Which of the following would NOT be considered a low-cost energy efficiency measure?

Upgrading HVAC systems is generally viewed as a significant investment compared to other options listed. This is due to the complexity and cost associated with purchasing and installing new heating, ventilation, and air conditioning systems, which can involve extensive modifications to existing infrastructure. In contrast, the other measures tend to be more accessible and less costly in terms of both materials and installation.

For example, installing LED lighting is a relatively simple and low-cost measure that typically offers a quick return on investment through energy savings. Adding wall insulation can also be considered a low-cost measure, particularly when tackling smaller areas or retrofitting existing structures. Performing energy audits often has very minimal costs associated and can yield substantial insights for improving efficiency effectively without significant upfront capital. These reasons contribute to classifying the upgrade of HVAC systems as a high-cost rather than low-cost energy efficiency measure.