The quest for low carbon and sustainable schools has gathered a head of steam that is taking us along at break-neck speed. A previous Secretary of State aimed to reduce the carbon emissions from new schools by 60% compared to those currently being built and the current Secretary of State has committed to ‘zero carbon’ schools by 2016. Are these aims achievable and, if so, how are we to meet the challenge? Not only is this aspiration challenging, but it must be met on a scale previously only dreamt of – in 15 years all 3500 secondary schools will be either rebuilt or renovated at a rate approaching 200 schools per year. This raises a number of highly pertinent questions.
Building schools is a complex task regardless of carbon emissions. An enormous range of activities have to be catered for and the range of skills and abilities of the occupants place an onerous burden on space planning and environmental services. The range of activities that are encountered require differing environmental conditions and levels of servicing, from quiet and highly occupied classrooms to kitchens and dining areas. All of these have specific needs to be considered before we can provide the best learning environment for the pupils. There is danger in this rapid embrace of sustainability and the rush to reduce carbon, save water, use renewable energy and reduce the embodied energy of the building that we can forget that the priority must be to provide a comfortable environment for the pupils of the school for what may be another 50 years.
When sustainability and saving the planet is put into a pre-eminent position, we need to answer the following questions:
- Do we have the knowledge base on which to make the correct decisions in the briefing process for these sustainable schools?
- Do we have sufficient skilled designers, architects, building services engineers , construction companies, contractors and suppliers to deliver these schools?
- Do we know if the technology we are proposing to provide the low carbon solutions actually works and if so to what extent?
- Do we have the data to judge which technologies and products are cost effective, so we can balance sustainability and payback?
We are all on a steep learning curve and those involved in decision-making do not know the answers to all these questions. So what can we do in this pell-mell rush to sustainability?
Here are five easy lessons on sustainability for you – synthesised from real school projects where our design team engineers have been involved. I have kept the schools anonymous because the lessons can apply at many schools. All the issues here relate to ‘sustainable’ aspects of the schools in one way or another. We have learned from these schools and hope that others may benefit from our experience of working to provide sustainable schools.
Lesson 1: Get real about pipe dreams
School A
The ambition was to develop a large secondary school – that would also be very sustainable – on a limited budget. The demands of the brief were to produce a school that met all of the requirements. Studies of sustainable energy sources and low carbon technology were made and solutions proposed. Photovoltaic power, wind turbines, combined heat and power from a biomass boiler and ground source heat pumps were all studied and detailed reports of costs and carbon savings were produced. In the event, the submissions from contractors to construct the school all exceeded the budget by a considerable amount. None of the bids could be accepted and the design had to return to the drawing board for a major redesign to remove as much cost as possible. Naturally, the sustainable design elements were ‘value engineered’ out of the project.
Lesson 1 summary: unreasonable expectations of what can be provided can lead to extra costs and delays
Lesson 2: Seek specialist advice and don’t ignore it
School B
An approach by architects for design guidance at the early stages of a school design was met with a detailed report on a variety of aspects of the design, some of which related to sustainable issues such as using daylight to avoid or reduce the dependency on electric lighting. A key part of the advice given was that at the proposed depth of the classrooms, daylighting would be poor if alternative glazing was not provided. Roof lights were recommended as the most suitable design option. Two years later, as the school was under construction, the client requested that the architect confirm that the daylight in the classrooms would be adequate given the single sided glazing and absence of roof lights. A rear-guard exercise was then undertaken to try to improve the daylighting without the roof lights which were then not possible to install given the structural design selected.
Lesson 2 summary: if expert advice is sought it is usually a good idea to take it.
Lesson 3: Watch out that political decisions do not compromise design
School C
A political decision was made to provide a new school in time for the following year’s intake in September. The resulting very fast-track design and construction forced the choice of fabric to off-site pre-assembled units for assembly on site – a solution which many consider to be sustainable because it will reduce on-site waste and better quality construction. The resulting thermally lightweight structure would, however, be very prone to overheating. A fraught period followed with significant pressure to find an acceptable solution to the problem. After much computer modelling the result was the proposal to install extra wall material in the internal walls to absorb some of the excessive heat gains with night cooling provided by natural ventilation. This provided a satisfactory solution but it was obtained at the cost of some stress and strain in the design process and delays in other aspects of the design.
