Heating Archives » Building Regulations South Africa
May 152013
 

Environmental Sustainability &
Energy Usage in Buildings

w house 25 800x510crp Energy Usage & Sustainability (SANS 10400X & XA)

Glazing and lighting are two vital factors when it comes to energy usage.

In 2011, in an endeavour to make our buildings more sustainable, and to decrease energy usage in South Africa, a new part was added to SANS 10400, The application of the National Building Regulations. Part X deals with environmental sustainability, and Part XA deals with energy usage in buildings.

In many ways these new regulations have turned the building industry upside down, but not in a bad way. However for the average man-in-the-street it has become a puzzle of note. Every week we get people writing into this web site asking for advice and information about the “new energy laws” and how they affect their building and renovations.

On the down side, it seems that new regulations have opened up a can of worms that has less-than-knowledgable people (and some scamsters) flippantly quoting “the new green laws” in an effort to force people to spend more money than they need to on energy-efficient materials, appliances and the like. While there is no doubt that we need to “go green” and get our act together (pun intended) in terms of energy efficient building, it is also important to know the difference between what we should do, and what we must do to comply with the National Building Regulations and other national standards.

What the National Building Regulations and Building Standards Act Says

While the Act was originally passed in 1977 (officially it’s Act 103 of 1977), a number of amendments have been added to it over time. In 2011, Rob Davies, the Minister of Trade and Industry added the sections that relate to environmental sustainability and to energy usage in buildings.

The motivation for this amendment is to reduce greenhouse gases caused by buildings and extensions to buildings. These relate to a number of specific occupancies that are defined in Part A of SANS 10400, namely:

  • A1 - Entertainment and public assembly Occupancy where persons gather to eat, drink, dance or participate in other recreation.
  • A2 - Theatrical and indoor sport Occupancy where persons gather for the viewing of theatrical, operatic, orchestral, choral, cinematographical or sport performances.
  • A3 - Places of instruction Occupancy where school children, students or other persons assemble for the purpose of tuition or learning.
  • A4 - Worship  Occupancy where persons assemble for the purpose of worshipping.
  • C1 - Exhibition hall Occupancy where goods are displayed primarily for viewing by the public.
  • C2 - Museum Occupancy comprising a museum, art gallery or library.
  • E1 - Place of detention Occupancy where people are detained for punitive or corrective reasons or because of their mental condition.
  • E2 - Hospital Occupancy where people are cared for or treated because of physical or mental disabilities and where they are generally bedridden.
  • E4 - Health care Occupancy which is a common place of long term or transient living for a number of unrelated persons consisting of a single unit on its own site who, due to varying degrees of incapacity, are provided with personal care services or are undergoing medical treatment.
  • F1 - Large shop Occupancy where merchandise is displayed and offered for sale to the public and the floor area exceeds 250 m2.
  • F2 - Small shop Occupancy where merchandise is displayed and offered for sale to the public and the floor area does not exceed 250 m2.
  • F3 - Wholesalers’ store Occupancy where goods are displayed and stored and where only a limited selected group of persons is present at any one time.
  • G1 - Offices Occupancy comprising offices, banks, consulting rooms and other similar usage.
  • H1 - Hotel Occupancy where persons rent furnished rooms, not being dwelling units.
  • H2 - Dormitory Occupancy where groups of people are accommodated in one room.
  • H3 - Domestic residence Occupancy consisting of two or more dwelling units on a single site.
  • H4 - Dwelling house Occupancy consisting of a dwelling unit on its own site, including a garage and other domestic outbuildings, if any.
  • H5 - Hospitality Occupancy where unrelated persons rent furnished rooms on a transient basis within a dwelling house or domestic residence with sleeping accommodation for not more than 16 persons within a dwelling unit.

But they specifically EXCLUDE garage and storage areas contained within these specified occupancies, as well as a number of other buildings that are used for commercial, industrial and buildings used exclusively for a variety of storage uses.

