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Difficulty: HardWeakening Arguments

To reduce peak summer energy demand, municipal planners in Ardenton mandated high-albedo reflective roof coatings for all commercial warehouses. In trial runs, warehouses with these coatings experienced a 20 percent drop in interior roof-level temperatures, leading to a 15 percent decrease in air-conditioning energy consumption. City officials now conclude that extending this mandate to all single-family residential homes will achieve a similar 15 percent reduction in total residential cooling energy consumption during summer months.

Which of the following, if true, most seriously weakens the city officials' conclusion?

  1. A
    Installing reflective roof coatings on residential homes requires specialized safety equipment that increases upfront application costs relative to commercial warehouse installations.
  2. B
    Residential air-conditioning units in Ardenton consume significantly more electricity per degree of interior temperature reduction than commercial cooling systems do.
  3. The vast majority of single-family residential roofs in Ardenton are heavily shaded throughout the summer by dense, mature tree canopies.Answer
  4. D
    Residential energy consumption for space heating during winter months in Ardenton has increased steadily over the past decade.
  5. E
    Commercial warehouses in Ardenton account for a larger proportion of the city's total peak summer electricity usage than single-family residential homes do.

Answer

The statement that the vast majority of single-family residential roofs in Ardenton are heavily shaded throughout the summer by dense, mature tree canopies.
The argument relies on an underlying assumption that single-family residential roofs exposure to sunlight is functionally similar to that of commercial warehouses. High-albedo reflective coatings work by reflecting direct solar radiation away from a structure. If single-family residential roofs are heavily shaded by dense tree canopies, direct sunlight does not hit the roofs in significant quantities. Consequently, applying reflective coatings will yield negligible temperature drops and fail to achieve the predicted 15 percent energy reduction.

Step-by-Step Solution

1
Identify the argument's premises and conclusion.
Premise: Reflective coatings on commercial warehouses reduced interior temperatures and led to a 15% reduction in cooling energy consumption. Conclusion: Extending the coating mandate to residential homes will achieve a similar 15% reduction in residential cooling energy consumption.
Understanding the precise link between evidence (warehouse trial) and claim (residential outcome) highlights implicit assumptions.
2
Identify the logical vulnerability in applying warehouse trial results to single-family homes.
The argument assumes that residential roofs receive comparable direct solar exposure and respond similarly to reflective coatings as commercial warehouse roofs.
Weakening questions require finding evidence that breaks the transferability of trial results from one setting to another.
3
Evaluate the option choices to find a relevant factor that disrupts the mechanism of action.
The statement noting that residential roofs are heavily shaded by tree canopies demonstrates that solar radiation rarely hits these roofs directly, making reflective coatings ineffective.
If reflective coatings do not receive direct sunlight, they cannot lower interior temperatures or reduce cooling energy usage as expected.

Key Concept

Weakening Arguments by Disproving Analogy and Transferability
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Topics

Weakening Arguments

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