Lesson 3 summary: do not let short term political or economic goals have too great an influence on the fundamentals of the design.
Lesson 4: Don’t allow time pressures to compromise design
School D
This was a school that was comprehensively designed to win a PFI bid. Extensive modelling and design work was undertaken on natural ventilation methods to provide good indoor air quality and on solar shading devices to avoid overheating in summer. A considerable amount of time and skill went into the ventilation strategy and provision of windows and openings to allow for night cooling the building. After winning the competition, the design of the window systems was let to another company who ignored the previous design solutions and proposed an alternative. This alternative provided a different approach to the ventilation and removed the combination of low and high level vents and installed only high level windows under control of a central system. The removal of a set of low level air inlets may have been cheaper and easier to design and install but it may not work as well as the initial design.
Lesson 4 summary: always be aware of the work that has been done to develop the design to its current status and check the reasoning behind any changes.
Lesson 5: Beware of product substitution
School E
A school was successfully constructed, but after occupying the school the teachers began to suffer from ‘sick building’ symptoms that were attributed to the poor ventilation of the classrooms. The windows installed provided little fresh air and this led to stuffiness and overheating in summer. The windows were not those specified in the design that had been signed off by the client but substitute windows had been fitted during construction. Natural ventilation is a sustainable option, but it must work correctly in both summer and winter providing good indoor air quality and contributing to keep the spaces cool in summer.
Lesson 5 summary : always check that product substitution is not used to speed the building or cut costs.
These five easy lessons are a plea from the heart from our design engineers. It is always possible to be reasonable in the brief, and it should always be possible to take account of what engineers design and see it through to the final school building as delivered. Of course, architects and building designers should aim high, but only as high as time and money allow. Modern sustainable and low carbon designs are testing at the best of times but given the twin squeeze of time and money, they can jeopardise long term performance. Rush is always the enemy of good design and this is particularly true in the evolving realm of sustainability. Trotting out the standard designs of the pre-climate change era was a different matter to producing a zero carbon school that also meets all the demands that the educational process places on the building.
We all want the best schools we can get – highly sustainable and BREEAM excellent – but we should not forget the costs, the practicalities and the timing of the project. The schools we are designing and building now will be with us for many years and could stand as a beacon to the effort and talents of design of the early 21st century. Let us all work to make the beacon a bright and shining example.
Hadley Learning Community - an exemplary sustainable school development
Telford and Wrekin Borough faced the need to replace aging infant and junior schools, bring together a split secondary school, and provide a new facility for young people with severe learning difficulties. Their conclusion was to develop a show-case new learning centre that would provide 420 primary places, 1200 secondary places and facilities for 150 children with profound learning difficulties. Together with this the scheme was also to provide early childcare facilities, a sports and leisure centre, a library and arts centre all accessible to the local population. The brief also specified exemplary levels of environmental performance. Not only did the school have to use less than half the normal target for school buildings, but it also had to use natural ventilation and not overheat in summer.
The project became the subject of a PFI bid, and Interserve Project Services put together a bidding team with Faber Maunsell as mechanical and electrical services, structural engineers and sustainability consultants. The multi-disciplinary team included the highly regarded AEDAS Architects’ practice, and educational experts from Bryanston Square. A major design effort began and the challenging brief required the most integrated design approaches possible. With the architects and educationalists working together to provide a layout for the school building that met all the educational and space planning requirements, we dealt with the energy and sustainable design issues. This required a detailed computer model being set up to determine how the building would respond to a number of design options for ventilation and how this would control the potential for overheating in the school. The bidding process lasted for many months with numerous iterations of the design until a suitable optimum was achieved.
The result is a learning centre of 30,000m2 which is a mixture of single and two storey accommodation that radiates from a central courtyard. The courtyard is an open space of some 100m diameter that includes a 150 seat performance space. This provides a secure internal focus for the occupants of the school that is separate from the parts that are open to the public. The security of the school is further maintained by using sophisticated access control beyond the reception area, with identity cards for regular users.
