It is one effort to make Hong Kong buildings 'greener' in the face of increasing world pressure to cut energy use and thereby help slow global warming, slow the build-up of construction waste that otherwise fills landfills and improve or reduce material use in the initial building. The university has set up a Centre of Renewable Energy looking into various forms of natural energy sources.

The team is studying different types of panel, called photovoltaic cells, in which semiconductors absorb light energy and convert it to electric current. They vary from a traditional silicon type to newer versions that incorporate unusual compounds such as cadmium telluride and copper indium diselenide. The silicon versions work well in laboratory conditions - cool temperatures, bright light - but poorly in the high temperatures that Hong Kong roofs experience, while the newer materials absorb light across more of the spectrum and are more robust than silicon in hot, humid conditions.

Initial findings look promising. 'You can get between 100 and 400 Watts per square metre,' says Dr Lo - enough to light and air-condition a room even when it's raining. And they are ideal for Hong Kong and the region, where use of electricity rises to a peak for air-conditioning when the sun shines.

Solar panels are better used not on the roof but as part of the structure of glass-covered buildings.

The team plans to fit panels above windows and on the roof of a student residence under construction, Graduate House, designed by architect Rocco Yim. The window panels can play a dual role, supplying electricity and shading the rooms.

As an architect, Mr Yim says his aim is also to show they do not have to be ugly.

There is little push for developers to incorporate energy-saving measures - which cost - when they are not the ones paying the bills. But Mr Yim and Ms Close say developers will move that way as tenants become aware of running costs and ecological concerns.

The Government has shown interest in the project, with visitors including Secretary for Planning, Environment and Lands Bowen Leung Po-wing and his principal assistant secretary Steve Barclay, electrical and mechanical services department director Hugh Phillipson and members of the Energy Efficiency Office. Yet the Government-administered Environment and Conservation Fund, criticised earlier this year for only spending about $14 million of its $50 million capital in three years, gave the researchers only $330,000 of a requested $8 million, leaving the group searching for cash to fit the panels to Graduate House.

Commercial backers should be sought since the panels have 'enormous commercial potential', says Mr Barclay.

Ms Close says Hongkong Electric is interested in the work and funding talks are ongoing.

But while the Schemes of Control direct power companies to make profits through building more power stations to serve demand peaks - just the sort of peaks that solar panels can slice off - there is little incentive for them to promote such technology.

The Government is negotiating with the utilities companies over 'demand-side management', in which users and providers both benefit from a cut in peak usage. An agreement is expected by the end of the year.

The power from the solar panels can be stored in a battery for later use, but it is far more efficient to push it back into the grid.

Yet while green buildings are on the agenda of conferences about every month in Hong Kong, few are actually built. Energy use is the most major environmental impact, yet still architects allow for and developers slap in more air-conditioning units - which use about 80 per cent of the building's energy - than are needed.

The only environmental building requirement covers Overall Thermal Transfer Value, which limits heat transfer through the exterior to 35 Watts/square metre. But it has been criticised because it does not cover total energy use. The figure is not stringent, but a concerned developer can fit tinted glass, leading to extra lighting and consequently air-conditioning to counteract the lights' heat.

Building regulations do not encourage sunshading since the area of the ground covered has to be paid for as part of the plot. There is no push to do better because developers do not know what clients they are building for, so they allow for the situation of heaviest energy use, and there is no demand.

A code drawn up by the Real Estate Developers' Association with the Centre of Environmental Technology, the building environmental assessment method aims to change some of this. Buildings are assessed on various criteria, from global concerns such as use of timber, through local issues such as noise, electricity use and waste disposal, to indoor concerns such as metering equipment, indoor air quality and lighting.

So far 10 buildings, such as the Hongkong Bank Building, have been assessed. All passed. Because it is voluntary, no building unlikely to meet the grade will be put up for inspection; but the idea is that eventually tenants will demand such quality, and pay a premium accordingly.

Citizens' Party environmental researcher Lisa Hopkinson says it is a good start. She is considering ways developers can be persuaded to think greener: on her list is the idea of cutting the land premium for ecologically sound designs, or a suggestion from US energy guru Amory Lovins that a median energy use can be calculated for a type of building, and those that use more pay a 'fine' while those that use less get a rebate on their bills.

The biggest push will come from more environmentally-aware clients. But Hong Kong has a long way to go.