The Innovators

Do you remember the days when a fibro shack was an innovative building? I don’t, but it was at a particular stage. There were masonry buildings, and timber buildings, then the masonry became a veneer on a timber building and then there was this new thing called fibro cement. There has always been innovation with building materials (with mixed results – fibro cement sheet in its original form had devastating health impacts) but the rate and diversity of innovation within the materials industry today seems unprecedented.

Materials are being re-examined from every angle – R values, embodied energy, waste reuse, environmental impact. There are Structural Insulated Panels, phase change materials, composite flooring, insulative masonry and yes … a low embodied energy cement sheet board that is a natural product and draws in CO2 as it cures.

These new materials are opening up opportunities for designers to do different types of buildings, and in doing so to optimise environmental outcomes – whether it be energy use, material efficiencies or eliminating waste.

There is no doubt that the ongoing evolution of new and innovative building products is evidence that the materials industry is rising to the challenge of a sustainable material world. What follows is a brief discussion of some of the materials and products that are pushing the boundaries in building construction.

Phase change material
Of particular relevance to the issue of embodied and operational energy is a product that uses a phase change material to moderate the temperature inside a building and significantly reduce the need for heating and cooling. About one-seventeenth the embodied energy of concrete, this material acts as thermal mass – capturing the heat from the day and releasing it at night, and carrying the coolth of the night into the day.

Phase change materials are materials that can change from a solid to a liquid. Water is a phase change material – it can change from ice to water, from water to steam, and back again. This product uses vegetable fat as a phase change material. The fat is encased in pockets within plastic sheets that can be installed behind a wall or ceiling lining. The material changes from solid to liquid at around 23–25°. To change the phase requires a lot of energy, which it gets from absorbing heat from the ambient air. However, it doesn’t start to absorb heat until the ambient air reaches 18° – and this is where it differs from “normal” thermal mass. At 18° it starts absorbing heat. It continues to absorb heat until the material reaches 23°, a process which takes many hours. Ideally in winter, it obtains this heat from passive solar gain. In summer it acts to moderate the internal temperature. When the ambient temperature drops below 23° the material starts to release the heat – which is when you need the heat again. It is acting as thermal mass – but only in a narrow temperature band.