Permanent Load Reduction starts by looking at the house as a system through the eyes of an ACCA Manual J load Calculation , instead of blaming the HVAC equipment. In this case study, diagnostic testing revealed severe infiltration, extensive duct leakage, poor delivered airflow, degraded attic insulation, and safety concerns tied to garage and combustion appliance connections. The result was a home where comfort problems, energy waste, and HVAC performance issues were all symptoms of deeper building-system failures.
This project illustrates exactly why Permanent Load Reduction must happen before serious equipment decisions are made.
Permanent Load Reduction in This Home
The project began with two familiar complaints:
- uncomfortable second floor
- higher than expected energy consumption
Initial inspection suggested what many contractors would assume: the HVAC equipment was struggling to keep up.
However, testing quickly showed the equipment was only part of the story.
The house had major air connections between the attic, basement, garage, and conditioned living space. At the same time, the duct system was leaking large amounts of conditioned air and delivering barely half of the airflow required for the installed cooling capacity.
Without Permanent Load Reduction, replacing the equipment alone would have done little to solve the underlying problems.
Permanent Load Reduction Findings
The testing numbers told the story immediately.
The blower door test measured 6,491 CFM50, equal to 16.3 ACH50, more than double what modern code benchmarks reference for homes of this type.
The duct system was also performing poorly. Testing revealed 1,716 CFM of total duct leakage, or 61.33 CFM per 100 square feet served, roughly five times typical code-level expectations.
Airflow delivery was equally problematic. The 3-ton cooling system should deliver roughly 1,200 CFM of supply airflow, yet measured airflow was only 661 CFM, about 55% of nominal airflow.
These findings immediately identified infiltration and distribution failures as the primary drivers of the home’s comfort and energy problems.
This is exactly the type of situation where Permanent Load Reduction becomes the correct first step.
The Homeowner Complaints
The occupants reported:
- persistent comfort problems upstairs
- uneven room temperatures
- higher energy bills
These symptoms aligned directly with what testing uncovered.
Second-floor rooms were communicating with the attic through knee wall leakage paths. Meanwhile, return duct sections located in the attic were poorly sealed and in some cases disconnected, allowing the system to pull attic air into the HVAC system.
In other words, the system was fighting outdoor conditions inside the ductwork itself.
What the Testing Revealed
Several major building and system defects were identified.
Attic insulation had degraded significantly. Effective insulation levels were estimated between R-7 and R-10, far below the recommended R-49 levels for this climate zone.
Knee wall assemblies lacked proper air barriers, allowing attic air to move through insulation cavities and directly influence second-floor rooms.
Additional infiltration pathways were identified between:
- attic and living space
- basement and upper floors
- attached garage and interior zones
The duct system had numerous leakage points that allowed conditioned air to escape while also pulling unconditioned attic air into the return system.
Bathroom ventilation deficiencies were also noted, and combustion safety concerns existed due to the connection between the attached garage and a natural draft water heater.
Each of these issues contributed to the inflated heating and cooling loads calculated for the home.
Visual Evidence From the Project
The project documentation includes a photos highlighting several key defects discovered during the inspection.
Images include:
- attic knee wall leakage pathways affecting second-floor comfort
- disconnected and unsealed return duct sections
- degraded attic insulation reducing thermal resistance
- penetrations and bypasses between attic and living space
- air connections between the garage and interior zones
Each image demonstrates how the building enclosure and distribution system were driving excessive load and poor HVAC performance.
How the Load Changed
This is where Permanent Load Reduction begins to show measurable impact.
Initial load calculations showed a heating load near 93,600 BTUh and a total cooling load near 39,400 BTUh.
When infiltration improvements alone were modeled, blower door levels were projected to drop from 6,491 CFM50 to approximately 3,895 CFM50.
That change alone reduced the heating load to roughly 76,600 BTUh and the cooling load to about 33,500 BTUh.
When attic insulation upgrades were added to the scenario, the heating load dropped further to roughly 72,350 BTUh, with cooling loads falling below 30,000 BTUh.
This illustrates the real purpose of Permanent Load Reduction: changing the physics of the house before selecting or modifying HVAC equipment.
Why This Case Matters
Many homes with comfort complaints are treated as equipment problems when they are actually enclosure and distribution problems.
In this case, the existing furnace output was around 72,400 BTUh, while the initial heating load exceeded 93,000 BTUh. The typical response might be to install a larger heating system.
However, Permanent Load Reduction shows a different path.
By addressing infiltration, insulation, and duct leakage, the load itself can be reduced dramatically. This allows HVAC equipment to operate within its intended performance range while improving comfort, energy efficiency, and indoor air quality.
This approach also improves combustion safety by reducing pressure imbalances and infiltration pathways connected to the garage.
Video Walkthrough of the Case Study
A short video version of this project walkthrough is available below. The video highlights the inspection process, diagnostic testing, and visual defects identified during the evaluation.
Want a Permanent Load Reduction Plan?
If your project has uncomfortable rooms, poor airflow, or excessive infiltration, the first step should not be equipment replacement.
Start with diagnostics and a Permanent Load Reduction plan.
Reducing the load before sizing the equipment leads to better comfort, safer homes, and HVAC systems that actually perform the way they were designed to.
