Thermospec Energy Efficient uPVC Products

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Energy Efficiency

Energy Efficiency Regulations:

The Law
The new Building Regulations SANS 10400XA sets out that window elements should in future be calculated according to the requirements of either SANS 204-2 (Natural ventilation) or SANS 204-3 (Mechanical ventilation). For specifiers, the key difference between the two is that SANS 204-2 requires window calculations to be carried out for each storey. To achieve compliance, the Aggregate Conductance and Solar Heat Gain has to be calculated.
In contrast, SANS 204-3 requires window calculations for each storey and each elevation and, to demonstrate compliance, the Aggregate Air-conditioning Energy Value has to be calculated.

The sustainability credentials of uPVC windows when compared with aluminium or timber have also recently been given a significant boost by the BRE (Building Research Establishment) which awarded uPVC an A+ rating in the commercial sector for its long term sustainability - the same rating which was achieved by timber and outperforming the aluminium alternatives.

Although in South Africa the fenestration market is still largely dominated by single-glazed aluminium frames, Bel-Essex uPVC anticipates that the introduction of SANS 10400 Part XA, alongside SANS 204, will accelerate the move towards more thermally efficient uPVC window and door systems.

The company points to the performance values of whole glazing elements in SANS 204 2/3 which show uPVC outperforming aluminium and steel windows in every configuration.

For example, a single-glazed aluminium window achieves a total U-value of 7.9 W/m²K and SHGC (solar heat gain coefficient) of 0.81, compared to a certified U-value of 3.69 W/m²K and SHGC of 0.48 for our Thermospec uPVC equivalent. A double-glazed, Low-E aluminium frame achieves a U-value of only 3.4 W/m²K compared to our calculated U-value of 2.01 W/m²K for a Thermospec frame in uPVC.

The U-Value is the thermal transmission coefficient of doors and windows.

The U-Value is calculated as W/m²K and refers to the amount of heat energy (W) given out per area (m²) at a given temperature difference (K).

A lower U-Value means a window or door has a better insulation performance, a higher U-Value is calculated for windows with a lesser performance.

uPVC vs traditional window and door designs:

Controlling the heat (or cold) within a building.

Windows are thermal holes. An average home may lose up to 30% of its heat or air-conditioning energy through its windows. Thus, investing in energy-efficient windows will save money every month.

Windows lose and gain heat by conduction, convection, radiation and air leakage. This heat transfer is expressed with U-values. U-values are the mathematical inverse of R-values. Lower U-values indicate higher insulating values.