BPI BA-T flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Conduction heat flow

Heat transfer through solid material driven by temperature difference. Calculated as Q equals U times area times delta T, where U is the assembly conductance and delta T is indoor-to-outdoor temperature difference.

R-value definition

Resistance to heat flow through a material or assembly, expressed in square feet times degrees Fahrenheit hours per Btu. Higher R-value means lower conductance, and layer R-values add in series.

Thermal bridging effect

Framing members, slabs, and penetrations conduct heat around insulation, lowering effective R-value. Effective U equals the area-weighted sum of frame and cavity conductances across the assembly.

Dew point temperature

The temperature at which air reaches saturation at constant moisture content. Surfaces below dew point collect condensation, so interior surface temperatures and insulation placement both matter.

Relative humidity meaning

Ratio of actual water vapor pressure to saturation vapor pressure at the same temperature, expressed as a percentage. It changes with temperature even when absolute moisture content stays constant.

Stack effect

Buoyancy-driven air movement caused by indoor-outdoor temperature and height difference. Warm air rises in winter, creating pressure differences that drive infiltration low and exfiltration high.

Air leakage versus diffusion

Air leakage moves moisture with bulk air through gaps and can carry far more water than vapor diffusion through materials. Sealing bypasses is usually the higher-priority moisture control step.

Moisture balance principle

Durable assemblies keep wetting sources smaller than drying capacity. Wetting includes rain, ground moisture, diffusion, and air leakage; drying includes drainage, ventilation, and diffusion outward.

Latent versus sensible load

Sensible load changes air temperature; latent load changes moisture content through evaporation or condensation. Air leakage and infiltration add both, which affects equipment sizing and comfort.

Pre-assessment scoping

Defining building type, vintage, occupancy, HVAC systems, and reported complaints before fieldwork. Scope determines instruments, sampling locations, and the sequence of site activities.

Site walk sequence

A structured inspection order, typically exterior drainage and envelope first, then interior moisture, air leakage, HVAC, and occupant patterns. Consistent order prevents missed systemic causes.

Pin-type moisture meter

An instrument that measures electrical conductivity between probes driven into material. Readings indicate relative moisture and require species or material calibration plus confirmation by another method.

Pinless moisture meter

A capacitance-based instrument that reads moisture through a surface without penetration. It is useful for scanning large areas but sensitive to density, coatings, and proximity to metal.

Blower door setup conditions

Exterior openings closed, interior doors open or pressure-balanced, combustion appliances off, and baseline pressures recorded. Setup consistency is required for comparable test results.

Occupant interview value

Structured questions about complaint timing, weather correlation, and recent renovations reveal patterns that measurements alone may miss. Interviews guide where to test and what to document.

Sampling plan documentation

Recording location, time, instrument, method, and calibration status for each measurement. Complete records support later analysis, reporting, and any dispute over findings.

Data quality checks

Repeat readings, compare instruments, flag outliers, and note weather conditions such as wind or stack effect. These steps separate real building behavior from measurement noise.

Zone pressure diagnostic

A manometer reading between a zone and outside while the house is depressurized. A reading near house pressure indicates connection; near zero indicates the zone is isolated.

ACH50 calculation

Air changes per hour at 50 pascals equals CFM50 times 60 divided by conditioned volume in cubic feet. It normalizes blower door leakage across buildings of different size.

Infrared survey conditions

Thermography needs a sufficient indoor-outdoor temperature difference, typically ten degrees Fahrenheit or more. Solar gain, wind, and wet surfaces create false anomalies.

Duct leakage testing

Pressurizing the duct system to 25 pascals and measuring airflow needed to hold it. Results are reported as CFM25 and as a percentage of total system airflow.

Pressure pan testing

Measuring pressure difference across a supply or return register while the house is depressurized. Higher readings suggest greater duct leakage to outside or other zones.

Combustion safety testing

Measuring carbon monoxide, draft pressure, and spillage under worst-case conditions. Reversed draft or elevated CO indicates a hazard requiring immediate corrective action.

Worst-case depressurization

Operating exhaust fans and closing interior doors to maximize negative pressure on combustion appliances. Testing under these conditions reveals whether flue gases can spill indoors.

Manometer zeroing

Setting the instrument reference to zero before each test so readings reflect actual pressure difference. Unzeroed instruments introduce offset errors that invalidate comparisons.

Tracer gas testing

Releasing a detectable gas and measuring concentration to identify air pathways or ventilation rates. It isolates connections that pressure tests alone may not resolve.

Field note essentials

Date, time, weather, instrument model and serial, calibration date, test conditions, and exact measurement locations. These details make results reproducible and defensible.

Photo documentation practice

Each image should include a scale reference, orientation, location label, and a note on what it documents. Unlabeled photos lose evidentiary value quickly.

Report structure

Objective and scope, methods, findings with data, limitations, conclusions, and prioritized recommendations. A consistent structure lets clients locate evidence behind each conclusion.

Fact versus interpretation

Measured values and observed conditions are facts; explanations and causes are interpretations. Reports should label each clearly and cite the method behind every number.

Recording negative results

Documenting tests that found nothing, including locations checked and methods used. This shows thoroughness and protects against later claims that an area was never examined.

Limitations disclosure

Stating inaccessible areas, weather constraints, and test conditions that reduce confidence. Honest limits prevent overreach and tell the client what further work may be needed.