daylighting buildings daylighting buildings

D Croghan: technical papers 1964/70

daylighting buildings

D Croghan: technical papers 1964/70

daylighting buildings

David Croghan

Cambridge UK June 2015

version 1.2

daylighting buildings A compilation of the author’s papers on the design of the novel transilluminated ‘artificial sky’ built in Cambridge U.K. in 1962 and on its subsequent use in examining then current regulations that determined directly or indirectly the layout of buildings in terms of daylighting in England & Wales. Previously published between 1964 and 1970, they have not been previously available on the internet. DOI:10.13140/RG.2.1.4184.1360

the author David Croghan (DC) was born in Norwich in 1933. Adult life commenced in 1951 with obligatory National Service that - over two years - took him to the School of Military Engineering at Chatham and then on active service to Egypt and Iraq that usefully involved some construction and surveying. He ‘went up’ to university in 1953 and studied at the Cambridge University School of Architecture (CUSA), gaining a Bachelor of Arts (BA) degree in 1956 and the Diploma in Architecture (Dip.Arch) in 1958. The titular degree of Master of Arts (MA) followed in 1960 and in the same year he qualified for registration as an architect and was elected an Associate of the Royal Institute of British Architects (ARIBA). From 1958 DC undertook postgraduate research at Cambridge, in 1963 submitting a successful thesis for the degree of Doctor of Philosophy (Ph.D). In the period 1962 to 1970 DC was variously director of the Science Research Council funded CUSA Daylight Research Group and visiting lecturer in Building Science and Construction at the CUSA and in Building at the CU Department of Land Economy. A number of technical papers were published and also he engaged in daylighting design consultancy. From 1968 to 1978 there was membership of the Daylight Panel of the National Illumination Committee of Great Britain that reported to the Commission Internationale de l’Eclairage (CIE). Architectural practice always had accompanied DC’s academic work. Between 1956 and 1965 he gained practical professional experience as an ‘architectural assistant’ (mainly during university vacations) and latterly as an ‘assistant architect’ (for longer periods) with established Cambridge architects Hughes & Bicknell, David Wyn Roberts, Sir Leslie Martin and Lyster & Grillet. From 1965 DC was a principal in private architectural practice, initially on his own account and later with partners Raymond Hooper and Glanfyll Lewis (as Anglian Architects) and finally solely with Dr. Lewis (as Croghan Lewis Associates). Ray and Glan had their office in Waltham Abbey, Essex, whereas DC’s was always in Cambridge. In 1970 DC left academia to concentrate on practice work that embraced a wide range of building types from military installations to Cambridge colleges, and also DC engaged in consultancy in energy conservation and as an expert witness in ‘right to light’ and building failure legal cases. DC was elected Fellow of the Royal Society of Arts (FRSA) in 1990 and a Member of the Academy of Experts (MAE) in 1994. He retired in 2006.

contact: [email protected]

daylighting buildings - contents foreword the papers: 1.1

‘The design of an artificial sky’

1.2

‘Transilluminated domical artificial sky’

1.3

‘Skydome at Cambridge’

1.4

Daylight and the form of office buildings’

1.5

‘A combined daylight factor meter and reflectometer for field use’

(The Architects’ Journal, London 22/07/1964, pp.215-220) (Light and Lighting, London 10/1964, pp.290-293) (The Builder, London 09/10/1964, pp.752-754)

(Corrected reprint from The Architects’ Journal, London 22/12/1965, pp.1501-1507) (Building Science, Oxford 1968, vol.2, pp.337-339)

with DU Hawkes:

1.6

‘Daylighting in dwellings 1 – Provisions of the Building Regulations 1965’

1.7

‘Daylighting in dwellings 2 – Performance of current block spacing controls’

1.8

‘Daylighting in dwellings 3 – Analysis of a questionnaire’

1.9

‘Daylighting in dwellings 4 – Spacing of low rise terrace housing’

(The Architects’ Journal, London 07/12/1966, pp.1435-1440) (The Architects’ Journal, London 04/12/1968, pp.1319-1323) (The Architects’ Journal, London 26/02/1969, pp.585-589) (The Architects’ Journal, London 23/09/1970, pp.727-733)

see also (by the same author 2015):

