J4D6 Walls and glazing

What is J4D6 Walls and Glazing?

J4D6 Walls and Glazing outlines the energy efficiency requirements for wall-glazing construction, focusing on both thermal and solar performance. Key points include:

Total System U-Value:

• Wall-glazing constructions must meet specific U-Value limits, which represent the overall thermal conductivity of the system. The limits vary by building classification:

  • For Class 2 common areas and Classes 5, 6, 7, 8, 9b, and non-ward areas of Class 9a buildings: U2.0.

  • For Class 3, 9c, and ward areas of Class 9a buildings:

    • U1.1 in climate zones 1, 3, 4, 6, or 7.

    • U2.0 in climate zones 2 or 5.

    • U0.9 in climate zone 8.

• Display glazing is limited to U5.8.

Calculation of U-Value:

The U-Value for wall-glazing construction must be calculated according to Specification 37.

Wall Components' R-Value:

Wall components must achieve a minimum Total R-Value based on the percentage of wall area in the wall-glazing construction:

• If less than 80% of the area: R1.0.

• If 80% or more of the area: the value specified in Table J4D6a.

Table J4D6a Minimum wall Total R-Value - Wall area 80% or more of wall-glazing construction area

Climate zone	Class 2 common area, Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area	Class 3 or 9c building or Class 9a ward area
1	2.4	3.3
2	1.4	1.4
3	1.4	3.3
4	1.4	2.8
5	1.4	1.4
6	1.4	2.8
7	1.4	2.8
8	1.4	3.8

Solar Admittance:

• Externally facing wall-glazing constructions (excluding wholly internal ones) must meet solar admittance limits specified in Table J4D6b for Class 2 common areas and Classes 5, 6, 7, 8, 9b, and non-ward areas of Class 9a buildings, and Table J4D6c for Class 3, 9c, and ward areas of Class 9a buildings.

• Solar admittance must be calculated according to Specification 37.

Table J4D6b Maximum wall-glazing construction solar admittance - Class 2 common area, Class 5, 6, 7, 8 or 9b building or Class 9a building other than a ward area

Climate zone	Eastern aspect solar admittance	Northern aspect solar admittance	Southern aspect solar admittance	Western aspect solar admittance
1	0.12	0.12	0.12	0.12
2	0.13	0.13	0.13	0.13
3	0.16	0.16	0.16	0.16
4	0.13	0.13	0.13	0.13
5	0.13	0.13	0.13	0.13
6	0.13	0.13	0.13	0.13
7	0.13	0.13	0.13	0.13
8	0.20	0.20	0.42	0.36

Table J4D6c Maximum wall-glazing construction solar admittance - Class 3 or 9c building or Class 9a ward area

Climate zone	Eastern aspect solar admittance	Northern aspect solar admittance	Southern aspect solar admittance	Western aspect solar admittance
1	0.07	0.07	0.10	0.07
2	0.10	0.10	0.10	0.10
3	0.07	0.07	0.07	0.07
4	0.07	0.07	0.07	0.07
5	0.10	0.10	0.10	0.10
6	0.07	0.07	0.07	0.07
7	0.07	0.07	0.07	0.07
8	0.08	0.08	0.08	0.08

1. SHGC for Display Glazing: The Total System SHGC (Solar Heat Gain Coefficient) of display glazing must not exceed 0.81 divided by the applicable shading factor outlined in S37C7.

Table S37C7a Shading multipliers — Northern, eastern and western aspects

G/H	P/H = 0	P/H = 0.1	P/H = 0.2	P/H = 0.3	P/H = 0.4	P/H = 0.5	P/H = 0.6	P/H = 0.7	P/H = 0.8	P/H = 0.9	P/H = 1
0	1.00	0.90	0.80	0.72	0.64	0.57	0.51	0.46	0.41	0.38	0.35
0.1	1.00	0.95	0.89	0.81	0.74	0.66	0.59	0.52	0.47	0.42	0.40
0.2	1.00	0.98	0.94	0.89	0.82	0.75	0.68	0.62	0.56	0.51	0.47
0.3	1.00	1.00	0.97	0.94	0.89	0.84	0.78	0.72	0.66	0.61	0.57
0.4	1.00	1.00	1.00	0.99	0.97	0.90	0.84	0.77	0.73	0.68
0.5	1.00	1.00	1.00	1.00	0.99	0.97	0.92	0.90	0.86	0.83	0.79

Table S37C7b Shading multipliers — Southern aspect

G/H	P/H = 0	P/H = 0.1	P/H = 0.2	P/H = 0.3	P/H = 0.4	P/H = 0.5	P/H = 0.6	P/H = 0.7	P/H = 0.8	P/H = 0.9	P/H = 1
0	1.00	0.93	0.87	0.82	0.77	0.73	0.69	0.65	0.62	0.60	0.58
0.1	1.00	0.97	0.93	0.88	0.84	0.79	0.75	0.71	0.67	0.64	0.62
0.2	1.00	0.98	0.96	0.93	0.89	0.85	0.81	0.77	0.73	0.70	0.68
0.3	1.00	0.99	0.98	0.96	0.93	0.90	0.87	0.83	0.80	0.77	0.74
0.4	1.00	1.00	0.99	0.98	0.96	0.94	0.91	0.89	0.86	0.84	0.81
0.5	1.00	1.00	0.99	0.99	0.98	0.96	0.95	0.93	0.91	0.90	0.88

J4D6 Walls and glazing on Better Building

Speckel automatically checks the provisions of J4D6 Walls and glazing against your design, as per Specification 37 Calculation of U-Value and solar admittance. Models can be simulated with simple DTS shading multipliers (Table S37C7a + S37C7b) or can be generated to produce a Performance Solution.