The structure of the building included a mixture of concrete, steel and wooden elements to achieve the ideal blend of cost, speed and sustainability. The roof is reinforced concrete using welded fabric rather than loose-laid bars. This was a quicker construction than other methods and provided a cost-competitive alternative to a lightweight roof. The greater thermal mass is a requirement to store daytime heat gains to prevent overheating of the classrooms.
Off-site fabrication of concrete panels and wall elements meant that on-site construction was very quick and the standardised sizes allowed for great flexibility in design. The curtain walling and the pre-cast cladding were designed to the same dimensions and therefore window placement was highly flexible. These elements were pre-fabricated off-site and this enabled on-site construction to be completed in less than a year.
To meet the challenging carbon foot print performance criteria biomass boilers were used, with the wood chip fuel sourced from local suppliers. The school heating system has an output of approximately 2MW. This is provided from a mixture of gas-fired condensing boilers serving underfloor heating throughout the building and a biomass fuelled boiler of 320kW that also serves the constant temperature requirements. The biomass boiler provides the bulk of the heating for the base-load requirements, and this is essential in order to provide the very low carbon design target for the school and the swimming pool. This type of operation regime is of course ideally suited to biomass boilers. The wood chip fuel is from local short rotation coppice and is stored locally in a bunker. Regular deliveries of the wood chip are required but these were allowed for in the design of the storage and access routes.
The ventilation strategy for the school was developed from the computer simulations and required the exposed thermal mass of the building, and the roof in particular, to work together with the ventilation to avoid overheating. The automatically controlled windows work to increase night time ventilation which uses the cool night air to remove heat from the fabric of the building. The result is a cool school for the start of the next day’s teaching. The ventilation design had to be mindful of the requirements of Building Bulletin 93 and the acoustic performance of the school, because a railway line ran along the periphery of the school grounds. Careful location of windows and the construction of a 5m high noise barrier ensured that intrusive railway noise would not be a problem.
To further reduce the environmental impact, a rainwater harvesting scheme was installed to provide water for flushing toilets and irrigation of planting. Rainwater harvesting was needed to meet the design specification which was significantly better than the water use of a typical school. The rainwater from the roofs is collected and stored in four 50,000 litre tanks. It is used for flushing toilets and irrigating the planting of the site. The tanks are located underground and this rather unusual choice was a result of the size of the tanks needed on this site. The normal installation at roof level was not an option.
In January 2007, the school came into operation and it certainly is a prime example of a learning centre to be designed as highly sustainable and indeed it has won numerous awards for its design. However, it is valid to ask if this design intention will be carried through into actual performance. These sustainable design solutions nearly always work at 100% on the drawing board or computer program. What is needed is a concerted effort to establish that they will work in practice and do so long into the future.
A recent report, ‘Building for the Future: Sustainable Construction and Refurbishment on the Government Estate’ has been published by the House of Commons Committee of Public Accounts. It deals with the sustainable credentials of work on buildings in the Government estate which in recent times has required a BREEAM excellent standard. To quote from the overview of the report:
“ Despite the attention given to targets and mandatory practices to deliver sustainability, much remains to be done if departments and agencies are to achieve key targets set out in the Common Minimum Standards. Mandatory environmental (BREEAM or equivalent) assessments were carried out in just 35% of new build projects and 18% of major refurbishment projects during 2005-06. The required environmental standards could be shown to have been met in only 9% of projects. The NAO’s own assessment of a sample of projects in 2005-06 found that many projects fell short of the required standards. The take-up of Quick Wins was also limited, despite being mandatory since 2003. Departments often did not conduct post-occupancy evaluations, though these are a well-recognised tool for improving building design and operation, and also a requirement of OGC’s Gateway Review process”
Whilst this requirement has not been extended to school buildings we should take the message to heart. If we do not follow-up the design with a real evaluation of its performance in practice we will not have an accurate picture of how sustainability is influencing the future of our planet.
John Palmer is Regional Director at Faber Maunsell’s Birmingham office. He is the Chairman of the recently formed CIBSE Schools Design Group and is the principal author of both Building Bulletins 87 and 101.