| Absolute Humidity | The weight of water in a given volume of air. |
| Absorbents | Granular substances that help clean up stains and spills without solvents or chemicals. |
| Accidental Pressure | An air-pressure difference between the indoors and the outdoors. |
| Accidental Ventilation | Random air movement into and out of a house. |
| Activated Alumina | A form of aluminum oxide used as an adsorption material in air filters, more correctly called activated alumina impregnated with potassium permanganate. |
| Activated Carbon | A form of carbon used as an adsorption or pollutant-reduction material in air or water filters, often derived from coconut, wood, or coal. |
| Active Ventilation | Ventilation caused by a fan. |
| Adsorption | The adhering of a gas onto the surface of a substance. |
| Adsorption Filter | A filter that removes gases from the air by the process of adsorption. |
| Air Changes per Hour (ACH) | The number of times the volume of air in a house is replaced with outdoor air during an hour. |
| Air Cleaner | There are several different types, but these useful appliances are no substitute for good cleaning and other preventive measures. |
| Air distribution | Movement of air throughout a house with a ventilation system or heating/cooling system. |
| Air Filter Arrestance | Also known as a dust weight-arrestance test, it measures only for larger and heavier particles. |
| Air Filter Efficiency | Describes the ability of an air filter to remove very fine particles of solid or liquid found in the air, such as aerosols, smoke, fumes, dust and ash. |
| Air Handler | A cabinet containing a fan. |
| Air Silencer | A device, similar to an automotive muffler, that can be used to absorb some of the sound generated in a ventilation system. |
| Air-Pressure Difference | The dissimilarity in air pressures between two locations that can cause air to move between them. |
| Air-to-Air Heat Exchanger (AAHX) | A balanced ventilation device capable of transferring heat (and sometimes moisture) between two airstreams. |
| Airflow Grid | A device that mounts inside a duct. |
| Airtight Construction | Building techniques that result in a house with a small effective leakage area (ELA) to conserve energy. |
| Airtight Drywall Approach (ADA) | Building techniques that result in a house with a small effective leakage area (ELA) to conserve energy. |
| All-Cotton | Understand the claims on the labels of your all-cotton items. |
| All-Natural | Be discerning. All-natural does not necessarily mean all-safe. |
| Allergen Slipcover | These bedding accessories are a must for people with severe asthma or allergic sensitivity to dust mites. |
| American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) | A professional organization that sponsors research and sets voluntary standards for the ventilation industry. |
| Antibacterial Products | The scientific debate continues over whether antibacterial soaps, sprays and wipes may end up doing more harm than good. |
| Apparent Sensible Effectiveness (ASEF) | A measurement useful in determining the temperatures of airstreams in a heat or energy recovery ventilator. |
| Arsenic | Highly toxic and a known carcinogen, sources of arsenic contamination include industrial and workplace exposure, ingestion of food and water containing arsenic-related substances and more. |
| Asbestos | A wide range of building materials may contain asbestos, particularly where insulation or heat and fire resistance are essential to safe construction.
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| Atmospheric Draft | The negative pressure in a chimney caused by rising, warm air and combustion by-products. Often referred to simply as draft. |
| Atmospheric Dust Spot Test | A method of testing medium-efficiency air filters. |
| ATP | Adenosine Triphosphate is the main energy transfer molecule present in all living (and once living) biological cells including animal, plant, bacterial, yeast, and mold cells. |
| Axial Fan | A type of ventilating fan having propeller-like blades. |
| Backdraft Damper | A device that allows air to only flow in one direction through a duct. |
| Backdrafting | Complete reversal of flow from a combustion appliance of its combustion by-products, usually due to negative pressures indoors. |
| Balanced Ventilation | A general ventilation strategy that results in the house experiencing a neutral pressure. |
| Basement Foundations | Unfinished and uninsulated basements have a high potential for mold growth and other contamination problems, but can be healthy with proper planning. |
| Bathroom Fan | Exhaust fans aren’t just for keeping the bathroom from smelling bad. |
| Batt | A widely used form of insulation. |
| Biocides | Evaluate whether a biocide-free product is what you want to use. |
| Biodegradable | Biodegradable is defined as “the ability of natural biological decay processes to break down complex compounds into simple molecules.” |
| Biofilm | Germs cooperate to build and maintain a barrier that keeps even strong disinfectants such as bleach and iodine at bay. |
| Biological Pollutants | Air pollutants, such as mold and pollen, that either are or once were alive, or by-products of metabolism. |
| Bisphenol A | Bisphenol A (BPA) is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. |
| Blower Door | A device used to pressurize or depressurize a house to evaluate its tightness. |
| Blower Door Test | Blower door tests help determine a home's airtightness.
