Sunshade design in New Zealand primary schools, C Mackay, M Donn

Tags: UVR, shade structures, verandah, UVR exposure, Low Energy Architecture, personal protection, UVR protection, CSNZ, play equipment, shade structure, activities, shade area, typical shade structure, UVI, research project, swimming pool shade, Sun protection, ample shade, school policies, sun-safe, Observation, Skin cancer, established trees, quality protection, translucent verandah, steel frame, translucent roofing, solid verandah, Faculty of Architecture & Design, NZ Government, New Zealand Primary Schools Christina Mackay School of Design, New Zealand, Victoria University
Content: PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 1 of 7
Sunshade Design in New Zealand primary schools Christina Mackay School of Design, Faculty of Architecture & Design, Victoria University of Wellington PO Box 600, Wellington, New Zealand Tel.: 64-4- 463 6264 Email [email protected]
ABSTRACT: The paper presents the general findings of a research project that aims to identify features of best practice in shade design for protecting school children from UVR exposure. Skin cancer is a major health problem in New Zealand mainly due to intense UVR levels and a large population of fair-skinned people. School children are particularly at risk because research suggests that over-exposure to UVR during childhood can lead to the development of skin cancer in adults. Also, the School Lunch-hour (including free out-door play) traditionally occurs over solar noon when UVR levels can be extreme. Although personal sun protection (hats, clothing, glasses and sunscreen) is practical for active sports, well-designed built structures can provide more comfortable shade for group or passive activities. With growing awareness of skin cancer risk, many schools have independently designed and built more shade. As part of this study, a variety of 29 shade structures in 10 schools throughout New Zealand were studied in detail. The paper presents an assessment of their use and effectiveness in providing UVR protection. Issues in sunshade design are discussed and best features presented Key words ­ primary school, sun-shading for UVR protection, environmental control
1. INTRODUCTION In 2001, Victoria University carried out, in consultation with the Cancer Society of New Zealand Inc (CSNZ), a baseline study of the provision of sunshading in New Zealand (NZ) [1]. The study revealed a lack of understanding of best sunshade practice for protection from damaging ultra-violet light for NZ conditions. In the 1980's, CSNZ ran NZ's first high-profile skin-cancer public education campaign [2]. In response to parents' concerns about children being sunburned while at School, the 1994-5 `Shady schools' programme was introduced to promote sunsafe behaviour. Sun protection for children is especially important as research confirms that solar UVR over-exposure in the first 15-20 years significantly increases the risk of developing both melanoma and non-melanoma skin cancer [3]. This growing awareness of the need for shade occurred after the NZ Government (in their Tomorrow's Schools initiative) devolved the responsibility for the design and management of school facilities to indiviDual Boards of Trustees. Therefore, both built and natural sun-shading initiatives have been designed or built by local architects, builders, shadefabric manufacturers and in the absence of any research and detailed guidelines. (The CSNZ publication, Undercover: Guidelines for shade planning and design was not published until late 2000) [4]. To date, the success of shade installations has not been evaluated. Through surveying recent initiatives, the research aims to identify features of best practice in
sun-shading in NZ primary schools. It is planned that results from this study will contribute to further guidelines for providing sun-shading in primary schools. Firstly, the paper discusses UVR protection. Secondly the methodology of the study is presented. Findings are presented and discussed and finally conclusions are drawn. 2. UVR PROTECTION In NZ in midsummer, UVR levels exceed UV Index (UVI) 12 at solar noon and are commonly above UVI 2 for up to 10 hours a day [5]. The World Health Organization recommends exposed skin should be protected when UVI is above 2. [6] In a typical school day, students are potentially exposed to levels above UVI 2 for 15 minutes morning break and for one hour for their lunch break. Further exposure might occur during 30 minute outdoor physical education or 20 minute open area swimming class and during free play after school. Sun-safe policies recommend students wear hats, sunscreen and protective clothing at these times. Research suggests that in practice these measures are not sufficient [7]. A study of the effectiveness of trees and various built shade structures found their protection factors to be low (between PF3 and 6) [8]. CSNZ promote a combined strategy of personal protection with environmental shade in order to reduce UVR exposure to safe levels [9]. The research uses the definition for effective shade, as proposed in CSNZ publication, Undercover. Shade is defined as effective if it
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 2 of 7
