Definitions - p


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Parallel Strand Lumber

Beams made from strands of wood fiber mixed with resins and pressed into large beams.

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Parallel Wiring

This is when a group of electrical devices, such as PV modules, are wired together to increase ampage, whilst the voltage remains constant.

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In climate modeling, this term refers to the technique of representing processes that cannot be explicitly resolved at the resolution of the model (sub-grid scale processes) by the relationships between the area averaged effect of such sub-gird scale processes and the larger scale flow.

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Passive House

A Passive House is a house designed to use Passive Solar Design principals to drastically reduce its energy demands by making full use of the energy supplied by the Sun, this thereby reduces ecological footprint of the building.

This can include its orientation, window placement, Trombe Walls, ventilation, thermal mass and living space placement. It also include the adoption of standards on energy efficiency to further reduce energy demands.

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Passive Solar

Passive solar design refers to the use of the sun's energy for the heating and cooling of living spaces. With this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun.

Passive systems are simple, have few moving parts, and require minimal maintenance and require no mechanical systems. Often the thermal characteristics of materials are extensively used, often termed as Thermal Mass design.

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Passive Solar Design

Passive Solar Design is undergoing a resurgence as more people not only recognise the comfort benefits and lower energy bills of solar architecture, but now see a way of helping reduce the polluting effects of green house gases through less reliance on fossil fuels for heating and cooling.

Basic house design principles include:
  • Orientation of the main living areas towards the North (or South if in the Northern hemisphere)
  • Glazing used to trap the warmth of the Sun.
  • Thermal mass to store the heat from the Sun.
  • Insulation to reduce heat loss or heat gain.
  • Ventilation to capture cooling breezes.
A well designed solar home should remain within 18 degrees C to 28 degrees C throughout the year and save 60% to 70% in average household heating costs.

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Passive Solar Energy

Passive Solar Energy is the energy captured by a building from the Sun and used to either heat or cool a building.

The heating is usually a direct mechanism, where as the cooling is done by using the Sun's energy to help displace heat within a building, for instance by 'sucking' air through a property using a roof ventilation system.

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Passive Solar Heating

Passive solar heating is one of several design approaches collectively called passive solar design. When properly combined, these strategies contribute to the heating, cooling, and day lighting of nearly any building. The types of buildings that benefit from the application of passive solar heating range from houses to large office facilities.

Passive solar heating typically involves:
  • Solar energy collection through properly-oriented, south-facing windows.
  • Storage of this energy by "thermal mass," which are building materials with high heat capacity such as concrete slabs, brick walls, or tile floors.
  • Distribution of the stored solar energy back to the living space, as required, via the mechanisms of natural convection and radiation.
  • Window specifications to allow higher solar heat gain coefficient for Solar facing glazing.
Passive solar heating systems do not have a high initial cost or long-term payback periods, both common with many active solar heating systems. 

Another benefit to passive solar heating is increased comfort: if properly designed, passive solar buildings are bright and sunny and in tune with climate and nature. As a result, there are fewer fluctuations in temperature, resulting in a higher degree of temperature stability and thermal comfort.

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Passive Ventilation

Passive ventilation is a natural ventilation system that makes use of natural forces, such as wind and thermal buoyancy, to circulate fresh air to and from an indoor space. 

Such passive ventilation systems work to regulate the internal air temperature as well as bring fresh air in and send stale air out.

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Peak Sun Hours

This is the equivalent number of hours per day when solar irradiance averages 1,000 w/m2. For example, six peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for six hours been 1,000 w/m2. A term often used in association with solar panels.

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Perfluorocarbon (PFC) is a powerful greenhouse gas emitted during the production of aluminum.

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Perfluorooctanic Acid

A fluorinated chemical thought to be a carcinogen that is turning up in the bloodstream of humans and animals. PFOA and related perfluorochemicals have been used for decades to make a variety of nonstick and water-repellent products, including Teflon and other nonstick cookware, stain treatments for carpets, waterproof clothing, greaseproof liners of food packaging, and some personal care products.

In 2006, manufacturers reached a voluntary agreement with the U.S. EPA to eliminate almost all use of PFOA by 2015, although the use of other fluorinated chemicals will continue.

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A layer of permanently frozen soil underground. An important feature of a tundra.

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Persistent Pesticides

Pesticides that do not break down chemically or break down very slowly and remain in the environment after a growing season.

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Phantom Load

This is the small but not insignificant amount of energy that some of your appliances, such as your television, stereo, answering machine, and microwave oven are using when they are turned off.

Unplugging the devices when you’re not using them or plugging them into a power strip with an on/off switch is often the only way to avoid this waste of power.

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Organic compounds that are byproducts of petroleum refining, tanning, and textile, dye, and resin manufacturing. Low concentrations cause taste and odor problems in water; higher concentrations can kill aquatic life and humans.

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Premature ageing of the skin as a result of excessive exposure to ultraviolet radiation.

Effects of photoageing on the skin include dryness, loss of elasticity, wrinkles, discolouration and changes in texture.

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Photochemical Smog

Air pollution caused by chemical reactions of various pollutants emitted from different sources.

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Photovoltaic relates to the production of electric current at the junction of two substances exposed to light.

Must often used with photovoltaic cells, i.e. solar panels. Where the cells are connected together to make a solar panel.

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Used in vinyl products to make them softer and more flexible; also in cosmetics, fragrances, food wraps, and other products. In baby boys, exposure to phthalates can likely increase the risk of birth defects and hormone changes. In men, they likely increase the risk of reproductive problems and hormone changes. The U.S. government regulates industrial discharges of phthalates, but they are unregulated in food products, cosmetics, and consumer and medical products.

