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MONDO ARC

Westminster Academy, London, England

Issue 49 Jun / Jul 2009 : Architectural : Education

Lighting Design: BDP Architect: AHMM


Martin Lupton and Luke Smith-Wightman of BDP Lighting explain the art of lighting design in school environments. using their work at Westminster Academy as a case study, they emphasise the important role of daylight, the guidelines associated with it and the need to consider electric light as an holistic element of the architecture and overall visual environment.

The current UK government is a significant way along the road of its plans to invest in the order of £2 billion in building and refurbishing schools. This offers the people who are involved in their design a unique, once-in-a-lifetime opportunity. Schools that are performing poorly or schools that are housed in aged decrepit buildings are being identified and re-built. Many of the UK’s schools buildings are between 50 and 100 years old and it is likely that this wave of new schools will stand for the same amount of time. In 50 years time education may be delivered in a completely different way so this could be the last opportunity many of us have to design the lighting for a school building.

The City Academies programme has seen new schools designed and completed by several prominent architects including Sir Norman Foster and Wilkinson Eyre amongst others. When the Government began this programme it was on the basis that they firmly believed that better designed environments will encourage more positive behaviour and improved academic performance.

As lighting designers, we are part of a growing awareness of the power of light and its role in design and usability of spaces and places. Our craft is widely recognised in environments where the commercial cost of design and high quality luminaires are seen as valuable investments. In retail spaces the link between brand quality and customer spend is well established – lighting can play a key role in supporting the brand image.

In commercial offices the value of lighting to the workforce is starting to be understood but the power of lighting in creating the right impression in the reception is fully accepted. In urban spaces the links between lighting and crime, the perception of safety and the creation of a night-time economy are completely accepted. In fact, lighting designers are employed and allowed to practise their art and science where there is perceived commercial value. But what about spaces where there is social value but limited commercial value?

It could be argued that urban lighting embraces some social elements and has positive benefit on the community it serves. In schools and hospitals, two of the most socially important spaces, the lighting design is, more often than not, left to the electrical engineer or even electrical contractor.

At BDP Lighting we are proud (and privileged) to be part of the minority of lighting designers, and part of a multi-disciplinary team, that enables us to practise the science and art of lighting in these environments. We are trying to bring the knowledge and experience learnt on other commercial projects into the school environment. Schools are the places where the thoughts and behaviour of our children are developed and moulded. Surely we all want this to happen in the best quality of environment possible? Lighting, both electric and natural, has a significant role to play in the quality of environment in a classroom.
Natural lighting has a significant role to play in the quality of environment in a classroom.

We consider daylight in terms of the daylight factor. Daylight factor is the percentage of exterior illuminance received on a reference plane within a room (Eint/Eext) and is a function of window size and transmission relative to the room area and surface finishes. However, this is a very broad and over simplified quantification of a very complex and highly subjective element of lighting and architectural design.

Historically, in the UK, up until the CIBS Code of 1977 the regulations required a minimum daylight factor of 2% in all classrooms. This is one of the elements that contributed to a generic classroom design with high ceilings and tall windows. This requirement was removed during the energy crisis as heat loss and energy use was more important than savings due to daylight and little was known of the psychological and biological benefits of daylight.

Current up-to-date guidance lacks this historic level of clarity in its recommendations. Much of the information is vague and difficult to interpret. One consistent statement, taken from “LG10: Daylight and Window design” published by CIBSE, that is repeated in most publications relating to daylight is:
‘An average daylight factor of below 2% generally makes a room look dull; electric lighting is likely to be in frequent use… an average daylight factor of 5% or more will ensure that an interior looks substantially daylit....’

Building Bulletin 87 - Guidelines for Environmental Design in Schools states that “where possible priority should be given to design for daylight as the main source of light in working areas”. It does not implicitly state what level of daylight but we can deduce this from the illuminance criteria. Typically we know that the exterior daylight availability exceeds 10,000 Lux for a significant portion of the school year. This means we need a daylight factor of 3% to achieve our design target of 300 Lux and 5% for all demanding teaching spaces. This deduction also needs to be implemented bearing in mind the words at the start of the quote “where possible”.

More prescriptive is the requirement that “Teaching spaces should have views out except in special circumstances. A minimum glazed area of 20% of internal elevation of the exterior wall is recommended to provide adequate views out.” This is supported by recent subjective research that found that view was a major contributor to the perception of daylight and could compensate for the reduced numerical value.

Building Bulletin 90 – Lighting Design for Schools states that “Unless there are over riding reasons for not doing so in certain rooms, the school designer should assume that daylight will be the prime means of lighting when it is available”. Again no implicit target is given but the mantra that “rooms with daylight factor greater than 5% will be considered to be day-lit and those with less than 2% will require frequent artificial lighting is repeated”.

BS 8206 Lighting for Buildings – Part 2: Code of practice for day lighting – this standard describes the good practice in day lighting design and presents criteria intended to enhance the well-being and satisfaction of people in buildings. Like all British Standards it is intended to give guidance and compliance with the standard does not confer immunity from legal obligations. Again, the criterion of a 5% daylight factor if a predominantly day lit appearance is quoted. Minimum daylight factors are quoted for dwellings (1% in bedrooms, 1.5% in living rooms and 2% in kitchens) but no other applications.

