R-value

When it comes to insulation, R-value is an important concept to understand. R-value is a measure of insulation’s ability to resist heat flow, with a higher R-value indicating better insulation performance. The R-value of thermal insulation is determined by several factors, including the type of insulation material, its thickness, and its density.

Understanding R-values in South Africa is important because it can help you choose the right insulation for your home. In general, homes in colder climates require higher R-values than homes in warmer climates. Your local building codes and climate zone will provide guidance on the minimum R-values required for different areas of your home.

 

Proper insulation with the right R-value can help improve your home’s:

 

• Energy efficiency
• Reduce your energy bills
• Increase your comfort
• Reduce the strain on your heating and cooling systems

 

When installing insulation, it’s important to follow manufacturer instructions and building codes to ensure proper installation and optimal performance. Inadequate or improper installation can reduce the insulation’s effectiveness and may even cause damage to your home.

South Africa has been broken up into climatic regions or zones. These zones require a certain R-value of insulation to be installed in order to be compliant with the building codes in South Africa. This is to ensure that homes are thermally efficient and not wasting energy.

 

KNAUF R-VALUE CHART

 

 

AEROLITE R-VALUE CHART

 

 

FABUFILL R-VALUE TABLE

 

 

ISOTHERM R-VALUE TABLE

 

 

WHAT IS INSULATION R-VALUE?

 

R-value / Thermal Resistance is a direct indication of the performance of the insulation.  The higher it is, the better the insulating effect the insulation will have. Also, the thickness of the material is an indication of its thermal performance. Thicker or denser insulation materials are generally more effective than their thinner less dense counterparts.

 

HOW TO CALCULATE INSULATION R-VALUE

 

R-value = Thickness (of the material) / Its Thermal Conductivity (or K-value)

The thickness is determined by the manufacturer – and will normally form part of the product range.  The K-value is determined in an accredited laboratory.  The manufacturer will produce a sample that is manufactured at a stated density (weight) and will submit to the laboratory for testing.  The idea is to achieve an as low as possible K-value, in other words, a low thermal conductivity – put plainly, the product must be a bad conductor of heat flow.

Once the K-value is determined, the R-value can be calculated, for example:

For a 50mm thick blanket with tested K-value of 0.046:

• 0.05 (thickness) / 0.046 (k-value)  = 1.08

As long as the manufacturer manufactures the other thicknesses in his range at the same density than the submitted sample, he can use the same formula and k-value to determine the R-values, eg:

For a 100mm thick blanket:

• 0.1 (thickness) / 0.046 (tested k-value)= 2.17

This is where the consumer must be vigilant – some dubious manufacturers may reduce the density or weight of their products to save on raw material.  If they do this, they cannot use the tested k-value and thus cannot claim a good thermal resistance.  Always demand to see the test report and stated density that the manufacturer uses.

Determined in the examples above is the so-called Product R-Value.  The fact is however that the roof tiles and ceiling (as well as other roofing materials) also contribute to the insulating effect.  In practice, the Total of both roofing material and insulation material must thus be considered.  So, if the insulation material is 2.17, and the roof and ceiling materials are 0.53, then the Total will be 2.7.  Refer to The Thermal Insulation Association of South Africa (TIASA) website for guidelines.

 

THINGS TO REMEMBER WHEN BUYING INSULATION

 

• Always get professional advice if doing a DIY installation.
• Use approved installers if getting it professionally installed.
• Increase thickness and density for higher thermal resistance.
• Look for insulation specs on the packaging to verify performance.
• Don’t buy products not displaying SABS tested/approved.
• Find out how long a product will last. Product’s sustainability over time.
• Check chemicals in the product. Some products are bad for your health.

 

If you are unsure as to what thickness and density you should be using for your climatic region CONTACT US