Building Challenges: Energy Efficiency

Urban Crossroads #101

 

 

The Arab World Institute building in Paris incorporates motor-operated windows that open and close to control the entry of sunlight into the building. © Pascal Maréchaux/Aga Khan Trust for Culture.

This is the first of a few articles that discuss challenges facing how we build, whether on the scale of an individual building or a complete city. They are challenges that affect countries throughout the world, both rich and poor, though each in its own way.

I will start with the challenge of energy efficiency. Although estimates vary, it is reasonable to state that about a third of energy consumption worldwide is connected to buildings, primarily for heating, air-conditioning, and ventilating them, as well as for lighting them and powering the electrical appliances they house.

On the urban level, transportation requirements take up a significant amount of energy. We generally devote about a quarter of our energy consumption to various forms of transportation, whether land, sea, or air, and a good percentage of that overall consumption is taken up by movement in the city.

So much of the world’s energy consumption therefore is devoted to satisfying the direct needs of living in buildings and moving between them. Achieving meaningful reductions in energy consumption accordingly will depend on how we address these needs.

For the longest time, it had been possible to only pay minimal attention to the subject of energy consumption, but that is changing for two reasons. The first is environmental. Since almost all our energy consumption comes from burning fossil fuels (primarily oil, gas, and coal) rather than from clean renewable energy sources (such as solar, wind, hydroelectric, and geo-thermal), and since energy consumption continues to increase worldwide, the result is higher levels of air pollution and global warming, both of which are connected to a wide range of adverse phenomena that include rising sea levels, the rapid spread of diseases, and significant climatic instability.

The second reason why we cannot ignore increasing levels of energy consumption is the price of conventional energy. Energy prices have soared over the past decade, and it seems they will continue to rise as emerging economies, led by China and India, undergo significant economic growth, thus becoming major energy consumers. At the same time, existing as well as newly-discovered fossil-fuel reserves most likely will not be able to keep up with the rapidly-increasing rates of energy consumption. Because of this discrepancy between supply and demand, we all are feeling the pinch. In Jordan, a common subject of conversation to have emerged over the past few years is the latest price of gasoline, diesel, and heating fuel. This is not surprising considering that the costs of heating and lighting buildings as well as transportation are eating up sizable portions of household and business budgets in the country.

So the subject of energy conservation in buildings finally is assuming increased importance (I will discuss the subject of transportation in a subsequent article) and addressing it is becoming a necessity rather than merely an expression of an environmental ethic embraced by a small number of environmental enthusiasts. There are numerous relatively straightforward and well-established design and construction interventions that can significantly bring down a building’s energy consumption. These include limiting the number and size of window openings, directing them towards the south, and protecting them from the sun’s rays through overhangs. Also important is the use of materials with high insulating qualities that may be placed inside walls and roofs such as polystyrene, rock-wool, or fiberglass, and before that, straw bale. In the case of windows, not only should they be well-sealed, but should also use double-glazing, which is far more effective in preventing heat flow between inside and outside than single-glazing. Even painting building roofs with a light color can help deflect heat gain in the summer months.

In addition, the more units (apartments, office suites …) are placed within a single envelop, the better. Accordingly, a dwelling in an apartment building, which is “protected” by other apartments from above, below, and the sides will consume less energy than a free-standing single-family house of an equivalent size. Furthermore, placing solar energy panels on buildings, whether for heating water or generating electricity, allows the buildings to create energy rather than merely consume it. Finally, plants can play an important role in helping conserve energy in buildings through providing shade from the sun and a barrier against cold or dust-carrying winds.

These are just a few methods through which energy efficiency in buildings has been and continues to be achieved. They are effective and work well. Unfortunately, most did not bother to incorporate these solutions as long as energy was cheap. I think of my own apartment, which my parents and I built back in the 1990s as a second-story extension to their house. The issue of energy conservation in fact was on our mind. We therefore did include insulation materials in the walls and roofs. When it came to double-glazing for windows, however, the price differential was high enough to convince us to go with single-glazing instead. When oil was selling at about ten dollars a barrel, achieving short-term savings trumped planning for long-term ones. However, as the price of oil has multiplied a number of times since then, putting considerable initial investments in creating energy-efficient buildings started to make a great deal of sense.

In exploring methods that maximize energy efficiency in buildings, we also need to take advantage of new technologies, particularly developments in computing technologies. For example, it is within our ability today to create “movable skins” for buildings that function as protective thermal layers, as with layers of clothing. Sensors connected to movable shading devises would continuously measure temperatures, and accordingly move those shading devises to cover windows as well as other building surfaces in order to control the amount of heat that enters or exits a building. These movable layers may even incorporate photovoltaic cells to transform light into electricity. The first prototypes for such systems will be expensive, but their prices will go down as they are produced in large quantities, and the energy savings they will bring about will contribute to making them cost effective.

The famed French architect Jean Nouvel made a very preliminary attempt at creating a moving building skin in his 1987 Arab World Institute in Paris. The building’s southern façade is sheathed with motor-operated windows that open and close to control the entry of the sunlight. These windows are inspired by the mashrabiyya (the lattice-like window screen common in the architecture of numerous sun-drenched parts of the Islamic world), but also are intended to function in the same manner as a camera lens aperture, which may be widened or narrowed to control the amount of light that goes through it.

The windows of the Arab World Institute provide a mere glimpse of what may be accomplished in terms of protective movable buildings skins. Such technologies have the potential to completely transform how buildings are constructed, how they look, and how they interact with prevalent climatic conditions. Unfortunately, very little has taken place in terms of developing novel building technologies for over a century, when innovations such as reinforced concrete and structural steel were introduced, and which, for better or worse, transformed how buildings are made. The knowledge required for introducing cutting-edge technologies into the building process exists. What we need are innovative, resourceful people with the necessary skill and creativity to transform that knowledge into an everyday reality.

Mohammad al-Asad

February 04, 2010

 

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