As always, non-defaults must be used for windows where possible and where supporting evidence is available. Where certified data is not available, see DEAP Section 3.2 on use of defaults:
For new dwellings (provisional or final assessment)1
For existing dwellings
1 Guidance is clarified in section 3.1.4
Example 1: Double glazed installed before 2004 and using Table 2.35
Use one of the following depending on the frame type:
| Glazing | Low E coating | Frame | Metal thermal break assumed | U-value (W/m2k) based on Table 6a | Solar transmittance (based on Table 6a) | Comment |
|---|---|---|---|---|---|---|
| Double | No | Wood/PVC | N/A | 3.1 | .76 | Air filled 6mm gap |
| Double | No | Metal | 4mm | 3.7 | .76 | Air filled 6mm gap |
Example 2: Double glazed installed between 2004 and 2009, using Table 2.35
Use one of the following depending on the frame type:
| Glazing | Low E coating | Frame | Metal thermal break assumed | U-value (W/m2k) based on Table 6a | Solar transmittance (based on Table 6a) | Comment |
|---|---|---|---|---|---|---|
| Double | Yes | Wood/PVC | N/A | 2.2 | .72 | Air filled, low E hard coat εn = .15, 12mm gap |
| Double | Yes | Metal | 4mm | 2.7 | .72 | Air filled, low E hard coat εn = .15, 12mm gap |
Example 3: Double glazed installed in 2010 or later, using Table 2.35
Use one of the following depending on the frame type:
| Glazing | Low E coating | Frame | Metal thermal break assumed | U-value (W/m2k) based on Table 6a | Solar transmittance (based on Table 6a) | Comment |
|---|---|---|---|---|---|---|
| Double | Yes | Wood/PVC | N/A | 2.0 | .72 | Argon filled, low E hard coat εn = .15, 12mm gap |
| Double | Yes | Metal | 4mm | 2.5 | .72 | Argon filled, low E hard coat εn = .15, 12mm gap |
It is not acceptable to vary the filling / gap / coating values when using the Table 2.35 approach. For example, if using Table 2.35 for a Double-Glazed window installed in 2014, you must assume the 12mm gap in Table 2.35, even though the gap identified on site could be larger than this.
The same filling / gap / coating parameters can be assumed for Triple Glazing based on the year of installation.
The DEAP Survey Guide states: “Representative photographs of the window, gap between glazing, manufacturer’s stamp can be used as supporting evidence when using defaults from Table 2.28.” This is elaborated below. There are examples of default selection using this method in the table below.
When sourcing U-value and g┴ from Table 2.28 and 2.31, there are several properties to be considered:
Table 2.36 - Gap selection when using Table 2.28
| Gap between panes | Option chosen in DEAP Table 6a |
|---|---|
| <12mm | 6mm |
| > = 12mm; <16mm | 12mm |
| > = 16mm | 16mm |
| Scenario | Gas filling type and glass coating | Gap and thermal break. | DEAP results for U-value (6a) & g┴ (6b) |
|---|---|---|---|
|
1) Double glazed PVC Overall glazing thickness measured 16mm |
No information on filling or coating available. Assume air filled with no coating |
Assume 4mm panes. Gap is 16-(4+4) = 8mm. Select 6mm option from 6a. Thermal break n/a for PVC. |
U-value = 3.1 W/m2K g┴ = 0.76 |
|
2) Triple glazed wood frame. Overall thickness measured 36mm |
No information on filling or coating available. Assume air filled with no coating |
Assume 4mm panes so gap is [36-(4+4+4)]/2=12mm. Select 12mm option in Table 6a Thermal break n/a for wood. |
U-value = 2.1 W/m2K g┴ = 0.68 |
| 3) Double glazed wood frame. Brochure states 18mm argon filled gap with hard Low-E coating. |
Argon filled. Hard coated. Assume highest en of 0.2 |
18mm gap present so select 16+mm option in DEAP 6a. Thermal break n/a for wood. |
U-value = 2.0 W/m2K g┴ = 0.72 |
|
4) Double glazed metal frame. Frame not cold to touch compared to glass. Overall thickness measured 18mm. |
No information on filling or coating available. Assume air filled with no coating |
Assume 4mm panes so gap is (18-(4+4) = 10mm. Select 6mm option. Frame not colder than glass so break is present. Assume 4mm thermal break. |
U-value = 3.7 W/m2K g┴ = 0.76 |