A blower door test is a diagnostic procedure used to measure how much uncontrolled air leakage exists in your home and to identify exactly where air is escaping or entering the building envelope. Air leakage is one of the largest contributors to high energy bills, uneven temperatures, humidity problems, and poor indoor air quality.

Rather than relying on assumptions or visual inspections, a blower door test provides measured, data-driven results that reveal how your home actually performs.

How a Blower Door Test Works

A calibrated fan is temporarily installed in an exterior doorway and used to depressurize the home. This creates a controlled pressure difference between the inside and outside of the house, exaggerating existing air leaks so they can be measured and located.

During the test, we:

• Measure total air leakage in cubic feet per minute (CFM)

• Evaluate how leaky the building envelope is relative to the home’s size

• Use pressure diagnostics, visual inspection, and airflow detection tools to locate leakage paths

What the Test Reveals

Blower door testing identifies air leakage through:

• Attic penetrations and top plates

• Crawl spaces and basements

• Wall cavities and knee walls

• Windows, doors, and framing connections

• Plumbing, electrical, and mechanical penetrations

These leaks can collectively equal having a window or more left open year-round, allowing conditioned air you pay for to escape while pulling in hot, humid, or cold outside air.

Why Air Leakage Matters

Uncontrolled air movement impacts your home in several ways:

• Higher energy bills due to lost conditioned air

• Uneven temperatures and comfort complaints

• Humidity intrusion, which can promote mold and mildew

• Reduced HVAC performance and lifespan

• Poor indoor air quality from outdoor pollutants and attic or crawl-space air

A blower door test quantifies these issues so improvements can be targeted and verified.

Blower Door Testing & Verification

Blower door testing is not only used to diagnose problems—it is also essential for verifying results after air sealing and insulation upgrades. By testing before and after work is completed, we confirm that improvements delivered measurable reductions in air leakage and real performance gains.

Leaky or disconnected duct systems are one of the most common—and costly—hidden problems in homes, especially when ductwork is routed through walls, floors, and ceilings. Even well-sized HVAC equipment cannot perform properly if a significant portion of conditioned air is lost before it reaches the living space.

Smart Space uses duct blaster testing and pressure pan diagnostics to measure duct leakage, locate failures, and identify disconnected or compromised duct runs that are otherwise invisible.

Duct Blaster Testing – Measuring Total Duct Leakage

A duct blaster test isolates and pressurizes the duct system independently from the home using a calibrated fan. This allows us to measure how much conditioned air is leaking from the duct system before it reaches occupied spaces.

During a duct blaster test, we:

• Pressurize the duct system to a standardized test pressure

• Measure total duct leakage in cubic feet per minute (CFM)

• Evaluate leakage relative to system size and home layout

• Establish a baseline for performance verification after sealing

This test provides a quantified measurement of duct leakage and confirms whether ducts are contributing to high energy bills, comfort issues, and poor system efficiency.

Pressure Pan Testing – Locating Disconnected & Failed Duct Runs

While a duct blaster test tells us how much air is leaking, pressure pan testing helps us determine where those leaks are occurring.

Pressure pan testing is performed in conjunction with blower door testing and is especially valuable when ductwork runs through walls or concealed chases.

This diagnostic method allows us to:

• Identify disconnected, crushed, or severely leaking duct runs

• Locate failed duct boots, wall cavities, and hidden transitions

• Detect air leakage behind finished surfaces without demolition

• Prioritize targeted repairs rather than guesswork

Pressure pan testing is one of the most effective ways to find major duct failures that cannot be seen during a visual inspection.

Why Duct Leakage Matters

Leaky or disconnected ducts can result in:

• Significant loss of conditioned air into walls, attics, or crawl spaces

• Uneven temperatures and rooms that never feel comfortable

• Increased HVAC run times and premature equipment wear

• Higher energy bills with little improvement from thermostat changes

• Indoor air quality issues caused by pulling air from unconditioned spaces

In many homes, duct leakage can exceed 30–60% of total system airflow, especially in older construction or homes with wall-routed duct systems.

Testing, Verification & Performance Improvements

Duct blaster and pressure pan testing are essential not only for diagnosis, but also for verifying results after duct sealing or Aeroseal upgrades. Testing before and after work confirms real leakage reductions and ensures improvements are measurable—not assumed.

Part of a Whole-Home Diagnostic Approach

At Smart Space, duct testing is integrated into our whole-home, building-science process. By combining duct blaster testing with pressure pan diagnostics, we can accurately measure duct performance, locate hidden failures, and design targeted solutions that improve comfort, efficiency, and system longevity.

Safety testing is a critical component of every Residential BPI Home Energy Audit. While improving energy efficiency and airtightness is important, it must never compromise the safe operation of fuel-burning appliances. Smart Space follows Building Performance Institute (BPI) standards to ensure your home’s mechanical systems operate safely under real-world conditions.

Our testing verifies that combustion appliances draft properly, do not spill exhaust gases into the living space, and are not affected by pressure imbalances caused by exhaust fans, duct leakage, or air sealing.

Worst-Case Depressurization Testing

Worst-case depressurization testing evaluates how your home behaves when all exhaust devices are operating simultaneously. This simulates real living conditions—bath fans, kitchen exhaust, dryers, and HVAC systems running together.

This test helps us:

• Measure pressure imbalances that can interfere with appliance drafting

• Identify conditions that could cause backdrafting or exhaust spillage

• Ensure air sealing or duct improvements will not create unsafe conditions

Draft & Spillage Testing

Draft testing confirms that combustion appliances are venting exhaust gases upward and out of the home as designed. Spillage testing checks whether combustion gases spill into the living space during appliance start-up or operation.

We test:

• Furnaces

• Water heaters

• Boilers

• Other natural gas or fuel-burning appliances

These tests verify that combustion byproducts—including carbon monoxide—are safely exhausted outdoors.

Zonal Pressure Diagnostics

Zonal pressure testing measures pressure differences between rooms, wall cavities, attics, crawl spaces, and the main living area. Pressure imbalances can draw air—and potentially combustion gases—from unintended areas.

This testing allows us to:

• Identify pressure-driven air movement between zones

• Diagnose duct-related pressure issues

• Evaluate how air sealing and duct leakage affect airflow pathways

Zonal pressure diagnostics are especially important in homes with ductwork routed through walls, attics, or crawl spaces.

Gas Leak Detection

As part of the safety evaluation, we perform gas leak detection at appliances and accessible gas connections.

This includes checking:

• Appliance connections and shutoff valves

• Supply lines at furnaces, water heaters, and boilers

• Mechanical rooms and utility spaces

Identifying gas leaks early helps prevent safety hazards and ensures proper appliance operation.

Why Combustion Safety Testing Matters

Safety testing protects occupants by:

• Reducing the risk of carbon monoxide exposure

• Preventing backdrafting and exhaust spillage

• Ensuring upgrades improve performance without creating hazards

• Verifying compliance with BPI standards and best practices

A home can be energy efficient and comfortable—but only when it is also safe.

Part of a Whole-Home, Data-Driven Process

At Smart Space, combustion and safety testing is integrated into our whole-home audit process. By evaluating pressure relationships, airflow, and appliance performance together, we ensure that recommended upgrades improve efficiency without compromising occupant health or safety.