The colour palette of buildings can be powerful design tools that communicate discrete or vivid messages about function, values and identity, strategically guide the flow of people, and highlight important architectural features.
Along with aesthetic considerations, colours can improve the energy efficiency of a building, while emerging technologies and innovations are revealing new ways exterior colours can enhance sustainability.
A paper published last year in the journal Buildings explored the perception of colour in urban spaces and suggested that in the face of a significant degree of urban structure complexity, the role of colour as a means and tool for shaping the image of the built environment was increasing.
The author said: “The combinations and diffusion of colour environments, corresponding to the diverse functions of individual elements of urban spaces, are conducive to intensifying aesthetic, emotional, synesthetic, associative and symbolic experiences.
“Colour is an important feature of architecture and urban spaces configuration and the wellbeing of its users, but considering colour choices is a complicated issue because colour preferences seem to depend on personal characteristics and psychophysical structure.”
A study conducted in Turkey last year investigated the use of paints with higher absorption values on exterior surfaces, finding a noticeable decrease in buildings’ energy consumption.
Higher absorption values reflect sunlight, causing the building to heat up less and consequently reducing the need for heating and cooling.
The authors explained that in hot climate regions, paints with low absorption values had proven more effective, whereas in cold climate regions paints with high absorption values had shown greater efficacy. They noted that while altering exterior paints’ absorption values had a positive effect on energy efficiency, it was crucial to consider factors such as climate conditions and building features.
Researchers from the University of Chicago last year invented a cladding material that changes colour to help with heating or cooling, and could be retrofitted to improve buildings’ energy efficiency.
The layers of the composite material include copper foil, plastic and graphene and – based on the outside temperature – can change its infrared colour, or the colour it appears under thermal imaging.
When used on a façade such as in the form of shingles, the material could potentially reduce the need for heating and cooling and lower a building’s overall energy consumption.
Assistant Professor Po-Chun Hsu, who led the research, said they had essentially figured out a low-energy way to treat a building like a person – adding a layer when cold and taking off a layer when hot.
He added: “This kind of smart material lets us maintain the temperature in a building without huge amounts of energy.”
As part of the research, modelling was conducted around the energy savings that could be achieved by applying the material to buildings in 15 US cities, representing 15 climate zones.
The results showed that in areas that experienced a high variation in weather, the material could save 8.4 per cent of a building’s annual heating and cooling energy consumption
on average, while using just 0.2 per cent of the building’s total electricity.
Another study exploring the energy efficiency of exterior colouring was undertaken by researchers at Purdue University, who developed ‘the whitest paint on record’ which reflected 98 per cent of sunlight.