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These 10 free DN questions are organized by exam domain, so you can see how each part of the Decarbonization NC3 Certification blueprint is tested. Reveal the answer and explanation under each question.
Carbon dioxide affects planetary temperature even though it makes up only a small fraction of the atmosphere. Which interaction with radiation explains its greenhouse effect?
Correct answer: A - It absorbs and re-emits Earth's infrared radiation, slowing heat loss to space.
A plant ranks two projects solely by annual greenhouse-gas emissions avoided. Project X would prevent leaks totaling 100 kg of fossil methane; Project Y would prevent release of 1 kg of HFC-134a refrigerant. All other emissions effects are equal. Using IPCC AR6 100-year global warming potentials of 29.8 for fossil methane and 1,530 for HFC-134a, which project avoids more CO2-equivalent emissions, and by how much?
Correct answer: A - Project X, by 1.45 metric tonnes CO2e per year.
A transit operator describes its new hydrogen fuel-cell buses as having a zero-greenhouse-gas fuel supply chain because the buses emit no CO2 during operation. Their hydrogen is produced by grid-powered water electrolysis. Which finding would directly undermine the supply-chain claim?
Correct answer: C - The electrolyzer uses electricity generated partly from fossil fuels.
An energy-procurement table labels uranium-based nuclear generation as renewable because it does not burn fossil fuel. Which replacement classification correctly distinguishes the fuel resource from the generation process?
Correct answer: B - Nonrenewable resource; non-fossil generation.
An eligible office building receives an ENERGY STAR score of 82 using complete, verified data. How should the facilities manager explain this result to the building owner?
Correct answer: D - Its energy performance exceeds that of approximately 82% of comparable buildings.
A warehouse has eliminated its weekend shift, but its general lighting still follows the old seven-day schedule. Security, emergency lighting, and frost protection are on separate controls. The lighting technician confirms that the unused zones can be switched off without affecting those services. Which change would eliminate the unnecessary operating hours using the existing equipment?
Correct answer: B - Update the general-lighting schedule and verify the resulting reduction in use.
An air-handling unit is cooling an office, but its heating coil continues to warm the supply air. The heating-valve command is confirmed at fully closed, and an independent flow measurement shows sustained hot-water flow through the coil. The valve is specified to stop coil flow when closed; there is no bypass, and the temperature measurements have been verified. What fault best fits these findings?
Correct answer: C - The heating valve is passing hot water despite the closed command.
During a heat-pump acceptance test, independently checked meters show a heating coefficient of performance of 3.2. Temperatures, pressures, and safety checks are normal. A manager proposes shutting the system down because its heat output exceeds its electrical input. The engineer should:
Correct answer: B - Keep it operating; delivered heat includes both electrical input and heat drawn from the environment.
A manufacturer purchases electricity from an independently owned utility. The utility reports the generation emissions in Scope 1; the manufacturer reports the emissions attributable to its purchased electricity in Scope 2. A reviewer objects that the same physical emissions appear in both inventories. Under the GHG Protocol, how should this be resolved?
Correct answer: D - Keep both classifications; they represent different companies' reporting boundaries.
Before an efficiency retrofit, a building used 100 MWh in one year. A validated baseline model predicts that the old equipment would have used 125 MWh under the reporting year's weather and operating hours. Actual reporting-year consumption is 110 MWh, with no other relevant changes. For weather- and operation-adjusted performance, the retrofit report should record:
Correct answer: C - 15 MWh saved, representing a 12% reduction against the adjusted baseline.
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