Automobiles get a lot of attention in our quest to become a more efficient society. Ironically, it is not our cars, but our homes that have the greatest energy-saving potential. And, given the long life expectancy of buildings, which often stand for decades or even centuries, it is especially important to make sure the ones built today ate done so to the highest possible environmental and efficiency standards.
A lot of the energy used in typical homes is simply expended to 'excite' air or water molecules to become warm or cool. How these molecules achieve, or remain in, ah excited state depends almost entirely on the standard of the building's appliances and how well it is insulated. For most houses already standing, as well as those being built today, there is still much room for improvement.
"The energy use in houses results in between 20 per cent and 25 per cent of all emissions of carbon worldwide ... Energy-efficiency measures can cut [consumption] in houses by 40 per cent or more," said Mark Levine, director of the Environmental Energy Technologies Division of the University of California at Berkeley, and an expert in energy-efficient buildings. "There is no other approach that has the potential to reduce carbon emissions nearly as much in a cost-effective manner," he added.
The house of the future is here ... and already decades old
The first energy-efficient buildings were constructed around 30 years ago, when the oil crisis of the 1970s made Europe's dependency on imported energy startlingly apparent. A new architectural mentali in ah tion of 50 per cent in Switzerland, according to the Neue Zurcher Zeiting (NZZ). The reduction was primarily due to improvements in boiler technology and tightened cantonal building codes relating to insulation. However, it was not until 1990/1991 that the country's first so-called 'zero-energy building' was erected in Widenswil, Canton Zurich.
Raising the bar
Since 1994, the Swiss MINERGIE[R] lablel has categorised energy-efficient housing. The federally regulated Swiss standard currently demands new buildings consume a maximum of 110 Kwh/m2a (see sidebar), down from an average 250 kwh/m2a in the 1970s; whereas the standards for M1NERGIE"-certified and 'passive' houses are 42 Kwh/m2a and 15 Kwh/m2a respectively: a dramatic difference.
Zero-energy buildings take efficiency one step further by covering or compensating for all of their energy needs through renewable energy sources (e.g. sun or wind).
What makes a house 'passive'?
The expression stems from the notion that such a house does not require active climate control via energy-consuming heating and cooling systems. Passive houses recycle and retain existing energy instead. In addition, they use renewable energy sources like solar and geothermic (also called...