Electricity is one of the – if not the – major operating costs of buildings and hence it is essential to thermally insulate buildings to reduce the growing energy costs and conserve energy resources, says the Saudi Arabia-based manufacturer of bricks and blocks El Maimani Red Brick & Clay Products Factories.
“Thermal insulation is an important issue and is essential in all types of buildings, especially the multi-storey towers, to minimise and optimise power consumption,” says marketing and project manager, Kamal Al Gobali.
Rockwool is one of the insulating materials commonly used for the outside walls in buildings, because of its outstanding properties (See Table1), he says.
“Primarily, it is easy to install and is highly resistant to heat and weather conditions. In addition, the material has a longer lifespan, is incombustible and thermal non-conductive, does not emit toxic gases when exposed to high temperatures and is competitively priced, the Al Gobali points out.
When used in conjunction with red clay bricks, it offers enhanced thermal properties, he adds. “To achieve the benefits of rockwool’s thermally-insulating properties, the material can be fixed directly on to clay red bricks on the exterior of the building. It is then clad with marble, granite or stone, which is installed on the rockwool.”
Difference in weights between red block and cement block
Red bricks, in turn, offer the advantages of lightweight construction, he says.
Al Gobali elaborates: “With the need to reduce construction loads on buildings, contractors, consultants and engineers are increasingly using lightweight building materials, such as red bricks, especially in multi-storey buildings, to ensure safety as well as good returns throughout the operational lifespan of projects.
“The importance of safety in multi-storey structures, which accommodate a larger number of occupants, is more pronounced to avoid any potential collapse, as had happened to a building in Makkah recently.
“Use of strong, lightweight materials in medium to high-rise buildings can reduce the requirement of concrete and reinforcement steel in structures by more than 15 per cent, in elements such as foundations, columns, beams and roofs. This can mean significant savings and hence better returns on investments.
Lightweight construction materials allow architects to increase the number of storeys as they reduce building loads, while the lower quantities of rebar and concrete needed reduces the extent of corrosion, thus prolonging the operational life of the building and considerably cutting the operating and maintenance costs, says Al Gobali.
He continues: “To explain the importance of lightweight materials, let us take a 12-storey building, 500 sq m in footprint, and compare the weight of red clay bricks and the cement blocks. The difference in weight is shown in Table 2.”
From this quantitative analysis, we can conclude the following:
• The weight of cement block buildings (1,382 tonnes) is double of buildings constructed with red clay bricks. This substantial increase in weight will add load on the concrete foundations, columns and beams, and thus increase the construction cost of a structure.
• As a result of this double weight, cement block walls may be exposed to permanent cracks, which in turn will increase the maintenance cost and the need to repeatedly repair such cracks;
• The excessive weight of buildings will considerably increase the deterioration rates of the reinforced concrete, which will lead to a shorter lifespan of the building.
The above study and analysis are an example of an actual project in Madinah, Saudi Arabia.
Special features of rockwool:
• It is a heat-resistant insulator, up to 1.35 sq m degrees/watt per 5 cm thick rockwool, as per the US specifications, ASTM C764, C518.
• It has sound acoustic properties, as per US specifications ASTM E413, as the rockwool achieves STC = 44 while the STC ASTM E413 requirement = 52 for internal walls and 58 for external walls.
• Incombustible, even at 100 deg C as per ASTME-119 specifications.
• It emits no toxic gases when exposed to heat because it is incombustible rock material.
• Harmless to health and insoluble.
• Does not absorb humidity.
• Does not disintegrate in the course of time because it is a natural rock material.
• It saves 70 per cent of the power consumption and of the air-conditioning equipment cost.