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Specialists in PR and marketing support for building services, building management and sustainability

 

The challenge of BSF
(written for H&V Review)

Building Schools for the Future is one of the UK’s biggest construction roll-outs in recent years. Ant Wilson and Richard Brailsford of AECOM explain why it needs to evolve with changing criteria


The Building Schools for the Future (BSF) programme is currently the government’s biggest spend on buildings. Not only is it designed to improve the school’s educational standards through a more productive working environment, it also incorporates stringent energy targets that will improve the energy performance of new schools. BSF is being driven by the Department for Children, Schools and Families (DCSF) and the delivery body is Partnership For Schools (PFS).

"However since BSF was first launched, the government’s thinking on how to meet its commitments has developed and energy reduction targets for schools have become more ambitious and are likely to get tighter still. In addition, the Primary Capital programme for the refurbishment/remodelling, and occasionally the replacement, of the country’s 23,000 primary schools is also coming ‘on stream’. There have been suggestions that the government will require primary schools to be more sustainable that their secondary cousins and, whilst energy use is only one part of sustainability, it would be reasonable to assume that energy targets for primary schools will be even tighter than for secondary schools.

Consequently, building services designers and the PFI consortia on these projects need to look more closely at how energy is delivered and managed in many schools that are still to be constructed or refurbished.

This whole subject needs to be considered in relation to the general background of carbon reduction programmes. The UK has committed to a carbon reductions target of 80% by 2050 – 10 years before the rest of Europe is expected to achieve this. According to 2007 figures, buildings emit some 45% of the UK’s carbon dioxide, so reducing carbon emissions from buildings is a key element in the government’s strategy.

At the same time, the government has stated that schools should be carbon-neutral by 2016, so it’s clear that school buildings are expected to make a significant contribution to the UK’s overall emissions targets. In this respect, though, it’s worth pointing out that there are two separate government consultations in progress at the moment that will help to define exactly what is meant by ‘carbon-neutral’ and ‘zero-carbon’.

So those are the aspirations but the reality offers a number of challenges.

A typical design for the present generation of low energy school will incorporate high levels of insulation, high amounts of heat reclaim and a low carbon heating source, (such as biomass boilers and/or solar hot water heating). In addition, schools now have much higher internal heat gains from IT usage than was the case a few years ago. Consequently, emissions from space heating are on the decline and by far the majority of the remaining emissions are due to electrical loads.

To reduce the CO2 effect of these electrical loads requires the electrical supply to be decarbonised, either on-site or off-site. Clearly, on-site generation of electricity is not only expensive, it also introduces increasingly sophisticated systems into schools with an associated increase in specialised maintenance requirements.

‘Small’ wind generation, whilst often useful as a teaching aid, rarely saves more emissions than were necessary to manufacture the components in the first place, whereas ‘large’ wind is usually problematic in an urban environment. Photovoltaics are expensive, though their price is falling, and their effective use requires careful planning and, again, there are maintenance implications.

Introducing mini combined heat and power (CHP) generation into schools would be feasible but, to be efficient, has to be limited to a size where the heat output can be utilised - with the only summer load being the daily domestic hot water demand. Therefore very large storage tanks will be required in order to flatten out loads.

For all of these reasons, we believe that while requiring all of the emissions savings to be made within the school grounds is financially and legally simple, it is increasingly poor value for money. Taking a wider view is financially and legally more complex, but leads to far better use of resources.

Taking this to an obvious level, and seeking to achieve these reductions at a national level, is clearly a massive undertaking. To date, we have been most successful in building individual supply points, such as wind farms, but we have been far less successful in joining users together to optimise economies of scale and variations of load patterns.

Similarly, city-wide schemes are still major undertakings but smaller localised schemes have the potential to deliver significant benefits. For example, equipping a school with CHP plant and linking local council buildings or housing estates to the power and heat produced is an obvious way of maximising the performance of the CHP plant and effectively making the school carbon-neutral because many of its emissions are ‘offset’ to other buildings.

As noted above, in all likelihood carbon targets will become tighter as BSF progresses and this may prove to be the most cost-effective and energy efficient way of moving forward. Indeed, several local authorities are already considering projects of this nature in anticipation of future energy and emissions targets.

Open all hours

Another consideration is the fact that schools are being encouraged to open their facilities to local communities, extending the operating day into late afternoon and evening. This has implications for the way that targets are measured and contractors are paid.

The current BSF design specification sets a total emissions target of 27 kgCO2/m2/yr during defined ‘core’ hours. Should the facility emit more CO2, during these core hours, the PFI consortium is required to pay the first 10% increase in fuel costs, and 50% of any increase thereafter. Should the building be more efficient in operation the consortium reaps the full benefit of the first 10% under target and 50% of any additional savings.

These ‘core’ hours extend to 6pm, the assumption being that after this time the pupils have gone home and the buildings are virtually empty. However, the extended use of school buildings means that many of the spaces are in use well beyond 6pm. This means that the consortium needs to be able to measure energy consumption very accurately to be able to gauge energy consumption within and outside those core hours.

In addition, the pre-heating of the school buildings, which begins before the core hours, contributes to the comfort conditions during core hours, so this needs to be included in the core hours measurements. The upshot is that very precise metering of individual services is required to manage the contractual elements of the BSF model.

There is also an inherent danger in this situation, insofar as schools within a given area may be competing with each other for ‘custom’. In summer, where the solar heat gains will be at their highest by around 5pm and internal heat gains are maintained through occupancy, there is a chance that the rooms being used for extra-curricular activities become too hot. This could lead to a demand for increased mechanical ventilation or even retrofitting of air conditioning to keep ‘customers’ happy. Either way, this would result in increased energy consumption outside the core hours that the BSF design criteria are based on - and certainly would not contribute to an overall reduction in CO2 emissions.

Moving forward

Another key challenge is that there have been no detailed post-occupancy studies of the BSF schools that have been built so far. And while the design models may have indicated energy efficient performance within BSF criteria, the reality once the buildings are populated by teachers and students may be somewhat different. Thus, designers currently working on schools that will be built over the next three to five years are still reliant on predictions resulting from their engineering expertise without real performance data to help them.

A case in point is how best to deliver ventilation in line with Building Bulletin 101 (Ventilation of School Buildings). This requires CO2 level indication in classrooms so that teachers can see when the ventilation rate needs increasing – as well as a mechanism by which to adjust ventilation rates. Currently some building services engineers prefer simple natural ventilation mechanisms by manually opening windows while others may promote more sophisticated actuator control of windows via a BEMS. Yet others may favour the use of mechanical ventilation (central or local) with various methods of heat recovery, including air source heat pumps. In-depth post-occupancy studies would help to resolve these issues and clarify the best way forward.

What we can be almost certain about, though, is that the BSF criteria we are working with today will change as the BSF programme evolves. Precisely how, we don’t know. For instance, will carbon neutrality by 2016 mean that schools which open their doors on 1st January 2016 be carbon-neutral? Or will this apply to schools that start their design on or after 31st December 2016?

In all likelihood, the agreed target will lie between these extremes but, whatever the final detail, as projects generally take between three and five years from inception to handover, the final date is only two or three project cycles away.

This is a major challenge for an industry whose products may be asked to last 100 years and where a major refurbishment would not normally expected for 15 to 20 years. But it’s a challenge we need to rise to if we are to deliver on the government’s commitment to reducing CO2 emissions.

 

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