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Get Sust!
PROJECTS SPOTLIGHT
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Learn this: Simplicity rules OK!
Sustainable and energy efficient buildings need not be crammed with expensive and potentially troublesome novel technologies. Thinking carefully about the building’s intended and potential future functions, and letting these aims drive the design forward can result in a highly successful end product, as John Crabb of the University of Exeter’s Centre for Energy and Environment and Devon County Council learnt, when they set out to design a “classroom of the future”.
Back in 2001, Devon County Council (DCC) secured funding under the government’s Classroom of the Future initiative, and set out to create a flexible zero-net-carbon teaching space as part of an extension scheme at Chulmleigh Community College, near Exeter.
In addition to the zero-net-carbon target, the brief to the architects, Devon Property, required the classroom to be:
- a flexible space, so that it could cope with potential changes to teaching practice
- available 24/7 so that it can be used for community activities
- accessible to all
- fully prepared for current and future IT needs
- function well alongside the other school spaces (the existing library and business
centre, and a new technology room and 24-hr café).
Perhaps most important was the additional project-specific aim - to develop a classroom design that could be readily adapted by other projects.
“We set ourselves the target of zero net carbon emissions when averaged across a whole year, but we knew this couldn’t be achieved by low-energy design alone,” John Crabb explained to delegates at the CIBSE Conference in March, where he presented a report about the Chulmleigh project.
Thinking it through
The design team started out by focusing on the three main “energy flows” for a building:
- ‘free’ daylight
- heat gains from people and equipment
- warmth from the sun.
They rejected the third option - solar gain - because it is not really needed in a well-occupied space. Indeed, in the summer months, it can result in overheating. In addition, it’s simply not reliable!
Opting for north-facing main glazing in the roof rather than the sides of the room cut down on potential glare, but maximising the use of free energy from daylight. Heat gains would cut the need for space heating, but the classroom would still have a residual energy demand which, if the overall target was to be met, would need to come from a non-carbon source.
“We reviewed the options and decided that building-mounted photovoltaic cells are likely to become a preferred option in the near future, when they will be more cost-effective,” said Crabb. “Once this decision had been taken, many of the design decisions flowed logically.”
The team opted for a well-insulated timber-frame construction, comprising prefabricated softwood panels with integral cellulose insulation, on a base of polished concrete, that incorporated local aggregates.
Natural ventilation is built-in, with low-level inlets and a high-level exit grille at the top of the roof structure. Motorised louvres at high and low levels are controlled by a carbon dioxide sensor in winter and by temperature sensors in summer. High and low-level windows can also be opened manually.
Making it flow
So far, so conventional. What’s different here is the way the team harnessed the power of the ‘free’ energy flows to create a design that reflects both the hidden and the highly visible energy sources.
Visitors can’t help but notice the innovative use of northern daylight in the Classroom of the Future. The classroom has a flat roof punched through by two large circular turrets. These are supported from below by a continuous deep-section wooden bean. Each turret is asymmetrical, with the taller northerly side glazed to provide good natural light, and a large sloping southerly surface, perfect for mounting the PV arrays. This elegant solution has to be seen to be fully appreciated (see Learn more, below).
But what visitors won’t notice is what is going on beneath their feet.
The combination of solid concrete flooring and a ready supply of renewable electricity (from the PV array) made underfloor heating via a ground-source heat pump an extremely attractive feature. The low-temperature underfloor system means that the heat pump works at optimum efficiency, plus there’s no need for radiators or room partitions, so the school gets full use of the floor space. The system can also be used to provide cooling in the summer.
Yet another advantage of underfloor heating is that it can be self-regulating. Once heat gains from occupants make the room temperature higher than the slab temperature (which is set at 19°C), the slab no longer acts as a heat source.
The learning continues
During the design phase, the team made full use of modelling techniques and simulation tools. For example, the internal daylight distribution was simulated using the ray-tracing programme RADIANCE; while APACHE software provided a full thermal analysis.
Now that the building is up and running, the design team can reflect on the process and the finished product. Crabb’s advice to others who want to achieve sustainability on a limited budget is:
“Aim for high levels of energy efficiency and air-tightness;
obtain as much energy from on-site generation as possible; and
ensure that retrofitting of on-site generation is enabled instead of hindered by your design.”
