Minimum Performance Requirement of Glazing for Exteriors
A-1 The panel size design of the exterior glass for the building is done in accordance with this Section considering the effect due to wind load, other imposed load, seismic design. The type of glazing to be installed is determined considering human safety in 7.
In the determination of the energy and thermal performance of the glazing, the three compliance approaches prescriptive in nature, defines the minimum glazing/glazing system requirement to be met.
The prescriptive values are specified with respect to the geographic climatic zone and glazing area of the building.
A-2 Building Fenestrations
The fenestration shall comply with the maximum glazing area weighted on -value and solar factor as given in Table 34.
The window wall ratio (WWR) is defined by the total fenestration area to the total gross area of the building envelope which is limited to 70 percent. The corresponding minimum visible light transmission is given below. For fenestration area greater than 70 percent, see other specialist literature.
| WWR | Minimum VisibleLight TransmissionPercent |
|---|---|
| 0 – 0.3 | 27 |
| 0.31 – 0.4 | 20 |
| 0.41 – 0.5 | 16 |
| 0.51 – 0.6 | 13 |
| 0.61 – 0.7 | 11 |
| Sl No. | Climate | Maximum U-Value W/m2K | Maximum SHGC | |
| WWR ≤ 40 Percent | 40 Percent < WWR ≤ 60 Percent | |||
| (1) | (2) | (3) | (4) | (5) |
| i) | Composite | 3.30 | 0.25 | 0.20 |
| ii) | Hot and dry | 3.30 | 0.25 | 0.20 |
| iii) | Warm and humid | 3.30 | 0.25 | 0.20 |
| iv) | Moderate | 6.90 | 0.40 | 0.30 |
| v) | Cold | 3.30 | 0.51 | 0.51 |
A-3 Weather Performance
Air infiltration from the fix litres shall be permitted within and from operable sash .
Water should be contained in the gutter and drained back to the exterior. Any uncontrolled water in excess of or more on the top surface of any exposed interior shall be considered as leakage.