Yes, passive design is highly effective in extreme climates, though the strategy shifts. In cold climates, the focus is on extreme airtightness, high-performance insulation, and maximizing solar gain. In hot climates, the focus shifts to shading, thermal mass, and maximizing natural ventilation to dissipate heat.

The biggest mistake is failing to account for the specific site topography and solar path during the initial design phase. If the building is not oriented correctly from the start, no amount of insulation or high-tech glass can compensate for the lost opportunity to leverage natural light and airflow.

Initial construction costs for a passive-designed home can be 5% to 15% higher due to high-performance windows, insulation, and specialized labor. However, these costs are typically offset by significantly lower utility bills and reduced maintenance requirements for mechanical systems over the building's lifespan.

Cellulose insulation will settle if it is installed loosely, such as in an open attic. However, when it is "dense-packed" into wall cavities at the manufacturer-recommended density of 3.5 to 4 pounds per cubic foot, settling is virtually eliminated.

Cellulose insulation is treated with fire-retardant chemicals, typically borates, which make it highly resistant to fire. It is tested to meet strict ASTM C739 standards, which include rigorous flame spread and smolder combustion tests, ensuring it is safe for residential use.