Certified Energy Auditor Building Envelope and Lighting Questions and Answers

Question 1

An energy auditor inspects the attic of a home in a cold climate and observes dark, dirty-looking patches on the fiberglass batt insulation directly above the interior ceiling joists. What is the most likely cause of this phenomenon?

Accepted Answer

Air leakage through ceiling penetrations carrying dust and moisture, which is then filtered by the insulation.

Answer

These dark patches are a classic sign of air leakage, also known as 'ghosting' or 'filtration soiling.' Warm, moist, and often dusty air from the conditioned space below leaks into the colder attic through gaps and cracks. The insulation acts as a filter, trapping the dust particles and creating the darkened appearance. This indicates a need for air sealing to reduce energy loss.

Question 2

Which of the following window performance metrics is most crucial for an energy auditor to consider when trying to reduce cooling loads in a hot, sunny climate?

Accepted Answer

Low Solar Heat Gain Coefficient (SHGC)

Answer

The Solar Heat Gain Coefficient (SHGC) measures how much heat from direct sunlight is transmitted through a window. A lower SHGC value means less solar heat is admitted, which is critical for reducing the building's cooling load and associated energy costs in a climate dominated by sun and heat. While a low U-factor is also important for reducing conductive heat transfer, SHGC directly addresses the impact of solar radiation.

Question 3

A lighting retrofit project involves replacing 400-watt metal halide lamps in a warehouse with 150-watt LED fixtures. Which metric best describes the energy efficiency of these light sources in terms of light output per unit of power consumed?

Accepted Answer

Luminous Efficacy (lumens/watt)

Answer

Luminous Efficacy is the standard metric for lighting efficiency. It is calculated by dividing the total light output in lumens by the total power input in watts (lumens/watt). A higher luminous efficacy value indicates a more efficient light source, as it produces more light for each watt of energy consumed.

Question 4

An energy audit of a commercial office building reveals that the perimeter offices, which have large windows, have their lights on at full brightness even on sunny days. Which lighting control strategy would provide the greatest energy savings for this specific situation?

Accepted Answer

Daylight harvesting with photosensors

Answer

Daylight harvesting is a control strategy that uses photosensors to measure the amount of ambient natural light entering a space. When sufficient daylight is present, the control system automatically dims or turns off the electric lights, thereby saving energy. This is the most direct and effective solution for the scenario described.

Question 5

When calculating the overall heat transfer of a wall assembly, an auditor must account for the wood or metal studs that interrupt the insulation. This phenomenon, where heat flows more readily through the framing members than through the insulated cavities, is known as:

Accepted Answer

Thermal bridging

Answer

Thermal bridging occurs when a more conductive material (like a wood or steel stud) creates a path of lower thermal resistance, allowing heat to bypass the insulation. This reduces the overall effective R-value of the assembly and must be accounted for in accurate heat loss or gain calculations. It is a significant factor in a building's thermal performance.

Certified Energy Auditor Certification Practice Test

Certified Energy Auditor Certification Practice Test

Certified Energy Auditor Building Envelope and Lighting Questions and Answers