‘daylighting by design’:

1. Artificial skies for building design – past, present and future 2. Some early examples of the use of an artificial sky

e-versions available from the author: [email protected]

© David Croghan 2015 Any part of this document may be copied for personal or academic purposes subject to appropriate citation except where the original publisher may have superior copyright.

photo: DC

The ‘Skydome’ at the Cambridge University School of Architecture on completion in 1962 On the right is the 1958/59 brick and concrete extension to the School designed by Colin St.J Wilson and Alex Hardy. The juxtaposition of the two was coincidental but not insignificant. The Skydome, a lightweight monocoque structure proportionately much thinner than an eggshell, was formed from two basic triangular aluminium panels that were readily replicated by machine. The Extension is a heavyweight traditional structure comprising many thousands of pieces each dependant on handcraft skills for manufacture and assembly. The ‘high tech’ Skydome took 10 hours to erect, whereas the Extension, essentially Roman in technical concept, took 15 months to build. Both approaches were of interest to students of architecture. The Skydome, designed by David Croghan for his PhD research, was an ‘artificial sky’. Such devices simulate, in a standardized and stable form, conditions experienced under the true sky on a dull overcast winter day that is taken as providing the minimum level of useful natural light in the latitude of the UK. Having fallen out of use after a fire in its control gear in the late 1970s, the Skydome was demolished in 2000 to make room for additional studio accommodation. In his 1970 architectural guide ‘Buildings of England, Cambridgeshire’, Nikolaus Pevsner generously describes this “silvery geodesic dome” as “small and handsome”.

foreword to daylighting

buildings

This collection of previously published papers is issued as, having been prepared some 45 years or more ago, they are not readily available. Mostly they have no presence on the internet and in some cases even the printed journals in which originally they appeared have ceased publication or been ‘taken over’, with libraries of back issues lost. On account of the passage of time, it is appreciated that the work reported now may have little more than archival interest. This booklet is dedicated to the memory of Sir Leslie Martin (1908-2000), the first Cambridge University Professor of Architecture and Head of the School of Architecture (1956-1973), and concerns mainly the construction and use of an ‘artificial sky’. Sir Leslie was the author’s PhD supervisor from 1958 to 1963. At inception – and quite possibly uniquely – pupil and master shared almost total ignorance of the chosen field of study: the measurement of daylight in buildings. A symbiotic relationship ensued. For the pupil it meant almost total freedom on the road to enlightenment at the end of which the master gained – for the School of Architecture – a useful research and teaching facility: an ‘artificial sky’, soon termed the ‘Skydome’, completed in 1962. Also, for the pupil – and for the School  there was approval, in 1963, of the first Cambridge PhD thesis in a scientific aspect of architecture. The Skydome, if not a quantum leap, represented a step-change in its field. Though by no means the first artificial sky, it was the largest apart from one in the USSR, it was the first based on a transilluminated hemispherical dome, and also it was the first installed in a school of architecture in the UK. In effect it was an analogue computer that enabled ‘daylight factor’ at any reference point in a model of a room of any complexity to be directly simulated and measured where ordinarily the elements of ‘sky component’, ‘externally reflected component’ and ‘internally reflected component’ arising from each window opening required to be separately and laboriously determined for each such point by graphical means. Only some 25 years later, with the ready availability of powerful personal computers, did it become possible to automate such calculations, but even today these – based on ever more sophisticated programs  remain arguably less satisfactory than physical model studies inherently attuned to the way architects think and work. The Skydome – its construction aided by grant from the Nuffield Foundation and later supported financially by the Science Research Council (SRC) – made possible the continuation of daylighting studies from 1964 by the author with two colleagues, Harold Pfitzmann (from October 1964) and Dean Hawkes (from January 1965), under the aegis of the Cambridge University School of Architecture (CUSA) Daylighting Research Group (DRG). Also, and importantly, the Skydome enabled the integration of such studies with the School’s teaching and – judging from the stream of ‘the great and the good’ visitors to whom it was demonstrated – this world-class device served well in supporting applications for external funding that assisted other individual workers and contributed to the establishment of the Centre for Land Use and Built Form Studies (LUBFS 1967), the precursor of the celebrated Martin Centre (1974). Though there is every indication that CUSA daylighting work was pre-eminent among UK schools of architecture during the 1960s, the ultimate value of the studies undertaken employing the ‘Skydome’ (in use until the late 1970s) is for others to judge, but certainly it was demonstrated that some of the official regulations and recommendations then in place nominally to ensure good daylighting simply did not work. Also, the author was emboldened to press for – successfully and usefully – the inclusion in official guides of model studies in artificial skies as an approved technique for daylighting design. In consequence it appeared in the 1964 revision British Standard Code of Practice CP3:Ch.1:Pt.1 ‘Daylighting’, in the Ministry of Housing & Local Government (MoHLG) Planning Bulletin No.5, ‘Planning for Daylight & Sunlight’ of 1964 and in its 1971 replacement, the Department of Environment (DoE) and Welsh Office ‘Daylight & Sunlight – planning criteria and design of buildings’. Such official acceptance is a prerequisite for the uptake of a technique. Additionally and importantly the ‘Skydome’ was used in consultancy to ‘prove’ the designs of a number of buildings of national repute. To many the initiation of daylighting studies at the CUSA and building of the ‘Skydome’ will appear as early and direct spin-off of the 1958 RIBA Oxford Conference, convened and chaired by Sir Leslie Martin, that promoted the inclusion of science and technology in architectural training. However, the author sees the origin of his research work as more prosaic. Below he explains.

