The transpired solar collector on the south elevation of the Active Classroom.

A year ago The Fifth Estate covered the UK’s first energy-positive office space, which is right next door to the UK’s first energy positive classroom. 

Both are designed by SPECIFIC, a part of the University of Swansea that’s engaged in integrating futuristic solar heat and electricity technologies together with storage possibilities in buildings. 

In its first year, the classroom generated more than one half times the energy it consumed. 

The Fifth Estate caught up with Christopher Bailey, an engineer working for SPECIFIC, to find out what they’ve been up to since then to wean buildings off fossil fuels for electricity, heating and cooling.

“One promising development is a revolutionary form of heat storage that SPECIFIC makes that looks like something you might have for breakfast with milk – especially since it sat in a bowl on the table where Christopher and I were having our conversation. Rather like vermiculite, and unlike cereal covered with a special patent coating, it’s designed to absorb water vapour containing heat from the air and store it.”

“We’re using solar air collectors – transpired solar collectors embedded in the steel walls of buildings such as warehouses,” Bailey says.

They are made at the nearby Tata Steel plant and are “very effective” at capturing solar heat, he explained. “The test building has eliminated the use of gas for heating as a result.”

“But because they don’t provide enough heat on their own to cover the night times, then heat storage technology is an ideal match. So we are also looking into inter-seasonal heat storage with thermochemical materials. That’s what this is in this container.” 

To store heat energy, solar-heated air is passed over a salt in the granule matrix, which removes moisture and stores the energy in an endothermic reaction. 

To recover the heat again, humid air is passed over the granules.

This creates an exothermic reaction releasing the heat, which can then be sent to wherever it’s needed.

“We have some teething problems, for example if it’s heated too quickly it loses its ability to absorb heat, but we’re working on that,” Bailey says.

“This can be used in the walls and floors of buildings, to smooth out and regulate extremes of heat and cold. 

“All metal sheds could have them.”

I suggested that it could be extremely useful in hot and humid climates, where buildings are hard to cool in any passive way, without the use of electrically driven airconditioning and dehumidifiers.

He agreed. “Although we are not currently piloting it in those climates. This is for use in climates like UK.”

There’s a demonstration building nearby in Margam.

Perovskite solar cells – still not a mature technology

Several companies including SPECIFIC, in partnership with Tata Steel, have been developing this type of printable solar cell it for years – and every year promising that it’s about three years away from being market-ready.

The company’s latest printed version of perovskite solar coating has reached about 9 per cent efficiency, Bailey says. 

“However, its ability to generate electricity dies away within just a couple of days. So we’re still working on it to find out what can be done to make them last as long as silicon cells. As soon as we crack it you’ll be able to print on plastic, glass and steel to make almost any surface generate electricity.”

It’s disappointing news that it is taking so long to perfect this technology. But there’s something else the company is working on that’s already working.

The underfloor heating printed coating system

It looks like a normal floor tile. But it’s far from normal.

“Usually with underfloor heating there’s a lag between switching it on and heat been delivered,” Bailey explained. “But this flooring is of low thermal mass so that doesn’t happen.”

“It uses the principle of resistive electrical heating,” he says. “It’s another printing technology that uses a conductive ink applied underneath the floor to deliver heat into the space. It’s been tested for over 30,000 hours already in a commercial context. We’ve been using in the Active Classroom for over a year.”

The advantages of underfloor heating are that there is no thermal stratification and you need only a low temperature to achieve the same level of comfort as with central heating. Also, it frees up the walls to use them for something else.

SPECIFIC runs several real-world demonstrator projects

There are 26 full-scale demonstrator sites in south Wales. They each incorporate some aspects of the Active Buildings concept. 

As well as showcasing the technologies, they are used to monitor and develop systems under realistic conditions and in a range of building uses. 

“Proving the concept in real buildings is critical for its adoption by industry, regulators and consumers,” said Bailey. “Part of the purpose of the demonstration is to show that these buildings can be made with products that are already on the market with the existing supply chains.”

The latest demonstrator project is social housing: 16 homes being built in partnership with Neath Port Talbot Council.

The idea of houses as power stations essential to a new City Deal, with funding from the Westminster government that has been arranged for the Swansea City area, which covers not just the city but a lot of rural hinterland to the north and west.

This means that there will be funding for more demonstrator projects, including retrofits. Watch this space.

David Thorpe is the author of the books Solar Technology and the new ‘One Planet’ Cities.

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