SANS 10400 – PRESCRIPTIVE ROUTE.

COMPLIANCE VIA PRESCRIPTIVE ROUTE.

Since this option does not actually require the appointment of a Competent Person – Energy (SANS 10400-xa), then this is the method which most architects are most likely to adopt on the long run. Mostly, the younger architects are the ones who are going to favour this method more than the seasonal or experienced architects. With this choice comes three main questions to consider.

  • WHO CAN USE THE PRESCRIPTIVE ROUTE?

    This route is generally available to everyone.  What this entails is none other than make sure that the design and the materials all follow all relevant provisions SANS 10400-XA and some of the provisions of SANS 204. Why is this very simple? It is the easiest of all the methods since in this case the Competent Person – Energy is not required.

  • WHAT DOES THE PRESCRIPTIVE ROUTE ENTAIL?

    In this section, the building has to be designed and built in such a way that it is in line with some of the mentioned features in the following paragraph. These requirements should all satisfy the below implications generally.
    - At least 50% of all the hot-water demand has to be met by other means other than the electric resistance heating.
    - Roof or some ceiling installations is actually needed and has to meet minimum requirements based on the climatic zone as well as the roof material.
    - Insulation is needed for all the exposed hot-water pipes.
    - No matter the condition, insulation is actually needed for the non-masonry walls.
    - Should there be a floor insulation, then there is the need for in-slab heating.
    - Some shading devices or other performance glazing skill is needed where the glass area are larger than 15% of the overall floor area.
    - Other building services which use energy or at times control the use of energy have to be provided in accordance with the SANS 204.
    -Moreover, all the orientation requirements in accordance with SANS 204 are non-mandatory, owing to the fact that fenestration design can be able to compensate for sub-optimal orientation.
    Usually, this method of compliance has to be chosen by the Appointed Person on the earlier stages of the project.

  • WHAT SHOULD BE DONE TO FOLLOW THE PRESCRIPTIVE ROUTE?

    To be able to meet the minimum prerequisites of the prescriptive route, then the architect in this case has to make sure that he/she indicates on the Schedule A form that it is this route which is actually being considered. This is done by ticking the first 7 boxes which are under the XA: Energy Efficiency in Buildings section. Moreover, the architect has to also communicate either each of the following on to the local authorities either on an attached schedule or on the actual plans. These include the likes of:
    - Water heating.
    In this section, you have to simply things such as the capacity, location and the choices of water heating which are available. Moreover, there should be an indication that at least more than 50% of the total water being heated has to be heated with mechanisms other than electrical resistance means.
    - Insulation.
    Here, there are four main insulation areas that have to be considered in general. For instance, you have to consider:
    i) Roof and ceiling installations – You simply have to specify the insulation type as well as the
    total thickness which is needed so as to achieve minimum total R-Value for insulation. This
    is usually based on the climatic value as well as the roofing material of choice.
    sans 10400-xa, energy efficiency, hot water pipes     ii) Hot-water pipes – Here, you should specify the minimum R-Value for the insulation on all
    the exposed water pipes as stipulated in the pipe diameter requirements. Case in point,
    pipes which have an internal diameter of less than about 80mm need an insulation touch
    up of a minimum R-value of 1,0. However, all the other types of pipes should have a
    diameter with a minimum R-value of 1,5.
    iii) Non-masonry external walls – If the building has got non-masonry external walls, then
    you have to specify the insulation so as to achieve the actual needed R-value, which is
    usually determined by the wall materials and the climatic zone. Usually, zones 1 ad 6
    need a total R-value of about 2,2 while zones 2 all the way to 5 need a minimum of 1,9.
    iv) Underfloor heating – Usually, if the building has an in-slab heating, then you have to
    specify under the slab-insulation with a minimum R-value of 1,0.
    - Glazed areas.
    sans 10400-xa, energy efficiency, hot water pipesin this section, the total glazed area including such as windows have to be taken into account. Moreover, the net floor area and the total glazed area have to be taken as a percentage of the net floor area. With the results:
    i) If this is more than 15%, then the fenestration has to be designed to comply with the
    SANS 204 based on the graph calculation which may actually need additional
    specifications of performance such as glazing or some shading over the glazed glass.
    ii) Should it be less than 15%, then no additional requirements will need to be satisfied.

Since this area has actually looked more on the R-value, what really defines the R-value of a material? This is none other than the thermal resistance of a material. You may also think of it as the ability of a material to prevent heat from passing via it. This may be obtained by simply dividing the thickness of the material by the actual thermal conductivity. Generally, coming up with a building shell so as to achieve a specific prescribed R-value makes it easier to achieve comfortable indoor temperatures despite external temperature changes. This hence needs less energy or heat for cooling.

OPTIONAL TECHNOLOGICAL CHOICES TO WATER-HEATING ACCORDING TO SANS 10400-XA.

From the foregoing, it is paramount to realize that there has been a consistent emphasis on replacing the existent electric water heating option. Each of these will be discussed below in details and hence the most applicable option can easily be drawn.

  • SOLAR WATER HEATERS.

    South Africa is one of those countries which have abundant sunlight and hence it would be ideal to harness the suns energy. Doing this can actually save up to 25% to 40% on electricity power which is literally wasted on “geyser” generated electricity. Usually, there are a number of solar water heaters which are available in a number of shapes as well as forms which actually impact on their cost, energy efficiency as well as the aesthetic beauty. Usually, there are three main options, namely:
    - Passive.
    These actually take the benefit of hot water behavior of rising above cold water. This usually
    allow natural water circulation without the need for an electric pump and hence cheaper on
    the long haul. With these systems, it is paramount that the tank be placed well above the
    collector plate, most preferably on the roof.
    - Active.
    With these, there is a bit of electricity which is actually needed to allow the circulation of
    However, you have to note that this mechanism does ensure that the tank is not
    exposed to the environment, rather it is concealed under the roof or within the house.

    Nonetheless, both of these options may have electricity as a backup in the event that there is no enough sunlight to warm the water to the required temperature for the convention cycle to commence.
    - Flat plate.
    This option basically collects the sun’s rays using a weatherproof box which, fitted with a
    glass cover.
    - Evacuated tube.
    Usually, the evacuated tube contains a series of parallel glass tubes which it uses. These are
    more designed for the cold climatic conditions, and usually they reach higher water
    temperatures than the flat-plate systems.

  • HEAT PUMPS.

    Water can actually be heated by simply extracting heat from the atmosphere via the use of heat pumps. This actually uses about 50% - 70% less electricity than the actual electrical water heater. This basically resembles some sort of an air conditioner unit which is attached to the exterior of a building and basically connected to a geyser on the inside. Usually, since these don not need any sort of roof space or direct sunlight, then these are easier to incorporate in houses as well as tailoring to suit the actual home design.

  • MISCELLANEOUS OPTIONS.

    Owing to the fact that the wording of the SANS 10400-XA is not prescriptive, this leaves the choice of technology which is actually open to invention and innovation. Case in point, there are other mechanisms which may be considered, the likes that recover heat from household items, such as from the fireplace, stove or actually make good use of combustible fuel like sawdust and gas.

 

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