2.1% or above across half of their area tested at 850mm above the floor. The second test applies minimum target illuminance (ET) targets to be achieved across 50% of a reference plane set at 850mm above the floor. These values, 100 lux for bedrooms, 150 lux for living rooms and 200 lx for kitchens mimic the traditionally applied ADF targets. Local climatic data is used and the ET should be achieved for at least half of the available daylight hours (i.e. for 2190 hours per year). BS EN 17037 Daylight tests summary table:   Sunlight within proposed accommodation The Annual Probable Sunlight Hours (APSH) tests discussed in the BRE Report are also to be replaced. Under the BS EN 17037 guidance, sunlight amenity is tested on any date between February 1st and March 21st for spaces receiving sun beams (i.e. those facing within 90 degrees of due south). The test determines the possible sunlight duration for that day: minimum being 1.5 hours,  medium being 3.0 hours, and  high exposure being 4.0 hours. The assessment is undertaken at a test point on the inside face of the window. Rooms with multiple windows can add the values for each window together where they occur at different times in the day. BS EN 17037 recommends that the at least one habitable room (living room, bedroom, nursery or kitchen) in a whole dwelling should comply with the guidance. View BS EN 17037 discusses the importance of ‘view’ on occupants of assessed spaces. It introduces several criteria that combine to form a view and provides guidance on assessing whether the view is rated as minimum, medium or high. A number of testing methodologies are discussed in the BS and all are used to determine the quality of the view and provide minimum window sizes driven by room size. This guidance can be applied to proposed units and neighbouring buildings. To assess ‘view’, test points are determined within the ‘utilized’ area of the room. These test points are not fixed and are chosen to represent where occupants are likely to spend much of their time. The test points are used to determine the horizontal sight lines and number of layers of view visible when tested at 1.2 m above the floor level. Additionally, the distance to external obstructions is determined. All of the factors are then assessed to determine the rating of the view. BS EN 17037 View tests summary table: Glare BS EN 17037 discusses the effects of overly bright areas or areas where there is a strong contrast between light and dark on the human eye. Importantly the new BS recommends that for areas where people cannot choose their position and viewing direction, protection from glare is provided. The standard discusses a number of tests that can be applied to assess the potential for glare and the effectiveness of the provided protection. In practical terms glare assessment is unlikely to be required in housing as a general rule as occupants can choose to change position or are able to use shading devices (blinds/curtains) to mitigate the instances. Summary BS EN 17037 changes the tests to be applied when assessing natural light provision within proposed accommodation. The previous daylight tests of ADF and DD/No-Sky Line are deleted and replaced. Sunlight tests are also deleted and replaced. Additional testing for ‘view’ is be introduced. The revised methodologies are significantly different from the ‘traditional’ approaches to assessing daylight and sunlight conditions for planning. They provide 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. The changes will have a pronounced effect on the way daylight and sunlight is assessed for all residential planning applications. Developers, architects and local planning authorities will need to familiarise themselves with the new guidance to ensure it is correctly applied in the design of new development and in the determination of planning applications Lichfields’ Neighbourly Matters team is well versed in the changes and has been using the revised calculations for some time to provide discussion and verification of findings for developments in dense urban areas. We would be happy to discuss the revised calculations and their impacts on natural light testing or can arrange a CPD session covering these new approaches to the assessment of daylight and sunlight.   [1] Ratio of illuminance received directly or indirectly from an overcast sky at a point on a reference plane to that received by an unobstructed horizontal plane.