School building historically happens in bursts, defined by the name of the ruling monarch or the decade in which it happened. A Victorian or Edwardian school is easy to visualise: imposing, solidly built with high ceilings and generously day lit. By contrast, a 1960s school is typically a statement of modernist architecture and progressive education, but also of cheap and lightweight construction, poor sound insulation, flat roofed, and usually freezing in winter.
Today's school building marks a radical departure, chiefly because of the Government's pound;45 billion Building Schools for the Future programme, which aims to rebuild or refurbish England's secondaries by 2021, with a separate pound;7 billion fund for tackling half the nations' primaries.
Aside from a massive investment in technology, a key goal is to improve the carbon footprint of new schools by reducing carbon dioxide emissions by 60 per cent. So are the new schools really more energy efficient than the ones they are replacing?
As a consultant specialising in building performance, I analysed the energy use and carbon footprints of a Victorian school, one built in the 1970s and a third built in 2004.
You may not be surprised that the 1970s school performed particularly poorly. Schools in that era were neither built to last nor with green issues in mind. Unexpectedly, the Victorian school and its 2004 counterpart (the latter hailed as a model of efficiency) performed almost identically.
The footprinting exercise involved an energy analysis of each school's gas and electricity consumption (and resulting carbon dioxide emissions), comparing the figures with national benchmarks.
The three schools studied were Leigh Primary in rural Kent; Michael Faraday Primary in Southwark, London, and Kingsmead Primary in Cheshire. Primary schools were chosen for ease of comparison.
Leigh Primary School was built in the 1890s with classic proportions and layout: two-storey, cottage-style architecture, high ceilings and generous glazing. The only major additions in more than 100 years have been a single classroom extension and a sports hall, which was built in 2004. Otherwise the school is mostly original.
The single-storey buildings of Michael Faraday School, built in 1974, were constructed to a style and standard typical of the era: a highly-glazed, lightweight timber and brick construction.
Structurally, the school is in poor condition, with aged boilers running full tilt to heat a building where the rooflight frames have rotted away. It has deteriorated so much that the caretaker can only do "crisis management". A new school is planned with completion scheduled for 2010.
Kingsmead Primary School opened in September 2004. The school was an attempt to create an exemplar of low energy design and construction: the main frame is made of timber from a sustainable source, it has a woodchip boiler, solar panels to top up the hot water and a rainwater recovery system to flush the toilets.
The carbon footprint of all three schools was assessed using the same methodology (see box on page 19). Actual energy use was adjusted to national weather conditions and by reporting energy consumption and carbon dioxide emissions per square metre of treated floor area. The primary assessment covered the major sources of carbon dioxide: fossil fuels, electricity and water supply for similar 12-month periods, between March 2006 and April 2007.
The energy data in the table on page 18 reveals that Kingsmead School is using 59 kWhm2 per annum for electricity and 119 kWhm2 per annum for gas. This leads to overall carbon dioxide emissions of 48kg of CO2 per square metre of floor area per annum. The Carbon Trust would expect the best primary schools to achieve 34kg of CO2 per square metre per annum (at the contemporary carbon factor of 0.43 for electricity).
The woodchip boiler proved the most difficult to get working properly and contributed to a much higher consumption of gas by the back-up boiler than was assumed by the design team.
The carbon footprint for Michael Faraday Primary, the 1970s school, was difficult to determine. The school doesn't monitor its energy meters, and the billing was sporadic and inaccurate. Taking this into account, the carbon footprint of Michael Faraday Primary School was between 66-71 kg of CO2 per square metre per annum.
Although Leigh Primary is smaller and has modest catering facilities, it's poorly insulated and not very airtight. Its carbon footprint has been calculated at 51 kg CO2 per square metre per annum. In other words, it's just a smidgen worse than Kingsmead - a school more than 100 years younger. So what does all this mean?
Leigh Primary School - the simplest, most basic school in this study - is the most revealing. Its carbon footprint is almost identical to that of Kingsmead Primary, regarded as one of the most sustainable new primary schools. Furthermore, Leigh Primary has long since paid back its initial investment and the energy used to build it.
Kingsmead's bio-fuel boilers, solar water heating and rainwater recovery systems are proving more demanding. The application of such sustainable technology is no guarantee of permanent good performance. It can put school administrators on a management and maintenance treadmill that they are neither trained for nor expecting.
Not that Government, the Department for Children, Schools and Families (DCSF) or the Carbon Trust would know this. No one in the education sector is carrying out a programme of post-occupancy assessments to determine whether pound;45 billion of taxpayer's money is actually improving the carbon performance of the schools estate.
