Can buildings ever generate more energy than they consume? Dave Parker went to South Wales to find out.
Specific” is the convenient and mellifluous acronym for the Sustainable Product Engineering Centre for Innovative Functional Industrial Coatings - just one of seven UK Innovation and Knowledge Centres set up since 2007. Based in Baglan, Port Talbot, Specific is run by a consortium led by Swansea University in strategic partnership with Tata Steel, glass producer NSG Pilkington and industrial chemicals giant BASF.
Chief executive officer Kevin Bygate says such partnerships can bridge the traditional gulf between the ivory towers of academia and the gritty realities of mass production and construction.
“Our brief is to develop ground breaking UK manufactured coatings for construction materials that can turn buildings into ‘power stations’, enabling them to generate, store and release all the energy they need,” he says.
“These coatings will be based on low cost, earth-abundant materials, and will typically be applied to glass and steel. The difference here is that we can take promising materials from the laboratory bench up to pilot production, and demonstrate them on full size buildings.”
At the laboratory stage, at the moment, are four distinct photovoltaic (PV) cell technologies - organic, dye sensitised, CZTS (copper, zinc, tin, sulphur), and perhaps the most promising, the so-called perovskite cells, which currently offer conversion efficiencies topping 20% on the laboratory bench.
In due course, all these technologies should progress to production trials in Specific’s £10M Pilot Manufacturing Resource Centre. This unique facility pairs academics and product development specialists, equipping them with state of the art technology ranging from near infra-red (NIR) ovens to 3D printers. Coatings can be trialled on pilot production lines, or subjected to accelerated weathering tests.
In particular, there is a focus on multi-layer PV cells that can be deposited onto a range of substrates without the complex technology needed to produce silicon-based cells. “We’re developing much more cost-effective and scalable alternatives to conventional laboratory-based manufacturing techniques,” says technology transfer fellow Justin Searle.
“For example, our NIR ovens heat materials very rapidly, avoiding the need for the usual lengthy heating steps in large scale production.”
Also in the centre is a demonstrator room, currently showcasing one of Specific’s earliest developments to make it to full scale - an underfloor heating system with a difference.
“It’s based on a resistive coating, essentially a graphite loaded paint which can be applied to any non-conductive surface,” explains building integration manager Joanna Morgan.
“Pass a low voltage DC current through it and it heats up very rapidly. It could be applied to walls or ceilings, but we’ve developed it as a coating for raised access flooring.”
Its attractions include minimal disruption during installation and the option of zoning the heat output. Searle adds: “We’ve had serious interest from NHS representatives, who like the fact they could eliminate radiators, which are a potential source of dangerous infections.
“And the system is a natural partner with PV.”
“Our brief is to develop ground breaking UK manufactured coatings for construction materials that can turn buildings into ‘power stations’”
Kevin Bygate, Specific
A full scale floor has recently been installed at one raised access floor manufacturer’s premises.
Another technology that has reached the full-scale trial stage is building integrated PV (BIPV), in the form of thin film cells deposited directly onto conventional standing seam roofing. Bygate says this approach promises massive reductions in installation costs.
“Instead of two separate contractors coming in one after the other - the roofing contractor followed by the PV panel installer - the roofing contractor can do everything in one visit.”
This approach to BIPV has been on trial since 2014 on Specific’s first full-scale test building, dubbed the Pod. Although not large, the Pod contains enough instrumentation to provide reliable data on the BIPV’s performance.
“We have to show how buildings can be designed or modified to dramatically reduce the energy they need, particularly their demand for gas”
Kevin Bygate, Specific
It also uses conventional lead-acid batteries as an energy store. At Specific, a number of other battery chemistries are being assessed in the hope of perfecting the balance between day to day usage and cyclic efficiency.
Surplus heat also needs to be stored more efficiently. Thermochemical stores based on phase changing materials have been around for some time, but these offer only diurnal storage at best.
Specific’s aim is to come up with an alternative approach that would offer long term interseasonal storage. In due course a prototype will be installed in its Solar Heating Energy Demonstrator (SHED) (see box).
Practical, cost-effective energy storage is the Holy Grail for proponents of alternative energy technologies. Fossil fuel apologists and nuclear energy enthusiasts have always portrayed the intermittent outputs of solar, wind and wave power as fundamental flaws. If Specific can really make significant advances in this area it will be a major breakthrough.
“Energy has to become not just renewable but reliable and affordable as well”
Kevin Bygate, Specific
Bygate has a clear vision of Specific’s mission.
“We need nothing short of a new Industrial Revolution,” he declares.
“Up to 75% of the energy this country consumes is down to the built environment. We have to show how buildings can be designed or modified to dramatically reduce the energy they need, particularly their demand for gas.
“Energy has to become not just renewable but reliable and affordable as well. Existing technologies have to be effectively integrated. We’re focusing on technologies that are economically attractive, because one of the big challenges is persuading building owners and occupiers to invest in energy-saving options.”
And he adds that the concept of buildings actually generating significant surpluses of energy is far from pie in the sky.
“The current energy distribution networks would have to be re-engineered - or perhaps the surplus energy could be used to charge electric cars close by.
“We’d need major changes to codes and legislation as well.”
Secrets from the shed
Close to Tata Steel’s giant Port Talbot steelworks in South Wales there lurks a building with hidden potential.
From a distance, it may look like any other light industrial unit on any industrial estate, seemingly clad in the ubiquitous profiled coated steel that remains one of Tata Steel’s most successful products.
Look closer - much closer - and the difference is obvious.
Once occupied by The Welding Institute, the 1990s building is now Specific’s Solar Heating Energy Demonstrator (SHED).
On its south west elevation 590m2 of the visible “cladding” is still Colorcoat, but this version is dubbed Colorcoat Renew SC, the latest variation on a 50-year-old theme.
The difference is the microperforations in the steel, and the positioning of the microperforated sheeting some 200mm in front of the original cladding behind to form a plenum.
This creates a “transpired solar collector”, a concept that originated in the United States in the 1990s. The perforated cladding absorbs up to 75% of the solar energy falling on it.
In most applications to date, relatively small fans are used to draw fresh air through the hot microperforations and up through the cavity, and the heated air either passes directly into the building or is fed into a conventional heating, ventilation and air conditioning system.
Preheating the incoming air like this can save up to 50% of daytime heating costs, it is claimed.
On the SHED, however, the Specific team has gone much further in the search for even greater efficiency.
Any surplus incoming heated air is diverted into an air source heat pump - basically a refrigerator running in reverse - which “concentrates” the energy in the incoming air and transfers it to water for storage overnight.
A convenient pit in the floor inherited from The Welding Institute houses the thermal store, a 20,000l tank of water that can reach 50°C. There are plans to replace this with a thermochemical store in the near future.
Even without an energy store, the system can be remarkably cost effective. Tata claims a typical payback time of less than 10 years, even without government incentives.
One square metre of Renew SC is capable of collecting up to 250kWh of energy per annum, it says. And the system can also be installed on suitable roofs, and be incorporated into building refurbishments with the minimum of disruption.
The SHED’s original gas boiler has been decommissioned and the building now relies on solar energy. Around 40% of the heating comes directly from the collector, the thermal store supplies the rest.