Insulating glass has great advantages in reducing self-weight and improving building performance. The performance of insulating glass can be optimized without increasing the cost. For triple glass units which containing 2 pieces of Low-E coating, some manufacturers put the Low-E film on the 2nd and 5th surface, and some put the Low-E film on the 2nd and 4th surface; what effect it has on the overall performance of the glass, this post will analyzes this through experiments.
Tests:
Two kinds of products, single silver and double silver low-e, are simulated and calculated. Each Low-E product has several different conditions at different positions when one piece and two pieces are respectively. And the two conditions of filling the gas cavity with air or argon are calculated respectively. The main factor affecting the glass performance of different Low-E products is the reflectivity, that is, the reflection of far-infrared heat radiation back to have better thermal insulation performance.
| code | Low-E coating | lOW-E QTY | Position | Glass | U value | SC | SHGC |
|---|
| 1 | Single silver CES11-80 | 1 | 2 | 5LE+9A+5+9A+5 | 1.49 | 0.60 | 0.52 |
| 2 | Single silver CES11-80 | 1 | 2 | 5LE+9AR+5+9AR+5 | 1.26 | 0.59 | 0.52 |
| 3 | Single silver CES11-80 | 1 | 3 | 5LE+9A+5+9A+5 | 1.49 | 0.67 | 0.58 |
| 4 | Single silver CES11-80 | 1 | 3 | 5LE+9AR+5+9AR+5 | 1.26 | 0.68 | 0.55 |
| 5 | Single silver CES11-80 | 1 | 4 | 5LE+9A+5+9A+5 | 1.46 | 0.63 | 0.54 |
| 6 | Single silver CES11-80 | 1 | 4 | 5LE+9AR+5+9AR+5 | 1.24 | 0.62 | 0.60 |
| 7 | Single silver CES11-80 | 1 | 5 | 5LE+9A+5+9A+5 | 1.44 | 0.68 | 0.60 |
| 8 | Single silver CES11-80 | 1 | 5 | 5LE+9AR+5+9AR+5 | 1.2 | 0.69 | 0.47 |
| 9 | Single silver CES11-80 | 2 | 2/3 | 5LE+9A+5LE+9A+5 | 1.44 | 0.55 | 0.48 |
| 10 | Single silver CES11-80 | 2 | 2/3 | 5LE+9AR+5LE+9AR+5 | 1.2 | 0.55 | 0.46 |
| 11 | Single silver CES11-80 | 2 | 2/4 | 5LE+9A+5LE+9A+5 | 1.23 | 0.53 | 0.46 |
| 12 | Single silver CES11-80 | 2 | 2/4 | 5LE+9AR+5LE+9AR+5 | 0.99 | 0.52 | 0.46 |
| 13 | Single silver CES11-80 | 2 | 2/5 | 5LE+9A+5+9A+5LE | 1.23 | 0.56 | 0.49 |
| 14 | Single silver CES11-80 | 2 | 2/5 | 5LE+9AR+5+9AR+5LE | 0.99 | 0.56 | 0.49 |
| 15 | Single silver CES11-80 | 2 | 3/5 | 5+9A+5LE+9A+5LE | 1.23 | 0.62 | 0.54 |
| 16 | Single silver CES11-80 | 2 | 3/5 | 5+9AR+5LE+9AR+5LE | 0.99 | 0.62 | 0.54 |
| 17 | Single silver CES11-80 | 2 | 4/5 | 5+9A+5LE+9A+5LE | 1.41 | 0.60 | 0.52 |
| 18 | Single silver CES11-80 | 2 | 4/5 | 5+9A+5LE+9A+5LE | 1.17 | 0.59 | 0.52 |
| code | Low-E coating | lOW-E QTY | Position | Glass | U value | SC | SHGC |
|---|
| 1 | Dual silver CES1-67 | 1 | 2 | 5LE+9A+5+9A+5 | 1.42 | 0.40 | 0.35 |
| 2 | Dual silver CES1-67 | 1 | 2 | 5LE+9AR+5+9AR+5 | 1.18 | 0.40 | 0.35 |
| 3 | Dual silver CES1-67 | 1 | 3 | 5LE+9A+5+9A+5 | 1.42 | 0.52 | 0.45 |
| 4 | Dual silver CES1-67 | 1 | 3 | 5LE+9AR+5+9AR+5 | 1.18 | 0.54 | 0.46 |
| 5 | Dual silver CES1-67 | 1 | 4 | 5LE+9A+5+9A+5 | 1.39 | 0.47 | 0.41 |
| 6 | Dual silver CES1-67 | 1 | 4 | 5LE+9AR+5+9AR+5 | 1.49 | 0.46 | 0.40 |
| 7 | Dual silver CES1-67 | 1 | 5 | 5LE+9A+5+9A+5 | 1.39 | 0.56 | 0.49 |
| 8 | Dual silver CES1-67 | 1 | 5 | 5LE+9AR+5+9AR+5 | 1.15 | 0.57 | 0.49 |
| 9 | Dual silver CES1-67 | 2 | 2/3 | 5LE+9A+5LE+9A+5 | 1.40 | 0.36 | 0.31 |
| 10 | Dual silver CES1-67 | 2 | 2/3 | 5LE+9AR+5LE+9AR+5 | 1.14 | 0.36 | 0.31 |
| 11 | Dual silver CES1-67 | 2 | 2/4 | 5LE+9A+5LE+9A+5 | 1.13 | 0.33 | 0.28 |
| 12 | Dual silver CES1-67 | 2 | 2/4 | 5LE+9AR+5LE+9AR+5 | 0.88 | 0.32 | 0.28 |
| 13 | Dual silver CES1-67 | 2 | 2/5 | 5LE+9A+5+9A+5LE | 1.13 | 0.37 | 0.32 |
| 14 | Dual silver CES1-67 | 2 | 2/5 | 5LE+9AR+5+9AR+5LE | 0.88 | 0.37 | 0.32 |
| 15 | Dual silver CES1-67 | 2 | 3/5 | 5+9A+5LE+9A+5LE | 1.13 | 0.46 | 0.40 |
| 16 | Dual silver CES1-67 | 2 | 3/5 | 5+9AR+5LE+9AR+5LE | 0.88 | 0.47 | 0.41 |
| 17 | Dual silver CES1-67 | 2 | 4/5 | 5+9A+5LE+9A+5LE | 1.37 | 0.44 | 0.38 |
| 18 | Dual silver CES1-67 | 2 | 4/5 | 5+9A+5LE+9A+5LE | 1.12 | 0.43 | 0.38 |
Conclusion:
Under the same conditions, the difference of the heat transfer coefficient of the cavity filled with air or argon is only related to the type and quantity of the Low-E film, and has nothing to do with the position.
When there is only one Low-E glass in triple glass units, the U value of the Low-E film on surface 4thand 5this the lowest, and the shading coefficient is the highest on surface 5th.
When there are two Low-E glass , the U value of the Low-E film is the lowest on the 2/3, 3/5, and the shading coefficient is the highest on the 3/5 sides, followed by the 2/5 sides. The lowest is 2/4th.
Even though triple glass units can have excellent U value,but the thick glass also has high requirement on windows frame and hardware ,causing high price.
Vacuum insulating glass is new trend ,with thickness only 25% of normal triple glass units, but with much better thermal insulation performace.Jinyao Glass tested the 10.2mm VIG with dual silver low-E, tested U value is just 0.47W/M2.K,VIG will make your windows more energy efficient.