David Croghan

Cambridge

July 2015

how it all began….. The author (DC) reports that his route to post-graduate research and his PhD thesis was not the usual one of progressing seamlessly from a brilliant first degree. After a very active national service in the army followed by initial over-indulgence in R & R (‘rest & recuperation’), an already unspectacular undergraduate career in Cambridge was interrupted in its second year by a summer term largely spent in bed with a fever. Later, his portfolio of design work prepared for the 4th-year Diploma in Architecture examination – carefully set out on his dining table prior to submission next day – was flooded overnight by accidental leakage of home-brewed beer from the flat above….. So, what further fortuitous events arose when DC sought to improve his situation? In 1957, while still a Diploma student, DC had participated in a ‘live project’ for the design of an extension to the Cambridge University School of Architecture. He made a model of its roof-lit lecture room and accompanied its co-architect and the School’s building science lecturer, Alex Hardy, to the Building Research Station at Watford to test its daylighting. Here they met Dr R G Hopkinson and his team of the BRS Lighting Section, acknowledged world leaders in their field, and were impressed by the Station’s ‘artificial sky’ (at that time a relatively small mirror-lined box) and generally by the application of scientific methodology to architecture. The next summer – 1958 – found DC working as an architectural assistant in the private practice office of the Professor of Architecture, Sir Leslie Martin, to gain the ‘practical experience’ required to qualify as an architect. This was just after the multi-storey slab and tower blocks of the high-density Alton West residential estate in Roehampton, London, were occupied and while those of Alton East awaited completion. Both – typical of many – had been designed in the Architects’ Department of the LCC headed by (the then) Dr J L Martin. However, by the time of taking up post in Cambridge in 1956, Professor Martin’s thinking had turned full circle to favour low-rise, high-density housing, his first private commission for which was ‘new build’ redevelopment on the Foundling Estate in St Pancras, London. This was designed in association with Colin St John Wilson and Patrick Hodgkinson. On this project, DC mostly was engaged in site layout analysis to show that a density of 136 ppa (persons per acre) could be achieved and which would be comparable to the maximum density then permitted by LCC (and many other planning authorities) for ‘high flats’: developments employing slab and tower blocks. However when daylighting in the proposed unusual split-level 3½-storey maisonettes was identified – by the client’s surveyor  as a potential problem DC once again became involved in building a model and testing it at the BRS. The result was fruitful. Not only was the building design ‘proved’, but also DC gained the support of Sir Leslie to register as a research student and in seeking financial support. The latter process was not entirely straightforward. Though Dr Hopkinson of the BRS had suggested approaching his own funding agency, the Department of Scientific and Industrial Research (DSIR), this body cavilled at aiding an applicant from an Arts faculty. The corollary was that neither would any Arts body fund scientific work! However, eventually a DSIR Research Studentship was secured and useful precedent established. By such circumstances did the study of daylighting in buildings come to Cambridge.

