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The paper examines the origins of the so‐called “grumble point” (a sky factor of 0.2 per cent) as the measure of daylight adequacy in rights to light disputes. It seeks to identify the rationale, and underlying scientific basis, for the adoption of this standard in the early twentieth century.

Analysis of archive materials.

The use of the 0.2 per cent standard does not appear to be based on empirical investigations involving human perceptions of adequate light. No evidence exists of the investigations reputedly undertaken by Percy Waldram during the early twentieth century. Waldram's own writings suggest that the standard began as a “rule of thumb” and was only later justified by reference to other independent reports. These generally do not support the use of the standard and, in any event, were soon superseded by other reports that concluded that it was too low. There is a lack of reliable evidence to justify the original adoption of the 0.2 per cent figure, and many of the assumptions underpinning modern rights to light practice are found to be based on inaccurate information.

Continues the debate, started in this journal in 2000, about the future of surveying practice in rights to light disputes.

Places new information in the public domain which has implications for the professional liability of surveyors advising clients in rights to light cases.

Presents the first investigation into the original scientific basis for modern rights to light practice since its introduction in the early part of the twentieth century.

Over the last few years it has been established that there is a need to re‐evaluate the basis of assessment of the sufficiency of daylight, in rights to light cases, where the loss of daylight after obstruction might lead to injunction and/or damages. The purpose of this paper is to further examine whether the methodology used by surveyors, whereby the effect of glazing, window frames and internal reflectance are ignored, is valid and whether theoretical values can be translated into real values obtained through practical experimentation.

Modern methods of assessment of daylighting, for design purposes, calculate a whole room average as a percentage of available daylight from a Commission Internationale de l’Eclairage (CIE) sky whereas Waldram's methodology, in rights to light cases, results in a contour line marking the series of points in a room where the task lighting, from a uniform sky, would be insufficient for normal use. These two methods appear incompatible and the conundrum is that whilst the courts are seeking to determine adequacy of daylighting to a room, the practitioners need to be able to measure the reduction in a way that has real meaning and can be valued.

By comparing theoretical results using the Waldram methodology with those obtained using the Building Research Establishment (BRE) methodology and with physical measurements on site and in an artificial sky dome, it can be demonstrated that results using the Waldram Diagram, or the proposed CIEL Diagram, can be translated into real values of daylighting for a room and that these values are more realistic than those obtained through the BRE methodology.

This research (which is ongoing) will be useful to practitioners and the courts in determining rights to light cases and is a significant contribution to the debate initiated in this journal by Michael Pitts some 12 years ago.

This paper follows the author's previous paper published in Structural Survey (Vol. 25 No. 2, pp. 98‐116), in which certain accepted methodologies, used in rights to light calculations were challenged. Now, following publication of the doctoral thesis entitled “The validity of daylight calculations in rights to light cases”, the aim is to examine two aspects of the calculation process – the Waldram diagram and the level of daylight that should be considered sufficient for ordinary purposes.

First, the mathematics of the Waldram diagram for rights to light cases are compared with the proposed alternative, which recognises a non‐uniform CIE sky as opposed to the artificial concept of the uniform sky proposed by Waldram. Second, the amount of light sufficient for ordinary use is measured in a controlled environment and compared with previous methodologies.

The proposed diagram more closely replicates the results of real measurements taken in a room, and the amount of daylight that should be considered as being the minimum necessary for ordinary use is likely to be around 2.5 times that currently accepted.

These results demonstrate that advice previously given by experts in court on the sufficiency of daylight to a building is flawed.

While many are questioning the validity of daylight calculations in rights to light cases, this paper establishes the proof that a new approach is required.

Aims to examine judicial attitudes to current surveying practice in rights to light disputes. Tests the assumption that the use of the Waldram methodology is endorsed by the courts and seeks to establish whether, despite its acknowledged limitations, its continued use can be justified on this basis.

Analyses reported judgments.

Neither the 50‐50 rule, nor any other aspect of the Waldram methodology, has the status of a rule of law, or is otherwise approved of by the courts. On the contrary, the methodology has been the subject of judicial criticism. Although the courts frequently rely on the expert evidence presented to them, they have consistently expressed disquiet over aspects of the methodology. Particular concerns have been expressed over its inability to cater for the effects of sunlight and externally reflected light, on its dependence on internal room design, and on its failure to distinguish task illumination from general room lighting. There is also no indication that the judiciary are aware of the extent to which the Waldram threshold of adequate illuminance falls short of that prescribed by contemporary standards. The paper concludes that the courts' attitudes to the Waldram methodology cannot therefore justify its continued use by surveyors, either when acting in the capacity of expert witness, or when advising clients who may be contemplating litigation in a rights to light dispute.

Makes a further contribution to the debate, started in this journal in 2000, about the future of surveying practice in rights to light disputes.

Places new information in the public domain which has implications for judges in future rights to light cases, and for the professional liability of surveyors when advising clients in contemplation of possible rights to light litigation.

Presents the first comprehensive analysis of judicial attitudes to modern rights to light surveying practice since its introduction in the early part of the twentieth century.

The purpose of this paper is to continue the debate started by M. Pitts and P. Chynoweth in previous issues of Structural Survey and examine some specific areas of concern regarding the methodologies used for calculating loss of daylight in Rights to Light cases.

Eight specific areas of concern are identified and each of these is analysed in turn, first to establish, where possible, the origin of the current methodology and then to test this against available current thinking.

