Fluid Thinking

3 April 2006 (Last Updated April 3rd, 2006 18:30)

A new form of glazing and cladding with 'variable' insulation can save both energy and money, claims Frederick B McKee, managing director of McKee Fluidized Glazing, in conversation with James Leavey.

Fluid Thinking

Dr Frederick B McKee is a name worth remembering: he has developed a unique glazing and cladding system that he claims will not only slash building costs and fuel bills but also significantly reduce the world's energy consumption. McKee, a UK-based engineer, and managing director of McKee Fluidized Glazing, has invented a way to keep buildings warm in winter and cool in summer by using windows filled with water.

FLUIDISED GLAZING AND CLADDING

'Fluidised glazing and cladding will be to the construction, glass and building industries what the jet engine was to the aircraft industry,' says McKee, who for the past 14 years has worked on all aspects of this revolutionary new technology. A former senior scientist/engineer with Marconi Research for 20 years, McKee was also a former managing director of Dunlop Solaronics Ltd and a consultant to Loctite, Saint-Gobain and Vegla.

'The fluidised glazing and cladding technology is particularly relevant at the moment,' says McKee, 'due to concerns about global warming, climate change and the production of greenhouse gases, which are mainly produced by burning nature's waste product - fossil fuels. It is also down to the stupidity and ignorance of the most intelligent beings on the planet, who have extracted this waste product because it burns easily with oxygen, releasing large amounts of thermal energy, CO2 and other polluting products into the atmosphere - just what nature has long tried to avoid.

"The skin's the thing for conserving energy"

'My new fluidised system is based on the premise that, at any given time, there can be a maximum of only two facades of a building absorbing direct solar energy, at quite large angles of incidence and with all facades absorbing lower levels of diffuse radiation, while all of the building's facades are losing energy by convection and radiation. The absorption area is much smaller than the area of loss.'

REVOLUTIONARY TECHNOLOGY

McKee's revolutionary system is based on a building feature that has until now been largely untapped: double-glazed windows. But instead of the usual air in the cavity between the two panes of glass, his system pumps water containing a chemical between the two panes.

Another version uses a second double-skinned panel on the inward facing surface separated from the first by thermal insulation, through which a second aqueous fluid is pumped, providing 'variable' insulation, so that the system effectively becomes triple-glazed, or triple-clad. In summer, the chemical in the water absorbs infrared energy, and with it heat from sunlight, without actually blocking the light. The water is then either circulated through a heat exchanger to thermal energy storage, which stores the heat for later, or redirects it to other parts of the building.

'The result is 90% to 98% energy saving compared with conventional buildings,' says McKee. 'Not only that, the capital cost of a fluidised building could be up to 24% less than conventional building costs. The building would not need additional cooling or heating, the colour of the building's facade could be changed at will, photovoltaics are now a viable renewable energy source and, best of all, there is zero CO2 pollution.'

SKIN CARE

In recent years, Professor Spiro Pollalis of Harvard University and other experts have suggested that a third to half of the world's energy is consumed by buildings. 'The skin's the thing for conserving energy,' says Pollalis.

Generally speaking, McKee agrees with Pollalis's view. 'But with modern offices and many industrial buildings, cooling can require more energy to be expended than that used for heating,' he explains. 'It has been said of a building by Lord Foster that, "the envelope is the temperature control element - analogous to the human skin, it separates the interior from the exterior."'

It certainly separates the two, but even by using the most advanced conventional glazing and cladding materials, 'skins' cannot control a building's interior temperature. In fact, it usually stops the transfer of heat to and from the building, which then has to be accomplished by other expensive and energy hungry cooling and heating equipment.

By simply controlling the surface flow in the 'skin' and the flow in the building's interior, the bi-directional energy transfer of the building can be fully managed. Also, the building's optical, insulation and aesthetic properties may be varied, over wide ranges.

"A third to half of the world's energy is consumed by buildings."

This is something that no other glazing or cladding facade construction can achieve, no matter how advanced or sophisticated. 'That said, it must be stressed that the fluidised glazing and cladding system is not a solar heating system as such. However, quite secondary to its main function, solar energy absorbed by the fluidised facades may be used for heating the building, when required.'