provides `at least 94% protection from direct UVR as well as controlling indirect UVR' [4]. (Indirect UVR includes `scattered UVR' from clouds and sky plus and `reflected UVR' from surrounding surfaces). `The shade should also be of sufficient size, in an appropriate location, and create a comfortable environment in both summer and winter `. [4] 3. METHODOLOGY The research is based on case studies of ten schools located throughout NZ: Dunedin, Christchurch, Marlborough, Wellington, Napier and Auckland. Schools with significant built shade were recommended by Ministry of Education property officers in each region. management practices were surveyed firstly by interviewing school principals to ascertain policy and practices, and secondly by observation of student behaviour at lunchtime. Environmental shade was surveyed in relation to site planning and use. At each school, three different built shade structures were selected for further investigation. Each structure was surveyed with respect to orientation, dimensions, materials and construction. Details of adjustments to allow for seasonal variations were recorded along with other relevant features (e.g. seating). Surveys were carried out during the lunch break, 12.30 ­ 1.30pm in all cases. Polysulphone patches were used to measure the UVR exposure over the one-hour period. A control patch (A) was positioned horizontally in open sunlight. In the centre of each shade structure, two patches were positioned at 1m above the ground; the first horizontally (B) and the second vertically (C) facing the most open side of the structure (in order to gauge the contribution of the scattered UVR). shade structure
B
A
C
1m
Figure 1: Diagram showing the placement of the three polysulphone badges under typical shade structure. Observations of use by students and staff of the shade structures were recorded using digital photographs. 4. FINDINGS: SUN-SAFE PRACTICE All schools, except for one newly opened school, presented current sun-safe policy documents. The composition of the policies varied, but overall the following issues were included:
· Shade education: including content, frequency and teaching methods. · Sun-safe practice: including times of day and year when the policy applies · Communications procedures for reminding parents and students of the policy (e.g. beginning of the summer season) · Personal shade (requirements for wearing hats, clothing and sun-screen) · Parental or caregiver responsibilities e.g. supply of sunhats and sunscreen · Promotion of good personal protection habits e.g. `Slip, Slop, Slap', listening to weather forecasts and `burn-time' forecasts · Discouragement of sunbathing · Approved lunch-eating locations · Timetabling of outdoor activities e.g. sports · Modelling of sun-safe behaviour by staff · Development of an environmental shade plan, including implementation goals e.g. shade-tree planting schemes · Sun-safe policy review procedure Observation confirmed varying compliance with school policies, but sun-shade provision should be considered within the context of these sun-safe policies. 5. FINDINGS: SUNSHADE PROVISION Each school site was investigated to determine the quantity and quality of shade available and how well the shade suited the activities performed underneath. 5.1 Total quantity of shade The CSNZ publication, Undercover, recommends a minimum useful shade area of 2.5m2 per student (when the sun is at its highest angle in mid-summer). As the surveyed schools were selected because they had shade structures, it is not surprising that the quantity of shade ranged from 2.4m2 to 54.2m2. Schools with ample shade generally had `inherited' mature trees. Schools with minimum shade were located on confined city sites. Shade was made up of the building shadow, exterior covered areas and trees. Observation confirmed that building shadow was not used for play by students. Generally classrooms were orientated with windows and doorways facing north. The south side of the building was blank and cool. 5.2 Types of shade The following shade types were identified: main entrance, covered ways, verandahs and porches, communal shade, library shade, court shade, playing equipment shade, sports field shade, swimming pool shade, staff area shade, and visitor shade. Analysis of shade types across the ten case studies revealed the following:
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 3 of 7
5.2.1 Main entrance Often entrance doors to the school administration were protected from the weather with a porch or verandah. Usually, people traffic prevented the area from being useful for other activities. In a two-classroom small country school, the entrance verandah was extended to become a multi-purpose space for library reading, and general activities. 5.2.2 Covered ways In three of the larger schools, covered ways with solid roofs provided wet weather access between blocks All three spaces were dark, narrow and bare. On the day of survey no lunch-time play was observed in these shades.
UVR protection. Assuming that the translucent roofing is polycarbonate (99% UVR barrier), the low rating will be due to the narrow width and subsequent proportional increase in scattered UVR. Three schools provided verandahs over 3m wide. These were successful in comfortably accommodating group activities in shade.
Figure 2: Covered way between classroom blocks. 5.2.3 Verandahs In half the schools, narrow verandahs (1550- 2200 wide), running the length of single-level classroom blocks, were a common feature. They provided covered access in wet weather and often stored shoes and coats. The narrow width limited their use for group teaching and free play. In several cases the installation of balustrades further confined the space.