Energy benchmarks are also dangerously out of date and flaky. The latest unpublished figures show considerable variation year-to-year, depending on samples, sample sizes and whether you look at best practice, typical or poor. Overall, the signs are that new schools are consuming far more energy than they should.
Information technology in classrooms may be the smoking gun, but DCSF analysis indicates no correlation between PC numbers and energy use. If true, this is worrying, as it throws the focus back on building systems such as lighting, fans, pumps and controls.
If the Government is serious about sustainability, then older schools deserve greater understanding - and continuing investment - by local authorities. Too many schools have suffered from decades of under-investment and poor maintenance. Demolition or sell-off by local authorities keen to divest themselves of older buildings is not justified without a proper carbon footprint assessment.
Some eras of school building have delivered poor quality construction and these schools should be replaced. But all schools should undergo a detailed examination of their intrinsic virtues - including energy, longevity, adaptability and value to the community - rather than just being replaced.
All new schools should be subject to full post-occupancy assessment and carbon footprinting - there's pound;45 billion to be spent wisely. Without that, we're flying blind on our way to carbon neutrality and we don't have much chance of getting there
Roderic Bunn BA FRSA is with the building research association BSRIA and is a trustee of the Usable Buildings Trust.
Number of pupils: 127
Wendy Wallace-Holman, headteacher, says:
"We have signs up around the school reminding people to switch off lights and computers and interactive whiteboards, and we've cut down on paper wastage.
"We've installed water hippos so the toilets don't flush more than they need to, taps that turn themselves off and a water butt for the garden.
"We don't have double glazing and that would be helpful in cutting down on heat loss, and we're looking at our heating system, which has developed piecemeal, so we have three different boilers."
KINGSMEAD PRIMARY SCHOOL
Opened: September 2004
Number of pupils: 213
Catriona Stewart, headteacher, says:
"We have had some teething problems with the new technology and it has not all worked like it should, but we've been using less electricity each year since we opened.
"People were used to coming in and turning lights on, but that's much rarer now as we've got used to using the daylight. The boiler seems to be working much better now.
"Our eco-group makes a weekly report in Friday assembly, and they monitor how much electricity we use and how recycling is going."
MICHAEL FARADAY PRIMARY SCHOOL
Walworth, south-east London
Number of pupils: 331
Karen Fowler, headteacher, says:
"The school is very hot in the summer and very cold in the winter, and the design is totally inappropriate for the way we work.
"We try to be as green as possible and we recycle, but it's very difficult to make a big difference.
"We are getting a new school, though, and we'll be moving in 2010. We want it to be as energy efficient as possible and we have had the architecture team working with us to try and make sure it is."
- Nick Morrison
Design of Sustainable Schools - Case Studies, DfES 2006, edited by Roderic Bunn. A free PDF of the carbon footprinting survey is available for download from www.bsria.co.ukbookshop.
CARBON FOOTPRINT METHODOLOGY
Carbon footprinting is not an exact science. While it's relatively easy to monitor energy consumption inside the school boundary, regular monitoring of carbon dioxide caused by transporting food, waste and staff to and from the school is more difficult.
Things change over time, so a carbon footprinting exercise can only ever be a snapshot.
The Department for Children, Schools and Families' published national benchmarks for electricity consumption are more than six years old and do not reflect the increased use of information technology such as whiteboards, projectors and server rooms.
It's not easy to compare schools on a like-for-like basis. The variables that act on a school in a city centre are different from those acting on a rural school.
For the purposes of this study I concentrated on the major causes of emissions: gas, electricity and water use within the site boundary.
Energy consumption was calculated from metered readings of electricity and fossil fuel (gas) for the most recent available year.
A mix of actual or customer readings were used, but one or two estimated readings could not be avoided. Estimated utility readings are unreliable.
The kilowatts per square metre per annum and kilograms of carbon dioxide per square metre per year were obtained by inputting the energy data into the energy analysis program CIBSE TM 22 Energy Assessment and Reporting Method. All the actual heating data was adjusted to national temperature figures, for comparison against prevailing benchmarks.
Energy benchmarking of schools is a subjective process, as the Carbon Trust data is neither up-to-date nor clear how the benchmarks are derived.
Electricity is more polluting than natural gas. A carbon factor of 0.43 kg CO2 is compatible with the 2002 benchmarks published by the Carbon Trust (Good Practice Guide 343: Saving Energy - A Whole School Approach). But the UK's energy mix is relying less on nuclear and more on coal, so a more contemporary carbon factor of 0.52 kg CO2 is more relevant for 2006-07 data used here.
This has the effect of raising the carbon dioxide emission figures for the three schools.
Water consumption data was obtained from metered readings for a representative year and compared to the benchmarks in Good Practice Guide 343.