W

Watt: a unit of power, power being the rate at which energy is used to do work. The unit rate at which work is done in an electrical circuit. One watt equals one joule of work per second. Also equal to one ampere (amp) under a pressure of one volt. Equal to 1/746 horsepower. Named after the Scottish inventor James Watt.

Walk-off mat

A design strategy for reducing the amount of contaminants introduced into an interior space by providing grating or other material to remove contaminants from shoes. A significant portion of contaminants in a building are brought in this way, impacting indoor environmental quality.

Warm-edge technology

Use of low-conductance spacers to reduce heat transfer near the edge of insulated glazing.

Waste heat recovery

The reclaiming of waste heat in a building to preheat cold water, or air, before it is fed into a water heater, or heating system.

Waste hierarchy

The State of Oregon has established a policy for statewide management of solid waste as follows: first, reduce the amount of solid waste generated; second, reuse material for the purpose for which it was originally intended; third, recycle material; fourth, compost material; fifth, recover energy from solid waste; and sixth, dispose of solid waste.

Wastewater

The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter.

Waterfree urinal

A urinal with no water line. Most designs use a specialized fluid that allows fluid to drain one-way into the sewer system.

Water-source heat pump

A heat pump that uses wells or heat exchangers to transfer heat from water to the inside of a building. Most such units use ground water (see Ground source heat pump).

Watts per square foot

A shorthand measure of the energy use of a building, often applied to indoor lighting. Energy codes often limit the watts per square foot based on building type and function.

Wavelength

The distance between two similar points of a given wave. Wavelengths of light are measured in nanometers (1 nm = 1 billionth of a meter).

Wetland

Land that is transitional between aquatic and terrestrial ecosystems and is covered with water for at least part of the year. These lands are important as buffer zones to help control flooding and also provide an ecosystem for many diverse species.

Wet-spray cellulose insulation

Insulation made from recycled newspaper and plant fiber is mixed with low-toxic binders and sprayed in wall cavities with water to adhere to joist or cavity surfaces. It is formaldehyde-free. This type of insulation is not advisable for high-moisture areas where mold could be an issue. Blown-in cellulose is loose-fill, or blown in with air (used in attic ceilings).

Whole-house fan

A fan typically centrally located in the ceiling of a house that draws fresh outside air into the living space, flushes hot air up to the attic and exhausts it to the outside. Windows must be open and adequate venting area must be present in the attic. An inexpensive way to cool a house when outside air is cooler than inside air, and not excessively humid. Must be well sealed and insulated during cold weather.

Whole-systems thinking

A process through which the interconnections of systems are actively considered, and solutions are sought that address multiple problems at the same time.

Wind power

Wind power systems convert the energy of the wind into electricity. Surplus electricity is often stored in a battery storage system for later use, or the power is passed back to the utility essentially making the meter go in reverse.

Window Shading

Any interior or exterior device for reducing unwanted heat gain from a window.

Wind turbine

A device for generating electricity from wind; a windmill.

Wingwall

Outside walls attached perpendicularly to exterior walls properly placed near windows to direct air into the windows for ventilation purposes. A negative pressure zone is created by the wingwall which stimulates air movement.

WMP

Waste Management Plan: a document detailing and recording amounts of construction debris to be sorted, collected, recycled, salvaged and disposed of on a job site.

Work

The application of a force through a distance. Energy is stored work. Power is the rate at which work is done, or the rate of flow of energy. The joule is exactly the amount of work done in exerting the basic metric unit of force (1 newton [N]) over the basic metric unit of distance (1 meter) (see Joule).

Worm Bin

System for on-site management of food scraps and other organic materials. Similar to a compost bin, a worm bin uses live worms to digest organic wastes, in a process known as "vermicomposting".