Pioneering Design for Sustainable Schools

Knowledge sharing is key in the fight against climate change. It’s no use having a good idea and using it once: we need to share innovations, technology and resources to ensure that good ideas can be used time and time again.

LETI (the London Energy Transformation Initiative) is doing sterling work in exactly this kind of knowledge sharing, by bringing together architects, engineers, property developers, academics, planners and contractors to come up with new solutions to the climate crisis. We’re delighted that our design for a new 6FE secondary school is a LETI Pioneer project – so we’d love to share with you some of the ways we’re making it a sustainable exemplar.

What Makes a LETI Pioneer?

LETI Pioneers need to show best practice in designing for a net zero-carbon future. In order to do this, they have to fulfil one or more of the following criteria:

• Meet specific energy use intensity (EUI) targets
• Meet specific embodied carbon targets
• Use fossil-free heating and hot water systems, selected with LETI’s Heat Decision Tree
• Develop a demand response strategy, and implement design and active measures to reduce demand on the electrical grid
• Generate enough off- and on-site renewable energy to achieve a zero-carbon balance

In addition, all LETI Pioneers must commit to monitoring and publishing data that shows their energy use.

To help meet these targets, design teams meet six times a year, with each meeting taking a different focus. So far we’ve discussed metering and embodied carbon.

Metering

Far more complex than just installing a smart meter, metering involves getting a full and multi-dimensional understanding of how a building uses resources – not just on paper, but in real operation. Showing operational energy use is not as simple as you might expect, and standard EPCs (Energy Performance Certificates) only reflect a building’s efficiency in theory. We’ve decided to use Display Energy Certificates for our project, as although they’re not required on buildings of this size, they provide a more accurate representation of how a building performs in practice.

An accurate metering system can tell you how much energy you’re using, but not how to reduce it. That’s why working with the client after handing over the building is key: even at this early stage, we’ve started considering a programme of “aftercare” for at least three years, where we can support the School in reducing its environmental footprint, and ensure that the energy-saving features we design into the site are being used to their full potential.

It’s also key to be open and honest about progress, to build up trust and accountability, and to give all users the information they need to help improve a building’s impact. A common phrase in approaching sustainability is “Be lean, be clean, be green” – we would add the encouragement to “be seen”, so that everyone can learn from the building’s performance.

Embodied Carbon

When people think about a building’s carbon usage, they often think of its ongoing efficiency: how well insulated it is, how much of its energy is drawn from the grid or from renewables, and so on. But this neglects the fact that much of a building’s carbon footprint has already been laid down before anyone moves in. This initial carbon footprint – “embodied” in the materials of a building, and the processes that have brought them together – has implications for every detail of construction, from gathering and processing raw materials to transporting them and assembling them on site, and even to their potential reuse if the building is eventually demolished.

Key decisions early in the project can have a massive impact. On our LETI Pioneer school, we’ve interrogated high-level design aspects such as size, scale and form, thinking carefully about how they could affect embodied carbon later in the process. Even something as simple as reducing ceiling heights can have a huge effect over multiple storeys and a large floor area.

Of course, the central question of embodied carbon is which materials to use. Specifying recycled materials cuts out much of the carbon produced by extracting and processing: Opalis UK, an online directory of reusable building materials, is one example of how we can start to tap into circular economy principles. Thinking about materials early on makes it easier to specify as many reused or reusable materials as possible, and to avoid creating a design which ties us to less sustainable options.

Putting targets for embodied carbon into the project documents is an important part of addressing the issue, and it would be great to see briefs targeting either LETI or RIBA figures. Specifications for materials already include a number of standard performance requirements such as fire retardancy or lifespan: adding embodied carbon figures to this list would ensure that if a product is changed later on, embodied carbon becomes a factor in replacing it.

What’s Next?

We’re excited by the progress we’ve already made in putting sustainability at the heart of our LETI Pioneer school. The design is fast developing, and there are plenty more discussions to be had about how to make it an exemplar for carefully considered design with a light environmental footprint.

We’ll be keeping you up to date with more details as things progress – watch this space!