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Not be confused with sustainable or ‘green’ building, which include criteria such as embodied energy and renewable materials (i.e.
timber); energy efficiency focuses only the energy usage of a building once the building is built. Typical issues effecting energy
efficiency include orientation towards north, window sizing and positioning, shading, choice of materials with regards thermal and
insulation properties, solar heating, natural cooling and daylighting. It is the planning and design of these aspects that are stipulated
by the new regulations. SANS 10400-XA provides the ‘deemed-to –satisfy’ requirements for compliance with the National Building Regulations
with regards energy usage, and SANS 204 specifies the design requirements to achieve the required levels of energy efficiency. An
example of a deemed-to-satisfy requirement is, in the case of fenestration, where the total fenestration area is only up to 15% of
the total floor area. It is in this case assumed that, given all the other requirements are met, such a building would not overheat
or loose excessive heat due to fenestration. If the percentage is over 15% , which would be the case for most non-economic type housing
( or Victorian style houses with small windows) architects and designers need to refer to the tables in SANS 204, which provide
solar exposure factors for windows depending on orientation and climatic zone, as well as a host of other info, on which their
calculations need to be based.
The success or not in achieving energy efficiency is the sum of many parts, as per the issues
above, and in essence part XA tells architects and designers what sum of parts is required and SANS 204 provides guidelines
and options on how to achieve this. As a rule, good design in terms of energy efficiency (as per SANS 204) will prevent the need to
add potentially expensive measures, ie double glazing to large south facing windows (where a huge amount of heat loss would occur)
or extra shading to west facing windows (which would otherwise cause the house to overheat), in order to meet the minimum requirements.
zone map | Differentiation by climatic zone is an integral part of the regulations
Below are some examples of the types of specification
Brick walls ranging from 140 mm solid brick plastered both sides to cavity walls (which is best because
of the air space between the two leafs of brickwork) complies with the requirements of SANS 10400-XA.
Non-masonry walls are
required to achieve a minimum total R-Value of R2,2 in climatic zones 1 and 6, and an R-Value of R1.9 in climatic zones 2,3,4
The insulation of roofs have been determined as the single biggest factor impacting on energy efficiency and this
is where the most radical departure from ‘but this is the way we’ve allways done it’ (for the most part anyway) is required.
R-Value of roof assembly ( ie all components of the roof and ceiling) required in Zones 1 and 4 is R3.7 with the other zones only
marginally less. This means, for a clay tile roof for example, that once one has deducted the R value of the tiles, ceiling, airspaces
etc. another 3.3 of R-value is still required by adding insulation. This equates to around 150mm of a typical cellulose fibre insulation,
which is a lot more than has generally been specified up to now. For roof’s with exposed rafters it is even going to change the way architects
and designers detail the roof construction – as with the previous method of putting insulation between 76mm purlins
there simply isn't going to be anough space.
Solar Hot Water Heating:
50% of all hot water in new houses needs to be produced
by methods other than electrical element heating – which, as solar water heating geysers still partially use electricity, it basically
means all hot water must be supplied by solar water heating systems, or alternatively a heat exchange type heatpump.
now also needs to be specified (as apposed to as previously just indicating a light point on the plan), taking in consideration light
levels, energy demand and energy consumption.
So now, architects and designers really have their work cut out for them. There
will be some teething problems with the new regulations for some time yet as architects and designers as well as local authority
plans examiners get to grips with the new requirements. All architects and designers have had to do a two day course in
order to be recognized as ‘competent persons’ as required by the regulations in order to do the calculations, and further delays have
been experienced in plan approvals until the building plans examiners were up to speed with the process.
While there has
been a knee-jerk reaction and a cry of yet more over-regulation by some, this is a very necessary and well timed intervention in averting
an energy crises. It is acknowledged world wide that the buildings are a massive consumer of energy, and this will position the construction
sector in South Africa, as in some other parts of the world, as a leader in the move towards a sustainable future.
Jacques Cronje - Jacques Cronje Timber Design
Inspected once, Inspected Right!®
Understanding the new Building Regulations in South Africa
Energy efficiency in buildings, up to recently, has
been a matter of choice. Having an energy efficient building is now, however, no longer just the preserve of those wanting to do the
right thing – what was a voluntary standard was written into law in Sept 2011 and was implemented and has become applicable as of
11 Nov 2011. These are the new SANS 10400-XA: Energy Usage in Buildings, and SANS 204: Energy Efficiency in buildings. The only exception,
as with the other new building regulations, was that where the design work on a project had commenced prior the publishing of
the standard, an application should have been submitted to the Local Authority within 6 months of the standard’s publication
date, requesting that the application be dealt with in accordance with the prior regulations.
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