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Physiographic Region

A portion of the Earth's surface with a basically common topography and common morphology.

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Harmful to plants.

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Planned Obsolesence

The art of making a product break/fail after a certain amount of time. Not so soon that you blame the manufacturer, but soon enough for you to buy another one and make more profit for them.

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Plant Association

A grouping of plant species, or a plant community, that recurs across the landscape. Plant associations are used as indicators of environmental conditions such as temperature, moisture, light, etc.

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Plate Tectonics

Geologic theory that the bending (folding) and breaking (faulting) of the solid surface of the earth results from the slow movement of large sections (plates) of that surface.

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Period in geologic history (basically the last one million years) when ice sheets covered large sections of the Earth's land surface not now covered by glaciers.

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Plug-in Hybrid

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Polar Air Mass

A cold air mass that forms in a high-latitude source region.

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Substance, especially man-made, that pollutes or contaminates an environment.

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Pollution Prevention

Reducing the amount of energy, materials, packaging or water in the design, manufacturing or purchasing of products or materials in an effort to increase efficient use of resources, reduce toxicity and eliminate waste.

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Polybrominated Diphenyl Ethers

Polybrominated Diphenyl Ethers (PBDE), is an industrial toxic chemical used as a flame retardant in plastics, furniture and mattresses. This is being progresively banned.

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Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture. It includes crop rotation, multi-cropping, intercropping, companion planting, beneficial weeds, and alley cropping.

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Post Consumer Waste

Waste collected after the consumer has used and disposed of it.

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Postmodern Science

Postmodern Science is a 'branch' of postmodernism.

Postmodernism is "post" because it is denies the existence of any ultimate principles, and it lacks the optimism of there being a scientific, philosophical, or religious truth which will explain everything for everybody - a characterisitic of the so-called "modern" mind. The paradox of the postmodern position is that, in placing all principles under the scrutiny of its skepticism, it must realize that even its own principles are not beyond questioning. As the philospher Richard Tarnas states, postmodernism "cannot on its own principles ultimately justify itself any more than can the various metaphysical overviews against which the postmodern mind has defined itself."

Basically, postmodern science shies away from trying to create a 'unified truth' and rather focuses on the here and now and what is can be 'deduced' from that. The trouble is this leads to science by agreed consensus of observation and trust - rather than the traditional scientific approach of knowledge advancement by experimentation and proving of a hypothesis - i.e. the scientific method

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Power Conversion Efficiency

The ratio of output power to input power of the inverter.

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Power Pool

An association of interconnected electric systems in a region, often having an agreement to coordinate operations and plans for reliability improvements.

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Precambrian Rock

The oldest rocks, generally more than 600 million years old.

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Precautionary Approach

The approach promoted under the Framework Convention of Climate Change to help achieve stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous interference with the climate system.

Note: In essence this is the 'just in case' approach; the trouble with it is it assumes the cost of doing something is essentially 'free' compared to the future cost of not doing something. Rather the opportunity cost of doing something regardless is not clearly taken into account (i.e. could the money being spent now on inefficient energy sources to combat climate change have been better spent on further energy research that could ultimately lead to no real environmental pollution at all?)  Everything has a cost.

Also the precautionary approach 'weakens' the need for more rigorous scientific principal based research; i.e. you just need to show (and not truthfully prove) a possible outcome to give support to the precautionary approach.

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The tendency of the Earth's axis to wobble in space over a period of 23,000 years. The Earth's precession is one of the factors that results in the planet receiving different amounts of solar energy over extended periods of time.

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Refers to recycled material that came from the manufacturing process. Pre-consumer recycling of scraps and discards diverts waste that may otherwise end up in landfills, and reduces use of raw materials.

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Prescribed Burning

Deliberate setting and careful control of surface fires in forests to help prevent more destructive fires and to kill off unwanted plants that compete with commercial species for plant nutrients; may also be used on grasslands. Also known as 'back burning'.

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Prevailing Wind

The wind direction most frequently observed during a given period.

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Price Preference

A percentage by which offered prices for recycled products are reduced for purposes of bid evaluation. 

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Primary Consumer

Primary consumers are usually herbivores that feed on plants and fungus, which are in turn Primary Providers. Secondary consumers, on the other hand, are mainly carnivores, and prey on other animals. Omnivores, who feed on both plants and animals, can also be considered a secondary consumer.

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Primary Energy

Energy embodied in natural resources (e.g. coal, crude oil, sunlight, uranium) that has not undergone any anthropogenic conversions or transformations.

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Primary Sector

That portion of a region's economy devoted to the extraction of basic materials (e.g., mining, lumbering, agriculture).

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Proxy Climate Indicators

Variables that are an indirect measure of some combination of climate-related variations back in time. These are used to determine temperature in a time when the thermometer was not yet invented. Examples include tree ring records, characteristics of corals, fraction of melted ice, concentration of salts and acids and the load of pollen trapped in air bubbles.

Note: Given these are indirect measures, the underlying accuracy of such measurements are not equivalent to direct measurement. Also the more indirect the measure (i.e. the more processes between what you are measuring and the temperature) the more inaccurate the representation of the temperature could be. Plus if one is not careful it is possible to 'cherry pick' your proxies to show (either knowingly or not) a pattern of temperatures not representative of the larger whole.

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Able to rot quickly enough to cause odors and attract flies.

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PV Module

A PV module is basically a solar photovoltaic module used in converting Sun light into electrical energy. They are usually manufactured as a sealed unit with a given output voltage and wattage rating. They are often grouped together to create a larger total power output. 

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An instrument used for measuring global solar irradiance.

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This is the process used to create biochar.

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