1.1

1.1

The Design of an Artificial Sky David Croghan

The Architects’ Journal, London 22 July 1964, pp.215-220 This paper outlines the development of ‘artificial skies’ as part of the model study technique for the prediction of levels of daylighting in buildings. Primarily it describes the design and construction of the ‘Skydome’ built at the Cambridge University School of Architecture in 1962 from the particular standpoint of architects. Designed in 1959/60, on completion in July 1962 the 7.6m Ø CUSA artificial sky was arguably the most advanced such device yet attempted. Also it was innovative in that it introduced the principle of ‘transillumination’ into the design of hemispherical domical skies. In this the direct light of lamps set outside a translucent diffusing dome is designed produce the required luminance distribution on its inner surface when viewed from the centre of the dome. Hitherto domical ‘skies’ had been lit indirectly by powerful and often hot up-lighters placed around their perimeters and, in some cases, also on their floors, which created not only problems with obstruction and heat, but rendered them inherently difficult to ‘tune’, particularly where it was required to simulate the CIE Standard Overcast (nonuniform) Sky (with its zenith three times brighter than its horizon). The only other type of artificial sky in use in the U.K. before 1962 was the mirrorlined box, typically of small dimensions and unsuitable for the work envisaged at Cambridge.

supplement to paper 1.1

the state of the art of ‘artificial skies’ prior to the CUSA ‘Skydome’ of 1962: Left: the UK Building Research Station’s Mk.1 ‘artificial sky’ of 1954, a mirror-lined box measuring 1.2m x 0.9 m x 0.6m with integral light source above a diffusing ‘Perspex’ panel. [RG Hopkinson & J Longmore 1954] This was the only ‘sky’ in use in the UK when DC was first involved in the study of daylighting in model buildings at the CUSA in 1957. In the foreground ‘daylighting’ conditions are being tested with numerous measuring photocells in a model room (with its back wall removed). In March 1959 this sky was loaned to the CUSA for the use of DC who soon found it too small for studies of anything more elaborate than single side-lit model rooms with limited external obstruction, emphasizing the need at Cambridge for a much larger device. photo: BRS

In 1961 BRS built a ‘Mk.2’ measuring 1.8m x 1.5m x 0.6m.

The ‘state of the art’ of artificial skies internationally at the time the author designed the CUSA ‘Skydome’ is well-summarized by R Kittler writing in 1959. He usefully categorizes and details artificial skies that had been used since 1914 and observes that “model measurement on extensive buildings with top plus sidelit interiors” requires “domes at least 5 to 10 metres in diameter.” He notes five then currently in use: (1) a hemispherical dome of 9m Ø of 1943-52 in Moscow by NM Gusev et al ., (2) a hemi-ellipsoidal dome 6.5m Ø of 1948 in Stockholm by G Pleijel, (3) a flattened dome 7.3m Ø of 1952 in Sydney, Australia by RO Phillips et al., (4) a 5m Ø hemispherical dome of 1955 in Warsaw by T Oleszynski et al., and (5) a 5.8m Ø hemi-ellipsoidal dome of 1955 in Texas by EE Vesey et al. Of these R Kittler illustrates (1) & (5) and also his own 1957 3.6m x 3.6m x 1.65m (effective height) octagonal mirror-box sky. [R Kittler 1959]

Below: section of R Kittler’s 1957 mirror-lined box sky at the Slovak Academy of Sciences, Bratislava, Czechoslovakia. Designed on the same principle as that at the BRS, but unlike the Mk.2, its effective wall height of 1.65m enables testing of roof-lit models. Also it was octagonal on plan. Both followed the ‘mirror box’ sky design established by G Pleijel of Stockholm in 1941.

