BPI HEP Energy Auditor key terms

The continuous layer of insulation and air sealing that separates conditioned space from unconditioned space. Gaps or breaks in it cause heat loss, condensation, and comfort complaints.

The air barrier layer that resists air movement between conditioned and unconditioned zones. It is often the same assembly as the thermal boundary but not always.

The part of a building intentionally heated, cooled, or both for occupant comfort. Its extent determines the building envelope area used in load and energy calculations.

Building volume that is not deliberately heated or cooled, such as attics, garages, and vented crawlspaces. It is outside the thermal boundary and drives many envelope losses.

Buoyancy-driven air movement caused by indoor-outdoor temperature differences, with warm air rising and escaping high and makeup air entering low. It strengthens in cold weather and tall buildings.

Unintentional airflow through cracks, penetrations, and poorly sealed assemblies. It raises heating and cooling loads, brings in humidity and pollutants, and can undermine insulation performance.

A measure of a material's resistance to conductive heat flow per unit area and temperature difference. Higher values mean better insulation performance for a given thickness.

The overall rate of heat flow through an assembly per unit area and temperature difference. It is the reciprocal of total assembly R-value and includes framing and surface effects.

Heat flow that bypasses insulation through framing, studs, or other conductive paths. It lowers the effective R-value of an assembly and can cause cold spots and condensation.

A weather metric summing, over a season, how far daily average outdoor temperature falls below a reference base. It indicates climate severity and scales heating energy use.

The outdoor temperature at which a building's internal gains offset its heat loss, so no heating is needed. It is also used for heat pump changeover settings.

Heat released inside a building by occupants, lighting, and appliances. These gains reduce heating load and can increase cooling load, especially in well-insulated homes.

A diagnostic test using a calibrated fan to pressurize or depressurize a building while measuring airflow and pressure. Results quantify envelope and duct leakage and locate air leaks.

Normalized envelope leakage expressed as house volume exchanged per hour at a 50-pascal reference pressure. It allows comparison across homes of different size.

Cubic feet per minute of airflow measured by a blower door at 50 pascals of pressure difference. It is the raw leakage number used in many tightness standards.

Pressurizing the duct system with a calibrated fan to measure leakage to outside or to conditioned space. It reveals energy losses and pressure imbalances affecting comfort and indoor air.

Diagnostic checks of combustion appliances, including spillage, draft, and carbon monoxide measurements. The goal is confirming safe venting and preventing backdrafting after air sealing.

Combustion gases escaping from an appliance's draft hood into the room instead of up the flue. It signals inadequate draft and creates a carbon monoxide hazard.

Reverse flow of flue gases into the living space caused by depressurization or a blocked chimney. Air sealing and exhaust upgrades can worsen or correct it.

Using multiple fans and pressure sensors to measure how pressure differences between zones drive air and pollutant movement. It helps explain comfort problems and moisture transfer.

Imaging surface temperatures with a thermal camera to reveal insulation gaps, air leaks, and moisture. Interpretation requires a temperature difference and care to avoid false readings.

Air escaping or entering ducts through joints, seams, and disconnects. Leakage in unconditioned space wastes conditioned air and can draw pollutants into the system.

A calculation tool that predicts building energy use from envelope, equipment, and weather inputs. Auditors use it to compare improvement scenarios and estimate savings.

The energy model representing the building as it exists before any upgrades. It is the reference against which predicted savings from proposed measures are measured.

Adjusting model inputs so predicted energy use matches utility bills or metered data. A calibrated model gives more credible savings estimates and flags input errors.

Adjusting energy consumption to remove the effect of weather variation, using degree days or modeled weather. It allows fair comparison of bills across periods and years.

A measure comparing the present value of lifetime savings from a measure to its installed cost. Values above one indicate savings exceed cost over the analysis period.

The number of years needed for annual savings to equal the installed cost of a measure. It ignores measure life and time value of money, so it is a rough screening tool.

Ranking proposed improvements by savings, cost, safety, and sequencing dependencies. It guides which measures go into the final work scope and in what order.

The written plan listing specific improvements, quantities, materials, and sequence for a project. It translates audit findings into an actionable, contracted scope of work.

Documentation of hazards identified during the audit and the controls required during work, such as combustion safety, asbestos, or moisture issues. It protects workers and occupants.

Outdoor air supplied to replace air exhausted by fans, dryers, or ventilation. Inadequate makeup air causes depressurization, backdrafting, and comfort problems.

Intentional supply or exhaust of outdoor air to control pollutants and moisture. Air sealing reduces natural infiltration, so mechanical ventilation may be needed after upgrades.

Closing unintended gaps in the pressure boundary to reduce infiltration and exfiltration. It improves comfort and saves energy but requires combustion safety checks before and after.

Unplanned additions to a project that expand work beyond the agreed work scope. Clear documentation and change orders help manage cost and client expectations.

Explaining audit findings, expected savings, and occupant behavior changes in plain language. It supports informed decisions and helps realize predicted performance.

The assemblies separating conditioned from unconditioned space, including walls, roofs, floors, windows, and doors. Its performance strongly drives heating and cooling loads.