Impermeable surface

A non-porous surface that generates a surface water runoff after rainfall..

Indoor air quality (IAQ)

The air quality within a building as it relates to the health and comfort of the occupants. IAQ can be affected by contaminants or gases. Chossing matierials , finishes, fixings and furniture that do not off-gas is the best route to ensuring air quality followed by adequate ventilation. 

Insulating concrete formwork (ICF)

Hollow lightweight block components that lock together without intermediate bedding materials, such as mortar, to provide a formwork system into which concrete is poured.

Intelligent building

The concept of a building that remotely monitors and controls its own systems including lighting, heating, IT and security.

Internal heat gains

Uncontrolled space heating from, usually, people, electrical applicances and lighting.

Interstitial condensation

Occurs when relatively warm moisture-laden air diffuses into a vapour-permeable material or structure such as fibrous insulation or a porous brick wall. If it is relatively warm on one side and below the dew point temperature on the other; this can result in the moisture-laden air reaching ‘dew point’ within the material and depositing liquid water at this point. Interstitial condensation presents a problem when it remains undetected, threatening structural damage such as timber decay, or degrading the effectiveness of insulation.