On November 19, the St. Augustine News took a hard look at home HVAC systems and how inefficient they can be. According to the News, the average home HVAC system "wastes 25% of the HVAC's energy draw," mostly due to leaks in the system. Worse:
"...a truly 'faulted' system could waste as much as 75% of the HVAC's energy draw.
These are huge percentages. If the average system wastes 25% of the HVAC's energy draw through leaks, it means that anywhere between 5-15% of a given building's total energy cost is wasted. Poof. Gone."