Hazardous waste
Waste that poses substantial or potential threats to public health or the environment. For the purposes of disposal, the Environment Agency provides information that categorises types of hazardous waste.
Heat capacity
More commonly known as ‘thermal mass’, it is the measure of how much heat a material can 'store’ heat in units of J/K.
Heat Exchanger
A device built for the efficient transfer of heat from one medium to another.
Heat island
An urban area which is significantly warmer than its surroundings.’
Heat Loss Parameter (HLP)
The building's specific heat loss (in units of W/K) divided by the building's floor area (measured internally – i.e. within the thermal envelope). Units W/K.m2
Heat pump
A device that moves heat from a low temperature heat source to a higher temperature heat sink. Examples include ground source heat pumps, air to air heat pumps, refrigerators and air conditioners.
Heat recovery
Captures waste heat energy and reuses it by returning it to systems or processes. This can include heating space and water.
Heat transfer
The transition of thermal energy from a hotter object to a cooler object.
Hot spots
Areas either on the outside of the building envelope, whose temperatures are significantly higher than the surrounding area. Usually only apparent through infrared thermographic survey they can have a number of causes including areas that have simply been heated by the sun or, more importantly, areas of differential heat loss occurring through the building fabric through means of leakage or thermal bridging.
Human toxicity
The impact on human health of toxic substances emitted to the environment..
Humidity
The amount of water vapour in the air. Relative humidity is defined as the ratio of the partial pressure of water vapour in a parcel of air to the saturated vapour pressure of water vapour at a prescribed temperature.
Hydrocarbons
Hydrocarbons are the simplest organic compounds that contain only carbon an hydrogen. Examples include benzene and methane..
Hydrochlorofluorocarbon (HCFC)
Man-made compound containing hydrogen, chlorine, fluorine and carbon. HCFCs have become popular following the phasing-out of the use of CFCs, which were used in the construction industry as blowing-agents in the production of insulation. Although HCFCs pose a much smaller risk to the ozone layer, they are also potent greenhouse gases.
Hydrofluorocarbon (HFC)
Man-made compound containing hydrogen, fluorine and carbon. HFCs have become popular following the phasing-out of the use of CFCs, which were used in the construction industry as blowing-agents in the production of insulation. Although HFCs pose no risk to the ozone layer, they are potent greenhouse gases..
Hygroscopic material
One which attracts moisture from the atmosphere. Hygroscopic materials are key to the concept of ‘moisture buffering’.
