As of the 10th November 2011, the National Building Regulations (South African National Standard 10 400 XA) require mandatory interventions to reduce energy consumption in new buildings and additions to existing structures. Amongst the stipulations are alternative options to achieving compliance using thermal insulation included in the building envelope.

The building owner is the person vested with the responsibility for ensuring compliance with the stipulations of the National Building Regulations.

However, this responsibility can be delegated to appointed building professionals such as architects and engineers, and competent people can be appointed by either the owner or building professional to ensure design compliance of specific aspects, such as thermal insulation.

To determine the applicable standard required, one needs to establish where the building is located as per the defined climatic zones, and know the building occupancy classification, as certain building types require specific energy demand and consumption targets are met.

The adjacent tables 2 and 3 indicate the maximum permissible annual electrical demand

 in VA per m2, as well as the maximum permissible electrical consumption in kw per m2 for specific building occupancy classes.

These buildings generally have HVAC (Heating, Ventilation, Air Conditioning)systems, as well as other energy consumers such as escalators and elevators. The design for these buildings would most likely vest with a team including architects, mechanical or electrical engineers, as well as competent specialists.

Other building occupancy classes may either

follow the Deemed–to-satisfy provisions for thermal insulation as indicated in the adjacent tables 4, 5 and 6, or may be the subject of a rational design by a competent person.

The Deemed to satisfy provisions are conservative, and will certainly reduce the energy required for heating and cooling to a comfortable living temperature. However, IsoBoard believes the comfort effects of the thermal insulation can be achieved through a Rational Design for each building, resulting in the equivalent energy usage as per the Deemed to satisfy provisions, for a lower intervention cost.

In adjacent table 7, an example is provided of the difference between the IsoBoard thickness intervention required

per region for Deemed-to-satisfy and calculated Rational Designs, for roofing/ceilings of different building types.

Following Rational design, the same level of energy conservation can be achieved with lower thickness specifications of thermal insulation, at a considerable cost saving.