Gorgeous Green House

The Renovation Journey of a 1940’s ‘Traditional’ to 2015 ‘Contemporary, Green & Gorgeous’


The Idiot’s Guide to SANS 10400. (Applicable to all new builds, not just green ones!)

Glandiolus dalenii flowering this month

Safety used to be the primary criteria for glazing. It’s got a lot more complicated!

Until very recently our building standards mainly focused on strength, stability, safety and the like.  Your windows could be as large (or small) as you liked, as long as you could show they wouldn’t kill people (too easily). You could put in as much lighting, heating and air conditioning as your heart desired and you could heat your water in any way you cared to (just about).  Rainwater that accumulated on your roof and other hard services as well as your waste water just needed to be routed into the municipal storm water systems.

This has all changed significantly under the recently released SANS (South African National Standards) 10400 regulations.  And lots of professionals in the building industry have been caught on the hop!  The domino effect has been delays in plans being approved, construction pushed out and in some instances halted, while everyone gets ‘up to speed’, certificated and educated.  It seems that our government’s invitations to consultative processes were largely ignored so the new standards were implemented with little fanfare.  It is only now that non-compliance is being identified by the authorities that architects, designers, builders and suppliers of goods and services to the industry are fast tracking their knowledge and skills.   These standards are not a South African invention.  In fact much of the science has been lifted from all the good work done in the rest of the world.  We are actually lagging far behind and currently only have 30 Green Star Rated buildings to brag about.  Our Green Building Council http://www.gbcsa.org.za has only been in existence since 2007.

So What is SANS 10400 all about? 

Before I go any further with this post I must get my disclaimer in!  I am not an expert on SANS 10400 and can only share the lessons I have learned with my own build.  The standards themselves are complicated and require lengthy calculations. I have no plan to get into the nitty gritties of such, nor will I address the standards in a comprehensive way.  My intention is to rather provide a general overview of what the key challenges are and offer some suggestions on navigating some of the worst bits.

As we are all aware we have an energy crisis in this country, because we’ve felt the pain of power cuts for protracted periods.  We also have a water crisis and infrastructure problems but we haven’t had rolling water outages (yet) or major life taking floods due to overburdened storm water systems so we are still somewhat complacent. By the way, these problems are not unique to SA, they are of concern all over the planet. So essentially, the new regulations have been implemented to mitigate these problems.

Basically, these regulations are forcing all new builds and alterations to be a lot greener than before.  Whether you are interested in building green or not, you won’t get your plans approved/passed until they achieve the minimum requirements.   SANS 10400 needs to be read in conjunction with SANS 204 and they cover everything about buildings from safety, glazing, lighting, ventilation structural design etc. etc.  I will be focusing on some of the issues contained in the Environmental Sustainability and Energy Usage sections (parts X and XA).

These standards may look very onerous but when one considers that 17% of our national energy is used in residential buildings and 10% in commercial ones it is clear that we need to be building a bit smarter.  It’s also quite sobering to learn that the buildings globally are responsible for a third of CO2 emissions either in their construction or lifespan.   The standards are also very complicated.  South Africa is divided into different climatic zones (not always with sound logic is seems) as Durban (annual temperature range 16°  – 28° C) and Mooi River ( 0.6°C  – 24.2°C)  are in the same zone.  There are different standards for different building use and even different calculations to be applied for rooms relating to the different directions they face.          


Qualified Professional

First and foremost you are going to need your intended architect and/or engineer to have been accredited by the Building Control Authority.  Do not assume this is already so.  Many professionals have attended various presentations etc. but unless you find their name on this website:  http://www.buildingcontrol.co.za/page34.html  they are not ‘deemed competent’ and your plans will not be approved.  If they are this far behind the starting blocks you are in for a protracted process of referrals (declined plans).  Best find someone who is qualified to do all the tricky calculations that are going to need to be done and generally up to speed on building green.


If your windows are large you may have to install fixed awnings

Glazing/fenestration/windows are always significant in building for reasons of comfort and aesthetics.  If yours represent more than 15% of your wall area things are going to get complicated because you will potentially take more energy off the grid to cool and heat your building.  Bottom line, you won’t be able to install standard single glazed windows.   To put in larger windows, calculations will have to be done to justify the fenestration plans.  These are based not only on the surface area but the type of glazing and framing proposed, your climactic zone etc. The overall aim is for your windows to let in as little heat as possible in summer (because you will then want to use air-conditioners) and let out as little heat in winter (because you will want to use heaters).  The directional of the window is also part of the calculation.  So basically, if you want big windows you may need to plan for some or all of the following to reduce your electricity draw :  Low E-glazing (film applied to the glass), double or even triple glazing to improve thermal performance, awnings, shuttering and wooden frames rather than aluminium.

Don’t be naive (like me) and believe that the ancient huge trees shading your property will get factored into the calculations.  I was feeling most upset that on one set of ‘referrals’ from council we were advised to install awnings on our very shaded outbuildings. I must confess to feeling rather foolish on taking pictures to council of the trees, cool and moist paving (close ups of moss included!) to have it pointed out that the next owner may just come and cut down the trees and therefore vegetation cannot feature in the calculations around fenestration. Makes sense from that perspective.

