Panelized housing

Panels are factory-constructed, trucked to the site, and placed on a permanent foundation and assembled by a crew. Panels may be studs and plates, or they may use another technology such as foam-core structural insulated panels (see SIPs). Panels can arrive either finished, or framed only.

Particulate

a. Fine dust or particles (e.g., smoke). b. Of or relating to minute discrete particles. c. A particulate substance.

Passive building design

Building configurations which take advantage of a natural, renewable resource (like sunlight, cooling breezes, etc.) Passive design strategies typically do not involve any moving part or mechanical processes.

Passive cooling

Using passive building strategies to relieve the cooling load of a building by capitalizing on such things as predictable summer breezes or by shading windows from direct summer sunlight.

Passive house (passiv haus)

A very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized. Any remaining heat demand is provided by a very small (potentially renewable) source. An energy recovery ventilator provides a constant, balanced fresh air supply. The result is an impressive system that not only saves up to 90% of space heating costs, but also provides a uniquely terrific indoor air quality. There is a Passive House certification. Commercial buildings can also be built with these strategies.

Passive solar heating

Using the sun’s energy (in the form of heat) to diminish a building’s heating load, usually through the use of large window areas which permit light penetration upon some massive material to utilize the material’s thermal storage capacity. Also referred to as sun-tempered (see Sun-tempered).

Passive solar systems

Systems that collect, move, and store heat using natural heat-transfer mechanisms such as conduction and air convection currents.

Payback period

An accounting term indicating the time required to recoup an investment. It is expressed as a ratio of investment cost to savings or income (usually annually). For example, if a new high-efficiency boiler costs $10,000 to install and saves $2,500 per year in fuel, the payback period is four years. Payback periods are critical to environmental and energy efficiency. 

Peak oil

As first expressed in Hubbert peak theory, peak oil is the point or timeframe at which the maximum global petroleum production rate is reached. After this timeframe, the rate of production will enter terminal decline. According to the Hubbert model, the production rate will follow a roughly symmetrical bell-shaped curve.

Pedestrian pocket

A simple cluster of housing, retail space, and offices within a quarter-mile radius of a transit system. Smaller scale than new towns or planned unit developments.

Pedestrian scale

An urban development pattern where walking is a safe, convenient, and interesting travel mode.

Permaculture

A unique approach to the practice of sustainable farming, ranching, gardening and living, by designing constructed ecosystems that serve the needs of human populations without degrading the natural environment. Permaculture sites integrate plants, animals, landscapes, structures, and humans into symbiotic systems while requiring a minimum of materials,

energy and labor to maintain.

Permanent loan

A long-term loan on real estate, such as a mortgage, from a financial institution. Subject to specific conditions, such as construction of improvements.

Permeable

Open to passage of fluids/gases. Important to know permeability of building materials in exterior walls if moisture problems are to be avoided.

Pervious paving

Paving material that allows water to penetrate to the soil below; this reduces the amount of water that needs to be treated by the water system and increases the water in the aquifer.

PEX

Cross-linked polyethylene: a plastic that is made from made from fossil fuels (carbon and hydrogen), it is not recyclable, but can be incinerated for a fuel source. Commonly used as flexible piping, it requires very few joints, has a lowered risk of leaks, is quick to install. It is not UV stable so needs to be shielded from the sun.

pH

An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral. Natural waters usually have a pH between 6.5 and 8.5.

Photocell

A device that measures the amount of incident light present in a space.

Photosynthesis

The utilization of light energy to create chemical bonds; the synthesis of organic compounds from carbon dioxide and water.

Phthalates

Phthalates (pronounced thay-lates) are a group of chemicals used in the manufacture of plastics. They often are called plasticizers. Phthalates can prolong the lifespan or durability of plastics and increase the flexibility of some plastics. In addition, phthalates have been used as solvents for other materials. They are used in hundreds of products, including vinyl flooring; adhesives; detergents; lubricating oils; food packaging; automotive plastics; plastic clothing, such as raincoats; and personal-care products, such as soap, shampoo, hair spray, and nail polish.  Phthalates are used widely in flexible polyvinyl chloride plastics (PVC), such as plastic bags, garden hoses, inflatable recreational toys, blood-storage containers, intravenous tubing, children’s toys, and some pharmaceutical and pesticide products. Some evidence points to phthalates acting as estrogen-mimics.