Moscow 1943

Bratislava 1957

Texas 1955

sectional drawings of ‘skies’ from R Kittler [1959]

Left: section of NM Gusev’s 9m Ø hemispherical sky of 1943 at the Moscow Academy of Building & Architecture. This and (above) EE Vesey’s 5.3m Ø hemi-ellipsoidal sky of 1955 at the Texas Engineering Experimental Station are both reflecting domes and illustrate the problem of obstructed floors that typically arises in this type of ‘skydome’ due to the necessary location of the lamps.

the upshot is that up to1962 there were only two types of artificial sky: ‘mirror-lined box’ and ‘reflecting dome’.

full text of paper 1.1

END of paper 1.1

1.2

1.2

A transilluminated domical Artificial Sky David Croghan

Light & Lighting, London Oct 1964, pp.290-293 This paper outlines the design of the ‘Skydome’ built in 1962 at the Cambridge University School of Architecture from the standpoint of lighting designers, with particular emphasis given to the layout and controls of the fluorescent lamp installation.


© Crown copyright 1962

The fluorescent lamp installation of the Cambridge artificial sky before installation of the inner diffusing dome. Photo taken by J. Longmore of the Building Research Station using a Robin Hill full -field (fish-eye) camera. Photometric calibration of the ‘sky’ at this stage showed good correlation with the ‘CIE Standard (nonuniform) Overcast Sky’ in terms of both light distribution from zenith to horizon (3:1) and in absolute level of illumination. The ladder was for maintenance access to the outer surface of the inner dome and to the184 fluorescent lamps that were mounted on 45 cranked meridional ribs of ‘Unistrut’ trunking at 8°intervals. Set between outer and inner domes, it followed their radii, rotating manually around a pivot at the zenith, with castors at floor level. A rotating heliodon arm of similar geometry, but set inside the inner dome, was planned but never installed due to non-availability – at that time - of a suitable large parallel beam lamp. This would have slid along the curved arm to produce variable ‘sun’ altitude.


END of paper 1.2

1.3

1.3

Skydome at Cambridge David Croghan

The Builder, London 9 Oct 1964, pp.752-754 This paper outlines the technique of daylighting design using models and artificial skies and describes the ‘Skydome’ built in 1962 at the Cambridge University School of Architecture from the standpoint of construction industry professionals, with particular emphasis given to its geometry, structure and components.

supplement 1 to paper 1.3 Cambridge University School of Architecture ‘Skydome’ artificial sky under construction

Lamp end caps being fitted to ‘Unistrut’ trunking ribs

photo: BICC

Inner grp translucent diffusing dome during assembly

photo: DC

supplement 2 to paper 1.3

at Crittalls factory, Silver End, Essex

‘Skydome’ assembly on site in Cambridge

photos: DC


END of Paper 1.3

1.4

1.4

Daylight and the form of office buildings David Croghan

The Architects’ Journal, London 22 Dec 1965, pp.1501-1507 (publisher’s ‘Corrected Reprint’)

This paper was first prepared as a background study during the generation of Sir Leslie Martin’s “Whitehall: a plan for a national and government centre”, HMSO 1965, to which the author acted as consultant. It appears as a ‘corrected reprint’ as, when first published, sub-editing had corrupted the sense of important text. This paper discusses planning regulations and recommendations then current. It observes that while these were based nominally on the achievement of adequate daylighting in central area office buildings, they produced and perpetuated a particular type of development that was neither particularly efficient in terms of land use nor in terms of floor space provided. Further and critically, the daylighting levels embodied in these controls were out of kilter with developing standards, particularly in comparison with those recommended for artificial lighting. Indeed the intended control of daylighting was almost meaningless in terms of producing adequate illumination. The main ’functional’ town planning tools – the Daylight Indicators and plot ratio limits – are shown to be particularly unsatisfactory in application to large sites. Not only do they not necessarily ensure the best possibilities for daylighting and view, but also they may exercise little regulation of physical form and apparent bulk. The remedy is seen to be in developing new measures which should bring together a number of factors: they should take into account total building bulk, and they should relate height to floor space, floor space to daylighting, outlook, subdivision, and to population density.


Whitehall: a plan…..

