Glossary
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Manual-J
Method developed by the air conditioning Contractors of America to size heating and cooling equipment.
Mass Effect
Describes the effect of a high-mass material on heating or cooling requirements. High mass materials such as concrete, used in floors and walls, can absorb and store significant amounts of heat, which is later released. In some climates (those with lots of sunshine, low humidity, and large daily temperature fluctuations), high-mass materials can mean a reduction in cooling and heating requirements by delaying the time at which the heat is released into the house.
Mass Spectrum
Characteristic fingerprint of a substance, which makes its identification possible.
Mastic
Strong, flexible material, which has a thick, creamy consistency when applied, used to seal ductwork. Also used to describe a type of ceramic adhesive.
Material Safety Data Sheets (MSDS)
A compilation of information required under the OSHA Commercial Standard on the identity of hazardous chemicals, health, and physical hazards, exposure limits and precautions.
Materials Recovery Facility
Commonly called a MRF (pronounced "murf"). A processing facility that removes recyclables from the waste stream. A "dirty MRF" removes reusable materials from unseparated trash; a "clean MRF" separates commingled recyclables.
Mechanical Ventilation
The use of fans and intake and exhaust vents to mechanically distribute ventilation and other conditioned air. See also "Ventilation, Natural."
Megalopolis
A single vast urban area formed by the expansion and merging of adjacent cities and their suburbs.
Methane
A colorless, nonpoisonous, flammable gas created by anaerobic decomposition of organic compounds. A major component of natural gas used in the home.
Microbial Growth
The amplification or multiplication of microorganisms such as bacteria, algae, diatoms, plankton and fungi.
Microbiological Organism
Broad range of living organisms, which typically can be viewed only through a microscope.
Micron
A measure of length; one millionth of a meter.
Model Energy Code (MEC)
A building code that requires houses to meet certain energy efficiency-related minimums such as insulation levels or energy consumption. Like most building codes, it is adopted on either a state or local basis, if at all, and may be amended.
Mold
Mold is a fungus that typically grows in a filamentous cobweb-like mass under damp conditions and is capable of producing staggering numbers of reproductive spores in as little as a few days. Molds are non-chlorophyll containing entities, which require organic matter, living or dead, for survival. Mold is a critical participant in the "recycling" of dead organic material on the planet. Molds are extraordinarily diverse in character and their relationship with humans span the positive (e.g., food, antibiotics) to the negative (e.g., pathogens, antigens, toxins).
Montreal Protocol
An agreement reached in 1987 at a meeting in Montreal, Canada, whereby a number of industrialized countries pledged to freeze CFC production at 1986 levels and then gradually decrease CFC production to 50% of 1986 levels by 1999.
Multiple-Use Development
The use of a piece of land for different purposes simultaneously, such as the use of riverside land for water filtration by plants, recreation, flood buffers, and wildlife habitat.
Mutagen
Any agent, such as a chemical, ultraviolet light, or a radioactive element, that can cause or accelerate the rate of mutation within an organism.