Phytoremediation

Low-cost option for site cleanup when the site has low levels of contamination that are widely dispersed. Phytoremediation (a subset of bioremediation) uses plants to break down or uptake contaminants.

Pleated-media filter

Inexpensive, but highly effective type of HVAC filter due to its great surface area. Able to give substantial protection to both equipment and indoor air quality.

Pollution

Generally, the presence of a substance in the environment that, because of its chemical composition or quantity, prevents the functioning of natural processes and produces undesirable environmental and health effects. Under the Clean Water Act, for example, the term has been defined as the man-made or man-induced alteration of the physical, biological, chemical and radiological integrity of water and other media.

Post-consumer

A material or finished product that has served its intended use and has been discarded for disposal or recovery, having completed its life as a consumer item.

Potable water

Water that meets drinking water quality standards and is approved for human consumption by state or local authorities.

Powder coating

A durable finishing method for metals using a dry, powdered plastic that is heat-fused onto the surface. No solvent is required and practically no waste produced.

Pre-consumer

Material diverted from the waste stream following an industrial process, excluding reutilization of materials such as rework, regrind or scrap generated in a process and capable of being reclaimed within the same process. Synonyms include post-industrial and secondary material.

Pre-fab

Shortened version of “prefabrication”. Prefabrication is the practice of manufacturing the components of an assembly or building in one location and assembling them in another.

Post-industrial

(See Pre-consumer).

Post-occupancy evaluation

A POE is an important part of feedback to the development team after a building is completed and occupied. Systems are monitored to ensure they are performing to their designed efficiencies. Occupant comfort is also monitored.

Power

The rate at which energy is consumed or produced. It is expressed in watts (W). A 1-watt source supplies energy at the rate of 1 joule per second. (A 100-watt lamp consumes energy at the rate of 100 joules per second; the human body involved in normal activity is rated at about 100W, a significant proportion being used to drive the brain). The sun radiates energy at the rate of about 70 million watts per square meter of its surface; at the equator the Earth receives a mean annual solar energy flux of around 1,400 watts per square meter.

Precautionary principle

Taking a cautious approach to development and environmental management decisions when information is uncertain, unreliable or inadequate.

Pre-cycling

(See Source reduction).

Pressed earthen block

Like adobe, pressed (or compressed) earthen block is made from a mixture of soil and aggregate with no chemical additives. Often machine manufactured at the construction site. Because there is relatively no quality-control routine compared with other types of manufactured block, its use may be limited, especially in high seismic zones. Careful engineering will be required to use this material in structural applications.

Pressure-treated wood

Wood that is chemically preserved with chromated copper arsenate (CCA), an extremely toxic chemical, to prevent moisture decay. The chemicals typically used are health hazards for workers. Such wood should not be burned because it produces toxic fumes, and must be treated as a hazardous waste when disposed of. Different grades of wood treatment are available for different applications.

Primary energy

Overall energy, including the energy used to generate the delivered energy and to transport it to a building. The energy used to make energy (see Delivered energy and Effective energy).

Psychrometric chart

A graphical representation of the thermodynamic properties of moist air. Used to ascertain the potential effectiveness of passive strategies to maximize human comfort.

Public Transportation

Mass transit, including bus and light rail systems. Siting a building near public transit is considered a sustainable building strategy, as it facilitates commuting without the use of single occupancy vehicles (see Mass transit).

PV’s

Photovoltaics: solid-state cells (typically made from silicon) that directly convert sunlight (solar energy) into electricity.

PVC

Poly-vinyl Chloride: a common lightweight, durable thermoplastic resin, used in a wide variety of building products, siding, gutters, plumbing piping, sheet flooring, and floor tiles. PVC is recyclable, but not many recycling centers accept it. Its manufacture has several risks for health and environment.