Spotlight on David Lea and low carbon design

 

When we build we reveal our vision of the future.” These words embody David Lea’s approach to designing buildings that are in harmony with the natural world. Today, this has never been more important and here at RISE Design Studio we will continue to take inspiration from Lea’s work, long after hearing the sad news of his death earlier this year.

RISE Design Studio David Lea

Beautiful buildings, minimal harm

At the heart of Lea’s long career as an architect was his desire to create low-impact buildings. Many of his projects were built mainly from natural products, including timber, hempcrete, locally quarried stone and lime render. His last major project included an auditorium built with seven metre high walls of rammed earth. This now renowned project – the Wales Institute for Sustainable Education (WISE) in mid-Wales – comprises a range of accommodation and workshops, with pools of water, paved terraces and timber-slatted galleries interspersed throughout. This keeps the inside spaces in ‘constant dialogue’ with the outside world with an almost Japanese feel.

The WISE centre, like many of his other projects, were based on design principles that embrace creativity, minimise waste and retain an element of simplicity that complements the natural world. In his first important work – a sheltered housing scheme in Surrey – Lea implemented a system of easily built timber details so as to avoid any wasteful cutting. In later phases of the same project, he incorporated lime-rendered wall finishes, a method that he used in combination with locally quarried stone in his other work.

Growing concern for the natural world

As Lea progressed through his career, his concern for the natural world grew and he became increasingly restless with life in London. Relocating to Snowdonia in North Wales, he focused increasingly on rebuilding his own property and cultivating his land as part of the wider ‘back-to-the-earth’ movement.

While in Wales, and through his work at the WISE centre, he was able to showcase his use of hempcrete – a mixture of hemp and lime – as a sustainable alternative to concrete. Students and staff continue to experiment with this material at the Welsh School of Architecture and there is growing interest and use in hempcrete in a wide range of architecture, construction and scientific circles.

An activist at heart

Most inspirational is the way in which Lea instilled in his students a crucial need to think about the future that they build. His appreciation of changing light, combined with creativity, simplicity and responsibility towards the environment, was distilled into the minds of so many architects who now have the opportunity to learn from and carry on his important work.

Rammed earth walls: natural and sustainable living

 

‘Rammed earth’ is a technique for constructing foundations, floors and walls from natural raw materials such as earth, chalk, lime or gravel. With the lowest enviromental impact of all building techniques currently used in the commercial construction industry, rammed earth is receiving growing attention and becoming more and more popular with architects, builders and clients alike. In this short post, we tell you a little more about the technique.

Rammed earth walls RISE Design Studio architect west london

Mixing it up

Rammed earth walls are made by ‘ramming’ a mixture of materials into place between flat, temporary panels called ‘formwork’. The panels are normally made of wood or plywood and they are clamped around the earth to make sure it doesn’t bulge when compressed. The materials rammed into the formwork generally include gravel, sand, silt and a small amount of clay.  An additive like lime, cement of asphalt is often added to make it extra strong.

The mixture is compressed inside the formwork by a mechanical ram and compacted to approximately 50% of its original height. The compression takes place in stages, usually in depths of 10cm to 25cm, and this is repeated until the top of the formwork is reached. This is the part of the process that results in the beautiful layers sometimes seen in rammed earth walls.

After the wall has been completed, the formwork is removed and a surface texture can be applied, e.g. by wire brushing or carving. The wall is normally too hard to work on after about one hour. As the walls dry and harden (ideally in warm weather), the compression strength of the rammed earth increases to a maximum of 4.3MPa (620 psi). This is less than concrete but sufficiently strong for domestic buildings.

Environmentally-friendly

Cured rammed earth has a high thermal mass. This means that it absorbs heat during the day and releases it at night, which reduces heating and cooling costs. Environmental impacts are also kept low if the amount of processing of rammed earth materials is kept to a minimum (i.e. artificial additives) and material is sourced locally where possible. Most of the energy used in the construction of rammed earth is in quarrying the raw material and transporting it to the site.

Healthy home

The composition of rammed earth allows it to absorb and release humidity from the inside of a building. This improves air quality, particularly for people who suffer from asthma. Rammed earth is also inorganic, which means that it won’t decay and does not support the growth of mould.

Back to our roots

More than 30% of the world’s population uses earth as a building material, hence this technique is not new. Properly constructed rammed earth can also last for thousands of years, demonstrated by the many ancient structures built using this technique which are still standing around the world.

It has received growing attention in recent years as the construction industry and its customers have a growing sense of the need for environmentally friendly and sustainable building practices. Not only does the technique offer opportunities for carbon-neutral building projects, the technique can be employed in a wide range of climatic conditions and for developing housing that would otherwise be constrained due to expensive construction techniques.

It is a technique that we have been exploring at RISE Design Studio, particularly in our drive to use local, sustainably-sourced building materials.