'The fluidised glazing and cladding system uses the vast available surface area of the building "skin" to cool and heat its interior, using only the small amount of energy required to pump fluid around the facades and interior, with natural dissipation of energy from all of the building's "skin".'

INTERIOR TEMPERATURE CONTROL

'With fluidised systems, the interior temperature of the building can be controlled and maintained at a constant level of, say, 22ºC throughout the year in over 85% of the developed world. Also, the fluidised system is active, not passive. It has memory, and may be temporal in action. In other words, energy exchanges do not have to take place at the same point in time.'

For fenestration areas, McKee's fluidised glazing consists of a glass fluid cell through which an aqueous fluid is pumped. 'The spectral characteristics of the fluid-glass combination are designed to approximate those of the human eye,' explains McKee, 'and so fluidised glazing appears to be transparent, and transmits large amounts of visible light. Yet it intercepts and absorbs most of the incoming solar radiation and outgoing infrared radiation from the building.'

'To provide adequate thermal insulation, an air or gas space and a third piece of glass are added to the room, or the interior side of the fluid cell. Solar control coated glass may also be used to considerable advantage in combination with the fluid cell, resulting in a double-glazed unit consisting of fluid cell air space glass, with radiant heat transmission less than 50% of the best available solar control double-glazing. Light transmission is high, around 50% to 60%. Heat energy transmission may be lower than 5%, while light transmission is sacrificed a little. And sound transmission is very low.'

RADIATION INNOVATION

According to McKee, this revolutionary new system means energy can either be used or dissipated. 'Direct solar radiation affects two facades, if that, for less than half a day,' he says, 'whereas thermal and radiative losses are from all facades 24 hours a day; and the available losses may far exceed the solar and internal gains of a building. With the fluidised system, solar energy is not reflected away but used when it is required and thermally and radiatively dissipated from all facades when it isn't.'

"McKee's new fluidised system could easily shake the building design industry to its very foundations."

Another bonus, according to McKee, is his system's 'unique' ability to solve condensation problems, especially in swimming pools and conservatories. 'At thermal equilibrium, the temperature of a body is such that the power absorbed equals the power lost,' he says.

With all other characteristics being constant, the equilibrium temperature is therefore solely dependent on the ratio of two areas: the area of absorption of energy to the area of loss of energy, which is obviously one for all solid window and cladding structures.

By using the normally very large surface area of a building, the natural law of thermal equilibrium temperature and the less well-known law of area dilution may be used to enormous practical advantage, as in the technology for zero energy building enclosures.

There are several examples of this, he says: 'By hydraulically connecting fluidised glazing and/or cladding panels on the north, east, south and west facades, the relative area available for losing energy is greatly increased, while the area of absorption remains relatively small. The result is that the temperature for thermal equilibrium and the fluid temperature are very much lower than for passive structures - in fact, only a few degrees above ambient and in most cases below human skin temperature, even on sunny days.'

'At night, when there is no solar energy to be absorbed, the fluid equilibrium temperature falls several degrees lower than the night-time ambient, due to radiation loss to the sky. This night loss is significant and can be used to cool the building's interior during the day. The Arabs have used sky radiation to make ice for centuries.'

A FLUIDISED FUTURE?

Meanwhile, McKee's new fluidised system for environmental control has been patented in most countries. If it is widely accepted and introduced, it could easily shake the building design industry to its very foundations. 'The result of introducing the fluidised system would be intelligent buildings that react autonomously not only to the world around them but also to the people and equipment within them,' says McKee.

Some time ago, McKee demonstrated his fluidised technology in some detail to a number of Arup's technical staff, including Professor Mike Holmes, a specialist in energy use and conservation in buildings. Arup was happy to confirm its 'ongoing interest' in McKee's fluidised glazing system. 'I am sure that given the right project and client, it would have a major impact on the overall performance of a building,' says Neil Noble, director and leader of Arup's research and development.

'Although we are not able to invest in a project like this, we would be keen to assist with the design development, as part of team. If, for example, you are able to get one of the major curtain wall or cladding manufacturers interested, we would be able to provide you with a design service to get the product to market.'

According to McKee, one of the reasons his fluidised system hasn't taken off yet is that some people think it is too good to be true. 'But all the evidence shows that it's not,' says McKee. 'What it now needs is a construction company with the vision to take it on.'