Energy Efficiency - Overview
If thermal ceiling insulation and high-performance window systems were introduced today into all new residential and commercial buildings, an astounding approximately 3500 MW of electricity could be saved by 2020.
This is almost twice the electricity currently produced by our only nuclear power plant in the country — Koeberg (1800 MW).
This principle was the main precept underpinning the recent publication of SANS 204: Energy efficiency in buildings, a scenario easily achievable by introducing sensible and practical measures that save energy when new buildings are both designed and built. By eventually making the three parts of this standard mandatory, the government will slowly but surely begin to achieve savings in energy and savings in the cost of providing that energy.
Growing environmental awareness and the increasing awareness of quality implies the need for standardized requirements and test methods.
SANS 204-1: This standard provides the general requirements for energy efficiency. According to the approach used in the revised South African Building Regulations and the new building code (SANS 10400 series), which should be published early in 2009, performance parameters are outlined first. These are then followed by the route to demonstrate compliance, either by rational design or deemed-to-satisfy rules.
Part 1 is largely based on two tables:
• Table 3 (Maximum energy demand per building classification for each climatic zone), and
• Table 4 (Maximum annual consumption per building classi- fication for each climatic zone).
Annex B contains an example of a compliance certificate, which, in future, will have to be completed by the responsible person (i.e. developer or owner), and submitted together with the building plans to the local authority for approval. This certificate also requires an energy audit to be conducted a year later, to prove compliance and measure the actual energy saved. This process is intended to facilitate any revisions of the standards that may become necessary. The certificate, therefore, should not be seen as a “policeman”, but rather an opportunity for continued improvement.
This first part of SANS 204 sets out general requirements for achieving energy efficiency in all types of buildings as performance parameters, and will eventually form part of the National Building Regulations. Parts 2 and 3, which deal with naturally ventilated buildings and artificially ventilated buildings, respectively, will eventually become part of the SANS 10400 National Building Code.
SANS 204-2 and SANS 204-3
Part 2 of the standard covers naturally ventilated buildings (with natural environmental control), while Part 3 is for artificially ventilated buildings with artificial environmental control.
Part 3 is for buildings with a central HVAC system (that is, humidity, ventilation and air conditioning). Buildings without air conditioning are covered by Part 2, which includes buildings containing free-standing heating or cooling (in other words, not centralised) systems.
While nominally separate parts, SANS 204-2 and SANS 204-3 both contain many common elements, and are therefore described together. Both contain deemed-to-satisfy rules.
Wherever possible, passive building design (where the need for energy to heat or cool the building is minimised), is encouraged. The standard follows the same order as when an actual building is constructed, i.e. first design, and then construction. Its key sections are:
- site and sitting (orientation and shading — to face north and use shading)
- building design (foundation, floor, walls, fenestration roof, and ceiling)
- building sealing (envelope, air infiltration, and leakage), and
- services (lighting and power, hot water services, and appliances)
Wherever possible, the efficient use of renewable energy (such as solar water heating, solar architecture, and energy-efficient appliances) is stipulated. In effect, the use of renewable energy is ‘free’, and as such is not counted in the actual energy consumption targets. For example, if the target set for the building is 200 kW hr/m², and 100 kW hr/m² can be generated by renewables, then the owner still has 200 kW hr/m² to use.