Maxilite products provide a source of soft, shade free natural light to building interiors. This results from the refraction by the glass fibre reinforcement in the sheet material, in contrast to the more direct and intense light and heat transmission of clear glass or clear plastic. The light transmitted excludes 99% of UVB radiation, thus minimising burning. Photosynthetically active radiation is transmitted through Maxilite allowing plant growth in greenhouse buildings.
Maxilite are available in a range of tints to reduce the level of light transmission if required.
Opal and Woolstore tints may not be available ex stock, but can be manufactured in minimum run quantities. Discuss with your Dimond representative well in advance of your required delivery date to ensure the product required to meet your light transmission needs will be available.
Design Method for Light Transmission
To calculate the level of light transmission through Natural Lighting installed in a building the following procedure can be used.
1. Select The Value Of External Illumination For The Location Of The Building Located from the following table.
| Location | Latitude (Degrees South) | External Illumination (Lux) |
| Auckland | 37 | 7700 |
| Wellington | 41 | 6450 |
| Christchurch | 43 | 5920 |
| Dunedin | 46 | 5380 |
External illumination for other locations may be interpolated by latitude.
2. Select The Recommended Minimum Level Of Internal Illumination In Lux, Refer AS/NZS 1680.2.4
3. Calculate The Daylight Factor (A) From:
- A = (Internal Illumination x 100) / External Illumination
4. Determine The Transmission Factor (B) For The Grade Of Natural Lighting selected from the range in the following table.
Relative Light Transmission
| Colour Type | Effective visible light transmission of new sheet % | Transmission factor (B) |
| HeatGuard 4 | 64 | 1.5 |
| Clear | 63 | 1.5 |
| HeatGuard 8 | 49 | 2.0 |
| Opal | 40 | 2.4 |
| Double Skin Clear or when using sky film | 55 (estimated) | 1.8 |
| Woolstore | 14 | 7.0 |
5. Determine Dirt Allowance Factor(C) from the following table.
Dirt Allowance Factor
| Locality | Class of Activity | Dirt Allowance Factor (C) |
| Country or outer suburban area | Clean | 1.2 |
| Country or outer suburban area | Dirty | 1.8 |
| Built up residential area | Clean | 1.4 |
| Built up residential area | Dirty | 2.5 |
| Built up industrial area | Clean | 1.8 |
| Built up industrial area | Dirty | 4.0 |
6. Determine Reflection Allowance Factor (D) from the reflection table for the surface involved within the building space using the following guidelines:
| Building space | Range | Typical Industrial |
| Ceiling | 0-30% | 10 |
| Glazing | 0-20% | 10 |
| Wall | 0-50% | 25 |
| Floors | 0-30% | 15 |
Typical Industrial Application Average Reflection: (10+10+25+15) / 4 = 15%
Reflection Table
| Average Reflection | Reflection Allowance Factor (D) |
| 15% | 1.05 |
| 25% | 0.96 |
| 30% | 0.93 |
| 34% | 0.88 |
| 40% | 0.84 |
7. Calculate Design Factor (E) from the other factors.
- E = A x B x C x D
8. Determine The Building Dimensions Factor (F)
- F = Building Length / (Wall Height – Working Plane Height)
9. Using E & F from above, on the following chart read off the percentage of Natural Lighting sheet required (G), for the relevant roof pitch.
Percentage of Natural Lighting Sheet Required (G)
10. Calculate the Area of Natural Lighting Required
Durolite area = (G x Floor Area) / 100
Design Example
Calculate the amount of clear Durolite required to give 110 lux of natural light in a building 60m x 18m x 6m walls with a 15° roof pitch in a built up industrial area of Auckland. The workbench is 1m above the floor, and the roof has a foil underlay.
From "External Illumination" Table = 7700 Lux
Internal Illumination requirement of 110 lux
1. A = (110 x 100) / 7700 = 1.4
2. "Relative Light Transmission" Table Clear Durolite transmission factor, B = 1.5
3. "Dirt allowance factor" Table, C = 4.0
4. Average reflection calculated as: (20+10+25+15) / 4 = 17.5
From "Average Reflection" Table, D = 1.05
5. E = 1.4 x 1.5 x 4.0 x 1.05 = 8.82
6. F = 60 / (6-1) = 12
From "Percentage of Natural Lighting Sheet Required (G)" Chart G = 11%
7. (11 x 18 x 60) / 100 = 118.8m² of Durolite required.
Sheet Layout
As a guide to Natural Lighting sheet layout, the designer should check that the following relationship holds,
- (Distance between Natural Lighting rows / Height of roof above working area) < 2
The achievement of even dispersed light can be enhanced by using half sheet widths.
