Electromagnetic Savannah
Commentary on science, technology and economics in Nigeria and beyond

Thursday, March 29, 2007

Green buildings to "slow global warming"

There's this story I just saw today which reports the result of a UN study which says that "better building design could have an important role to play in slowing down global warming". The two main areas in which there's heat usage is by heating and lighting, it says. Well, the good old energy-wasting incandescent light bulb is being seriously challenged by the energy-saving compact fluorescent light bulb in terms of usage - the latter has come down quite a bit in price over the last few years from about 13 dollars in 1990 to under 3 dollars today. But reducing energy wasted on heating is another matter... it costs quite a bit to insulate houses, so it's not as easy to adopt measures to 'greenify' your house heatwise as it is lightwise.

But surely, Nigerians don't have the same problem of needing insulate their houses to conserve heat? If anything, they have damned too much of the stuff - I'm sure more than one person has wished they could package the excess heat, export it to colder climes and make a goodly amount of cash the process. Well, insulation works both ways - it keeps the warmth inside from escaping into the cold outside, and it keeps the heat outside from getting into the coolness inside. Except that in the kind of tropical temperatures you find in Nigeria, it's more a case of keeping the searing heat outside from getting into the blazing heat inside. In other words, insulation may help to lower the ambient temperature inside, but it doesn't lower it enough.

There is of course the option of using air-conditioning, but that is extremely energy-hungry. Of course, there's always the option of using the less energy expensive
evaporative cooling option - but even this only works well in dry regions where water evaporates quickly enough to provide a cooling effect. So, if you can't keep the heat out, and it's too costly to keep the heat down through air-conditioning, you can always opt for natural cross-ventilation. Unlike the temperate regions in Europe where the direction of the wind is unpredictable from day to day, most of Africa is swept by trade winds which tend to blow in a fairly consistent direction - they're either north-easterly or south-westerly (above the Equator). This means that buildings can be designed so that their windows open to these directions so that the winds blow through the buildings and help to cool the interior.

Of course, you can have too much of a good green thing - witness the following dialogue:

Stinkingly Rich Big Man: Yes, so Mr. Architect, you say you've finished the design of my grand mansion?

Environmentally Conscious Architect: Indeed, Chief. You'll be glad to know that I've incorporated the very latest eco-principles in this design so that your house is truly green!

SRBM: Hm... I don't know about that. I want my house painted pink and purple like the house of my friend, Chief Kanganka O. Kanganka.

ECA: No, what I mean is that it will have a minimal footprint on the environment.

SRBM (getting perturbed): I'm getting confused at your talk of green footprints. I haven't asked for a walking house. All I want is a big mansion.

ECA (flustered): All right... well, let me take you through the design. As you can see, this is the living room - notice how there are large windows on opposite walls and how room is oriented to take maximum advantage of the natural ventilation.


SRBM: OK...

ECA: And next to the living room, we have the dining room which also has large windows and is oriented to take advantage of the natural ventilation.

SRBM: Yes...

ECA: And next to the dining room, we have the kitchen which also has large windows and is oriented to take advantage of the natural ventilation.

SRBM: Wait... so I have to walk through the dining room from the living room to get to the kitchen?

ECA: Yes... but it's necessary in order to maximise the natural ventilation.

SRBM (somewhat disgruntled): OK, carry on...

ECA: And next to the kitchen, we have the master bedroom which also has large windows and is oriented to take advantage of the natural ventilation.

SRBM (annoyed): Wait! What are you telling me? That I have to walk through the kitchen to get to my master bedroom?

ECA (stammering): Y-yes... but that's a small price to pay for a comfortable environment. Think of the cool breeze you'll be enjoying every night in your bedroom.

SRBM (still annoyed): Well, I think it's a high price! I can't be stumbling through pots and pans to get to my bedroom. In fact, the only thing more annoying than that would be to have people stumbling through my bedroom to get to somewhere else.

ECA (hesitantly): Er... well, actually, I was just going to talk about the other bedrooms which will be next to yours and which will oriented to take advantage of the natural ventilation... but perhaps we've already got too much natural ventilation in the house as it is. Maybe I need to think some more about this. (Gathers papers hastily and departs.)

Perhaps what would really be cool is if we had smart buildings which were like valves - they supported a unidirectional flow of heat so that heat was allowed to flow out of the building, but wasn't allowed to flow in. Somehow, I suspect we're still some way away from that kind of technology...

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1 Comments:

  • The use of Insulating Concrete Forms (ICF's) in buildings can also lessen the impact of global warming. It can't be used for all buildings though....the tallest building I've seen with this building method is a 3 storey building.

    If I were in SRBM's shoes, I'll probably not want the ECA's design :-)

    By Blogger Nilla, At 30 March 2007 at 06:00  

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