GLOSSARY

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HUMECTANT

A substance that promotes absorption/retention of moisture. see _absorbent_


HUMIDITY

The measure of moisture in the atmosphere. From an air quality standpoint, humidity in a built environment should be maintained between 30 and 50%. Excessive humidity is encountered above 60% RH, with humidity above 70% can cause secondary damage to hygroscopic material, and is ideal for mould growth


HUMIDITY CONTROL

Removing water vapour from air at an equal or greater rate that evaporated from wet materials (structure and contents). see _balanced drying_


HUMIDITY GRADIENT

The relative humidity in a boundary layer of air over a surface, with humidity nearest the surface layer being 100%, then 99% in the next layer, 98% and so on, until it merges with the RH of ambient air.


HUMIDITY MONITORING

The organized observation and recording of ambient humidity at a site.


HVAC

Heating Ventilation and Air Conditioning


HYDROGEN PEROXIDE

H2O2; An antiseptic and an oxidizing bleach normally used in a three percent (3%) solution for disinfecting.


HYDROSTATIC

Relating to pressures exerted by fluids (e.g., water may exert hydrostatic pressure on below ground exterior walls and slab sub flooring.


HYDROSTATIC PRESSURE

The pressure exerted on one side of a surface by the presence of water on the opposing surface.


HYGROMETER

Any of a variety of instruments used for measuring the humidity in air. cp _moisture meter_