Figure 4: The 3m width and low front edge of this verandah (S27) produced high protection shade. This example, demonstrates the common design fault of placing steps (natural seats for children) outside the shade, in direct sun, during the middle of the day. The use of solid materials restricts light and winter sun to the adjacent classroom. In another case, a newly constructed PVC membrane canopy formed a 5.6m wide `verandah' to a 1960's classroom block. The size and location allowed the shade to be used as an extension of the classroom as well as for outdoor play and group gatherings. On the survey day it was used for art classes.
Figure 3: Students eating lunch on a long narrow verandah (S19 ­ refer to section 6). Translucent roofing panels transmit light and heat to the space (and neighbouring classrooms). By measurement, this verandah provided relatively low
Figure 5: At the centre, this PVC membrane verandah (S18) provides less than 80% protection from UVR. Although the shading material is an excellent barrier to direct sun, the high sides and missing panels are open to scattered UVR. The membrane transmits some light and shields from rain.
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 4 of 7 5.2.4 Communal shade Communal shade is defined as a space where 35 students could gather comfortably in a group. The communal shades surveyed were constructed using a wide variety of structure and materials and provided space for a variety of activities.
Figure 8: 9x9m PVC membrane shade `pods' (S24) provide dry and safe inside/outside multipurpose spaces. Figure 6: The raised timber `stage' under shade fabric `sails' (S6) formed seats for students for use while eating their lunch. During the lunch hour, this shade was observed to be a popular scene for junior play. At its centre the structure achieved 95% UVR protection. This is achieved by a high performing shade cloth and the large area of centralized shade. Figure 9: A timber trellis clad octagonal shade pavilion (S15) of 6.8diam is designed as a play space for senior students. At the centre, the recorded UVR protection was only 78%. (The protection is approximately proportional to the open area in the trellis).
Figure 7: The shade cloth `pavilions' (S4) were used for group functions and for students eating lunch. The picnic tables beneath are a popular meeting place for parents waiting to collect their children or supervising their play on the adjacent adventure play- ground. The pavilions gave good UVR protection (over 90%). The canopies are easily demountable for removal over the winter months. This strategy will prolong the life of the shade fabric. At a new school, classrooms opened onto shade `pods'. For further weather control, the side facing the playground is fitted with large glazed sliding doors. This design offered very high UVR protection (97%). Situated in sub-tropical Auckland, this weather-controlled space could be used all year.
Figure 10: A large mature tree (S17) provided natural shade for students eating lunch and playing. At its centre, it also gave good UVR protection (94%). The old tree requires regular maintenance and its structural stability is presently in question.
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 5 of 7 impaired by support poles of sails and pavilions. In all cases the material used was shade fabric, constructed as sails or stretched over a pavilion frame. 5.2.7 Shade over playing equipment In all ten schools, at least some adventure play equipment and sand-pits were covered by either trees or shade-cloth.
Figure 11: A pergola planted with deciduous vines (S28) creates cool summer shade at a school in the hot Hawkes Bay region. The combination of trellis and planting gives excellent protection from direct sun (99%). Communal structures included a refurbished 70 year old traditional play shed (S12). The brightly painted murals and performance successfully invited junior children to use it for their imaginative play. The 3-sided shed in solid materials provided deep shade (98% protection) 5.2.5 Library extension shade Providing shaded areas for reading, adjacent to the school library, was popular with six schools. Shade over seating was provided by pergolas (with vines), shade fabric sails (S7), and verandahs. 5.2.6 Shade over courts Four schools provided shade over hard courts adjacent to the junior school classrooms.
Figure 13: An oversized suspended shade-cloth (S29) provides effective shade (89% protection) over play equipment.