The Building Research Establishment Environmental Assessment Method (BREEAM) for Schools: the most recently published document on the use of daylight within schools and assesses the amount of daylight with regard to Health & Wellbeing of the occupants. In this document clear targets are given. For one credit at least 80% of the spaces should achieve a Daylight Factor exceeding 2%. For two credits (in a multi-storey building) all spaces must exceed 3%. In addition to this the room depth criteria must be met to ensure uniformity.

As the physiological and biological effects of daylight become more widely understood and appreciated the reasons and justifications for high levels of daylight in schools can be enforced. Recent research indicates that high levels of daylight are a very positive contributor to academic performance and behaviour of students. Research in the USA, by the Pacific Gas and Energy Company, showed that students in classrooms with the highest daylight factors (in the order of 10%) progressed up to 20% faster on maths test and up to 26% faster on reading tests. The results of similar research in Sweden showed significant correlation between behaviour and daylight. In broad terms this research has also shown that student who attend “day lit” schools outperformed students from “none day lit schools” by 7%-14%.

In addition to this very school specific research, other research demonstrating that high levels of natural light are essential to controlling melatonin and contribute to general motivation, alertness and well being

Considering all the sources of information described above, the use of daylight as the main source of light within schools is going to be a key factor, not only in their success as buildings but also in the academic performance of the students.

In practical terms, the design of a classroom is a series of compromises to achieve the best environmental conditions. Large windows cost more than solid walls, have a poorer acoustic performance and are worse performers in terms of thermal insulation. To achieve a daylight factor of 5% in a typical 8m x 8m classroom with a single external wall requires a glazed area that covers the entire window wall from desk height to the ceiling. This is quite an onerous requirement, but an important one nonetheless, especially in the light of the information about the effect of daylight student performance, behaviour and well-being.

In Westminster Academy, BDP Lighting worked with architects AHMM to maximise the daylight performance of the building to create a stimulating, efficient and low energy lighting installation. Two key architectural elements were used to increase diffuse skylight in classrooms and control sunlight in the atrium:
1. A glazed roof to the atrium with deep baffles to reflect direct sunlight into the space;
2. Light wells that bring natural light into the rear of classrooms that face onto the atrium.

Designing the atrium lighting, the aim was to maximise diffuse skylight ingress, whilst controlling sunlight and providing some direct views of the sky.

The baffles are painted matt white on their south facing side, to optimise reflected sunlight and coloured on the inward facing north side. Their spacing, inclination and height were carefully designed to attenuate the majority of sunlight entering the glass roof, whilst allowing some shards of sunlight in to animate the space.
The light wells to the internal rooms underwent an iterative design process. Various influencing factors, such as roof aperture size and area of glazing were varied to demonstrate the benefit of particular changes.

Sunlight:
Sunlight is a very important part of natural lighting that can create an inspirational and uplifting emotional response. In a classroom space it can also be uncomfortable and glaring, so a good blind system or sophisticated external shading is an integral part of any classroom space. In more informal, general spaces however providing a connection with the outside environment is essential. The kinetic movement of the sun through a space is a great indicator of the passage of time and most people would express a preference for this connection with the outside world. In the development of the central atrium space for Westminster Academy the solar screening to the glazed roof was designed to offer full solar shading from sunlight coming from the south but allow sunlight to penetrate the space at the start and end of the day.

The louver system allows a high degree of diffuse light to enter the space, both by reflection of sunlight and direct passage of diffuse skylight. When the sun does enter the space at the start of the day it paints dramatic stripes of light into the dining area that will be used by pupils arriving early for breakfast. At the end of the school day the sunlight dramatically crosses the protruding geometric blocks of the classrooms on the opposite faces of the atrium.

Artificial Lighting:
Our attention to the quality of lighting in classrooms was quickly focused and developed in the first school project we worked on in 2002 - an academy in Bristol for 1200 students with an integrated unit for children with hearing impairments. Good lighting is incredibly important deaf and partially deaf people. The ability to be able to clearly discern lip, facial and hand movements is of prime importance as the eye is used in place of the ear as the means of understanding speech. In fact, the same criteria also apply for teaching in general – teachers need to be seen by the students and need to see the students.

The lighting text books offer two criteria for the design of a standard classroom – 200 lux on the teaching wall or black board and 300 or 500 Lux on the working plane depending on the type of lesson. We decided that it was important to ensure good vertical illuminance through-out the space, not just on the teaching wall and focused our attention on the selection of a luminaire with a suitable photometric distribution.

Historically, in the UK, classrooms were lit by recessed prismatic luminaires, however even these spaces did not escape the spread of the Category Rated linear louvred luminaire and many modern classroom suffer from the same issues of our cave-like badly lit office spaces. Poor vertical illumination, harsh shadows and dark upper walls and ceilings are all symptoms of this type of lighting system. This is something we wanted to avoid at all costs in our classroom lighting solution.