The law (because this is part of the Act – not SANS 10400) states that these “occupancies” (types of buildings) must be:

  • capable of using energy efficiently while fulfilling user-needs in relation to various things including thermal comfort, lighting and hot water; OR
  • have a “building envelope and services” that facilitate the efficient use of energy that is appropriate to the function and use of the building as well as its geographical location and its internal environment.

So it is not a one solution fits all situation. For instance, what works for a house in Durban may not make the same structure energy efficient in Cape Town! In addition, the legislation excludes the “equipment and plant” required for conducting business – if the building is used for business.

Hot Water Heating Requirements

XA2 requires that at least a half – “50% (volume fraction) of the annual average hot water heating requirement shall be provided by means other than electrical resistance heating including but not limited to solar heating, heat pumps, heat recovery from other systems or processes and renewable combustible fuel”.

So you can use a conventional geyser IF you meet the 50% requirement. And if you are renovating, you certainly don’t have to toss all your existing water equipment and go solar – even though there is absolutely no doubt that it’s the way to go.

What is Required

The orientation, shading, services and building envelope must be designed according to SANS 10400 Part XA. Alternatively the rational design of the building must be done by a competent person who “demonstrates that the energy usage of such building is equivalent to or better than that which would have been achieved by compliance with the requirements of SANS XA, or has a theoretical energy usage performance, determined using certified thermal calculation software, less than or equal to that of a reference building in accordance with SANS 10400 Part XA”.

If you’re looking to change jobs, becoming a person competent to specify these requirements is one way to go! It is something that is not easy for someone who hasn’t got the relevant training to get their head around.

What 10400 XA Says

As with all national standards, 10400 XA has a number of definitions, some of which are in the glossary that is part of the Act.

A few of the important definitions that relate to this particular part of the standard are:

  • Building envelope Elements of a building that separate a habitable room from the exterior of a building or a garage or storage area 
  • Competent person Person who is qualified by virtue of his education, training, experience and contextual knowledge to make a determination regarding the performance of a building or part thereof in relation to a functional regulation or to undertake such duties as may be assigned to him in terms of the National Building Regulations
  • Fenestration Any glazed opening in a building envelope, including windows, doors and skylights
  • Fenestration area Area that includes glazing and framing elements that are fixed or movable, and opaque, translucent or transparent

Requirements of 10400 XA

The requirements of this new national standard cover:

  1. Hot water supply
  2. Energy usage and building envelope
  3. Design assumptions
  4. Building envelope requirements

The standard also defines the different climatic zones of South Africa.Climate zones XA1 Energy Usage & Sustainability (SANS 10400X & XA)

To be a little more specific, the main centres for each zone are:

  • Zone 1 – Johannesburg and Bloemfontein
  • Zone 2 – Pretoria and Polokwane
  • Zone 3 – Makhado and Nelspruit
  • Zone 4 – Cape Town and Port Elizabeth
  • Zone 5 – Durban, Richards Bay and East London
  • Zone 6 – Kimberley and Upington

Building Envelope Requirements

This is probably the most vital part of the new regulation, and it addresses orientation, floors, external walls, fenestration, and roof assemblies – but not in a lot of detail.

Floors

If any type of underfloor heating system is used in a home, this must be insulated under the concrete slab with insulation that has a minimum R-value of at least 1,0. The R-value is the thermal resistance (square metre K/W) of a component. According to the Standard, it is “the inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other surface for a unit temperature difference between the two surfaces, under steady state conditions, per unit area”.

Roof Assemblies

Any roof assembly must achieve a minimum R-value for the direction of heat flow. This is specified in several tables in the regulations.

 Minimum total R-values of roof assembliesPart XA Min total R values of roof assemblies Energy Usage & Sustainability (SANS 10400X & XA)

Roofs with metal sheeting affixed to purlins, rafters or battens made of metal are required to have a thermal break that consists of a material with an R-value that is not less than 0,2, and which is installed between the sheeting and the support. In addition, roofing assemblies that utilize metal sheeting must achieve a minimum total R-value that meets the requirements shown in the table above. Insulation must also be installed with an R-value that meets the specified in the table below.