Figure 12: Triangular shade-cloth `sails' (S14) are visually appealing, but they do not achieve good overall coverage. Only 47% protection was recorded. Court shade was used for eating lunch, free play and physical education classes. The decision to prioritise the covering of junior courts was unanimous. While staff observed senior students extended their play to the extremities of the site, younger students played closer to their `home' classroom. Junior play is less structured and not
Figure 14: A local artist designed this attractive sand-pit shade structure (S3). UVR protection of 64% (horz) and 88% (vertical), suggests that this shade-cloth is under-specified. Other sandpits also used shade-cloth as the shading material. City schools reported that low structures are attractive for climbing and subject to vandalism. One school solved these problems by fencing the area to exclude cats and dogs and installing the shade-cloth only during school hours in the summer. 5.2.8 Sports and playing field shade For active sports, personal UVR protection is most appropriate, but for passive spectators, shade protection is worthwhile. In all schools the only shade around playing fields was from trees. Deciduous Trees placed along the northern boundary gave excellent summer shade while allowing sun onto the field in the winter. Alternatively, evergreen
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 6 of 7
or deciduous trees placed on the south side of a field provided shade from the high summer sun. No schools surveyed had build shade around sports fields. 5.2.9 Swimming pool shade Four schools used off-site pools. One school had an indoor pool, which students were encouraged to use during lunch break when UVR levels are extreme. Two schools provided pool-side shade using shade cloth. Figure 15: The shade-cloth (S16) provides 80% protection for spectators and classes waiting to use the pool. 5.2.10 Staff area shade Two schools provided an outside area with shade for staff to gather for morning tea and lunch. One school provided picnic tables with large umbrellas above them. This amenity provides the opportunity for staff to `model' adult sun-safe behaviour. 5.2.11 Shade for school visitors In all schools the caregivers, often accompanied by pre-schoolers, require a place to wait while collecting their junior school children. In the survey, they used various agreed shaded locations; a central communal shade and seats adjacent to play areas used by their visiting pre-school children. In a small rural school, parents met under trees adjacent to the car-park. 6. FINDINGS: UVR PROTECTION OF SHADE STRUCTURES The UVR measurements on both the horizontal and vertical planes are presented as a percentage of protection in relationship to UVR measured at the control patch (A) in the open. Percentage protection at the horizon patch (B) primarily indicates the quality of the shading material above, while percentage protection at the vertical patch (C) is an indication of the effect of scattered UVR (from the sky) and reflected UVR (from surrounding surfaces). The following table presents the findings on the quality of UVR protection provided by 29 selected shade structures.
shade structure and type
UVR protection of 29 shade structures solid porch S23 PVC membrane pavilion S24 solid verandah S27 pergola with vines S28 PVC membrane pavilion S25 solid verandah S12 rectangular shade-cloth sails S6 tree S17 translucent verandah S20 solid verandah S22 shade- cloth of steel frame S4 solid verandah S2 translucent verandah S5 rectangular shade-cloth sails S29 translucent verandah S26 translucent verandah S8 triangular shade-cloth sails S7 shade-cloth pavilion S10 triangular shade-cloth sails S13 rectangular shade-cloth sails S16 cloth on steel frame S1 solid + translucent verandah S19 shade-cloth pavilion S11 PVC membrane verandah S18 translucent verandah S9 trellis gazebo S15 triangular shade-cloth sails S21 shade-cloth of steel frame S3 triangular shade-cloth sails S14 0% 20% 40% 60% 80% 100% Protection (%) protection at horizontal patch B (%) protection at vertical patch C (%) 7. DISCUSSION The quantity of shade varied greatly. Schools with established trees benefited greatly. For the benefit of future generations, a landscape and planting programme should be a priority for all schools wit h inadequate shade. Building shadow, porches and covered ways are of little use as students did not inhabit these spaces. The bench-mark of 2.5m2 shade per student should exclude these and be used as a minimum. While any shade might be considered `good' in decreasing cumulative UVR exposure, the minimum desirable percentage protection of a shade structure needs to be considered in terms of the skin type and personal UVR protection of the users and the expected duration of stay. Without any protection, a person with sensitive skin would sunburn from a UVR `dose' of 2 SED's (200J/m2) [10]. When the outside intensity is UVI 12, in a shade structure with 81% protection, this dose would be received in one hour. As it would be expected that children outside playing would being using personal protection, lower UVR protection would be adequate for shade over
PLEA 2003 ­ The 20th Conference on Passive and Low Energy Architecture, Santiago ­ CHILE, 9 ­ 12 November 2003 Paper Code Nz1 Page 7 of 7