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| Borax | A natural salt, also known as sodium borate, that has become popular as a nontoxic ingredient in homemade green cleaners. |
| Bottled Water | It’s convenient and healthful, but is it “green?” |
| Breathing Zone | The breathing zone in a room usually extends from a few inches off the floor to about 6 feet off the floor. |
| British Thermal Unit (BTU) | The amount of heat required to raise the temperature of 1 pound of water 1°F. |
| Building Envelope | The exterior portion of a structure, usually insulated, that surrounds the conditioned space. |
| By-Products of Metabolism | Solids, liquids, and gases given off by living creatures as a normal part of the life process. |
| CADR | Look for these numbers when comparing portable room air cleaners. |
| Canadian Standards Association (CSA) | An organization that maintains standards used to certify products for safety, rate products for performance and to complement the requirements in codes. |
| Candles | They create a warm, cozy atmosphere — and present some hazards as well. |
| Capital Cost | The installed cost of equipment. |
| Carbon Dioxide (CO2) | A colorless, odorless gas released in exhaled breath, or by combustion processes. |
| Carbon Monoxide (CO) | A colorless, odorless, poisonous gas released during the incomplete combustion of carbon-containing fuels. |
| Carbon Monoxide Alarm | Every home should have at least one CO detector. |
| Carbon-Dioxide Sensor | A device that senses the carbon dioxide concentration in the air and can be used to control a ventilation system. |
| Carcinogen | A substance that tends to cause cancer. |
| Castile Soap | Soap made from a variety of vegetable oils that is a healthy alternative for allergy sufferers and those with sensitive skin. |
| Category A Room | A room, such as a bedroom or living room, that is often occupied for long periods and requires general ventilation. |
| Category B Room | A room, such as a kitchen or bathroom, in which moisture or pollutants are generated, that has special ventilation requirements. |
| Caulk | A product that’s essential to a well sealed home. |
| Central Vacuum System | Central vacuums have a number of advantages over portable units. |
| Central Ventilation | Any general-ventilation strategy, i.e., balanced, central-supply or central-exhaust; with or without heat or energy recovery. |
| Central-Exhaust Ventilation | A general-ventilation strategy that uses an exhaust fan to remove air from a house. |
| Central-Supply Ventilation | A general ventilation strategy that uses either a supply ventilation fan or a forced-air heating/cooling fan to draw air into a house. |
| Centrifugal Fan | A ventilating fan with blades resembling a squirrel cage or a hamster wheel, often used in furnaces and ventilating devices. |
| CFL | Compact fluorescent lamps offer great energy savings over traditional incandescent or halogen lighting. There are trade-offs, however. |
| Chemical Sensitivity | Chemical sensitivity is hypersensitivity or intolerance to numerous chemicals at very low exposures or concentrations. |
| Chimney | A vertical structure or conduit that usually carries combustion by-products out of a house. |
| Chlorofluorocarbons (CFCs) | Chlorofluorocarbons define a category of chemicals which contain chlorine, fluorine and carbon. |
| Circulating Air | Air that moves from room to room or throughout a house. |
| Combustion Air | Air that enters a house specifically to be used in the combustion of a fuel. |
| Combustion By-Products | Gases and particulates released during the burning of a fuel. |
| Combustion Gases | Gases released during the combustion of heating and other fuels that can include carbon monoxide, sulfur dioxide, and nitrogen dioxide. |
| Combustion-Air Duct | A duct through which combustion air travels from the outdoors to a combustion device. |
| Concrete | Durable, versatile material made of four main ingredients: cement, aggregate, water, and admixtures. |
| Concrete-Slab Foundations | Easily constructed in a healthy manner, it can be part of a house foundation or built separately from the footings and foundation wall. |
| Condensation | The changing of a gas or vapor into a liquid, accompanied by the release of heat. |
| Conditioned Space | The part of a house, within the building envelope, that is kept at comfortable controlled temperature and humidity levels. |
| Controlled Pressure | An air-pressure difference between the indoors and the outdoors, purposefully induced by ventilation equipment. |
| Controlled Ventilation | Purposeful air movement into and out of a building in a regular way. |
| Convective Air Currents | The movement of air resulting from heat transference through the air by convection. |
| Crawl Space Foundations | Unlike basement foundations, a crawl space is not considered part of a home’s living space. Crawl spaces are usually accessed only to repair pipes, ducts or mechanical equipment. |
| Cubic Feet Per Minute (CFM) | A unit of measurement used to rate a fan’s capacity. |
| Damper | A device, often motorized or manually adjustable, used to vary or control the airflow in a duct. |
| Dander | Another word for dandruff, it is used most often to describe pet skin particles and adhering body fluids such as saliva that end up in our homes. |
| Decibel (dB) | A logarithmic unit of measurement used to express sound intensity. A difference of ten decibels is 10 times as loud as a difference of 1 decibel. |
| Deck | They need a physical exam yearly, just like you do. |
| Defrost Mechanism | A device used in heat or energy recovery ventilators to melt any ice that builds up in the core in cold climates during below freezing temperature conditions. |