Model of the unbuilt, highly controversial 1965 project for the redevelopment of government offices in Whitehall by Sir Leslie Martin. In the centre foreground are the Houses of Parliament and, left, Westminster Abbey, both largely unaffected. The proposal foundered as, following a change of government, it lacked political support: particularly it lacked an effective champion at ministerial level. Also it attracted vociferous criticism from the conservation lobby. The outcome might well have been different had the scheme compromised by preserving established frontages to Whitehall and the Horse Guards. Also, although phased development was implicit, it might have been prudent not to have shown so clearly the new work extending all the way from St. James’s Park to the Thames.

see Martin, J L, ‘Whitehall: a plan for a national and government centre’, HMSO 1965

Sir Leslie’s predilection for relatively low-rise area development is evident in his 1958 project for housing at St.Pancras, London (1958) and that for horizontal megastructures in his Oxford libraries (1960) and laboratories (1963) designs. At the same time as the Whitehall study (1964/65), the government offices in Marsham Street were under construction in the then prevailing style, that of 21-storey slab blocks (now demolished).

Typical section of offices blocks. The proposal would double useable floor space without increasing building height above the existing maximum of 10 stories. Good daylight penetration and external view would be achieved by stepping.

Good natural lighting was a leading aim in all Sir Leslie’s work. David Croghan is pleased to have contributed.

Martin, Harold Wilson and the Architecture of White Heat”, Farnham: Ashgate, 2013.

For a recent analysis of the Whitehall project see Adam Sharr & Stephen Thornton ‘Demolishing Whitehall: Leslie


END of paper 1.4

1.5

1.5 A combined Daylight Factor Meter and Reflectometer for field use David Croghan

Building Science, Oxford 1968, vol.2, pp.337-339 This brief paper describes a self-contained, rechargeable battery-powered combination unit developed for fieldwork by the Daylight Research Group of the Cambridge University School of Architecture. The reflectometer component replaces a separate, cumbersome mains-powered instrument.


The standard ‘EEL’ BRS daylight photometer Tripod-mounted on the left is the ‘directional photocell’ that is directed to a natural or artificial ‘CIE non-uniform overcast sky’ at an angle of 42.5°, the zone of average luminance. The 25mm diameter ‘reference photocell’ in the middle foreground is placed inside an actual or scale model room at any reference point (typically horizontally on the ‘working plane’ at table top level of 900mm). Internal circuitry allows ‘daylight factor’ – the light at the reference point expressed as a percentage of that simultaneously available ‘outside’ – to be directly read from the scale of the moving coil galvanometer mounted in the instrument box. The interior photocell is ‘cosine-corrected’ with an opal Perspex outer disc to achieve linear response to light at all angles of incidence. In 1961, seeking to re-calibrate one of the above instruments held by the Cambridge University School of Architecture, David Croghan approached the University’s Cavendish Physics Laboratory asking if it had a photometer bench. Professor (later Sir) Brian Pippard regretted he could not help, suggesting that the CUSA “must surely be the last outpost in town of 19th century physics”…..


END of paper 1.5

1.6

1.6

Daylighting in Dwellings 1 – provisions of the Building Regulations 1965 D.Croghan and D.Hawkes

The Architects’ Journal, London 7 December 1966, pp.1435-1440 This is the first of a series of four study papers produced by the Daylighting Research Group at the Cambridge University School of Architecture. The Building Regulations 1965 provide no mandatory guidance on the provision of daylighting in dwellings (and neither does any subsequent revision). Indeed there is no reference to lighting, either generally or specifically in that it is a main function of windows to admit daylight. Indeed, there is no requirement to have windows in any room. The designer appears to be left with the vague dictum in the superseded Model By-laws of 1952 that “modern practice is to put in windows of adequate size.” Whereas it can be shown that dwellings planned in accordance with the ‘space about buildings’ provisions of those Model By-laws may frequently enjoy daylighting up to the standards of the British Standard Code of Practice CP3: Chapter 1 Lighting: Part 1 (1964) Daylighting, their current equivalent, Part K of the Building Regulations, is shown – by photometric measurement in scale models under the Cambridge ‘artificial sky’ – to be virtually meaningless in terms of provision of adequate daylighting. Part K considers the provision of open space and ventilation and the height of habitable rooms. The only mandatory control of the provision of daylighting in dwellings in England and Wales arises where a local planning authority incorporates standards in a statutory development plan. Though not seeking proliferation of measures for the legislative control of building design, it is recommended that future revision of the Building Regulations should include specific mention daylighting in dwellings, most suitably by a ‘deemed to satisfy’ clause incorporating the latest B.S. Code of Practice for Daylighting. A footnote contrasts the situation in England and Wales with that in Scotland, where the Building Standards (Scotland) Regulations 1963 are a veritable textbook of good practice in designing for daylight.