There is a reasonable justification for adopting a value of 500 foot‐candles, although this is not in fact the minimum value. The only justification for using a Uniform Sky appears to be mathematical and another, more accurate, sky model could be used. The Waldram Diagram can legitimately be adjusted to any suitable dimensions provided that the measurements are always taken as a ratio of the chart area. There is no justification for using a work surface height of 850 mm, nor is there any evidence of justification for assuming that 1 foot‐candle of light is adequate for normal use but there is justification in legal terms for ignoring window frames, glazing and internal reflectance.

It can be shown that there is a case for reassessing the methodologies currently accepted by the Courts and therefore that there is scope for further research to establish a new more accurate method.

Whilst many are questioning the validity of daylight calculations in Rights to Light cases, this paper takes some of those questions and establishes whether there is in fact cause for concern.

This study introduces a series of articles which respond to Pitts' call for a debate into current rights to light practice. It summarises relevant areas of law as well as current measurement and valuation practices in this area. Describes the Waldram methodology, grumble point, fifty‐fifty rule and the concept of equivalent first zone loss. It also shows how these concepts are used to determine the amount of damages payable where a right to light has been infringed and calls for others to contribute to the debate proposed by Pitts.

The purpose of this paper is to encourage discussion on whether the acceptable standards of natural illumination have increased since Colls was decided in 1904. It invites discussion as to whether new parameters should be set or whether the 50/50 rule should be changed. Reference is made to the circumstances in which the grumble point of 0.2 per cent was calculated and to the method of measuring this accurately with the aid of a Waldram diagram. Comments are invited from readers to continue the debate.

The purpose of this paper is to continue the research set out in the consideration of trees in rights of light cases Part 1. To consider whether it is possible to measure a tree with sufficient accuracy that the impact on daylight within a building can be predicted in a way that can be applied in rights to light cases.

By reading published research on tree growth rates, crown transparency and theoretical modelling it is intended to determine the available methodologies for predicting light transmission through tree crowns. Then by inspecting common oak trees in all parts of the country, it is intended to review whether the available methodologies are capable of producing a relatively accurate result using manual methods or whether it is necessary to devise a software solution.

The research found that whilst theoretical methods exist for predicting light obstruction by trees, these could not be used in practice and that manual methodologies would not provide sufficient accuracy. However, survey techniques such as 3D Point Cloud can be taken further with the development of a software solution that uses an algorithm to predict branch size and location where these are not visible in a survey.

This research concentrates on the theoretical aspect of assessing trees in rights to light cases. It is usually necessary for a live legal case to occur before research into software takes place. It will be necessary to develop the software and then test survey a tree in full leaf and in the absence of foliage to determine whether the algorithm is sufficiently accurate and this will take time.

This research concentrates on the theoretical aspect of assessing trees in rights to light cases. It is usually necessary for a live legal case to occur before research into software takes place and the conclusion reached was that it will be necessary to develop the software and then test survey a tree in full leaf and in the absence of foliage to determine whether an algorithm is sufficiently accurate and this will take time. It has also been demonstrated that trees may be considered as existing obstructions in rights to light cases and that once software has been developed and tested then it will enable developers to show that their proposals have less impact on the daylight within an adjoining property than would be the case if trees are ignored.

In many instances, the economic development of a site, especially social housing, is limited by the rights to light of adjoining owners. Where it can be shown that the light levels enjoyed by those owners are already impaired by existing trees then this may assist the developer.

At this point no one else has researched this subject to the extent contained in this paper.

The purpose of this paper is to establish a methodology by which the impact of trees may be assessed in rights of light cases.

By considering the available technologies and theoretical modelling, the research demonstrated that the loss of daylight resulting from the existence of trees can be evaluated to a reasonable degree such that their effect in rights of light cases may be taken into account by the courts.

The extent of obstruction to daylight that is caused by trees changes from season to season, i.e. trees grow in height and/or width and deciduous trees tend to lose their leaves during the winter. Measurement of the trees should occur during winter months and reasonable approximations can be made.

Further research is advisable to provide a more complete compendium of tree types and to build a reliable database of transparency values and rights of light software will need to be modified to simplify the calculation process.

The consideration of trees in rights of light cases may be very significant. A dominant owner may be more affected by a proposed development if part of their light is already obstructed by trees and a servient owner may have an argument that existing trees cause a significant obstruction which might, in the right circumstances, reduce or remove the actionability of their proposals.

This research will have considerable benefit to anyone contemplating rights of light involving obstruction by trees.

This is the first time that the use of BRE transparency factors for trees has been considered in connection with rights of light.

In our chapter we describe the analysis of categorisations as an important part of narrative criminology. Categorisations of people (as offenders, victims, witnesses, etc.) are a central component of the communicative construction and processing of crime. Categories are associated with assumptions about actions and personal characteristics. Therefore, categorisations play a prominent role in the question of whether and how someone should be dealt with or punished. Narratives essentially consist of categorisations as well as the representation of a temporal course of interactions and actions. Analysing categorisations can therefore provide decisive insights for narrative criminology. With the research method of ‘Membership Categorisation Analysis’, categorisations can be reconstructed in detail. We describe this potential by reconstructing how the defendant ‘Dave’ categorised himself in the context of his main trial and how he was categorised by others in order to justify a judgement against him. Our analysis shows that categorisations, which are socially impactful and often controversial, must be established by particular narrative manoeuvres.