| Degree Day | A unit of measurement used to estimate fuel consumption and heating or cooling costs, based on temperature and time. |
| Dehumidifying Heat Pipe | In humid climates, even air conditioned air may feel clammy without the assistance of a little technology. |
| Dehumidistat | A control device that can be used to activate a ventilation system when the relative humidity rises. |
| Deliberate Holes | Openings (inlets or outlets) that are purposely placed in a house through which air can enter or leave. |
| Demand-Controlled Ventilation (DCV) | The process of automatically supplying air to, and removing air from, a house whenever needed by the occupants. |
| Depressurization | When the air pressure inside a house or room is less than the atmospheric pressure outside the house or room. |
| Desiccant | A substance that absorbs moisture, used in some energy recovery ventilators to enhance moisture transfer between airstreams. |
| Desuperheater | Desuperheaters work in tandem with geothermal heat pumps to heat water. |
| Dew Point | The temperature at which air is saturated with moisture (100% relative humidity), below which condensation will occur. |
| Di-octyl Phthalate (DOP) | An inert gas used to test high-efficiency (HEPA) particulate air filters. |
| Diffuser | A grille designed to direct airflow in a specific pattern into a room for proper distribution. |
| Diffusion | The migration of molecules of a gas or a vapor (or a liquid) from an area of high concentration to an area of low concentration. |
| Diffusion Barrier | A material that slows down the amount of diffusion through a solid material, often used in insulated walls. |
| Diffusion Retarder | A material that slows down the amount of diffusion through a solid material, often used in insulated walls. |
| Dilution | The mixing of fresh air into stale air to reduce the concentration of pollutants; also applies to liquids. |
| Dilution Air | Air that mixes with combustion by-products prior to their being expelled from a house through a natural-draft chimney. |
| Displacement Ventilation | A method of very effectively moving air through a room, generally only used in specialized applications. |
| DOP-Smoke-Penetration Test | A method of testing high-efficiency (HEPA) air filters. |
| Double-Flow Ventilation | A general ventilation strategy that results in the house experiencing a neutral pressure. |
| Downdraft | A term often applied to kitchen exhaust fans that pull air downward. |
| Draft | A breeze or current of air in a room, often uncomfortable. |
| Drying Potential | The ability of a substance to dry out after it becomes wet. |
| Duct | A conduit for moving air, made from a variety of materials and in a variety of shapes. |
| Ductboard | A semi-rigid fiberglass material with an aluminum-foil facing on one side, used to construct ducts. |
| Dust Mites | These tiny creatures can cause allergies and other respiratory problems. |
| Dynamic Wall | An insulated part of a house’s structure through which outdoor air can pass from the outdoors to the indoors and is tempered in the process. |
| Effective Leakage Area (ELA) | ELA is the whole house leakage area at a pressure difference of 4 Pascals assuming a single flow point with a smooth, rounded area (Discharge coefficient = 1.0). |
| Electret | A plastic material that carries a permanent static charge, used in some air filters. |
| Electrical Cord | Perform this simple safety check. |
| Electrically-Commutated Motor (ECM) | A higher-cost type of variable-speed motor that utilizes electricity efficiently, especially at low speeds. |
| Electromagnetic Radiation (EMR) | The electrical and magnetic energy surrounding electrical wires and appliances. |
| Electrostatic Air Filter | An air filter composed of plastic materials that capture particulate pollutants using static electricity. See also electret. |
| Electrostatic Precipitator | An air filter that generates a high voltage which causes particulates to become electrically charged and cling to metal plates having an opposite charge. |
| Endocrine disruptors | The term “endocrine disruptors” is used to describe substances that are not produced in the body but act by mimicking or antagonizing natural hormones. |
| Energy-Recovery Ventilator (ERV) | A balanced ventilation device that transfers both heat and humidity between the exhaust and supply air streams. |
| Engineered Wood | Engineered wood has become a popular choice for environmentally preferable flooring. |
| Enthalpy | The total amount of heat contained in air, the sum of the sensible heat and the latent heat. |
| Environmental Agents | What the scientists mean when using this term. |
| Environmental Illness (EI) | A medical condition involving hypersensitivities to a wide variety of common air and food contaminants at very low levels. |
| Epigenetics | The development and maintenance of an organism is orchestrated by a set of chemical reactions that switch parts of the genome off and on at strategic times and locations. Epigenetics is the study of these reactions and the factors that influence them.
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| Equivalent Leakage Area (EqLA) | EqLA is the whole house leakage area at a pressure difference of 10 Pascals assuming a single flow area with a sharp edged orifice (Discharge coefficient = 0.61). |
| Equivalent Length | The length of straight duct that would have the same resistance to airflow as a fitting. |
| ERV | Energy recovery ventilators (ERVs) are heat recovery ventilators (HRVs) that exchange moisture between the two air streams.
