Are high-rise buildings the future for Dublin?
NO:
The age of skyscrapers is at an end. It must now be considered an experimental building typology that has failed.
Let's pretend you are choosing a new flat in a city location. What is the maximum number of storeys that that building should be if you want to remain comfortable and safe in that building over time? The world is getting warmer and the fourth report of the Intergovernmental Panel on Climate Change, published last April, is much more alarming that the first three.
On top of that, oil will be really expensive by 2020, because we have now passed the peak of oil production for global supplies.
The last place in the world that you want to be when the lights start going out in an extreme weather event like a violent storm or a heatwave is 20 stories up in a glass tower!
I give a wide range of good reasons why we should never build tall buildings again in the book, Adapting Buildings and Cities for Climate Change: A 21st Century Survival Guide. The height of a building affects its internal climate. It has proven nigh on impossible to prevent all south-facing apartments in high-rise buildings from overheating in summer, and all north-facing ones being cold in winter due to radiant gains and losses.
A building develops its own internal micro-climate, and heat from the lower floors will rise by natural buoyancy, making the higher floors hotter. The higher the building, the greater this problem of thermal stratification, and the more energy has to be thrown at cooling the upper floors. Tall buildings, by their very nature of being tall, can use twice as much energy as equivalent low buildings.
The higher the building, the more it costs to run, because of the increased need to raise people, goods and services, and also, importantly, because the more exposed the building is to the elements, the more it costs to heat and cool. The higher the building, the higher the wind speeds around the building, the more difficult to keep it out, and the more the wind pressure on the envelope sucks heat from the structure.
The higher the building, if standing alone, the more exposed to the sun it is, and the more it can overheat. And hence the higher the building, the more it costs to keep the internal environment comfortable.
With increasingly poor standards of environmental design, including widespread excessive use of glass and rapidly increasing levels of equipment use, in particular of computers, air conditioning becomes more and more essential. Air conditioning can quadruple energy costs at a stroke, giving them a disproportionately high carbon-emitter status, at a time when carbon taxes for homeowners are being spoken of.
So on top of high running costs, homeowners would also have to consider that they may have to pay far higher carbon taxes associated with high-rise buildings in the future.
The bottom line is that the cost of conventional energy will soar over time and glass towers are the most expensive buildings on earth to run, with their lifts and the water pumping and the fact that they need much more heating and cooling, being stuck up there, exposed to the worst of the sun and the wind and the cold.
Who knows what global economies will do in a fossil fuel-challenged future - but you certainly cannot run a glass tower on renewable energy. For example, the geometric properties of towers make it difficult to utilise solar hot-water systems for occupants because of the low ratio of the external building surface area to the number of occupants.
The lights in cities around the world are going off more commonly every year and you should choose a flat to which you can easily carry a bucket of water to and walk down from comfortably to do your shopping when the power in your neighbourhood does fail. And don't forget that the home should remain tolerably comfortable, even in extreme weather when those lights do go out.
It is difficult to understand exactly how different the 21st century will be from the last 100 years, but the smart money won't go aloft in the future - not least because smart money does not want to live in a "target building" since 9/11.
If you were thinking of buying the "full-view" penthouse on the 40th storey of a new tower, with fixed windows and central air conditioning, do your children and yourself a favour.
Think again, because it is likely to be a bad investment in the short, medium and long term too. Play safe, because you will need to in a rapidly changing 21st century.
Sue Roaf is visiting professor at Arizona State University and at the Open University. She is an author of numerous books and academic papers, an Oxford city councillor and works with the Green Consultancy and the Carbon Trust.