END of paper 1.6

1.7 1.7

Daylighting in Dwellings 2 – performance of current block spacing controls D.Croghan and D.Hawkes

The Architects’ Journal, London 4 Dec 1968, pp.1319-1323 This is the second of a series of four study papers produced by the Daylighting Research Group at the Cambridge University School of Architecture. In the background of this study was government policy that erroneously equated residential high density only with high-rise building and restricted cost subsidy to the latter. Though the disastrous collapse of the East London 22-storey tower block Ronan Point in May of 1968 was ultimately to influence change, at the date of publication this policy still seemed secure. Where the previous paper in this series studied specifically the implications of Part K of the Building Regulations 1965 as a daylighting obstruction control, this paper considers three other Ministry of Housing and Local Government (MoHLG) controls that separately or in combination frequently determine the spacing of building blocks and influence either intentionally or indirectly the provision of daylight. These are: (a) the Daylight Indicator D1 in MoHLG Planning Bulletin No.5, 1964, (b) the ‘suggested minimum street widths’ in MoHLG ‘Density of Residential Areas’, 1952 and (c) the regulations for new streets in MOHLG Model By-laws Series IVD, New Streets, 1946, reprinted 1958. The primary concern is with the natural lighting of low-rise terrace housing, an area poorly served by research which largely has followed post-war preoccupation with the problems of high flats. The study was carried out using model buildings tested under the University of Cambridge ‘artificial sky’. The broad conclusion is that existing block spacing control means almost nothing in terms of the consistent satisfaction of the daylighting recommendations of the B.S. Code of Practice CP3, Part 1 Daylighting, 1964. It is recommended that any new or revised control for the spacing of dwellings in low-rise developments intended to ensure good interior daylighting levels should directly consider: room size and proportions, window size and position, and height and distance of obstruction. If such parameters were considered, a reduction in block spacing could be expected without prejudice to good interior daylighting. This could lead to the achievement of higher densities and further reduction in cost of low-rise dwellings in relation to high-rise flats. Note: AJ sub-editors, early anticipating the building industry’s proposed change to metric at the beginning of 1973, introduced into this paper of 1968 some rather clumsy metric conversions, not all of which have been checked. Where inconsistency arises, imperial dimensions should be preferred.


END of paper 1.7

1.8

1.8

Daylighting in Dwellings 3 – analysis of a questionnaire D.Croghan and D.Hawkes

The Architects’ Journal, London 26 Feb 1969, pp.585-589 This is the third of a series of four study papers produced by the Daylighting Research Group at the Cambridge University School of Architecture. This paper analyses response to a questionnaire circulated in June 1966 to 134 local authority planning officers and architects and to 44 architects in private practice, staff architects of development companies and official development groups. In view of unavoidable complexity, the response rate was a satisfactory 46%. The questionnaire sought information primarily on: (a) the extent to which daylighting is considered in the design and layout of residential buildings; (b) which prediction techniques or which regulations are most likely to be employed in designing for daylight; and (c) the degree to which these techniques are understood. Response indicated that daylighting matters were widely considered by local authority officers when designing dwellings and layouts, and when determining planning applications, but mostly in relation to high flats. Application to low-rise housing was indeterminate: some considered it was essential while others held that other criteria were dominant. However, where the provision of good daylighting was a consideration in planning layouts, most respondents quoted the ‘space about buildings’ provision in former Model By-laws or the current Building Regulations as the main determinants. That these in fact have almost no relation to adequate natural lighting (see paper 1.8) likely indicates only an awareness of mandatory minima for block spacing. Though some two-thirds of respondents claimed to use the MOHLG Daylight Indicators that are intended to regulate building layouts to ensure good daylighting, many realistically observed that standards for street widths and ‘privacy distance’ often took precedence. This is perhaps providential, as the suitability of the Indicators has been found dubious (see paper 1.9). They are least good in regulating low-rise development, and the questionnaire elicits that 85% of new units fell in this category. When designing for interior daylighting, respondents overwhelmingly relied on ‘experience’ or rule-of-thumb, the latter based usually on the old By-law standard that window area should be at least 1/10th the floor area of the room (an unreliable guide, see paper 1.19). The use of the BRS Daylight Protractors and Nomograms and other such design aids was found to be limited, many finding them too complicated (or, more likely, counter-intuitive). The general conclusion of this study is that a simple new tool was required that combined both block spacing and interior daylighting design and which related particularly to low-rise housing.