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| Evaporation | The changing of a liquid to a gas or vapor, requiring heat. |
| Exchange Rate | The rate at which indoor air is replaced with outdoor air. |
| Exfiltration | Air leaving a house through random holes in the structure. |
| Exhaust Air | The air leaving a house through a ventilation system. See also supply air. |
| Exhaust Grille | A grille through which stale air leaves a room. See also supply grille. |
| Exhaust Ventilation | A general-ventilation strategy that uses an exhaust fan to remove air from a house. An equal volume of make-up air enters either by way of through-the-wall vents, through a fresh-air duct connected to a forced-air heating/cooling system, or through random holes in the structure of the house. |
| Exhaust-Only Ventilation | Ventilation strategy that uses one or more fans to exhaust stale air that is replaced by outdoor air entering through passive inlets and/or random leaks. See central-exhaust ventilation. |
| Extended-Surface Filter | An air filter configured to have a large amount of surface area to minimize resistance to airflow. See also medium-efficiency filter. |
| Extermination | Extermination is one of the components of integrated pest management. |
| Fan Door | A device used to pressurize or depressurize a house to evaluate its tightness. |
| Filtration | The process of removing particles or pollutants from air or water. |
| Fire Alarm | Professionally monitored systems are most often found in commercial settings. |
| Flat-Plate Core | A metal, plastic, or treated-paper device that is used in some heat or energy recovery ventilators to transfer heat and sometimes humidity between two separate airstreams. |
| Flood | How to stay safe both during and after a disaster. |
| Forced Draft | A system utilizing a fan to blow air into the combustion chamber of a combustion appliance. |
| Formaldehyde | A common gas found in indoor air, often released from building materials, consisting of 1 carbon atom, 2 hydrogen atoms, and 1 oxygen atom. |
| Formaldehyde-Based Glues | Common glues that hold together manufactured wood products such as plywood, oriented strand board and medium density fiber board. |
| Foundation | Supports a house and transmits its load to the ground or soil. It can have a significant impact on the health and integrity of a home. |
| Fragrances | Synthetic fragrances and scents, added to a wide-range of consumer products, are among the most common household air pollutants. |
| Fresh Air | Outdoor air that is brought indoors. |
| Fresh-Air Duct | A duct through which air travels from the outdoors to the indoors to benefit the occupants, often integrated with a forced-air heating/cooling system. |
| Fried Dust | Popular term for airborne debris which burns when it comes into contact with very hot surfaces. |
| Fungus | Mold, mildew, yeast and mushrooms are common examples. |
| Geothermal Heat Pump | A geothermal heat pump or ground source heat pump (GSHP) is a central heating and/or cooling system that pumps heat to or from the ground. |
| Green Cleaning | Cleaning to protect both health and the environment. |
| Grille | An often decorative covering on a wall or ceiling through which air moves to or from the conditioned space. |
| Hardboard | Manufactured wood product used in home construction for interior wall paneling, underlayment for carpeting and exterior siding. |
| Hazardous Waste | These products can threaten your family’s health and the environment. |
| HE Washing Machines | HE washers save significant energy over traditional washing machines by decreasing the amount of water needed per load and shortening drying times. |
| Headspace | The breathing zone in a room, in residences it usually extends from a few inches off the floor to about 6 feet off the floor. |
| Healthy Home Checklist | Done regularly, these tasks will help ensure clean air and greater safety inside your well-functioning home. |
| Heat Pipe | A sealed tube partially filled with a refrigerant, used in some HRVs to transfer heat between two airstreams. |
| Heat Pump Water Heaters | A heat pump also can be used to heat water - either as a stand-alone water heating system, or as a combination water heating and space conditioning system. |
| Heat Pumps | For climates with moderate heating and cooling needs, heat pumps offer an energy-efficient alternative to furnaces and air conditioners. |
| Heat-Recovery Ventilator (HRV) | A balanced ventilation device capable of transferring heat between the exhaust and supply airstreams. |
| HEPA Filter | Stands for High Efficiency Particulate Air filter, often used in hospitals and laboratories. |
| HERS | A home energy rating involves an analysis of a home’s construction plans, and onsite inspections. |
| Home Ventilating Institute (HVI) | An organization that certifies the airflow, sound, and energy performance of residential ventilation equipment. |
| HRV | Brings fresh air in and takes stale air out, while conserving heat or cooling energy. |
| Humidifier, Whole House | Basic tips on controlling humidity output. Don’t have a humidifier? You might not need it after all. |
| Humidistat | A control device that can be used to activate a ventilation system as the relative humidity falls. See dehumidistat. |
| Humidity | Humidity is moisture in the air in the form of invisible water vapor. See absolute humidity and relative humidity. |
| HVAC | Heating, ventilating and air conditioning explained. |
| Hydronic Heater | An electric appliance using hot liquid inside copper tubing to deliver heat. |
| Hygrometer | A device that senses relative humidity. |
| Hypoallergenic | This type of labeling is not quite a promise that an item will not trigger an allergic reaction. |
| ICF or Insulating Concrete Form | Insulating Concrete Forms or ICFs are popular in green building projects because of their thermal performance, durability, non-outgassing materials, and other reasons. |
| IFH | The International Scientific Forum on Home Hygiene (IFH) is a registered charity with the mission to provide practical advice and guidance on the promotion of health and well-being through improved hygiene. |
