Which of the following is in accordance with BPI Technical Standards?

In accordance with BPI Technical Standards, it is important to ensure that heating and cooling systems operate efficiently to maintain energy savings and indoor comfort. The correct choice highlights that all uninsulated ducts located in unconditioned spaces must be insulated. This standard exists because unconditioned spaces—like attics, crawl spaces, or garages—are subject to temperature extremes, which can lead to significant energy loss if ducts are left uninsulated.

When ducts are insulated, they help to retain the temperature of the air within them, ensuring that conditioned air does not lose its thermal qualities before reaching its destination. This reduces the workload on HVAC systems, enhances efficiency, and ultimately leads to cost savings on energy bills. In contrast, the other choices suggest either a partial or unnecessary approach to duct insulation, which does not align with the objective of maintaining optimal performance and energy efficiency as set by BPI standards.