Title: Unit 9 Glossary
Course: HAC 140 Weatherization > Section: HAC 140 Weatherization

Unit 9 Glossary

Terms

Term | Definitions
Air changes per hour (ACH) | The number of times in one hour that all of the air in a home is replaced by outside air through air leakage and/or ventilation.
Air transport | Movement of moisture vapor by convective air currents.
ASHRAE | American Society of Heating, Refrigerating, and Air-Conditioning Engineers. International technical society which develops standards for those concerned with refrigeration processes and the design ...
Bulk moisture | Large amounts of water intrusion, for example from wind-driven rain or sub-surface water.
Capillary action | Movement of liquid water across a material as a function of the surface tension of the water and the porosity of the material.
Carbon dioxide (CO2) | One of two main products of complete combustion of a hydrocarbon. (The other is water vapor.)
Carbon monoxide (CO) | Carbon monoxide is a tasteless, odorless, colorless, and poisonous gas that is a by-product of incomplete combustion of fossil fuels. It is usually caused by a lack of air to support combustion or ...
Climate zone | An area with a prevailing climate that distinguishes it from other areas by parameters such as temperature, rainfall, and humidity.
Cubic feet per minute (CFM) | A measurement of air movement past a certain point or through a certain structure. Used in pressure diagnostics to quantify air leakage.
Diffusion | Movement of water vapor through a material as a function of the driving force across and the porosity of the material.
Dilution | Relying on adequate ventilation to reduce the concentration of pollutants to acceptable levels.
Elimination | Removing the source of the pollution.
Encapsulation | Containing the pollutant so it will not affect air quality.
Indoor air quality (IAQ) | The quality of indoor air relative to its acceptability for healthful human habitation. Assessing and ameliorating, when necessary, the quality of indoor air is a major concern of the weatherizati ...
Lawrence Berkeley National Laboratory (LBNL) | Member of the national laboratory system supported by DOE though its Office of Science. It conducts unclassified research across a wide range of scientific disciplines.
Minimum ventilation guideline (MVG) | Process used to emphasize the ventilation needed after a building is tightened to the maximum practical extent.
N-factor | Used to convert readings taken at CFM50 to CFMnatural, the amount of air leakage that occurs naturally. The N-factor depends on climate, building height, and shielding from wind. N ranges from 9.8 ...
Pascals (Pa) | Metric standard for measuring pressure differences. 248 pascals equal one inch of water column, approximately the weight of one Post-it note.
Performance standard | Specification of the conditions that will exist when a satisfactory job is performed.
Permeance rating | Number that quantifies the rate of vapor diffusion through a material.
Porosity | Measure of the void spaces in a material, expressed as either a fraction or a percentage of the total volume of material.
Prescriptive standard | Specifies in detail the requirements and test procedures to be followed.
Radon | A radioactive gas present in certain soils that decomposes into radioactive particles. In certain areas, radon compromises IAQ when it enters the home through basements or craw spaces.
Relative humidity (RH) | The amount of water vapor in the air, expressed as a percentage of the maximum amount that the air could hold at a given temperature.
Savings-to-investment ratio (SIR) | A calculation that determines the cost-effectiveness of a weatherization measure by dividing the estimated savings over its lifetime by the cost. SIR is computed over the lifetimes of the retrofit ...
Zone pressure diagnostics (ZPD) | Using a blower door to determine the interconnectivity of various building components, which helps the practitioner locate the pressure boundary and know if the air and thermal barriers are aligne ...