END of paper 1.8

1.9

1.9

Daylighting in Dwellings 4 – the spacing of low-rise terrace housing D.Croghan and D.Hawkes

The Architects’ Journal, London 23 Sep 1970, pp.727-733 This is the last of a series of four study papers produced by the Daylighting Research Group at the Cambridge University School of Architecture. The findings of the three previous papers are summed-up as being: 1. 2. 3. 4. 5.

There was no (and still not any) mandatory control of daylighting in dwellings in England and Wales other than where a local planning authority has incorporated standards in a statutory development plan. The MoHLG Daylight Indicators, the standard most frequently adopted by local planning authorities, have little relevance in application to lowrise housing that forms the bulk of new residential building. The then current block spacing controls, including the MoHLG Indicators, meant almost nothing in terms of the satisfaction of British Standard daylighting recommendations. The then existing techniques for detailed prediction of daylighting in dwellings were considered by many practitioners to be too complicated for use at an early design stage. The prediction techniques most widely applied gave only the daylighting provided for a given window, whereas a designer is usually more interested in determining window sizes to achieve a given daylight factor and distribution.

The present paper completes the series by offering a simple guide for use at early design stage for determining the spacing of low-rise terraced dwellings and determining window sizes to ensure adequate daylighting in a limited range of common situations. The method takes into account the use and size of rooms and the height and distance of external obstruction. In essence the guide comprises a set of five diagrams of selected sample rooms and table on a single A4 sheet, though there are additional notes of explanation and application to some special but not uncommon cases, such as sloping sites and stepped terraces. In further addition there is: (a) a description of the photometric model study made in the Cambridge University School of Architecture ‘Skydome’ on which the guide is based, (b) a graphical demonstration of the relationship between daylighting standards and other block spacing parameters that may take precedence, and (c) a worked example of the application of the guide.


END of paper 1.9

tailpiece: always in the background when geodesic domes are proposed……

Richard Buckminster Fuller, American doyen of the geodesic structure who had visited the CUSA in 1958, kindly granted permission for the use of his ‘invention’ in the construction of the Cambridge artificial sky “without royalty”. It was not entirely certain that he held valid proprietary rights, but just in case….. In the event, his above letter of 17 May 1959 was found difficult to read and even more difficult to interpret (most people being defeated by phrases such as “a plurality of vari-sized cut-offs and omni joinery”), and it was decided to proceed from first principles employing Archimedean geometry (as originally had ‘Bucky’). The form finally selected by David Croghan for the CUSA Skydome was a hemi-truncated icosahedron with its hexagonal and pentagonal faces modified by sub-division into their constituent triangles with the central nodes projected onto the circumscribed sphere. In terms of frameless panel manufacture, this produced only two basic ‘differs’. Fuller’s more complex sub-division would give 4 ‘differs’ in a dome of comparable size and gains advantage only in reducing panel size in larger diameter domes. Though DC has no wish to denigrate Fuller’s considerable achievements, it is interesting that ‘his’ geometry (in a US patent of 1954) appears in prior use 30 years earlier in 1922-24 by optical engineer Dr Walther Bauersfeld for the geodesic tubular steel frame of a 16m diameter domed trial planetarium known as ‘Zeiss 1’ formerly on the roof of the Zeiss factory in Jena (see Krausse J. [1993], Architecture from Projection, Anabas Verlag, Geissen).