In October last year, the Climate Change Committee (CCC) warned that buildings should not take 1.5°C as the baseline for climate adaptations. Its guidance is to design for at least a 2°C rise by 2050, with 4°C by 2100 still a possibility for long-term structures. For schools and educational estates expected to remain in service for decades, this demands a fundamental rethink of building services strategy.
THE OVERHEATING PARADOX
Overheating is now one of the most pressing risks facing building designers and property managers. Research by RHOSS and the Polytechnic University of Turin has revealed an interesting paradox where buildings designed for high energy efficiency by minimising heat loss are now struggling to keep heat out. Well-insulated buildings with high internal heat loads can reach a point where further insulation works against them, trapping heat and driving up cooling demand.
The consequences for learning are well documented. A meta-analysis by the Lawrence Berkeley National Laboratory suggests that performance falls by nearly 9% when indoor temperatures reach 30°C. Many organisations, including the Environmental Protection Agency, recognise that classroom temperatures directly affect student performance, making thermal comfort an educational issue as well as a facilities one.
YEAR-ROUND CLIMATE CONTROL
The traditional approach of switching from heating in winter to cooling in summer is becoming obsolete. With milder winters and more extreme summers, schools need HVAC systems that provide year-round climate control, addressing both overheating and heating demand without compromising net zero commitments.
Advanced reversible heat pumps address both sides of this challenge.
These systems move heat rather than generate it, making them far more efficient than combustion-based alternatives. And, with the ability to switch seamlessly between heating and cooling, they provide year-round comfort from a single integrated system, reducing capital expenditure, simplifying maintenance and lowering operational emissions. For schools with more complex demands, polyvalent (four-pipe) heat pumps go further still, simultaneously generating heating and cooling while recovering energy from one process to support the other.
High-temperature models can now deliver hot water at up to 75°C or more, making them compatible with legacy radiator circuits designed around 70 to 80°C supply temperatures, allowing schools to decarbonise through phased retrofits without replacing existing pipework or radiators/heat emitters to minimise cost to the Local Education Authority (LEA).
AIR QUALITY AND HEAT RECOVERY
Climate resilience in schools also requires attention to air quality. As buildings become more airtight, ventilation becomes increasingly important.
The Energy-related Products (ErP) directive requires all new Air Handling Units (AHUs) to include heat recovery as standard, pre-heating or pre-cooling incoming air and reducing the load on heating and cooling plant. By reclaiming up to 90% of thermal energy from exhaust air, heating demand can be reduced by 25 to 40%.
It is also worth mentioning the importance of filtration, with the National Educational Union (NEU) recommending improved ventilation and filtration of fresh air to help maintain good air-quality and improve concentration in the classroom. The NEU also suggests the use of a properly designed air conditioning system as an effective way of reducing air temperatures in the classroom.
This can now be achieved using fully integrated heat pump air handling units with zero defrost design, that can maintain a constant supply air temperature all year round regardless of the weather conditions (within design conditions) without interruption from a defrost cycle in winter.
Refrigerant choice is also worth considering at the specification stage. With the phasedown of high global warming potential hydrofluorocarbons under F-gas regulations accelerating, specifiers should ensure new systems use compliant refrigerants. Natural options such as propane (R290) offer negligible global warming potential and excellent thermodynamic performance.
Designing for yesterday’s climate is no longer sufficient. Every building services decision, whether for a new campus or a phased retrofit, should be made with a warmer future in mind. The technology to achieve it exists today. www.klima-therm.co.uk
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