What is new in SANS 10400-XA:2026?

The practical shift

What changes in the 2026 workflow?

The 2026 edition asks designers to keep calculations closer to the part of the building that each input serves. A favourable result elsewhere in the building should not hide a weak storey, tenancy, opening group or assembly.

Do not silently convert a 2021 project

Keep the selected standards edition in the project record. A municipality may still request the 2021 edition during a transition period. When moving a project to 2026, review its storeys, occupancies, opening assignments, material properties and service schedules rather than changing only the report title.

Building envelope

Clause 5.1: Orientation

The building orientation is expressed through eight sectors: North, North-East, East, South-East, South, South-West, West and North-West. For Zones 1 to 7, the primary orientation follows the facade with the largest combined fenestration area relevant to solar gain. Zone 5H instead places greater emphasis on openings used for natural ventilation and prevailing winds.

What the project team should record

• The primary facade for every storey, not only a single building-wide direction.
• The orientation of every window, glazed door and other vertical glazed element.
• The selected town, energy zone and whether Zone 5H considerations apply.

Solar control

Clause 5.2: Shading

Solar-facing openings in the West, North-West, North, North-East and East sectors can be classified as shaded when the selected device satisfies the clause. Permanent horizontal shading is checked from its projection and the height being shaded.

External shutters, blinds or screens can also form the shading solution when they provide the required solar restriction and, where adjustable, can be readily operated. Openings that do not meet the shading rule are not automatically non-compliant: they move into the Unshaded SHGC group for Clause 5.3.

Three useful classifications

• Shaded: a solar-sector opening whose shading solution meets Clause 5.2.
• Unshaded: a solar-sector opening without qualifying shading.
• Southern: South-West, South or South-East fenestration, handled separately for SHGC.

The largest workflow change

Clause 5.3: Fenestration

Use whole-element values that include both glass and frame. Centre-of-glass ratings do not describe the complete opening and should not be substituted for the total U-value or SHGC. Vertical fenestration and rooflights also follow separate assessment routes.

Step 1: divide the project correctly

Calculate each storey independently. Where a storey contains more than one occupancy or tenancy, allocate the relevant nett floor area and each opening to the zone it serves. One tenancy cannot benefit from a more favourable ratio in another tenancy.

Step 2: calculate U-value independently

Area-weight the whole-element U-values of all included vertical fenestration in the assessment zone.

Step 3: keep SHGC groups separate

Calculate an area-weighted SHGC for shaded solar-facing fenestration and another for unshaded solar-facing fenestration. Do not blend the two groups into a favourable combined average. Southern-sector fenestration remains visible in the schedule and contributes to the area ratio and U-value assessment; Table 4 gives it an “Any solution” SHGC route.

Table 4 at a glance

Intermediate Table 4 bands at 35%, 45%, 55% and 60% remain applicable. Use the complete official table for assessment.

Additional opening checks

• In the Southern Cape Condensation Problem Area, do not rely on single low-E glazing alone to achieve the required U-value.
• Windows, doors and rooflights forming part of the envelope must satisfy the applicable SANS 613 air-leakage requirement.

Clause 5.3.9: Rooflights

Rooflights are assessed against the floor area or space they serve. Up to 1.5% allows any U-value and SHGC solution. Ratios above 1.5% use progressively tighter Table 5 limits, while ratios above 10% require a maximum U-value of 2.0 W/m²K and SHGC of 0.25.

Floor insulation

Clause 5.4: Floors

The floor route depends on what the floor does and which boundary it forms. A ground-bearing floor without underfloor heating is not assessed in the same way as a suspended envelope floor.

• Underfloor heating: provide insulation with R ≥ 1.0 m²K/W to limit losses to adjacent ground or surroundings.
• Suspended envelope floor, Zones 1, 2, 6 and 7: insulation R ≥ 1.5 m²K/W.
• Suspended envelope floor, Zones 3, 4, 5 and 5H: insulation R ≥ 1.0 m²K/W.
• Moist exposure: the selected insulation must retain its thermal properties under the applicable conditions.