| IICRC | An acronym for the Institute of Inspection, Cleaning and Restoration Certification, now known as the The Clean Trust, a standards and certification organization. |
| In-Line Fan | A ventilating fan made to attach a duct at each end, often called a tube fan. |
| Inches of Mercury | A unit of pressure measurement. About 3,386 Pa. equals 1” hg. |
| Inches Water Gauge | A unit of pressure measurement. About 250 Pa. equals 1” w.g. |
| Induced Draft | A system utilizing a fan to exhaust air from the combustion chamber of a combustion appliance. |
| Infiltration | Air entering a house through random holes in the structure. |
| Infrared Thermography | Thermographic inspection measures surface temperatures by using infrared video and still cameras. These tools see infrared light (light that is in the heat spectrum) to detect temperature variations of the building's "skin", showing warmer areas in lighter colors and cooler areas in darker colors. |
| Inlet | An engineered opening through which fresh air enters a house. |
| Insulation | A material that inhibits the flow of heat. |
| Ionizer | A device that generates ions (usually negatively charged), sometimes for the purpose of cleaning the air. |
| Irritant | A substance that causes a part of the body to become overly excited or sensitive. |
| Jump Duct | A short duct connecting two rooms through which air can move when pressure imbalances occur between the rooms. |
| Kilowatt Hour (kWh) | A unit of measuring electrical energy equal to 1,000 watts of power consumed over an hour. |
| Ladder Safety | How to do it right when you have to work high off the ground. |
| Latent Heat | The amount of heat that must be removed from air to change the water vapor from a gas to a liquid without changing its temperature. |
| Latex Gloves | These indispensable tools help guard against infection and chemical exposure. |
| Lead Paint | If it’s in good shape, it just needs regular cleaning to avoid hazards. |
| LEDs | Solid-state lighting (SSL) technology uses semi-conducting materials to convert electricity into light. |
| LEED | The U.S. Green Building Council Leadership in Energy and Environmental Design (LEED) Green Building Rating System™ is a nationally accepted benchmark. |
| Liters per second (l/s) | A metric unit of measurement used to rate a fan’s capacity. One liter per second is equal to approximately 2 cubic feet per minute. |
| Living Space | The part of a house to which the occupants normally have access, or habitable rooms; also called the occupied space. |
| Local-Exhaust Ventilation | The quick removal of air pollutants from near the source to the outdoors. |
| Loose Fill Insulation | A form of unfaced insulation. |
| Made from Recycled Materials | This is a phrase often used when all or part of an item is made from a previously manufactured material or product. |
| Magnahelic Gauge | A type of pressure-measuring device. |
| Make-Up Air | Outdoor air that enters a house to replace air that is exhausted from the house. |
| Manometer | A gauge for measuring air-pressure differences, of which there are several types. |
| Manufactured home | A home that is wider than 8 feet and longer than 40 feet (for an area greater than 320 square feet); built on a permanent chassis and assembled in a manufacturing plant. |
| Masonry | Building construction using materials such as concrete, tile and glass blocks, stone, brick and brick veneer. |
| Mats | Want to stop dirt and dust at the door so it does not damage floors or become airborne? Try a set of these. |
| Mattress | Turn and vacuum twice a year for better sleep — and better health. |
| MCS | Here’s what multiple chemical sensitivity means. |
| MDF | Medium density fiberboard (MDF) is a manufactured wood product widely used in home construction. MDF is produced from fine wood fibers which are bonded with resins or glue. |
| Mechanical Ventilation | The process of supplying air to, and removing air from, a house using a fan. |
| Media Filter | A filter that relies on a fibrous material, usually polyester or fiberglass, to physically strain particulates out of the air. |
| Medium Density Fiberboard | MDF is a manufactured wood product widely used in home construction that is produced from fine wood fibers which are bonded with resins or glue. |
| Medium-Efficiency Filter | A particulate filter, usually in the 30–40% efficiency range when measured using the atmospheric dust spot test. |
| MERV | Stands for Minimum Efficiency Reporting Value. |
| Metal Cabinets | Often overlooked, metal cabinets can be an attractive, low-odor, easy to clean, and durable option. |
| Microban | It’s how advancing technology helps people keep bacteria at bay.
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| Microbes | The scientific name for what many people call germs or bugs. Microbes contribute to bad smelling bathrooms, but also function as natural cleaning agents. |
| Micron | A millionth of a meter. |
| Microwaves | Microwaves are a form of electromagnetic radiation; that is, they are waves of electrical and magnetic energy moving together through space. |
| Mildew | It’s usually another name for mold. |
| Mixed-Gas Sensor | A device that senses oxidizable gases in the air and can be used to control a ventilation system. |
| Modular home | A home that is built in a factory in sections, transported to a site, lifted from the transport by crane, and rested on a prebuilt foundation. |
| Modulating Damper | A motorized damper that can be opened and closed a variable amount. |
| MRSA | Info about drug-resistant staph infections. |
| MSDS | What’s a Material Safety Data Sheet, anyway? |
| MTBE | MTBE (methyl tertiary-butyl ether) is a chemical compound that is manufactured by the chemical reaction of methanol and isobutylene. MTBE is produced in very large quantities (over 200,000 barrels per day in the U.S. in 1999) and is almost exclusively used as a fuel additive in motor gasoline. |
| Multi-Port Ventilator | An exhaust device having several suction connections for running ducts from different rooms. |