playground equipment. However, it would be unreasonable to expect students to don hats and wear sunscreen to move through doors to a verandah or communal shade. As learning spaces, these may be occupied for an hour or so and this `outdoor' time is in addition to routine play breaks. Shade `pod' (S24) provided high protection (9799%), but it is so enclosed that it barely has an `outdoors' feel. Its achievement is to create a large, safe, dry, light and bright, multi-purpose space at reasonable cost. The results also suggest that deep verandahs (e.g. S27) with low edges also provide quality protection (87-99%), but it should be noted that polysulphone patches were placed in the centre and protection would decrease markedly towards the open edge. In some cases (e.g.S6), very good lateral protection (93%) is achieved because trees and planting obscure the open sky (and therefore filter scattered UVR). This use of planting maintains a sense of being outdoors. North-facing deep verandahs have a significant impact on their host classroom. Ideally, classrooms are largely naturally lit and heated by the sun. Translucent roofing to the verandah (e.g. S19) can allow this. A range of 7993% protection (horizontal) was recorded with translucent roofing. As composition of this roofing is unknown, the low results may be due to the use of a product which allows UVR penetration. (Alternatively the design may admit too much scattered UVR). Modern clear polycarbonates are 99.9% UVR protective and transmit Solar Radiation (heat) as well. This heat is essential to make the `shade' warm enough for comfort in temperate, windy, coastal NZ. The predominant use of shade-cloth over play equipment and courts is an economical solution. A range of 47-95% protection (horizontal), with a median of 82%, was recorded under shade-cloth. Although scattered UVR from the sky will be reducing protection, this result suggests that many fabrics were under the recommended specification of 94% protection. As playground should be part of a combined sun-safe strategy, along with personal protection, 82% overall protection may be adequate. 8. CONCLUSIONS The study uncovered a wide variety of sunshade initiatives. The variety is possibly due to the absence of Ministry of Education guidelines. Identified shade types include: well established trees, communal shade (for group gatherings, luncheating and play); classroom verandahs (for class activities, eating lunch and play); shade over junior courts, play equipment and sand-pits; trees edging playing fields (for spectators); covered swimming pools (or at least spectator shade) and shade for staff and visitor areas. Best features of shade design include: appropriate design form and choice of shading material to suit the degree of personal protection used and the duration of use; seasonal shade-cloth over courts and play equipment; verandah roofs which transmit heat and light; blocking of direct sun
and shielding of scattered UVR (from the open sky) to spaces requiring high protection. The varied New Zealand climate means different sun-shade solutions are appropriate for different locations. Translucent materials can create much needed `warm shade' for coastal areas. Solid or green shade can shield the heat of sun in hotter inland areas. Where rainfall is frequent, impermeable materials create useful wet-weather play space. ACKNOWLEDGEMENTS The author acknowledges: University Research Fund of Victoria University of Wellington for project funding; Mike Donn, co-researcher; Erin Collins and Aimee Wong, research assistants; Dr Peter Gies, ARPANSA; and Project Advisory Group members Carolyn Watts, Cancer Society of NZ (Inc); Tony Condor, Building Research Association of NZ, Frank Hodgkinson, Ministry of Education; Dr Philippa Howden-Chapman, Wellington School of Medicine and Kathy Nield, Industrial Research Limited. REFERENCES [1] B. Joubert, C. Mackay, Shade provision in New Zealand ­ a baseline study 2001, http://www.arch.vua.ac.nz/cpbr/sunshade/baseli ne_study.pdf, 2001 [2] The Cancer Society of New Zealand, Melanoma Awareness Campaign, 1988-1995. 1995, The Cancer Society of New Zealand: Wellington. [3] P. Autier and J.Dore, Influence of sun exposures during childhood and during adulthood on melanoma risk. Int J Cancer, 1998. 77: p. 533537 [4] J. S. Greenwood, G.P. Soulos, N.D. Thomas, Undercover ­ Guidelines for shade planning and design, Cancer Society of NZ (Inc), 1998 [5] NIWA, UV Atlas, http://www.niwa.co.nz/services/uvozone/atlas accessed 17 June 2003 [6] World Health Organization, Global solar UV index ­ a practical guide, World Health Organization 2002 [7] E. Milne, D.R. English, B. Corti, D. Cross, R. Borland, P. Gies, Christine Costa and R. Johnson. Direct measurement of sun protection in primary schools, Preventive Medicine 29, 4552 (1999) [8] P. G. Parsons, R. Neale, P. Wolski, A. Green, The Shady side of solar protection. Med. J. Aust. 168; 327-330, 1998 [9] Cancer Society of NZ (Inc) and Health Sponsorship Council, Sunsmart in New Zealand, http://www.sunsmart.co.nz accessed 17 June 2003 [10] CIE Research Note (1987). A reference action spectrum for ultraviolet induced erythema in human skin. CIE J, 6, 17-22

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