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Preventing overheating in schools Schools generally have a lower heating demand than other types of buildings. Typically, schools need to be warmed in the mornings before the pupils arrive. As human heat output contributes to building temperatures, we should consider that a class of 30 pupils would contribute approximately 4.5 KWh of heat energy to the building. Therefore, in a well-insulated building less heating is required throughout the day, and good ventilation to counteract the effect of human heat output is critical for large periods of the year. Although term time does not usually coincide with the UK’s hottest temperatures, there have been occasions in May where temperatures have been excessive, making it difficult for students to learn. Often, schools expand their sites with the addition of a series of boxy, lightweight classrooms which are low cost. This design is often implemented due to budgetary reasons but we as designers could be doing more. Sometimes this is done due to limited budgets but capital infrastructure cost bears little consequence when we consider overheating and the associated operational costs of having a mechanical cooling system running constantly due to poor building design. Unfortunately, schools rarely receive enough capital investment. We need only look at the current state of the education sector where schools are losing teachers as they cannot afford to pay both energy bills and teachers’ salaries. Having exposed concrete soffits as increased thermal mass, exterior shading to keep the building cool, and securely opening windows at night to cool the building are the best strategies to deal with overheating in schools.
What’s the solution? If the government goes ahead with the gas boiler ban for new builds, will this ban extend to the retrofit market? If so, will hydrogen energy become the replacement? Ostensibly, there hasn’t been enough investment in hydrogen energy or incentives from the government to make this viable. As a result, we are likely to see a lag where purchasers are going to potentially face a ban on gas boilers, without a real alternative to consider, other than heat pumps. We must also look to fabric improvements as this can greatly affect occupant comfort. Consider glazing
ADF MAY 2023
for example, which can contribute to overheating. We must first get the building fabric right and then maximise natural ventilation. Then, and only then, should we apply mechanical means to solve the risk of overheating that could not be designed out by fabric first and natural solutions. We must begin designing our buildings in a way which is sympathetic to heat. Architecturally, in the UK we are keen on buildings with low ceiling heights, and small compartments which overheat very easily.
In addition to Spanish building design, the built environment sector could refer to Victorian buildings, as architects of the time designed structures which were excellent at preventing overheating. Consider any Victorian building with its high ceilings, spacious interiors and top-opening windows that allow for single-sided ventilation in a room.
Given the current climate crisis, it is imperative that we adapt our current approach to building design, and we must start solving these problems that are all too often characteristic of modern British buildings.
Alex Hill is managing director at Whitecode Consulting
WWW.ARCHITECTSDATAFILE.CO.UK
We need only look at the current state of the education sector where schools are losing teachers as they cannot afford to pay both energy bills and teachers’ salaries
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