A breath of fresh air

Poured-concrete walls, dark, musty corridors. No sunlight, no laughter – and a dreadful, if functional, line in cast-iron column radiators. Who said school days were the best of your life?

Step forward the new generation of educational buildings. Not only designed to show the general populace how seriously the government takes its commitment to a low-carbon economy. Not solely constructed to educate future generations on the importance of sustainability. But also built to provide kids with the kind of bright, breezy, contemporary environment where they might actually want to learn.

The new Michael Tippett School in Lambeth, south London, is a class example. From its sunlit entrance lobby to surprisingly airy classrooms, natural daylight works hand in hand with natural ventilation. A searing, sticky June day is quickly replaced by a pleasant coolness as Durgesh Chadee of structural and services engineer Gifford begins an absorbing guided tour from the double-height foyer.

The special needs school is the first to be completed under the Building Schools for the Future (BSF) programme, to which the government has pledged a staggering £45bn on renovating and rebuilding schools in England and Wales within the next 10-15 years. The scheme aims to reduce energy use by at least 60% against the 1990 baseline. Not a bad proposal when you consider schools alone are responsible for 15% of energy used in UK public and commercial buildings.

In the three years since BSF was launched, the issue of carbon emissions has surged to the top of the government’s agenda. The present goal is to provide zero-carbon new schools by 2016.

The school was developed in record time. M&E contractor Goldhall Electrical was on site for just six months, in a contract worth £1.4 million. Pupils moved in on schedule this February.

“The old Michael Tippett School was demolished and the kids didn’t have anywhere to go, so it was all constructed very quickly – within nine months in total. It was a challenge for everyone. The m&e contractor hadn’t dealt with many school projects before, so it was a challenge for them too. That’s why we’re all proud of this one,” says Chadee.

Despite the timescale, the project was a traditional build, with all m&e work carried out on site.

“There’s always the cost element with prefab, and I think that, because the m&e team was in early enough, they didn’t need to go down that avenue. The major kit is localised in a single plant room – just two boilers and the combined heat and power system. The rest is simple.”

The client has its own maintenance team, though current discussions with both Gifford and Goldhall may lead to future maintenance contracts.

In full flow

To design and install the natural ventilation system that lies at the heart of the Michael Tippett School’s environmental standing, Gifford and Goldhall Electrical had to be in sync with the architects from early on.

“If the building fabric and the form aren’t right from day one, you might as well forget natural ventilation,” says Chadee. “Architects can be very precious about their facades, and it takes a lot of discussion to get natural ventilation right. Luckily, with Marks Barfield architects that went really well. They were up for a low-energy building.”

The school has a lot of exposed mass. In the classrooms there are no false ceilings, so all cabling is surface-conduit.

“It isn’t recessed, so we get a good degree of thermal mass. In the summer months, we just cool the fabric at night, then use that cooling during the daytime,” explains Chadee.

The ceilings are also high and work well with the natural ventilation system.

“I’m working on projects that have low floor-to-ceiling heights, and we can’t make natural ventilation work. You just don’t get the heat to rise up,” says Chadee.

“I’m working on another school that is a refurb project, and we have to assist the natural ventilation by introducing fans to help the air blow through.”

Even the Michael Tippett School had its share of problems. The sports hall design had to be changed from a naturally ventilated scheme to a mechanically ventilated one.

“We just couldn’t fit enough louvres to make it work,” admits Chadee.

Gifford commissioned Ashdown Controls to design an advanced building management system for the school.

“The clever thing is the interaction between the underfloor heating and the natural ventilation,” says Chadee, with some pride.

Architects can be very precious about their facades and it takes a lot of discussion to get natural ventilation right

“If in winter you open the windows, you have a real problem. The underfloor heating won’t be able to cope with heating up the building. But the system is set up to bring on an audio alarm if the space isn’t getting up to temperature quickly enough, so people will be warned to shut windows.

“Most schools have the heating running with the windows open, but they end up having a big energy bill.”

The school’s BMS network is based on the latest Trend IQ3xcite controllers, which feature web capability and can be accessed from any personal computer.

“This gives Lambeth increased flexibility when it comes to remote site management,” explains Chadee.

The current intention is to regularly monitor all the BSF buildings in London.

A Building Bulletin guide recommends that a guaranteed amount of fresh air – in this case three litres per second per person – should be supplied. The team decided to achieve this by using motorised metal louvres at both the front and back of classrooms, to ensure good levels of cross-flow ventilation. These vividly coloured louvres shade ambitiously glazed classrooms and, on the outside, provide the school with its distinctively playful, cheery character.

“It’s not a mainstream school, and that certainly helps as well, because we don’t have that many pupils in each classroom. It’s a different story when you have 30 pupils in every room. Here we only have 10 to 15,” adds Chadee.

Value engineering

Along with the ventilation system, other sustainable features include sedum roofing and a Dachs mini gas-fired CHP unit, installed by Goldhall. With the use of low/zero-carbon (LZC) technologies, Gifford has predicted a 13.4% saving on carbon emissions. Michael Tippett is also one of the first UK schools to receive a BREEAM ‘very good’ rating.

At the design stage, the team decided to use a combination of carbon dioxide and temperature sensors to regulate classroom environments. When the design was developed by the contractor, however, plans for CO2 sensors were discarded.

“This was primarily down to cost. Value engineering was needed to bring the project back to budget,” explains Chadee.

“There wasn’t that much cutting on the services side. We did have to change our selection of light fittings. We had to use different manufacturers to the ones we’d had in mind in order to keep the costs down. But with regards to the quality of the installation, I don’t think we missed out too much.”

The majority of the school’s lighting, however, is purely PIR-controlled, contrary to original specification.

“Daylight sensors had to be omitted, as we made the decision to stay within budget, but school management also comes into it: teachers will turn lights off.”

The approach paid off. The project was completed well within budget at a total cost of £7.4 million.

As Michael Tippett is a specialist school for disabled pupils and those with learning difficulties, the m&e team had to consider a range of special requirements. Hoists are prominent throughout the building, which also requires a large quantity of power points so that wheelchairs can be conveniently recharged.

Metal conduit was used throughout the installation, as pupils are likely to damage plastic.

The underfloor heating system has the added benefit of removing the need for radiators, which have the potential to cause injury.

Match changes

The very fabric of the building also takes its occupants into consideration. Free-standing, laminated-timber columns bring the practical benefit of flexibility. As exterior walls and internal partitions are disengaged from the structural frame, they can be easily adapted if the school’s future requirements or student intake change.

Chadee, however, is secure in the knowledge that modifications to services or design will not be required for any other reason. It is the first BSF project that he has been involved in from start to finish, and the first school he has delivered that passes the new Part L requirements by some margin.

“This building has been designed to stand 30 years with no need for changes or extensions,” he says with assurance. “And we are confident that it will stand the test of time.”