Washington was the first State to institute air barrier requirements with both a maximum material air leakage requirement and a whole building maximum air permeability rate with testing requirements for buildings six stories and higher.
12.
Thus the required pressure / flow ratio can be obtained from the ratio of the two manometer readings, and when fed into the Carman equation, yields an " absolute " value of the air permeability surface area.
13.
Due to the low water content and air permeability, within 5 15 minutes of tamping, the concrete must be covered with a 6-mil poly plastic, or it will dry out prematurely and not properly hydrate and cure.
14.
Part L controls the insulation values of building elements, the allowable area of windows, doors and other openings, air permeability of the structure, the heating efficiency of boilers and the insulation and controls for heating appliances and systems together with hot water storage and lighting efficiency.
15.
In addition to insulation requirements and limitation of openings of the building fabric, this part considers solar heating and heat gains to structures, it controls heating, mechanical ventilation and air conditioning systems, lighting efficiency, space heating controls, air permeability, solar emission, the certification, testing and commissioning of heating and ventilation systems, and requirements for energy meters.
16.
The purposes of calendering are to upgrade the fabric hand and to impart a smooth, silky touch to the fabric, to compress the fabric and reduce its thickness, to improve the opacity of the fabric, to reduce the air permeability of the fabric by changing its porosity, to impart different degree of luster of the fabric, and to reduce the yarn slippage.
17.
Next the material for the air control layer is chosen to provide a suitable air flow rate at the chosen depressurisation, taken as 10 Pa in this case . ( The air flow rate could be determined from the desired U-value at the depressurisation of 10 Pa . ) From Table 4, fibreboard has an appropriate air permeability of 1.34x10 " 3 ( m 2 / hPa ).
18.
Dynamic insulation works best with a good thickness of insulation so taking 200 mm of cellulose insulation ( k = 0.04 W / m �C ) the dynamic U value for an air flow of 0.31 mm / s is calculated using equation ( ) above to be 0.066 W / m 2 �C . If a lower dynamic U-value is required then a material with lower air permeability than fibreboard would need to be selected for the air control layer, so that a higher air speed through the insulation at 10 Pa can be achieved.
