The Passivhaus template developed for the 21st Century Schools programme in Wales offers a BIM-ready primary, medium and secondary school solution that can be tailored to individual needs of clients and sites. And it provides ideal learning environments with consistent outcomes in terms of cost, quality and sustainability while delivering better whole-life value through heavily reduced operational and maintenance costs.
Two primary schools in Carmarthenshire have been designed to the world’s most rigorous energy and comfort standard known as Passivhaus. The success of the new buildings has led to us being asked to use the template for two more primary schools in Wales - the country’s first Passivhaus secondary school and even an eco-hostel and a museum.
Our design was developed for the Welsh 21st Century Schools Programme but also helps the Welsh Government meet the ambitions of its Wellbeing of Future Generations Act 2015. By using the Passivhaus standard we’ve locked quality into the buildings so they continue to perform to the highest standard over the years while at the same time freeing up thousands of pounds of school budget through low running costs that can be spent directly on the children’s education, now and in the future.
Even more importantly the fresh air flowing through the schools and into the bright engaging classrooms creates an enlivening environment in which to be taught that helps keep the children alert and engaged in their learning.
Passivhaus is high-quality design
Passivhaus uses good design to create an airtight structure that requires very little energy for heating and cooling. It demands meticulous attention to detail, rigorous design and construction and the result is that heat losses are reduced so much that the sun or captured heat from human occupants – we call it kiddywatts in the schools - can provide pretty much all the warmth needed even in the depths of winter. Cooling is achieved by ventilating the building at night or opening the windows.
At our two schools in Carmarthenshire – Trimsaran and Parc y Tywyn - we’ve been able to refine the designs and develop new innovations never used on Passivhaus buildings before. And working with our partners Dawnus, Carmarthenshire County Council, Architype and The Urbanists, we’ve evolved the standardised school building agenda into something more flexible, more in tune with local authority clients’ requirements, more sustainable and more Welsh.
We’ve provided consistent quality and sustainability while delivering better whole-life value. Our client accepted that for a very small increase in capital cost on a Passivhaus school they could save 80% on heating bills every year the schools are in use. And working to Passivhaus standards challenged our engineering thinking.
Pushing the boundaries
Take the foundations for example. The Passivhaus schools sit on raft slabs over continuous insulation to provide that solid cushion underneath that keeps the warm air in. In conventional design these could be more ‘structurally efficient’ by being thinner in the places where they carry less weight. But the same thickness of raft slab throughout ensures a simple construction and consistent insulation, reducing potential cold spots.
Because the schools are so airtight, we had to avoid the risk of the children getting too hot so our models mapped the heat generated by staff and pupils and worked out how to reuse these kiddywatts as alternatives to more obvious heat sources like radiators. The most useful way of capturing this heat was to supply fresh air into the classrooms and then using specifically selected air paths to take the air warmed by the people to the centre of the school and main hall.
We have been delighted with the response to the schools. Trimsaran head teacher Sharon Owen told us her school “is spacious, light and airy and has improved pupils' pride and self-esteem. The temperature is constant and so pupils don’t overheat, thus improving concentration levels.”
And the schools are building blocks in Carmarthenshire County Council’s future school development. “Our partnership on both Ysgol Trimsaran and Ysgol Parc y Tywyn projects has been key in steering our evolution of a Fabric First approach to 21st Century Schools,” the council’s Projects Delivery Team leader Andrew Tidy told us.