ABOUT THE R-VALUE
The Thermal Resistance Value, commonly expressed as “R-Value” is measured as:
R Value = Thickness of insulating material ÷ Thermal conductivity of material.
The Thermal Conductivity is the rate of heat flow through one metre of uniform type of material, expressed in watts per metre Kelvin.
So, it can be seen that the thicker the layer of insulation being measured, the higher the R-value. This is not surprising, isn’t it? However, the higher the Thermal Conductivity, the lower the R-value.
With the introduction of uniform standards for measuring the effectiveness of various insulations, the Thermal Insulation Association of South Africa, TIASA, has introduced a range of total recommend R-Values for each of 7 different Climatic Zones.
When carrying out measurements, bear in mind that the recommendations refer to the TRV’s of the total system – including static air gaps and roofing materials – and cannot be compared with R values of the bulk insulation products. Make sure that test methods used are clearly declared in order to avoid a poor basis for comparison between different types of materials. Otherwise you may end up installing a much thicker layer of insulation than is necessary. Remember, static air is also an insulator and this contributes to the overall insulation effect. It is important to seal off all draughts however, because these rapidly lower the insulation properties of air by stimulating convection.
Eco-Insulation is a fantastic sealer of draughts inside cavities, because it spreads rapidly across the space being insulation and fills, literally, every nook and cranny. Once the product settles, it mats together and stays there.