In modern offices we are moving away from this and using supplemental uplighting or direct/indirect luminaires and direct/indirect is the solution that we used in Westminster Academy.

Lighting design intent
The internal and external lighting scheme is intended to work in close harmony with the architecture: complimenting the raw materials of the building whilst providing high performance illumination with minimal energy and maintenance requirements.
The architecture demanded an absence of ‘styled’ luminaire design – giving way to the palette of galvanised industrial trunking, bare T8 battens and primary geometric shapes. But this approach to the selection of lighting equipment was not at the expense of lighting performance and visual comfort.
Spatial volumes are generously and evenly illuminated with direct / indirect lighting in the classrooms and low luminance light sources in circulation spaces.

Classrooms
The classroom lighting solution offers direct / indirect illumination coordinated with an acoustic baffle array. Single and twin lamp versions of the same luminaire ensure a consistent appearance between 300 lx (general) and 500 lx (science, art) classrooms. Several custom sized blank panels were developed to enable rows of luminaires to coordinate precisely with acoustic baffles.

Luminaire used: Fagerhult Closs with Beta louvre
Lamp: 35W T16 - 4000K
Lighting control: Daylight linked, closed loop dimming to all luminaires adjacent to windows


The Atrium
The atrium is lit entirely from the adjacent walkways – where continuous rows of trunking mounted linear fluorescent batten luminaires create a strong graphic intervention in the space. These luminaires provide light for the atrium, the walkway and the adjacent wall - which features large, graphic text quotations. A prismatic sleeve reduces the luminance of the T5 lamps, whilst their mounting position, above the walkway, enables convenient access for maintenance.

Luminaire used: Zumtobel Tecton with prismatic controller accessory
Lamp: 35W T16 - 4000K
Lighting control: Daylight linked switching at each level


Lecture Theatre
Different use lines of light in the ceiling provide the ambient illumination for this space, whilst fluorescent ‘sticklites’ on the walls provide a strong yet playful feature against the raw concrete walls. The conduit has been arranged to give the impression of an integrated circuit.
Dimmable halogen spotlights are mounted to lighting track on the walls to provide additional accent light to the stage area. These are wall mounted to allow convenient access for maintenance.

Luminaires used: Selux M100, Encapsulite Sticklite with magenta filter
Lamps: 35W T16 - 4000K
Lighting control: All luminaires are controlled on a ‘scene set’ dimming system to provide the flexibility required in a lecture theatre


Staff room, canteen and cafe area
The lighting in these spaces is designed to provide a distinct break from the teaching environments. A custom pendant luminaire, using a warm white compact fluorescent lamp, was developed for the staff and dining rooms. Flexible, track mounted halogen spotlights were employed in all three spaces to provide accent lighting to walls, notice boards, food display cabinets and dining tables.

Luminaires used: Custom pendant by ‘Lightform Ltd (now ‘Aether Lighting’), Erco 3 circuit track, Concord ‘Torus’ spotlight/
Lamp: 32W CFL - 3000K, 50W GY6.35 TH capsule lamp
Lighting control: Daylight linked switching and wall mounted switches


General circulation routes
Circulation routes feature a simple, 18W bare batten luminaire with a custom, lacquered metal finish to better compliment the raw material finishes throughout the building. These are carefully coordinated with acoustic baffles.
Staircases feature coloured sticklites (similar to lecture theatre) mounted to walls and fluorescent battens integrated into the structure.

Luminaires used: Whitecroft Lighting custom 18W ‘Trimpak’ batten, Encapsulite Sticklite with various filter.
Lamp: 18W T26 - 4000K, 14W T16 4000K
Lighting control: Daylight linked switching and wall mounted switches


With daylight as the primary source of light, the artificial light needs to be developed to support this strategy and maximise the benefits. The opportunities to save energy and reduce maintenance must be embraced with automatic control. However, it must not be forgotten that most schools have a single in-house maintenance contractor – the caretaker – and his responsibilities will be both varied and numerous.

Maintenance must be as straight forward as possible. If a school can be designed with a minimum number of lamp types, that respond to daylight and operate only when required, then it will have a long life and be simple to maintain.

Schools are one of the most socially important spaces that we as designers, architects and engineers can be involved in. These are the places where the thoughts and behaviour of our children are developed and moulded. Lighting, both electric and natural, has a significant role to play in the quality of environment in a classroom. High levels of controlled daylight and good vertical illumination are the key design criteria for the creation of a successful classroom. However in the strive for innovation and creative design we must not forget the how these important buildings work, the length of time they are design to stand and the many different users that will inhabit and operate them.

Simplicity and robustness of operation is a fundamental requirement.
In many spaces we have come to realise that horizontal illuminance is a poor measure of design quality, and in schools in particular this is true.

Modern styles of kinaestic teaching rely on visual interaction between the students and teacher and therefore the visual focus is usually on the vertical rather than the horizontal. High levels of concentration are essential from the students and anything that can detract from this must be eliminated. It is essential that all lighting – natural and electric – is controlled and delivered into the space in a comfortable way.

www.bdp.com
www.ahmm.co.uk

 

Pics by David Barbour, Sanna Fisher-Payne, BDP Ltd







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