Metal sheeting roof assembliesPart XA Metal sheeting roof assemblies Energy Usage & Sustainability (SANS 10400X & XA)

Clay tiles used for roofing must achieve a minimum R-value as in the first table above. Insulation should be in accordance with the specifications shown below.

Part XA Clay tile roof assemblies Energy Usage & Sustainability (SANS 10400X & XA)

The other standard that you need to know about is
SANS 204 (2011): Energy efficiency in buildings.  

 

Apr 202013
 

Electric Cables – What is Legal

conduits On Underlay509 Electric Cables

We get a lot of questions about which electric cables are legal and how they must be installed. So here is a brief rundown of the different types of legal cabling available and the way an installation could be done. There are various accepted methods and we illustrate a general one here. When a builder has to wire a home, he will first lay conduits, which are plastic or metal pipes fixed in place above the plastic damp-proof underlay and the steel reinforcing.  (See the picture above.)

These pipes are layed out according to the house plans and extend upwards from the floor, and will be built into the walls later when the bricklayers start their work. The concrete for the floors will then be placed, and the conduiting will run within the floor slab. From there they can be chased, or cut, into the walls so that they can be routed to various outlet points where plug points and lights are required. The electrician will later pull the wires through these tubes. There are classes of cable that do not need to be encased in conduit and can be chased into, and laid directly under the plaster. Two examples of these are Surfix and Flat-Twin-and-Earth cables. A full specification can be found in the Aberdare brochure below. When the roof is on and waterproof the cables can also be layed in the roof space for overhead lighting and other fittings.

Wiring electrician185 Electric Cables

A qualified electrician gets to work sorting out all the wires that come together at the distribution box.

Be Guided by What the Law Says about Electricicty and Electric Cables

By law a fully qualified and registered electrician must be  responsible for the wiring. It is a good idea for all homeowners to familiarise themselves with, and be able to identify, different types of cable and flex to ensure that all materials used in the installation are up to standard (literally – they need to meet the relevant South African National Standard).The National Building Regulations and Building Standards Act does not cover electricity and nor does SANS 10400. Electricians must comply with SANS 10142: The Wiring of Premises.

Depending on the class of cable the non-conductive insulation material around the wires inside cables and flex are different colours to make it easy to identify them. Green, or green and yellow, is the earth; live wires are brown or red; and neutral is either light blue or black. Once the wiring in a building is complete the entire system must be checked by an accredited person (from Eskom or the municipality/ local authority) who will issue a certificate of compliance.

Aberdare Cables have an excellent brochure (see below) that should help to identify the various cables associated with the electrical installation in a house.

Download (PDF, 2.47MB)

[Note that we have no affiliation with this company and reference to their brochure does not imply any particular recommendation.]

Mar 112013
 

Fenestration and Glazing Guidelines, Procedures and Calculations.

Windows house335 Fenestration Calculations

The guidelines featured in the pdf below give an idea to anyone wanting to calculate the Fenestration Compliance Procedures in terms of Sans 10400-XA:2011 and SANS 204:2011, what is required and what is involved.

There is a step-by-step guide to area (nett floor) calculation with reference to the parts of the regulations that apply. A SGHC (solar heat gain calculator) is also supplied, to calculate the heat conducted in and out of a building. There are a couple of “real life” calculations at the end of the document that illustrate how this was achieved.

You will see that the calculations that need to be done to comply with the Regulations are not at all straightforward. But you do, in any case require a “competent person” to draw up your building plans, submit them to the local authority, and take responsibility for the project (including ensuring that construction is in accordance with the plans). A competent person should be well equipped to interpret fenestration and glazing guidelines as well as procedures and the calculations. If not, it is the responsibility of that person to include someone who is in the project.

