Ordinary buildings as power stations?

A new positive energy office that can generate more energy than it uses was opened on Swansea University’s Bay Campus on 21^st June, coinciding with the summer solstice.  The longest day of the year is an appropriate date to launch a building that embodies a radical approach to harnessing solar power to produce its own energy needs and more besides. Its creators are hoping to exceed the 50% excess energy produced by their smaller award-winning active-classroom. The new building is part of the Buildings into Power Stations project which aims to address the need for low carbon, affordable and secure energy supply by combining new and existing technologies into the fabric of buildings to generate, store and release solar energy.

Ratcliffe on Soar power station, Nottingham. Source: Alan Murray-Rust (Use under Creative Commons agreement)

The new building is called an active-office because it combines passive heat conservation with active generation of energy from solar power using the entire building—not just the roof but also the walls and the windows. The active-office uses smart technology to monitor demand and, together with 110KWh energy storage in eight compact batteries, it stores and releases surplus energy back to the building or to the National Grid when it is needed.

Power stations of the future? The new positive energy #ActiveOffice with curved solar cell roof behind the #ActiveClassroom which produced 60% more energy than it used last year. Source: Specific.eu with permission.

“If all buildings worked in this way you would not need power stations as they are sized for the peaks in demand,” says Joanna Clarke, the architect of the active-office. Smoothing out the peaks and troughs of un-synchronised supply and demand is key. On a hot, windy day the National Grid operates at capacity due to wind and solar energy production.  “The energy can’t go anywhere, so unless you have that battery storage the energy is wasted,” she says.

Dr Justin Searle, Industrial Technology Director for the academic-industrial partnership SPECIFIC behind the active-office, explains how they are tackling this problem: “You combine technologies so there is some redundancy and some overlap. We are looking at combining the thermal element with photovoltaic and the control systems are there to choose which technologies are best at any point in time.” Both Clarke and Searle say that how long it will take for widespread adoption of this approach depends as much on the policy environment as on the technology, but they are focussing their efforts on what is possible and closing the gaps between research, commercialisation and mass production.

One product already commercially available is the active-office roof. It uses a thin-film made from CIGS photovoltaic cells which are pre-bonded onto metal sheets. More flexible than traditional solar panels, there are added benefits for design and construction. It frees up the architect to “move away from linear lines to curves” says Clarke: “There is no need to pierce the roof and as the thin-film photovoltaic is lighter this means that the building structure can be modular and built off-site,” making construction cheaper and quicker.

The TSC on the wall of the active-classroom. Source: Hilary Guite.

Another commercially available product is the TSC, Transpired Solar Collector, which clads the building. This is a sealed metal box, perforated at the front, which absorbs the heat from sunshine, even in low levels of light, and passes that heat onto outside air as it is sucked by a fan through small perforations into the cavity behind. Searle says, “Combining this with an air-source heat pump is what is new.” Pre-heated air from the TSC is used to improve the efficiency of the heat pump to provide both space heating and hot water. Different solar thermal technology is also able to store any excess heat for use at a later point in time within a thermal store.  Searle reports a frequent comment they’ve had is that the active buildings feel fresh and airy, related he thinks to the TSC’s frequent fresh air exchanges.

New to the market is a window that is also a solar panel. Made from silicone strips bonded onto glass it is, “like horizontal blinds that you can see through,” says Clarke. They generate small amounts of electricity but she sees the potential: “Most big office buildings are all glass. Imagine the amount of energy you could generate.”

Window coated with solar strips. Source: Hilary Guite.

The technology uplift costs, those costs needed to make the buildings able to capture the sun’s energy, have come down from 20% to 10% between building the active-classroom and the active-office. Both Clarke and Searle, think they will come down further when higher levels of production are involved. Searle says in addition new business models, policy and legislation are needed. He believes that real world data from demonstrator buildings like the active-office will help to influence these things and “accelerate market adoption”, hopefully leading to more buildings turning into power stations in the future.

Dr. Hilary Guite is studying for an MSc in Science Communication at Imperial College London

Banner image: Battersea Power Station from the river, Alberto Pascual / Wikimedia Commons