IAQ

Indoor air quality: the cleanliness or health effects of air in a building are affected by the amount of compounds released into the space by various materials, particulates, combustion gases, outdoor pollution, mold, and microbial contaminants. IAQ is heavily influenced by both choice of building materials (and cleaning procedures) and ventilation rates.

ICF

Insulated Concrete Form: expanded polystyrene or wood forms that are left in place after the concrete is poured for a foundation or wall. The foam increases the thermal performance of the structure over non-insulated concrete.

IEQ

Indoor environmental quality: encompasses all aspects of the indoor setting including air quality, ventilation, thermal comfort, lighting, and noise.

I-joist

A manufactured wood product so named because its section looks like an upper case I. The top and bottom chord are lumber or laminated wood, and the vertical web is plywood or oriented strand board.

Impervious cover

A ground cover that does not allow water to pass through it to the soil below. Many jurisdictions have restrictions on the amount of impervious cover allowed on a building site, in order to reduce stormwater runoff and resulting non-point source pollution.

Incandescent bulb

An incandescent bulb is the most common and least energy-efficient lamp. Electricity runs through a tungsten filament that glows and produces a soft, warm light. Because so much of the energy used is lost as heat, these are highly inefficient sources of light. Halogen lamps are a special, more energy efficient type of incandescent lamp containing halogen gas to produce a brighter, whiter light than incandescents.

Indigenous

Existing, growing, or produced naturally in a region.

Infill

Developing on empty lots of land within an urban area rather than on new undeveloped land outside the city. Infill development helps prevent urban sprawl and can help with economic revitalization.

Infiltration

Uncontrolled inward air leakage through cracks in a building envelope. May also refer to air leaking outward (see Air exfiltration and Ventilation). In stormwater management refers to entry of runoff into the soil.

Infiltration planter

A structure or container with an open bottom to allow stormwater to slowly infiltrate into the ground. They contain layers of gravel, soil with good drainage, and vegetation.

Infrared radiation

Electromagnetic radiation whose wavelengths lie in the range from 0.75 micrometers to 1000 micrometers.

Infrastructure

Services and facilities provided by a municipality or private party, including roads, highways, water, sewage, emergency services, parks and recreation.

Infiltration planter box

A structural facility filled with topsoil and gravel and planted with vegetation. The planter has on open bottom, allowing water to infiltrate into the ground. Stormwater runoff from impervious surfaces is directed into the planter box, where it is filtered and infiltrated into the surrounding soil.

Insolation

Amount of solar energy reaching a surface per unit of time.

Insulation

A material (e.g., fiberglass, rock wool, recycled fibers, cellulose, straw) which effectively slows down the movement of heat. Typically installed around a living space (e.g., in the walls and attic) to improve comfort and reduce heating and cooling bills. Material having a relatively high resistance to heat flow and used primarily to retard the flow of heat. Measured by R-value. The higher the R-value, the more insulating the material. R-value is inversely proportional to U-value (see U-value).

Integrated design

A holistic process that considers the many disparate parts of a building project, and examines the interaction between design, construction, and operations, to optimize the energy and environmental performance of the project. The strength of this process is that all relevant issues are considered simultaneously in order to “solve for pattern” or solve many problems with one solution. The goal of integrated design is developments that have the potential to heal damaged environments and become net producers of energy, healthy food, clean water and air, and healthy human and biological communities.

Invasive plant

Both indigenous and non-indigenous species or strain that is characteristically adaptable, aggressive, has a high reproductive capacity and tends to overrun the ecosystem in which it inhabits.

IPCC

Intergovernmental Panel on Climate Change: a scientific intergovernmental body set up by the World Meteorological Organization (WMO) and by the United Nations Environment Program (UNEP). The IPCC was established to provide the decision-makers and others interested in climate change with an objective source of information about climate change. The IPCC does not conduct any research nor does it monitor climate related data or parameters.

IPM

Integrated pest management: a coordinated approach to pest control that is intended to prevent unacceptable levels of pests by the most cost-effective means with the least possible hazard to building occupants, workers and the environment.

IR

Infrared radiation:  electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red", red being the color of visible light with the longest wavelength.

IRR

Internal rate of return: the true annual rate of earnings on an investment. Equates the value of cash returns with cash invested taking compound interest factors into account.

ISO 14001

The International Organization for Standardization: ISO specifies the international requirements for an environmental management system.

IWM

Integrated Waste Management: the complementary use of a variety of practices to handle solid waste safely and effectively. Techniques include source reduction, recycling, composting, combustion and landfilling.