• ACH50 / ACHn: Air changes per hour at 50pa / Air changes per hour at natural conditions.
  • CFM50 / CFMn: Cubic feet per minute at 50pa / CFMn: Cubic feet per minute at natural conditions.
  • BAS: Building Air-flow Standard. The minimum amount of air changes through a house in one hour. Equal to .35 ACH or roughly of the air in a house, by volume, in one hour or one full air change in three hours.
  • CAZ: Combustion Appliance Zone, any area that has a combustion appliance (as the name implies…) such as heating equipment, fireplace, gas oven, gas dryer, etc.
  • CFL: Compact Fluorescent lamp (aka “light bulb”). Look for 82+ CRI (Color Rendering Index) and warm white light (Color Temp: 2800-3000K) for interior household use. Higher color temp will look more “blueish” or cool white (4000-5000K).
  • CO: Carbon Monoxide. A potentially deadly, odorless, colorless gas produced as a result of incomplete combustion. Any combustion appliance can produce CO (e.g. Gas ovens & range tops, heating appliances such as boilers, furnaces, hot water heaters, gas dryers, barbecues, cars, fireplaces, candles, cigarettes, etc.)
  • DHW: Domestic Hot Water heater.
  • Friable: describes a material that can crumble or become powdery. Used to describe asbestos that is or can easily become crumbled or powdery and may become air-born if disturbed. Contact specialist for testing.
  • GWB: gypsum wall board, aka: drywall, Sheetrock.
  • Knee wall: typically a short wall, usually under three feet in height. Found in top story of house where roof cuts through the tops of walls and creates small attics behind the wall and above the ceiling. Difficult but very important to insulate and air-seal properly.
  • R value: Resistance of a material to thermal conduction. Used for insulation rating. Inverse of U value. R=1/U
  • SIR - Saving to Investment Ratio.
  • Stack Effect: Warm air moving upwards in a house. See Section 5 Building Science for more info.
  • SSE or Steady State Efficiency: how efficiently a furnace converts fuel to heat, once the furnace has warmed up and is running steadily. However, furnaces cycle on and off as they maintain their desired temperature. Furnaces typically do not operate as efficiently as they start up and cool down. As a result, steady state efficiency is not as reliable an indicator of the overall efficiency of your furnace as AFUE. AFUE: Annual Fuel Utilization Efficiency, the most widely used measure of a furnace's heating efficiency. It measures the amount of heat actually delivered to your house compared to the amount of fuel that you must supply to the furnace. Thus, a furnace that has an 80% AFUE rating converts 80% of the fuel that you supply to heat -- the other 20% is lost out of the chimney. AFUE takes into account the cyclic on/off operation and associated energy losses of the heating unit as it responds to changes in the load, which in turn is affected by changes in weather and occupant controls.
  • U value: Transmission of heat by a material. Used for rating windows & doors. Inverse of R value. U=1/R.