Energy-efficiency rules for new homes (SANS 10400-XA)

Since 2011, new buildings and extensions in South Africa have had to meet energy-efficiency requirements set out in SANS 10400-XA, part of the National Building Regulations. Most homeowners only hear about it when their architect explains why the roof needs more insulation or why the windows need different glass. Here is what it means in practice.

What the regulations cover

SANS 10400-XA sets minimum requirements for:

• Insulation of roofs and ceilings, and in some cases walls
• Glazing: how much glass you can have and how well it performs
• Hot water: a proportion of hot water must come from a source other than electric resistance heating, such as a solar water heater or heat pump
• Orientation and shading of the building

The aim is to reduce the energy needed to heat, cool and light a home.

The 2021 edition

A revised second edition of SANS 10400-XA was published in 2021. The main changes include:

• New energy zones. The country is divided into energy zones with different requirements. The new edition uses a revised zone map.
• Fewer compliance routes. The “reference building” route was removed, leaving the prescriptive route (following the tables and rules) and the performance or rational design route (showing by calculation that the design performs at least as well).
• Self-contained standard. The requirements previously found in a separate standard (SANS 204) are now included in SANS 10400-XA itself.

Your architect or a competent person must show how the design complies when the plans are submitted.

Roofs and ceilings

Insulation in the roof is the most effective way to keep a house warm in winter and cool in summer. The regulations require a minimum total thermal resistance (R-value) for the roof assembly, which depends on the energy zone. In practice, this usually means insulation laid over the ceiling or fixed under the roof.

Glazing

Large windows are one of the main sources of heat loss and gain. The regulations limit the area of glazing relative to floor area unless the glass performs well enough. Modern homes with large glazed walls often need:

• Double glazing
• Low-emissivity (low-E) glass
• Thermally broken frames
• Overhangs or shading on north and west walls

This is often where design ambitions and regulations meet, so involve your architect and window supplier early.

Hot water

A minimum of half of a home’s hot water must come from methods other than electric resistance heating. The usual options are solar water heaters and heat pumps. This rule has a direct effect on monthly electricity bills.

Walls

In some energy zones, masonry walls must meet minimum thermal performance. Standard double brick walls generally comply. Lightweight walls, such as timber frame or light steel frame, need insulation in the cavity.

Does it apply to renovations?

The rules apply to new buildings and to extensions. Alterations to an existing building may need to comply in the affected areas, depending on the scope. Ask your architect.

Why it is worth doing properly

Energy efficiency is not only about compliance. A well-insulated house with good glazing and shading is more comfortable, cheaper to run and less dependent on the grid. We build to the energy-efficiency requirements on all our new homes and extensions. If you are planning a build, get in touch.