| Multiple Chemical Sensitivity (MCS) | A medical condition involving hypersensitivities to a wide variety of common air and food contaminants at very low levels. |
| Mutagen | A substance that causes changes in chromosomes or genes. |
| N95 respirator | An essential tool used to protect people from hazardous fumes during certain jobs. |
| Nanometer | A distance unit representing one-billionth of a meter. |
| nanoparticle | An ultra-small, highly microscopic particle. |
| Nanotechnology | Nanotechnology describes the creation and use of materials, devices and systems which control matter at the atomic or molecular level or “nanoscale”. |
| National Coalition Against the Misuse of Pesticides (NCAMP) | A nonprofit organization devoted to pesticide safety and alternative, less toxic methods of controlling pests. |
| Natural Aspiration | The negative pressure in a chimney caused by rising, warm combustion by-products. Often referred to simply as draft. |
| Natural Draft | The negative pressure in a chimney caused by rising, warm combustion by-products. Often referred to simply as draft. |
| Natural Pressure | An air-pressure difference between the indoors and the outdoors, induced by natural phenomena such as wind, stack effect, and diffusion. |
| Natural Ventilation | Random air movement into and out of a house caused by natural pressures. |
| Negative Ions | Negatively charged atoms or groups of atoms that will cling to oppositely charged surfaces. |
| Negative Pressure | When the air pressure inside a house or room is less than the atmospheric pressure outside the house or room. |
| Net Free Area (nfa) | The amount of unobstructed open area of a grille, inlet, or outlet. |
| Neurotoxin | A substance that is poisonous to the nervous system, spinal cord, brain, etc. |
| Neutral Pressure | Air pressure inside a house that is equal to the atmospheric pressure outside the house. |
| Neutral-Pressure Plane | That part of a house that experiences neutral pressure as a result of stack effect, or as a result of combined pressures. |
| Noise Pollution | The traditional definition of noise is 'unwanted or disturbing sound'. |
| Nontoxic | Nontoxic is defined as not being harmful at concentrations normally used. However, most people believe that it means a substance is innately harmless — and this just isn’t so. |
| Occupied Space | The part of a house to which the occupants normally have access, or habitable rooms; also called the living space. |
| Odor | Don’t cover up, clean up. Here’s how. |
| On-Purpose Ventilation | Purposeful and directed air movement into and out of a building. |
| Optical Brighteners | Is your laundry really sparkling white or are you just seeing things? |
| Organic Chemical, Compound | Any substance that has carbon molecules in its structure. |
| Organic Gardening | Organic gardening is the practice of producing crops by avoiding the use of synthetic chemical fertilizers, pesticides, fungicides, and growth regulators. |
| Oriented Strand board (OSB) | As with construction-grade plywood, it can often be used in a healthy house if it is well-separated from the living space. |
| Outgassing | The release of volatile gases from a solid material as a part of aging, decomposition, or curing. |
| Ozone | “Good up high, bad nearby,” according to one government agency. Here’s why. |
| Partial-Bypass Filter | A filter that removes some contaminants from the air, but allows some air to pass through without contacting the filter, usually to minimize the resistance to airflow. |
| Particle Board | Made from small softwood particles that resemble coarse sawdust, and is usually held together with potent urea-formaldehyde (UF) glue. |
| Particulate Filter | An air filter designed to remove particulates from the air. |
| Particulates | Solid (or liquid) air pollutants, as opposed to gases. |
| Parts Per Millon (ppm) | A small unit of measurement, often used to express the concentration of pollutants in the air. |
| Pascal | The pascal (Pa) or kilopascal (kPa) is a unit of pressure measurement. |
| Pascal (Pa.) | A small unit of pressure measurement, useful in diagnosing houses for tightness and ventilation. One pound per square inch (psi) equals about 7,000 Pascals. |
| Pass-Through | An opening between two rooms through which air can move when pressure imbalances occur between the rooms. |
| Passive Solar | A home-energy alternative or addition to gas and utility electric. |
| Passive Ventilation | Caused by house pressurization or depressurization, not directly caused by a fan. Infiltration and exfiltration involve passive air movement. |
| People Pollutants | Solids, liquids, and gases given off by humans as a normal part of the life process. |
| Perchlorate | As a pollutant, perchlorate is found in groundwater, surface water and soil and has proven to be a pervasive contaminant of agricultural and manufactured food products. |
| Permanent-Split-Capacitor Motor | A type of electric motor characterized by a main winding and an auxiliary winding wired in series with a capacitor. |
| Permeable Wall | An insulated part of a house’s structure through which outdoor air can pass from the outdoors to the indoors and is tempered in the process. |
| Personal Health Record (PHR) | A Personal Health Record (PHR) is a tool that enables you to collect, manage and share past and current information about your health or the health of someone in your care. |
| Pesticides | Chemical compounds formulated to kill living creatures. |
| Phosphates | Once widely used to soften water for use in washing machines, some makers have reduced use of these chemicals. |
| PicoCurie per liter (pC/l) | A unit of measurement used to determine the concentration of radon in the air. |
| Pier Foundations | Often used in hot, humid climates, a pier foundation lifts a house up off the ground reducing health hazards from direct soil contact. |
| Plywood | Material made of several layers of wood glued together, which is widely used in home construction. |
| Poly Moisture Barrier | Sheets of heavy plastic that help keep moisture out. |
| Polyurethane and polyisocyanurate | Polyurethane can be a flexible foam, as used in upholstery, or a rigid foam, as in insulation.
