Turning down the thermostat on HK's crazy air conditioning

PUBLISHED : Wednesday, 19 May, 2010, 12:00am
UPDATED : Wednesday, 19 May, 2010, 12:00am

On a recent visit to Hong Kong, one British-born engineer found himself bemused by what he saw - and heard - going on around him in Queen's Road, Central.

'This is crazy, just crazy,' he hollered, raising his voice to be heard above the roar of air-conditioning plants from the nearby buildings. 'It makes no sense at all.'

What confounded the visiting engineer was not Hong Kong's language or cuisine, but the ferocity of its air conditioning, which is often set to chill our offices and shops to a frigid 18 degrees Celsius.

To put that degree of cooling into perspective, it's as cold as Hong Kong's daily average temperature in the middle of winter, when many of the city's inhabitants only venture outside wrapped to the gills in the full accoutrement of coats, hats, scarves and gloves.

Maintaining such wintry interior temperatures even in the height of summer creates problems.

As our engineer explained, when it's hot outside, air-conditioning plants have to work that much harder in order to keep the air temperatures inside our buildings down.

Of course running air conditioners at full tilt like that uses up a lot of energy. And because air conditioners are simple heat-exchange mechanisms, it also generates an awful lot of hot air, which is pumped out into the surrounding environment.

The trouble is that pumping out hot air raises the external temperature even further, which means the air conditioners must work even harder to maintain a stable temperature inside.

That uses more energy, and generates more excess heat, which is then pumped out into the environment, raising the temperature of the immediate surroundings yet more.

The results of this madness are sky-high electricity bills and the so-called urban heat-island effect, which according to the Hong Kong Observatory raises the temperature in the city's streets by as much as 4 degrees above where it would otherwise be.

What is worse is that this effect is exacerbated by Hong Kong's urban planning policies.

Slab-like monolithic buildings create towering walls which shut out breezes from the harbour and block all air movement, turning our streets into fetid canyons choked with diesel-exhaust fumes that cannot escape.

Unfortunately, two new government initiatives intended to tackle the problem show few signs that they will get to grips with the underlying issues.

Part of the trouble is that government policy has long focused on generating revenue from land sales instead of on creating a pleasant city for people to live and work in.

So, for example, in order to maximise the number of plots that can be sold, private developers are required to incorporate public facilities like bus stations into new projects in return for concessions on extra gross floor area - a policy which results in ever taller and bulkier buildings.

Aware of public misgivings, the government's Council for Sustainable Development has invited comments on gross floor-area concessions. But according to a new paper published by independent think tank Civic Exchange and sponsored by the Hong Kong Real Estate Developers Association, the scope of the government's consultations is not nearly ambitious enough.

Instead of looking at new developments on an individual basis, Civic Exchange argues that the government needs to approach planning on a neighbourhood scale, allowing for ventilation corridors between buildings and more open space - the current standard is just 2 square metres per person, roughly the size of a grave plot - to reduce the heat-island effect.

'Open space is the most important thing for keeping city centre temperatures down,' agrees Ian Brownlee, a former Lands Department official, who advocates removing 16 city centre sites from the government's application list for land sales and turning them into parks. Perhaps surprisingly, the developers' association supports his idea.

Similarly, the government's second initiative, its proposed Building Energy Efficiency Bill which sets minimum design standards for new buildings, is a nod in the right direction.

But again, the proposed measures lack ambition. For one thing, the government's bill only sets standards for building designs. It says nothing about their commissioning and operation.

That's self-defeating. It is pointless demanding that buildings are designed to be energy efficient if you then fail to ensure they are managed efficiently. It's no good demanding that the windows are made of special insulating glass, if the doors are then left open to blast cold air into the street.

Extending the requirements to encompass commissioning and operation could result in energy savings of 30 per cent, argues Civic Exchange, well worth the extra expense and effort involved.

Secondly, the proposed bill only covers new developments, which leaves some 98 per cent of Hong Kong's buildings unaffected.

Civic Exchange argues that the bill should be broadened to cover the energy performance of all buildings, with blocks given energy-efficiency labels just like kettles, and regular audits conducted to monitor performance.

That sounds onerous, but Mike Kilburn, environmental programme manager at the think tank, points out that other jurisdictions, including Singapore, have introduced similar schemes. An equivalent system here would create a thriving market in energy efficiency and generate significant energy and cost savings, he says.

Implementing these proposals would require a major change of mindset among Hong Kong's officials. But taken together, they could help to alleviate the heat-island and canyon effects and to reduce the air-conditioning craziness which so offended our visiting engineer.

As a result, Hong Kong could become a far more pleasant place to live. The effort would be well worth it.