Energy efficiency

energy efficiency

Energy Efficiency In New Homes and Extensions

hot water geysers and energy efficiency
If you are not sure how energy efficient your home is you should have an energy audit inspection. Water heating and solar energy are very much the things to combat load shedding!

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It is a fact that the lack of energy efficiency of normal residential geysers results in the use up to 30% of the electricity in water heating. This and uninsulated homes can result in the use of up to 60% of the electricity used in a home! This has resulted in the move to solar and other reusable energy sources.

Eskom, once regarded as the country’s greatest state asset, has dragged the economy down with its load shedding. Power shortages and load shedding in the last years have galvanised the South African Government to take measures to secure energy efficiency in industrial, commercial and residential facilities. 

The National Climate Change Response White Paper also commits South Africa to make a fair contribution to the global effort to stabilise greenhouse gas concentrations in the atmosphere within a time frame that is compatible with sustainable development.

To lessen load shedding and reduce the demand for energy usage, the government has introduced energy-saving regulations.

Regulations governing energy efficiency

Energy efficiency is now law! As of 11 November 2011, 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.

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 the design requirements for energy efficiency. A building meeting these requirements does not overheat or lose heat excessively. Moreover, 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.

Of course, the following is also applicable to existing homeowners who would like to make their homes more energy-efficient!

How can you make your home more energy efficient?

Roof Insulation

The biggest change in 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 to 7, the new requirement is R3.7, with a slightly lower requirement of R2.7 in zone 5H. As an example, a concrete tile roof in Zone 1 will require an additional 3.35 R-value by adding insulation.

This equates to around 135 mm of typical fibreglass blanket insulation (Think Pink Aerolite etc.), higher than previously specified!

Look through the trapdoor in your ceiling. If there is a minimum thickness of insulation, incorrectly placed insulation or none at all, this should be your first step to becoming more energy efficient! Don’t be bluffed by claims of good insulation with reflective tile underlays. They are only effective in reducing the radiant heat in summer and have very little effect in winter when you need insulation the most!

energy efficiency by using solar energy for water heating

Wall Insulation

The 2021 SANS 10400-XA: Energy usage in buildings has a new revision that requires the construction of cavity walls in place of 230 mm solid brick external walls. This energy-saving change is applicable in all the energy zones in South Africa except in zones 3, 5 and 5H.

energy efficiency by using solar energy for water heating

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

Energy efficiency in hot water heating

50% of all hot water in new houses must now be produced other than by an electrical heating element. Although solar water heating geysers still use some electricity they do fall within this stipulation. Therefore, solar water heating systems or a heat exchange heat pump must supply all hot water.

Solar geysers

Solar panels and geysers 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.

The hot water produced by the solar panels is usually used up by showers, baths and dishwashing in the evening. As a result, there is no hot water for the morning. In addition, on less sunny days it may only produce 150L at 35°C. Therefore, an electrical element is required for hot water for morning use and less sunny days.

Electrical elements supplement most solar water geysers. However, a properly sized solar water heater still has high energy efficiency producing 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. In addition, 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’s energy efficiency results in a 75% saving on water heating costs. Furthermore, it can be connected to existing geysers!

Energy-efficient Lighting

A light point symbol on floor plans previously indicated light positions. Lighting is now specified in building plans. Furthermore, the specification also considers light levels, energy demand and energy consumption.

Use CLF and LED globes to 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 an LED bulb 25 times longer than a normal light bulb.

The impact of the energy efficiency regulations

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

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The TPR Valve and Dangerous Geyser Installations

geysers and hot water heaters
During inspections, I found that approximately 40% of the installations of water heaters (geysers) do not comply with the SANS 10254 specification. In addition, of that 10% were dangerous!

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High-pressure geysers

Most modern geysers in South Africa are high-pressure hot water heaters.

Never work on geysers yourself unless you are a licenced plumber and you know what you are doing! They are high-pressure vessels and can explode.

Home inspectors report that the most common defect in South African homes is an incorrectly installed geyser. Notably, this defect is potentially dangerous and is mainly a result of untrained, or unsupervised workers installing hot water heating systems.

Exploding geysers kill people in South Africa every year.

Temperature and pressure release valves

All high-pressure water heaters must have a temperature and pressure release valve (TPR valve). This valve controls two critical functions: pressure and temperature. Therefore, do not tamper with this valve!

If the thermostat fails and the temperature rises beyond 70°C, pressure increases. In this case, with the rising temperature, the TPR valve on the geysers will be released if it is working correctly. Moreover, this happens either because of excessive heat or pressure.

If the TPR valves are faulty, the boiling point of water can rise above 120°C! The pressure will reach a point where the geysers’ pressure tanks rupture. At this point, the water turns into steam instantly. As a result, the 150-litre water in your geyser will now occupy 240,000 litres of space! This results in an explosion of the ferocity of a half kilogram of dynamite ( approximately 2½ sticks). Not only will the damage be excessive, but, as a consequence, lives can be at risk.

Defective installations

In my experience, about 4 in every 10 geysers have not been installed correctly, therefore, it is a good idea to have yours inspected!

Also, during periods of water cutoffs, do not use hot water or open hot water taps! You will burn out the element!

Ensure that a home inspector or plumber inspects your geyser installation!

These videos show extreme cases of hot water heater explosions:

Also, read the following: Geyser Explosion – Kimberley and a Geyser explosion survivor has lost everything.


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