Item Term
Definition
32 Low-emissivity (low-e)
double glazing products
Low emissivity (low-e or low thermal emissivity) double glazing products are
characterised by a glass surface condition that emits low levels of radiant thermal
(heat) energy.
33 Municipal solid waste
Solid waste produced by domestic, commercial and industrial sources.
34 Odour filters
Filters that can remove odour from an exhaust stream.
35 Overall construction waste Amixture of waste and surplus materials arising from construction activities, such as
site clearance, excavation, refurbishment, renovation, demolition and road works. It
includes waste concrete that is generated from concrete batching plants and cement
plaster manufacturing plants not set up inside the construction sites.
36 Ozone depletion potential
Ozone depletion potential (ODP) is the relative amount of degradation to the ozone
layer caused by a chemical compound.
37 Photocells
Photocells can be used for automatic control of indoor lighting. A photocell is a type
of resistor. When light strikes the cell, its resistance decreases and allows current to
flow more freely. In contrast, its resistance increases when dark. Therefore, when
applying in lighting control, a photocell can read the level of lighting, incorporating
daylight influence, and automatically adjust the artificial lighting level of a single or a
group of luminaries.
38 Power factor
Power factor is the ratio of the average power available and the actual amount of
power used. Power factor is an indication of efficiency.
39 Prevailing wind
Prevailing wind is wind that blows predominantly from a single general direction over
a particular point on the building
40 PVC content
Polyvinyl chloride, commonly abbreviated PVC, is the third-most widely produced
plastic, after polyethylene and polypropylene. PVC is used in construction because
it is more effective than traditional materials such as copper, iron or wood in piping
and profile applications. It can be made softer and more flexible by the addition of
plasticisers, the most widely used being phthalates. It emits gases and is potentially
harmful to humans, and can cause irritating respiratory illnesses such as asthma.
41 Quality Water Recognition
Scheme for Buildings
A voluntary scheme launched by the Water Supplies Department that encourages
building owners to maintain their plumbing systems properly in order to ensure good
quality of water at the taps.
42 Quality assurance
Quality assurance (QA) refers to the engineering activities implemented in a quality
system so that requirements for a building or a space will be fulfilled.
43 Quality control
Quality control, or QC for short, is a process by which entities review the quality of all
factors involved in construction and operation of a building.
44 Red meat
Meat that is red when raw, for example beef or lamb.
45 Renewable energy
certificates
Tradable certificates that represent proof that 1 megawatt-hour of electricity is
generated from an eligible renewable energy resource.
46 Reverberation time
At a given frequency or frequency band: (1) the time, in a unit of a second, that is
required for the sound pressure level in the enclosure to decrease by 60 dB after the
source has stopped. (2) the time is seconds given by T
60
= 60 dB/R, where R is the
rate of decay of sound in the room expressed in decibels per sound.
47 Radon
Radon is a radioactive gas that has no taste, smell nor colour which occurs naturally
in rocks and soils, particularly granite. Granite is very widely used in concrete for
building construction in Hong Kong. Radon is therefore emitted from the walls, floors
or through cracks and openings in the ground. If a building is not well ventilated,
radon gas will become trapped and accumulate, particularly at floor level owing to its
heavy nature. Studies have revealed that long term exposure to radon may increase
the risk of lung cancer.
48 Scrubbers
A scrubber is an air pollution control device that is used to remove particulates and/
or gases from an exhaust stream.
49 Surge arrestors
A surge arrestor is a device that protects electrical power systems from damages
caused by lighting.
50 Switchgear
Switchgear is the combination of electrical disconnecting switches, fuses or circuit
breakers used to control, protect and isolate electrical equipment.
Appendix F
Hong Kong Green Building Council 215