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| Porosity | Capacity of a material to be penetrated through its pores, for example, by gases or vapors. |
| Positive Pressure | When the air pressure inside a house or room is greater than the atmospheric pressure outside the house or room. |
| Pounds per square inch (psi) | A unit of pressure measurement. |
| Pressure Washer | They’re great outdoor cleaning tools, but they can cause severe injury or damage if misused. |
| Pressurization | When the air pressure inside a house or room is greater than the atmospheric pressure outside the house or room. |
| Preventive Maintenance | A preventive, systematic approach to health, safety and comfort is a homeowner’s best defense against poor air quality, unexpected breakdowns and expensive repairs. |
| Protective Gloves | Keep your hands (and, sometimes, forearms) safe from bacteria, spores or caustic chemicals. |
| Psychometric Chart | A graph used to determine the moisture content and energy of air at different temperatures. |
| R-value | How effective is your insulation? |
| Radiant Cooling | Radiant cooling cools a floor or ceiling by absorbing the heat radiated from the rest of the room. |
| Radiant Heating | Forced air heating is not the only option. |
| Radon | A naturally occurring radioactive gas, often released from soil and rocks. |
| Radon Daughters | The natural radioactive decay products of radon, some of which release harmful radiation. |
| Radon Progeny | The natural radioactive decay products of radon, some of which release harmful radiation. |
| Random Holes | The miscellaneous cracks, gaps, and openings in a house between the indoors and the outdoors through which air can move. |
| Range fan | The hood has a removable filter that’s essential for reducing airborne grease. |
| Recirculate | To move air through the living space without adding fresh air or removing stale air. |
| Recirculating Range Hood | A ductless range hood, one that is not connected to the outdoors. |
| Recyclable | Recyclable only means recycled if the consumer, middle man and manufacturer all participate. |
| Recycled | Only a limited number of items are created of 100% post-consumer material. |
| Recycling Symbol, Plastic | How to “read” plastic containers for recycling. |
| Relative Humidity (RH) | The amount of moisture in air compared to the maximum amount of moisture that air at that temperature can contain, usually expressed as a percentage. |
| Return Air | Air from a living space that enters an air handler, such as a furnace or air conditioner, and is returned back to the space. |
| Rotary Core | A slowly spinning wheel typically made of corrugated material (metal, plastic or treated paper) tightly stacked; used in some heat or energy recovery ventilators to transfer heat and moisture between two airstreams. |
| Rubber Gloves | Some jobs require greater hand protection than others. |
| Safety Goggles | Your eyes are vulnerable. Here is how to protect them. |
| Sealed Combustion | A system in some furnaces, boilers, fireplaces, and water heaters that is immune to pressure imbalances in a house because it draws combustion air from the outdoors into a sealed chamber and expels by-products to the outdoors. |
| Secondary Ventilation | Ventilation for the quick removal of air pollutants from near a source. See also local-exhaust ventilation. |
| SEER | Seasonal Energy Efficiency Ratio (SEER). |
| Sensible Heat | The amount of heat involved in raising or lowering the temperature of air, not including any heat required to cause water vapor to change state (e.g. from a gas to a liquid). |
| Sensible Recovery Efficiency (SRE) | A measurement, that does not include latent heat recovery, used in determining the amount of energy passed between airstreams in a heat or energy recovery ventilator. |
| Separation | The principle of isolating pollutants from the living space. |
| Shaded-Pole Motor | A type of low-cost, usually inefficient, motor whose starting torque is provided by a permanently short-circuited auxiliary winding. |
| Sheathing | Sheathing adds strength and wind resistance to house walls, and is now made in a variety of materials. |
| Sick Building Syndrome | The term "sick building syndrome" (SBS) is used to describe situations in which building occupants experience acute health and comfort effects, but no specific illness or cause can be identified. |
| Single-Port Ventilator | An exhaust device having only one suction connection for a duct from the living space. See also multi-port ventilator. |
| SIP or Structural Insulated Panel | Structural insulated panels (SIPs) are high performance building panels used in floors, walls, and roofs for residential and light commercial buildings. |
| Solid-state lighting (SSL) | Solid-state lighting (SSL) technology uses semi-conducting materials to convert electricity into light. Light-emitting diodes (LEDs) are an example. |
| Sone | A linear unit of sound measurement used to express sound intensity. Two sones are twice as loud as one sone. |
| Sone Rating | A sone is a measurement of loudness typically applied to ventilation fans. |
| Sound Attenuator | A device, similar to an automotive muffler, that can be used to absorb some of the sound generated in a ventilation system. |
| Source Control | The principle of using nonpolluting materials in the living space, or of removing polluting materials from the living space. |
| Spillage | A situation where some of the combustion by-products spill into the living space, rather than go up the chimney, usually due to insufficient draft. |
| Spot Ventilation | Ventilation for the quick removal of air pollutants from near a source. See also local-exhaust ventilation. |
| Spray-On Insulation | Insulation products that start out as a liquid, but end up as a solid. |
| Squirrel-Cage Fan | A ventilating fan with blades resembling a squirrel cage or hamster wheel, often used in furnaces and ventilating devices. |
| Stack Effect | The naturally occurring phenomena of warm air exerting pressure on cooler air that results in warm air rising. |
| Stale Air | The air leaving a house through a ventilation system. |
| Static Pressure | The amount of pressure exerted against the walls of a duct or airway, created by the friction and impact of air as it moves. |
| Static Pressure Drop | The change in pressure resulting from resistance to airflow. |
| Strain Hygrometer | A relative-humidity sensing device containing a spiral-wound material that is sensitive to changes in relative humidity. |
| Supply Air | The air entering a house through a ventilation system. Also, the conditioned air passing from a furnace/air conditioner into the living space. |
| Supply Grille | A grille through which fresh air enters a room. See also Exhaust grille. |
| Supply Ventilation | A general ventilation strategy that uses either a supply ventilation fan or a forced-air heating/cooling fan to draw air into a house. |
