PrepTest 124, Section 2, Question 7
In Western economies, more energy is used to(90 more words not shown)
On which one of the(6 more words not shown)
- ATechnology used to(13 more words not shown)
- BAnother oil crisis(9 more words not shown)
- CBuildings will gradually(9 more words not shown)
- DEnergy bills in(14 more words not shown)
- EEnergy-efficient technologies based(14 more words not shown)
Reading the argument
The technology is saving money now. How do we know what it will save a century from now?
More efficient lighting, heating, and ventilation have cut energy bills. I'm happy to accept that success. But the author moves from several billion dollars in current annual savings to more than $200 billion in annual savings 50 to 100 years from now. A lot can change in that time.
Energy use could change. Energy production could change. The technology itself could change. Today's savings don't by themselves establish the much larger future figure. We need to ask which conditions the author is relying on to keep this projected benefit possible.
What we’re looking for
This is a necessary-assumption question, so we want something the reasoning needs, not just something that might help. My concern is a future change that would undermine the savings. The author doesn't have to insist that everything stays exactly the same; the needed assumption should rule out a change that would defeat this particular forecast.
Working the answers
- ACorrect
The technology cannot become so expensive that using it is financially out of reach. The forecast depends on buildings obtaining savings from these efficiency measures. If the measures become prohibitively expensive, the author can no longer simply project those benefits into the future. This addresses our concern about a future change undermining the savings. It doesn't claim that any increase in cost would erase every benefit.
- B
The earlier oil crisis helps date the past decline in energy consumption. That doesn't mean another crisis is required for efficient buildings to save money. The savings could continue without a repeat of that historical event.
- C
Buildings could keep consuming more energy than transportation and still save a great deal through improved efficiency. We need the efficiency savings, not a reversal in which sector consumes more energy. The ranking doesn't have to change.
- D
Saving $200 billion is not the same as having bills $200 billion lower than today's bills. What if a growing population uses many more buildings? Total bills could rise while efficient technology keeps them $200 billion below what they otherwise would have been. The conclusion concerns money saved through efficiency, not a required decline from today's total.
- E
Improvements needn't rest on new scientific principles. Existing principles could support wider use or better versions of current technology. The author predicts large savings, but doesn't need this particular kind of scientific development for the reasoning to work.
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