>> O N SITE
SUSTAI NAB I LIT Y
SELECTING THE APPROPRIATE CEILING INSULATION The use of insulation in buildings has been a legislated requirement in South Africa since 2011. All buildings constructed six months after the standard was published should have the required level of insulation. This legislation has led to an increase in demand for insulation products, which has had a positive effect on the industry in that a number of new products were introduced and new uses were found for existing products. Products available in the market include fibre glass (Glasswool), polyester, expanded polystyrene and foam insulation. This article is aimed at assisting the specifier in the choice of the correct insulation products as informed by the legislated performance requirements, specifically in relation to fire and thermal performance. Among other fire classifications, insulation products should be categorised as either noncombustible (Class A) or combustible (Class B). Claims like “non-flammable”, “combustible at 750°C” and “does not melt” are not valid and may be misleading. These terms or claims are not used in any SANS standards to describe local building materials or to inform their selection thereof.
One can also look at SANS 428 classification: If the classification starts with an A, it is a non-combustible product; if its starts with a B, it is a combustible product. Noncombustible products can be used in any building, with no limitation of use. Combustible products are not supposed to be used in buildings such as hospitals, hotels, halls, prisons, dormitories and residential institutional buildings such as old age homes because they present a greater fire risk to the users and the building. Thermal performance claims are important because they form the basis of fulfilling the intention of the energy performance requirements contained in the National Building Regulations. Some of the key factors that influence the selection of thermal insulation are thickness of insulation, type of insulation, density of insulation and climatic zone. This means that not all insulation materials are equal. For example, 135mm thick polyester insulation has a lower performance when compared to 135mm thick fibre glass/glasswool insulation – density and thermal conductivity dependent, of course. As a result, one should always consider the type and thickness of insulation against the respective climatic zone. This also means that insulation cannot be
SANS 10400-XA Deemed to satisfy roof insulation requirements for pitched roofs
CLIMATIC ZONES
classified as “meeting SANS 10400-X requirements” without further clarifications. This statement is common in the industry. Customers should refer to the following table for guidance on thickness, type and density requirement in different climatic zones when selecting the most common flexible/loose-fill ceiling insulation products. Be on the lookout for thermal performance claims that are not clear. For example, “from … to …” (range) thermal performance claims on one product thickness. The questions specifiers should ask are: What is the performance that the customer will be receiving? Am I selecting the lower value or the higher value? The tendency at the point of sale in these
Climatic zone 1
2
3
4
5
6
Density (kg/m2)
Thermal conductivity (w/mK)
Cellulose fibre
27.5
0.040
135
115
100
135
100
130
Fibre glass
10-18
0.040
135
115
100
135
100
130
Polyester
11.5
0.046
160
140
120
160
110
150
Polyester BOQ
24
0.038
130
110
90
130
90
125
Type of insulation
Deemed to satisfy thickness (mm)
Source: TIPSASA Thermal Specification Guide 40 LEADINGARCHITECTURE & DESIGN JUNE/JULY 2019
situations has been to focus on the higher value, which might mean that the customer gets shortchanged in the event the insulation performance is of the lower value. We suggest that customers should exercise caution when purchasing products that do not give a specific thermal performance value. The national building regulation SANS 10400-XA, if implemented correctly and responsibly, will ensure that buildings use less energy when compared to similar buildings not constructed in accordance with the energy regulations. There is also an additional benefit in that insulated buildings are more comfortable to live in. However, as a customer you should consider the type of insulation used, the insulation thermal performance, the fire safety and the climatic zone when choosing the most appropriate insulation for your building. For further clarification, feel free to contact Saint-Gobain Advocacy and Standards Watch Technical Specialist, Farayi Muhamba, on 012 657 2800 or farayi.muhamba@ saint-gobain.com
