BPI BA-T key terms

A path through the building envelope where heat conducts more readily than through adjacent assemblies, such as a steel stud or concrete slab edge, lowering local surface temperatures and overall insulation performance.

The designated continuous layer in an assembly that controls heat flow, intended to align with the air barrier and be verified in the field against design drawings.

The continuous system of materials that limits uncontrolled air movement between conditioned and unconditioned spaces, preventing drafts, moisture transport, and energy loss.

Unintentional outdoor air entering a building through leaks, cracks, and penetrations in the envelope, driven by pressure differences from wind, stack effect, and mechanical systems.

Vertical air movement caused by buoyancy, where warmer indoor air rises and exits high in the building while outdoor air enters low, producing pressure differences across the envelope.

The temperature at which air reaches saturation and water vapor begins condensing into liquid, a key threshold for predicting where moisture forms inside assemblies.

A material layer that resists water vapor diffusion, positioned within an assembly to keep moisture from condensing on cold surfaces while still permitting drying.

A measure of thermal resistance, indicating how well a material resists conductive heat flow; higher values mean better insulation, and units are assigned per inch or per assembly.

The overall rate of heat transfer through an assembly, expressed as the reciprocal of total R-value; lower values indicate better insulating performance for the whole assembly.

The rate at which water vapor passes through a specific material of given thickness, used to classify materials as vapor barriers, retarders, or permeable and to judge drying potential.

The study of moist air properties and their relationships, including dry-bulb and wet-bulb temperature, humidity ratio, and enthalpy, used to evaluate comfort and moisture conditions.

The amount of water vapor in air expressed as a percentage of the maximum it could hold at that temperature; it changes with temperature even if moisture content stays constant.

A measured difference in air pressure between two locations, such as indoors and outdoors or across a barrier, that drives air leakage and is central to diagnostic testing.

A diagnostic procedure using a calibrated fan and pressure gauges to depressurize a building and quantify envelope air leakage, typically reported at a reference pressure.

A normalized leakage metric describing how many building air volumes leak per hour when the building is held at 50 pascals of pressure difference during a blower door test.

A procedure that pressurizes a duct system with a calibrated fan and measures airflow needed to hold a set pressure, revealing leakage in ducts and connections.

The use of a thermal imaging camera to visualize surface temperature differences, helping locate insulation gaps, air leakage, moisture, and thermal bridges in assemblies.

A small handheld device producing a visible smoke trail that reveals the direction and relative strength of air movement at cracks, penetrations, and assembly joints.

The documented process of comparing an instrument's readings against a known reference standard and adjusting or accepting it to ensure measurement accuracy and traceability.

The quantified range within which a true value is expected to lie given instrument error, environmental conditions, and procedures, informing whether results are defensible.

A programmable device that records sensor readings such as temperature, humidity, or pressure at set intervals over time, supporting trend analysis of building performance.

A visual inspection technique using a camera on a flexible probe inserted into cavities or behind finishes to observe concealed conditions without destructive demolition.

An assessment method that opens or removes building components, such as cutting drywall or drilling test holes, to directly verify concealed assembly details and conditions.

A structured initial inspection in which the assessor traverses the building, recording visible conditions, systems, and occupant concerns to scope later diagnostic work.

A documented, objective record of conditions seen on site, including location, date, and description, forming evidence that supports findings and recommendations in the report.

The environmental and contextual factors at an assessment, such as weather, occupancy, and building operation, that can affect readings and must be recorded alongside data.

Paired measurements taken before and after an intervention, such as air sealing, to quantify the change in performance attributable to the work performed.

A quality-focused process of verifying that building systems are designed, installed, and operating according to the owner's requirements and documented design intent.

The act of confirming through evidence, such as photos, measurements, or re-testing, that installed work or reported conditions match the design or stated scope.

An organized collection of site photographs with captions, dates, and location references, used as evidence and cross-referenced within the assessment report.

A documented record tracking who collected, handled, transported, and stored samples or data, preserving their integrity for analysis and potential dispute resolution.

A defined procedure specifying how, where, when, and how many samples or measurements are collected, ensuring results are representative and reproducible across assessors.

A concise opening section of a report that states the purpose, key findings, and principal recommendations for decision-makers who will not read the full document.

The report section pairing observed conditions, supported by evidence, with prioritized corrective actions, costs, and rationale so readers can act on the assessment.

A written statement defining the boundaries of an assessment, including systems inspected, tests performed, exclusions, and deliverables, which frames the report's conclusions.

Drawings and records reflecting the actual constructed condition of a building, used as a baseline when comparing field observations against design intent.

Energy absorbed or released during a phase change, such as water evaporating or vapor condensing, without a change in temperature; it drives moisture-related loads.

An initial set of readings documenting pre-intervention conditions, providing the reference against which later performance changes are compared and verified.