| acid rain | commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. the more accurate term is acid precipitation. clean or unpolluted rain has a slightly acidic ph of 5.6, the extra acidity in rain comes from the reaction of air pollutants, primarily sulphur dioxide and nitrogen oxides, with water in the air to form strong acids (like sulphuric and nitric acid). the main sources of these pollutants are vehicles and industrial and power-generating plants. |
| ach (air changes per hour) | air outside a building is constantly infiltrating through cracks in a building shell and exchanging with inside air. ach is the measure of the rate at which this occurs. for example, an ach or 0.5 means that all the air in the building will change out in two hours. |
| adaptable buildings | buildings that can be easily remarketed, retrofitted, or reconfigured to better meet the changing needs of occupants, maintenance, and the larger community. |
| adobe | is basically dirt that has been moistened with water, sometimes with chopped straw or other fibres added for strength, and then allowed to dry in the desired shape. commonly adobe is shaped into uniform blocks that can be stacked like bricks to form walls |
| aecb | association for environment conscious building |
| aerobic digestion | decomposition of organic waste using micro-organisms and oxygen in the process. |
| air brick | a perforated brick usually to be found in external walls to provide ventilation to ground floor joists. |
| air changes | a measure of the air exchange in a building. one air change is an exchange of a volume of air equal to the interior volume of a building. |
| air infitration | uncontrolled inward air leakage through cracks in a building envelope. may also refer to air leaking outward (called air exfiltration). |
| alcove | a recess often found to both sides of a chimney breast. |
| architrave | traditionally a moulded wood strip around the edge of a door covering the joint of door frame and plaster or other wall finish. |
| aseismic buildings | buildings constructed so as to withstand different degrees of earthquake damage. |
| autoclaved concrete | mix of lime, sand, cement and water are mixed, and then put into moulds, where an aluminium powder is added, which causes the mass to expand. it is then put into a steam-curing chamber (autoclave), which gives it strength. the resulting material has many benefits (non-combustible, easily worked, low u-value, etc.) |