Wall performance routes

Clause 5.5: External walls

Start by selecting the correct route. Heavy walls with a surface density of at least 270 kg/m² use Table 6. Lighter walls use the Table 7 R-value or CR-value route. Eligible Category 1 buildings can use the single-leaf masonry provision when the nominal masonry thickness is at least 140 mm.

Items that need an explicit decision

• Whether the wall is heavy or light, based on the complete wall system surface density.
• Whether a Table 6 deemed-to-satisfy construction is being used for the applicable energy zone.
• Whether Category 1 eligibility is met, including occupancy, building area, basement and support-spacing conditions.
• Whether connected metal sheets, studs, tracks or battens have a thermal break of at least R 0.2 m²K/W.
• Whether attached garages, verandahs and similar spaces are included in or separated from the thermal envelope.

Continuity matters

Clause 5.6: Roof assembly

The roof check is not only a material-thickness calculation. The insulation must form a continuous thermal barrier, meet the total R-value for the energy zone and direction of heat flow, and remain compatible with roof construction and building services.

• Most zones require a total roof R-value of 3.7 m²K/W; Zone 5H uses 2.7 m²K/W.
• Faced flexible bulk insulation beneath cladding needs the appropriate spacer or continuous-packer arrangement to control compression and catenary.
• Reflective insulation values depend on emissivity, heat-flow direction and the adjacent airspaces.
• Thatch routes depend on material type, zone and either installed thickness or thermal resistance.
• Ceiling bulk insulation should overlap the wall member by at least 50 mm or fit tightly against the wall where appropriate.

Air tightness

Clause 5.7: Building sealing

Building sealing is best handled as an applicability checklist. Confirm the general envelope, then activate the specific checks that match the roof, appliances and external openings in the design.

1. Minimise air leakage through envelope roofs, walls, floors, windows and doors.
2. Seal wall-plate and roof junctions where the ceiling-void requirement applies, and provide tile underlay or a radiant barrier to tiled roofs.
3. Provide a closable damper or flap to an applicable open solid-fuel chimney or flue.
4. Seal the edges of external doors and similar openings serving conditioned spaces or habitable rooms.

Building services

Clause 6.1: Hot water supply

Map the building use to a defensible demand profile, then separate demand, storage, heating source and distribution checks. Where electrical resistance is supplementary, it may cover no more than 50% of the annual average hot-water requirement by volume.

• The supply and installation route must align with SANS 10252-1.
• Domestic heat-pump products must align with SANS 1687 and installation with SANS 1352.
• Exposed hot-water pipes to indoor or outdoor air require appropriate insulation in accordance with SANS 10252-1.

Connected lighting

Clause 6.2: Lighting

Calculate lighting per occupancy. Add the connected load of internal fittings and building-supplied external lighting, then divide by the nett floor area of that occupancy.

H3 and H4 occupancies using only LED or CFL fittings follow the deemed-to-comply route. Other technologies still need the Table 10 check. Occupancies other than H3 and H4 require both occupancy and daylight sensors, arranged so that no individual sensor serves more than 100 m².

Equipment efficiency

Clause 6.3: Air conditioning

Unitary and packaged equipment is checked against Table 11 by equipment type and capacity band. Record cooling capacity, heating capacity where applicable, COPC, COPH and the heating method for every included unit.

The minimum values vary substantially: a small unitary split below 7 kW, for example, follows a different COP band from packaged equipment or a water-cooled chiller. Resistance-heating limits and the referenced test method also depend on the equipment category.

Putting it into practice

A reliable 2026 project workflow

1. 1
   Confirm the required edition

   Record whether the authority requires 2021 or 2026 before calculations begin.

2. 2
   Define storeys and occupancies

   Make their nett floor areas reconcile to the building total.

3. 3
   Assign every component

   Link openings and envelope designs to the storey and occupancy they serve.

4. 4
   Calculate in clause order

   Orientation, shading, fenestration, rooflights, floors, walls, roof, sealing, then services.

5. 5
   Resolve technical reviews

   Use the component explanation to correct missing or out-of-range inputs.

6. 6
   Issue a traceable report

   Show calculation scope, inputs, targets and results without hiding failures in building-wide averages.