Monitoring at Chulmleigh is on-going. The controls for the heat pump, underfloor heating and the natural ventilation systems record performance data, although there have been some teething troubles with this system. Nevertheless, the figures indicate that the classroom is operating within expectations.
What is clear, however, is that the building may occasionally fail to meet the standards some people expect from modern buildings (i.e. those with air-conditioning). So perhaps the most important lesson that will be learnt in this classroom is that the occupants play an important role in their own comfort!
Learn more:
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• | John Crabb’s presentation to the CIBSE Conference can be downloaded from www.cibse.org |
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• | Visit Exeter University’s Centre for Energy and the Environment at www.ex.ac.uk/cee |
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• | Photos of the Classroom of the Future are at www.chulmleigh.devon.sch.uk |
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Ask the fellows...
Construction professionals say that construction waste is not seen as a mark of failure, but often as an indicator of success! And architects say they don’t have the time or readily available information to specify recycled products. But all parties are willing to learn more about how to cut waste and increase the uptake of recycled construction products.
That’s the message that came across loud and clear when a team from consultancy Kotuku literally got on their bikes and rode around four London boroughs to find out about the pitiful state of waste reduction and recycling in the Capital. But that’s not all... The team devised a cunning way to tapping into the wasteful operatives’ psyche...
Waste is endemic in the construction industry, and with growing concern for the sustainability of construction and ever-tougher landfill regulations, something has got to be done about it.
Kotuku spent two years researching the problem and came up with a novel solution – the Café Van – which travels around building sites delivering short and snappy presentations on waste minimisation and recycling materials to site workers and managers during their daily tea-breaks.
The Café Van has proved extremely successful:
- more than 80% of the people who used the Café Van said that what they heard would influence the way they will work on site in future;
- knowledge of construction-related environmental issues almost doubled among participants; and
- after the three-session course, only 7% of participants felt they didn’t know very much about sustainability and resource efficiency (down from 66% before they visited the Van).
But the Café Van is only part of the story, which is described in more detail in Kotuku’s recently published report Ask the fellows....
The project began in November 2003, and the first 12 months were spent talking to a wide range of construction industry stakeholders in four London boroughs: Lambeth, Wandsworth, Kensington & Chelsea, and Hammersmith & Fulham.
The Kotuku team kicked off their project by cycling some 450 miles around the streets of these boroughs to identify all the sites where small and medium-sized enterprises (SMEs) were engaged in construction work. Armed with the data on who was doing what, and where, they re-visited a number of these sites, as well as the offices of architects, quantity surveyors, skip hire companies, builders’ merchants and – crucially – clients. At each visit they posed a series of open-ended questions:
- Why do practitioners in the construction sector waste so much material?
- What do people in the building industry think about recycled and recovered materials?
- What would need to happen to change the attitudes and behaviours that are creating current waste levels?
- What would need to happen for more recycled and recovered materials to be specified and used?
The results of these discussions paint a fascinating, and occasionally surprising picture of current construction practices.
The key finding is that:
- waste is not seen as a mark of ‘failure’, but often as an indicator of ‘success’.
Most of the people questioned had not thought about the environmental impact of their construction work. And worse, numerous architects said they did not have the time or resources to specify recycled materials and components.
Crucially, the discussions asked people at all levels in the industry what they thought could be done to reverse the wasteful practices:
- Increase the cost of waste disposal? This would have a negative impact because costs would simply be passed down the line to clients.
- More legislation? There is already a large body of environmental legislation, but the industry tends to ignore it.
- Improve risk management? The contractual nature of the industry means that waste is always ‘someone else’s problem’; only a radical culture change would make people take their responsibilities seriously.
- Rewards for good environmental practice? This would be viewed favourably by many builders and could help to influence others, providing the real cost benefits were clearly demonstrated.
But the resounding message from the survey was that:
- improving education and communication at site-level would have an immediate and positive impact.
This, together with lessons learnt during the surveys about how best to get in touch with the ‘fellows’ who are creating the waste, led directly to the development of the Café Van project.
Learn more:
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• | Read Kotuku’s full project report ‘Ask the fellows...’ at www.kotuku.org. |
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