| Supply-Only Ventilation | A general ventilation strategy that uses either a supply ventilation fan or a forced-air heating/cooling fan to draw air into a house. |
| Synergism | The interaction of two substances such that the combined effect is greater than the sum of the individual effects. |
| System | The dynamic interrelationship of components designed to fulfill a purpose. |
| Teratogen | A substance that interferes with the development of a fetus or causes birth defects. |
| Terpene | Terpenes are hydrocarbons - organic compounds made up of hydrogen and carbon - mainly from plants, and the main constituent of essential oils. |
| The Clean Trust | Formerly known as The Institute of Inspection, Cleaning and Restoration Certification (IICRC), The Clean Trust is an ANSI-accredited standards setting body for the flooring inspection, floor covering and specialized fabric cleaning, and disaster restoration industries. |
| Thermographic Inspection | Thermographic inspection measures surface temperatures using infrared light (light that is in the heat spectrum) to detect temperature variations of the building's "skin", showing warmer areas in lighter colors and cooler areas in darker colors. |
| Through-the-Wall Vent | A deliberate opening in an exterior wall through which air moves. The direction of air movement can be inward or outward, depending on the pressure difference between the indoors and the outdoors. |
| Total Dissolved Solids (TDS) | Total dissolved solids are dissolved particles found in water that are small enough to pass through a .45 µm filter. |
| Total Recovery Efficiency (TRE) | A measurement that includes latent heat recovery, used in determining the amount of energy passed between airstreams in a heat or energy recovery ventilator. |
| Total Solids (TS) | Total solids are the weight of total dissolved solids (TDS), total suspended solids (TSS) and settleable solids per unit volume of water. |
| Total Suspended Solids (TSS) | Total suspended solids, sometimes called filterable solids, are typically larger particles found in water that will not pass through a .45 µm pore-diameter filter. |
| Toxic substance | A chemical or agent that constitutes a potential hazard to human health at acute or chronic exposure levels. |
| Toxoplasmosis | A concern for pregnant women and anyone with a weakened immune system. |
| Tracer Gas | A gas, often inert, that is used to evaluate the air-exchange rate in a house. |
| Transfer Duct | A short duct connecting two rooms through which air can move when pressure imbalances occur between the rooms. |
| Transfer Grille | An opening between two rooms through which air can move when pressure imbalances occur between the rooms. |
| Trisodium phosphate (TSP) | A granular, alkaline cleaning product sold in hardware and paint stores. |
| TSCA | The Toxic Substances Control Act (TSCA) requires EPA to compile, keep current, and publish a list of each chemical substance that is manufactured or processed in the United States. |
| Tube Fan | A ventilating fan made to attach a duct at each end. |
| U-Factor | U-Factor measures the rate of heat transfer and tells you how well the window insulates. |
| United States Environmental Protection Agency (USEPA) | A federal agency charged with monitoring and regulating environmental quality, including air quality, and providing research-based information to the public. |
| Unscented | Product labeling can be confusing. |
| Urea-Formaldehyde Foam Insulation (UFFI) | A type of insulation widely used in the 1970s that sometimes released formaldehyde gas, now rarely used. |
| UV-C | UVC has been shown to inactivate viruses, mycoplasma, bacteria, and fungi, whether suspended in air or deposited on surfaces. |
| Vapor | The gaseous form of a substance that is normally a liquid at room temperature. |
| Vapor Barrier | It’s an essential component of construction in a healthy home. |
| Vapor Pressure | A force that drives vapor molecules from an area of high concentration to an area of low concentration. In homes this typically refers to water vapor pressure. |
| Vapor Retarder | A material that slows down the amount of diffusion through a solid material, often used in insulated walls. |
| Vapor Steam Cleaners | Vapor steam cleaners are versatile machines that offer the benefit of chemical-free cleaning. |
| Ventilation | The process of supplying air to, or removing air from, a house, most often with a fan. |
| Ventilation Air | Air that enters a house specifically for the purpose of ventilating. See also combustion air. |
| Ventilation and air pressure | The bringing in of fresh air and the exhausting of stale air, and how air pressure differences are involved. |
| Viruses | Microorganisms that can cause a lot of mischief, viruses need hosts for propagation. |
| Volatile Organic Compound (VOC) | A class of hundreds of different molecular compounds containing carbon that easily evaporates, often released from building materials and found as contaminants in indoor air. |
| Water | While quality is generally quite good, blanket assurances can’t be given. |
| Water Conditioner | These systems often soften hard water. |
| Water Purifier | These systems rid water of everything from chlorine to microbes and heavy metals – an important consideration for those with health issues. |
| Water Quality Association | The Water Quality Association (WQA) is a not-for-profit international trade association representing the residential, commercial, industrial, and small community water treatment industry. |
| Water softener | Water softeners improve water’s sudsing ability, save on soap costs, make cleaning easier, and reduce mineral buildup or scale. |
| Water softening terms | Courtesy of the Water Quality Association (WQA). |
| Water Well | Chemical analysis – and some common sense – will keep your water supply healthy. |
| Weight-Arrestance Test | A method of testing very low-efficiency air filters. |
| Well-Ventilated Area | Another term you’ll see frequently. What do we mean? |
| Wetting Potential | The ability of a substance to become wet after it has dried out. |
| Whole-House Fan or Whole House Comfort Ventilator | A ventilation system, usually an exhaust fan, used to move air through an entire house, usually in high volumes for the purpose of summer cooling. |
| Wind | A naturally occurring phenomenon that can cause a house to experience positive or negative air-pressure differences. |
| Wood: Softwood vs Hardwood | How to chose the best wood for your home and health. |
| WQA | The Water Quality Association is a not-for-profit international trade association representing the residential, commercial, and industrial water treatment industry. |
| Xeriscaping | Xeriscaping and xerogardening refer to landscaping and gardening in ways that reduce or eliminate the need for supplemental water from irrigation (Wikipedia). |
| Zeolite | A mineral that helps get rid of odors. |
