Energy Trust : Trade Ally Home : Weatherization

EXISTING HOMES

Weatherization Specification Manual

GLOSSARY

10% of conditioned floor area – Used to calculate the effectiveness of a duct sealing installation. A duct system is considered to be well-sealed if the measured CFM50 leakage is less than 10% of the conditioned floor area.

Air sealing target areas – Locations of high importance for effective air sealing, including: attic and basement hatches, plumbing and electrical penetrations, large gaps in walls or exterior surfaces, window and door framing.

Air barrier – Interior (conditioned) space to exterior (unconditioned) space should be separated by a continuous and complete barrier to air movement, with any penetrations sealed as well as possible.

Baffles – Rigid material used to contain loose-fill insulation.

Building cavity duct – Any enclosed cavity used for a forced-air duct system. This includes joists where sheet metal forms a pan across the joists.

Combustion appliance – Any fuel-burning appliance.

Combustion Appliance Zone (CAZ) – A conditioned space or enclosed area containing a combustion appliance for the purpose of space heating or water heating.

Complete measure – An installation of an Energy Trust incentivize-qualifying measure which meets all requirements in the Weatherization Specifications Manual and the minimum requirements at all reasonably accessible locations. For example, attic insulation must be R-38 over the entire surface adjacent to conditioned space and ducts must be sealed at every joint and seam.

Conditioned basement – Any basement containing HVAC ducts and/or is accessible from another conditioned space. Other basements may be considered conditioned if they are largely connected to the conditioned space of the house and separated from the outside.

Conditioned space – Enclosed areas that directly receive space conditioning, meaning they contain HVAC vents, electric-resistance heaters or wood stoves. Alternatively, spaces which are not directly conditioned but are largely connected to a conditioned space and have an effective barrier from the outside shall be considered conditioned. Garages are usually considered unconditioned space, unless there is a vent feeding conditioned air to the area.

Crown attic – Uppermost attic flat, adjacent to a sloped cavity; commonly seen in one-and-a-half-story homes.

Cubic Feet per Minute (CFM) – Rate of flow for air movement between defined areas.

Denim insulation – A nonfibrous insulating material which does not require a vapor permeable air barrier in human contact areas.

Encapsulated batts – Unfaced fiberglass batts with a perforated vinyl cover (can serve as a vapor permeable air barrier in human contact/storage areas). Acceptable for installations.

Enclosed cavity – Space bordered on all sides by rigid material.

Exterior attic access – Entry into unconditioned attic space that connects directly to other unconditioned areas, including garages and outside.

Exhaust device - A mechanical unit intended to remove indoor air pollutants, including bathroom exhaust fans, dryers and mechanical ventilation devices.

Faced batt-type insulation – Faced batts have an air and/or vapor barrier on one side, usually made of kraft paper. The facing shall always be placed adjacent to the warm surface being insulated and shall not be sandwiched between insulation or installed, which creates a condensing surface on the cold side of the insulation.

Flex duct – Flexible plastic sheeting over a metal wire coil.

Ground cover – Six millimeter or thicker, black polyethylene used to exclude water vapors emanating from soil in unfinished crawlspaces or basements.

Human contact area – Location where occupants go for routine maintenance or storage.

IC vs Non-IC rated light fixtures – Insulation contact-rated fixtures do not need to be baffled to prevent insulation from contact. Insulation may be piled directly on top of fixture. Non-IC-rated fixtures must be baffled to prevent heat build up.

Interior attic access – Entry into unconditioned attic space directly connected to a conditioned area.

Knee wall – A short wall between an attic floor and a sloping roof, and which separates a conditioned and unconditioned space.

Minimum Ventilation Level (MVL) – Lower limit of natural ventilation due to leakiness of a structure below which mechanical ventilation must be installed.

Net free area – The net area of unencumbered venting, meaning the total area of the vent minus the area blocked by screens or louvers.

Open wall(s) – Any vertical barrier between conditioned and unconditioned space where the framing is visible from any side.

Passive ventilation – Natural ventilation of a space caused by wind or temperature-driven convection. Does not include moving parts such as fans.

Pony wall – For the purposes of the Weatherization Specifications Manual, any vertical barrier between conditioned and unconditioned space which is less than full wall height. For example, the wall between a skylight and the open attic space.

Post and beam – Floor construction using a support system of beams typically spaced 30”–48” OC. Requires 12” spacing for any support material (See UN 2.2 for spacing/spans).

Register – A ventilation grill separating HVAC ducting from conditioned space.

Rake – Horizontal section of side attic.

Return – Duct that brings conditioned air from the house to air handler.

Rim or band joist – Area of a home where the concrete foundation meets the floor joists.

Side attics – Unfinished areas located on the same floor as and adjacent to finished spaces. May be considered conditioned or unconditioned, depending on certain criteria.

Skylight – Any window unit in an opening in the roof assembly and which is installed at a slope of 15 degrees from vertical or greater.

Sloped ceilings – Angled ceilings—including vaults—over conditioned spaces which may follow the roof line or intrude into the attic space above and may require special consideration when installing insulation.

Spray foam insulation – A foam plastic material that is applied with a foaming agent for use as insulation.

Supply – Delivers conditioned air from the air handler into the home.

Thermal envelope – The plane where thermal and air barriers exist to reduce heat transmittance and air leakage. The thermal envelope should be continuous in order to maximize effectiveness.

Thermal barrier – An assembly or material that is installed to prevent heat from conducting between conditioned and unconditioned space.

Unconditioned space – Space within a building that is not heated or cooled by an active system or directly linked to conditioned space; outside.

Unfaced batt-type insulation – Batt-type insulation with no vapor or air barrier attached.

Upper attics – Unfinished areas located above finished spaces. Upper attics are usually considered unconditioned space except in rare cases.

Vapor permeable air barrier – Any material that substantively blocks air from passing, including housewraps, but allows water vapor (which may pass through narrower pores than air) to pass through.

Vapor barrier – A material restricting the movement of water vapor from an area of high vapor pressure to one of lower pressure. Material with a perm rating of 1.0 or less is normally considered a vapor barrier.