Download (PDF, 250KB)

Nov 152011
 

Chimneys, Flues, Hearths and Fireplaces
Used for Space Heating

FireplaceBR1 Space Heating

A freestanding fireplace with a flue that goes through ceiling

Anyone searching through the National Building Regulations for information about chimneys and flues, hearths and fireplaces, might go straight to the part that deals with Fire Protection. The next step would probably to look through the part that deals with Walls – after all chimneys are often built with bricks and mortar and often extend from a wall. Or Roofs might seem to be a good place to look.

But no, you are not going to find the information you are looking for in any of these three sections of the NBR. The information you need is in Part V of the Act. This section is very short, and deals only with the design, construction and installation of fireplaces and hearths that have chimneys and/or flues.

 

 

 

 

 

 

 

The legislation states:

“(1)  Any system of space heating in any building shall be so designed, constructed and installed as to operate safely and any flue, flue pipe or chimney used in such system shall be so designed as to safely remove any smoke or noxious gases produced by such system.

“(2)  The requirements of sub-regulation (1) shall be deemed to be satisfied where the design and construction of any flue pipe, chimney, hearth or fireplace complies with SANS 10400-V.” That’s it.

SANS 10400-V: Space Heating

As with all the Standards that make up SANS 10400, if you ensure that your installations comply with the SANS it will be “deemed to satisfy” the law. But other Standards are often cross-referenced. This Part of SANS 10400 makes reference to:

  • SANS 10177-5, Fire testing of materials, components and elements used in buildings –– Part 5: Non- combustibility at 750 °C of building materials.
  • SANS 10400-A, The application of the National Building Regulations –– Part A: General principles and requirements.
  • SANS 10400-B, The application of the National Building Regulations –– Part B: Structural design.

Like all the published SANS, it has a list of useful definitions, some of which you will find in our Glossary of Terms.

Examples include:

  • chimney That part of a building which forms part of a flue, but does not include a flue pipe
  • flue Passage which conveys the discharge of a heat-generating appliance to the external air
  • flue pipe Pipe forming a flue, but does not include a pipe built as a lining into a chimney

Hearth and fireplace are not defined!

Chimneys

Chimneys must be designed and erected from materials that are non-combustible – which of course stands to reason. It is also important that they don’t become a fire hazard, particularly to those materials adjacent to the chimney structure. Further, chimneys should not reinstalled in shafts or ducts that might be affected by heat.

Timber is one of the combustible materials that we commonly use in our homes, and the regulation states that elements including joists for timber floors, trimmers or roof trusses may not be built within 200 mm of the inside of any chimney.

There are additional regs that relate to dimensions, for instance where the walls of a brick or block chimney are less than 190 mm-thick, it must be lined with a flue lining that is made of a material that will withstand the action of any flue gases and won’t crack or soften. The flue lining must also extend throughout the full height of the chimney.

There are also regulations that relate to the height of the outlet – this has not changed since the regulations were published previously in 1990 (and of course you can download these free). Below you can see the chimney positions.

Part V opening or adjacent structure Space Heating

Opening or adjacent structure

Part V roff pitch 10 deg or more  Space Heating

Position when the roof pitch is 10 degrees or more

Part V Roof pitch less than 10 deg Space Heating

Roof pitch less than 10º

Flue Pipes

This is all largely common sense. Flue pipes may not be designed or installed if they are going to become a fire hazard to adjacent material. They may also not be connected to shafts or ducts that form part of any ventilation system. And they may not be installed in shafts or ducts that are likely to be adversely affected by heat.

Hearths and Fireplaces

Any fireplace that is used for burning “solid fuel” MUST have a hearth that is make of a non-combustible material that is sufficiently thick. It must extend no less than 500 mm in front of the grate or fire basket and not less than 300 mm beyond each side of the grate or fire basket.

Timber floor joists and trimmers – or any other combustible material – may be built into a hearth.