Buildings capable of generating their own power for heating and cooling purposes belonged to the realm of science fiction not so very long ago. Now they’re becoming increasingly prevalent, with tech giants including Apple paving the way for their widespread adoption.
In many ways it’s no surprise because, according to industry research, heating buildings is one of the biggest challenges in the drive to provide affordable yet secure low carbon energy on a grand scale. The electricity used to control building temperatures accounts for nearly half our energy consumption globally and around a third of our carbon emissions.
Government directives the world over are striving for nearly zero-energy buildings (nZEB) by the end of next year, and for net zero carbon buildings by 2030, meaning they will have to be 100% sustainable as far as heating, hot water, ventilation and cooling requirements are concerned. The race is well and truly on to find new ways to harvest nature’s free energy.
For such ambitious carbon-neutral goals to be achieved, building architects and construction engineers need to devise ways of transforming buildings from being net users to net producers of electricity, and to do this they will need to start exploiting building structures. Thus far, the energy generated by large buildings has been heavily dependent on solar panels mounted on rooftops. The concern, however, is whether this limited space is large enough to support enough panels to meet the total energy demand of their hosts. Solar panels currently account for three-quarters of all PV systems.
Building facades offer more usable space than rooftops
In densely populated cities such as London, Hong Kong, Dubai, Beijing or Kuala Lumpur, the cost of land per square meter is at a premium so building structures are expanding upwards to make best use of the available space. The usable rooftop area where solar panels can be installed is therefore limited.
Building facades, on the other hand, are expanding in size, but their contribution to a building’s total energy requirement is minimal because PV technology has not been integrated into construction materials such as glass, metal or tiles on an industrial scale. Not only do those materials offer the potential to contribute significantly to a building’s total energy yield – by incorporating building-integrated PV (BIPV) capabilities into their makeup – but those base materials can also contribute to insulation, making structures more energy efficient, and help reduce noise pollution.
A construction material that lends itself particularly well to BIPV technology is glass. Even in its basic form it can effectively heat a building as a result of the greenhouse effect. BIPV products offer the potential to outweigh the importance of solar panels in the carbon neutral building revolution even though they currently cost more than conventional solar panels. Most cost calculations simply have to take into account the mark-up on a conventional facade when a new envelope is being built. Such calculations have demonstrated the return on investment for glass BIPV facades can be achieved within ten years.
More PV means more cleaning
However, as the widespread deployment of BIPV materials gains momentum, so too does the challenge of keeping said materials clean, because BIPV panels cannot perform optimally unless they’re able to maximize the amount of energy absorbed. The amount and frequency of cleaning needed depend on where a building is situated and its size. The taller the building, the more difficult and expensive it is to clean, requiring specialist equipment such as cleaning robots and colossal amounts of water. The amount of electricity needed to power such equipment could potentially outweigh the benefits of adopting renewable energy in the first place.
The only way the construction industry is ever going to achieve the desired zero-carbon utopia is if it transforms buildings into mini power stations, but to do that it is necessary to eliminate, or at the very least massively reduce, cleaning requirements. So far this has proved technically challenging and economically unviable.
A solution on the horizon
There could be a solution on the horizon, though, thanks to pioneering research and development being carried out by a consortium of companies including industrial coatings specialist Opus Materials Technologies. The company has secured more than £4 million in U.K. and EU funding and is working with academics, researchers and scientists to develop Solar Sharcâ , an easy clean, hydrophobic durable transparent coating based on nanotechnology. The coating can be easily applied to a glass substrate as part of the manufacturing process of BIPV or as a retrofit application to existing BIPV installations.
Field trials have delivered promising results and if the technology were to go mainstream, the high maintenance costs associated with renewable energy could be eradicated, changing the face of energy production forever by enabling buildings to be self-sufficient in their energy requirements and active contributors to the global grid system.
