0-Probe:  A method used to test HEPA and ULPA filters for leaks utilizing either an aerosol photometer or discrete-particle counter. A sampling probe is moved in a series of parallel, slightly overlapping strokes across the test area at a distance of approximately 2.5cm (1 inch) from the filter face.

Z-bar Flashing: Bent, galvanized metal flashing that’s installed above a horizontal trim board of an exterior window, door, or brick run. It prevents water from getting behind the trim/brick and into the home.

ZDDP:  An antiwear additive found in many types of hydraulic and lubricating fluids. Zinc dialkyldithiophosphate.

ZEFON Air-O-Cell:  A non-inertial sampling device produced by Zefon Corporation for collection and analysis of a wide range of airborne aerosols. These include mold spores, pollen, insect parts, skin cell fragments, fibers (e.g. asbestos, fiberglass, cellulose, clothing fibers) and inorganic particulate (e.g. ceramic, fly ash, combustion particles, copy toner). Airborne particles are impacted onto a glass microscope slide that is coated with a sticky substance. Particles deposited onto the slides can be observed directly under the microscope. The concentration of particles per unit volume of air can then be calculated.

Zenith Angle:   The angular distance from the sun to the zenith (the point directly above the observer) (at noon: latitude - solar declination).

Zeolite:  Any one of a family of hydrous aluminum silicate minerals, whose molecules enclose cations of sodium, potassium, calcium, strontium, or barium, or a corresponding synthetic compound, used chiefly as molecular filters and ion-exchange agents.

Zeotrope:  A blend of refrigerants having a temperature glide greater than 5° 

Zero:  The temperature of pure melting ice under standard atmospheric pressure on the Centigrage and Réaumur scales.

Zero Absolute:  See absolute temperature and pressure. 

Zero Discharge Water:  A discharge limit applied to manufacturing and commercial establishments in which only normal human sanitary wastewaters may be discharged to the municipal sewerage system. All other types of wastewater, such as that water used in manufacturing processes, are not included in zero discharge water; these wastewaters must be recycled, and the resulting waste products must be taken to an alternate and approved disposal facility.

Zero Emission Vehicle (ZEV): Vehicles which produce no emissions from the on-board source of power (e.g., an electric vehicle).

Zero Energy Building (ZEB):  A building with a net energy consumption of zero over a typical year because the energy provided by on-site renewable energy sources is equal to the energy used. Buildings approaching this goal may be called near zero energy buildings or ultra-low energy buildings.

Zero Energy House:  Any house that averages out to net zero energy consumption. A zero energy home can supply more than its needs during peak demand, typically using one or more solar energy strategies, energy storage and/or net metering. In a zero energy home, efficiencies in the building enclosure and HVAC are great enough that plug loads tend to dominate and so these homes must have the added focus of high efficiency appliances and lighting.

Zeta Potential:  The potential across the diffuse layer of ions surrounding a charged colloidal particle.

Zinc Whiskers:    Small crystals of zinc which can grow naturally from the surface of certain zinc plated flooring systems. Commonly occur on the bottom of woodcore access panels. See Zinc Whisker Article for more details.

Zone: The occupied space or group of spaces within a building which has its heating or cooling controlled by a single thermostat.

Zone 7:  Common name for the Alameda County Flood Control and Water Conservation District, Zone 7.

Zone of Aeration:  That subsurface soil zone above the free groundwater table wherein soil pores contain both air and water.

Zone of Initial Dilution (ZID):  When wastewater is discharged into a water body, its transport can be divided into two stages with distinctive mixing characteristics.  Turbulent mixing in the first stage is determined by the initial momentum and buoyancy of the discharge.  The second stage covers a more extensive area in which the waste is mixed primarily by ambient laminar mixing and diffusion.  The in which the first stage turbulent mixing occurs is the zone of initial dilution.

Zone of Saturation:  That subsurface soil zone wherein soil pores are completely filled with water.

Zone System:  A method of dividing a home into zones and enabling you to control the amount of comfort provided to each.

Zone Valve: A device, usually placed near the heater or cooler, which controls the flow of water or steam to parts of the building; it is controlled by a zone thermostat.

Zoned Airflow: A Baker Company patented design feature in which the airflow velocity is greater behind the viewscreen than over the work surface, increasing the cabinet’s containment capabilities. 

Zoned Comfort Control:  Controls the temperature based on the heating and cooling needs in each area or “zone” of a home, eliminates hot and cold spots. Dampers are used to direct hot/cold air to certain areas (or zones) of the home only when and where it’s needed.

ZonePerfect Plus:  Our exclusive zoning system, designed to work in conjunction with
properly matched HVAC products to enhance energy efficiency by as much as 30%.

Zones: The classification of asthma signs and symptoms in an asthma action plan. Usually the zones include the Green Zone (all is well, continue with regular medicines and activities); the Yellow Zone (trouble starting; follow doctor’s instructions for Yellow Zone); and Red Zone (DANGER! Get to the emergency room as quickly as possible). These are determined by symptoms and peak flow readings.

Zoning:  A method of dividing a home into different comfort zones so each zone can be independently controlled depending on use and need; an air conditioning system capable of maintaining varying conditions for various rooms or zones.

Zoning System:  A method of dividing a home into different comfort zones so each zone can be independently controlled depending on use and need; an air conditioning system capable of maintaining varying conditions for various rooms or zones.

Zoonosis:  A zoonosis is a disease of animals that may, under natural conditions, be secondarily transmitted to humans – a disease that is communicable between animals and humans.