Which of the following aspects is NOT included under SMACNA guidelines?

The correct choice identifies that energy efficiency is not a specific aspect included under the SMACNA (Sheet Metal and Air Conditioning Contractors' National Association) guidelines. SMACNA primarily provides standards and guidelines related to installation procedures, indoor air quality, and construction site management, focusing on best practices in sheet metal and air conditioning work.

Installation procedures cover the specifics of how to properly install HVAC systems, ensuring that they function effectively and safely. Indoor air quality emphasizes the importance of maintaining healthy indoor environments, addressing issues such as ventilation, air circulation, and the materials used in the construction process. Construction site management guidelines are designed to help contractors manage their project sites efficiently while minimizing disruptions and hazards.

While energy efficiency can be indirectly influenced by proper installation and maintenance practices as recommended in SMACNA guidelines, it is not a central focus of these guidelines. Energy efficiency is typically covered by other standards and certifications that specifically address how systems can be optimized for energy use, such as LEED standards themselves.