Energy Efficiency

energy efficiency

Regulations governing energy efficiency

Energy efficiency is now law! New buildings and extensions are required to be energy efficient in terms of SANS 10400-XA Energy Usage in Buildings and SANS 204 Energy Efficiency in buildings, as from 11 November 2011.

Energy efficiency focuses on the energy usage of buildings once completed. The following impact on energy efficiency:

  • North orientation
  • window sizes and positions
  • shading
  • thermal and insulation properties of materials used
  • solar heating
  • natural cooling

SANS 10400-XA

The new regulations stipulate planning and design requirements. SANS 10400-XA provides the ‘deemed-to-satisfy’ requirements to comply with the National Building Regulations regarding energy usage.

 SANS 204

This regulation specifies design requirements for energy efficiency. A building meeting these requirements does not overheat or lose heat excessively. As a result, the regulation addresses building orientation, correct positioning and size of windows, use of natural light, natural heating in winter, natural cooling in summer and general insulation.

When energy efficiency is part of the design it is cost-effective. There is no need for expensive double glazing for south-facing windows or extra shading for west-facing windows.

energy efficiency

Climatic zone map | Differentiation by climatic zone is an integral part of the regulations

Roof Insulation

The biggest change of the regulation is to the insulation of roofs. Roofs have the biggest impact on energy efficiency. The correct amount of insulation will save 30 – 40% on heating costs.

In Zones 1 and 4, the requirement is R3.7, with slightly lower requirements in the other zones. A concrete tile roof in Zone 1 will require an additional 3.3 of R-value by adding insulation.

This equates to around 150mm of typical cellulose fibre insulation, higher than previously specified.

Hot Water Heating

50% of all hot water in new houses must now be produced other than by an electrical heating element. As solar water heating geysers still use some electricity, solar water heating systems, or a heat exchange heat pump must supply all hot water.

Solar Water Heaters

Solar water heaters use the sun’s radiation to generate heat. The amount of solar energy collected depends on the size of the solar panel: a 3m­² solar panel connected to a 150L geyser produces 150L of 60°C water, on a sunny day. On less sunny days it may only produce 150L at 35°C. Therefore, this would require an electrical element to further heat the water.

If you have 150L of 60°C water at the end of a sunny day, and the water is used up at night, there is no hot water for the morning. An electrical element will be needed to produce hot water for morning use.

Therefore, to ensure hot water throughout the day, solar water heaters are supplemented with electrical elements. But, a properly sized solar water heater produces savings of 50% on water heating bills.

Hot water heat pumps

Domestic hot water heat pumps work differently. The heat pump uses a small amount of electricity to extract a lot of energy from the surrounding air. The heat pump therefore indirectly uses solar energy. It is also able to produce hot water continuously. A high-efficiency heat pump takes approximately 1½ hours to re-heat a 150L geyser.

The heat pump produces 400% more heating energy than it uses in electrical energy. Therefore it produces a 75% saving on water heating costs.

Lighting

A light point symbol on floor plans previously indicated light positions. Lighting is now specified in building plans. The specification also gives consideration to light levels, energy demand and energy consumption.

CLF and LED globes replace normal light bulbs. CLF bulbs use 65% less energy to produce the same lighting as a normal light bulb. LED lighting consumes 75% less energy. In addition, a CLF bulb lasts  10 times and a LED bulb 25 times longer than a normal light bulb.

The impact of these regulations

Building costs will increase as a result of the new energy efficiency regulations. However,  homeowners should recoup these costs in the savings generated over time.

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