You would be very wise to also check that your intended fenestration supplier has had their product appropriately tested:   www.aaamsa.co.za  or www.saggga.co.za or www.safiera.co.za

Renewable Energy

Providing your own energy will not automatically allow you bigger windows.

Fascinatingly, many of the new standards have come into being because of our energy crises, but if your building plans show that you are making provision to make your own via wind turbines or photo voltaic systems (our plan) you will not automatically get Brownie Points that enable you to have for example bigger windows.  The evaluators at council do not have a formula that calculates a relaxation for you because you are generating your own energy.  You might get quite a shock to learn that you need to put in double glazing (double the price) and even lose some of the windows planned. In other words you have not met the category   Deemed-to-satisfy: This path to compliance is met by showing that various building features meet minimum requirements. These include glazing dimensions, insulation thickness and wall types.

To get special dispensation you will have to make a special case. Known as  Rational assessment: This path to compliance allows the use of additional calculations to show that a building, irrespective of glazing size and insulation thickness, uses less energy than either a value provided by the XA standard, or a reference building that complies with the deemed-to-satisfy requirements.  Phew!

Ok, so that jargon just means that if you live in Durban you need to get hold of an electrical engineer who will draw up a whole lot data showing your energy consumption, how much you will supply from your renewable sources and how much you may still need to draw from ESKOM.  Please note, that it must be an electrical engineer, not your architect or your PVC supplier or your favourite blogger’s calculations.  All of this will need to be notarised.    Apparently, however, in the rest of the country this may not be the case as the code only requires only that this “competent person” be qualified on the basis of their experience and training.  It is clear the implementation is not being applied consistently across the country!

Water Heating

Old fashioned electrical geysers are no longer an option. You will be required to install a greener alternative.  You will find some useful information on my posts of December and January on solar and induction geysers and heat pumps.

Water Use, Re-use and Disposal

Our storm water systems are under pressure. All new builds will be scrutinized for their water management plan

Because our storm water systems are under increasing pressure, water disposal on your property will be carefully scrutinized   Your roof area and all your hard surfaces will be measured and depending on the type soil in your area (soil type permitting) you will in all likelihood be required to install an engineer designed soak pit.  These can be very costly in addition to being detrimental to any plants you may have in the garden!

You might be skimming quickly over the paragraph above because you are patting yourself on the back for already making provision for massive volumes of rain water harvesting and storage.  This you are going to use in the loos and showers and washing machine.  In addition, you’ve planned to re-cycle your grey water to irrigate your organic veggies.   You’ve consulted a water expert fundi like Alex Holmes http://www.pulawater.co.za   who has drawn up charts and graphs to show rainfall and your water consumption and you know your excess is tiny.  Your green halo is shining. So you’re exempt right?  WRONG!!  The evaluators do not have rainwater harvesting in their formula so you will need to make a special case for yourself if you want reduce the size of your soak pit.  But do persevere.  Talk to the Storm Water custodians at your local council (not the plan evaluators), make a case and back it up with hard figures and fingers crossed.  There are many sustainable options that could be implemented.

Water management is such an important topic that is going to need its own post to do it justice so watch this space.

Building materials

Bricks/block, roofing, insulation, pipe lagging (yes apparently we need insulation for pipes in a city that never gets cold) etc. etc. must be carefully considered. Many of the materials you use will have associated energy related numbers that may or may not be acceptable.  There is a plethora of new products on the market.  Please be very wary of ‘Green Washing’.  Look for SA Bureau of Standards approval and other relevant ratings and or registrations.

I know that if you put together a competent team on your build and do your homework, you should be able to navigate these regulations with relative ease.



Induction Geysers: are they a green option if you have no sun?

induction geyserThe Gorgeous Green House outbuildings are in deep shade. Their distance from the main house means that running water from the solar geyser is not viable.  I’ve been looking into an induction geyser as an option just for the outbuilding.

How it Works

Using a magnetic induction process, the water is heated more rapidly than conventional water geysers.  The electrical supply to the generator in the unit is converted into a magnetic field which heats the water.   There is no direct alternating current (AC) in close proximity to the water, which makes the unit safe.  Quality unit includes a high density thermal insulation layer, to sustain the water temperature.  multiple protection measures usually in place: dry burn, overheat, low/high voltage, surge and overheat protection

Electrical Usage

  • To heat a conventional 150L geyser from 20’C to 65’C takes two and a half hours and uses approximately 7.8kw of electricity
  • To heat the same amount of water via an induction heater will take approximately 1 and a half hours and uses approximately 3kw of electricity
  • Operating cost Approximately 1/3 of the cost of a conventional geyser
    Substantial water saving due to location of the unit


  • Easy to install
  • Quick access to hot water
  • Only uses power while heating
  • Saves water
  • Saves electricity
  • Saves space
  • Exceptionally safe
  • Requires a 15 Amp wall plug – just plug in and switch on


  • The unit needs to be placed close to the are of use as heat will be quickly lost through the pipes.
  • If the unit is at a distance, water pressure will also be impacted


I need to purchase a 75L geyser as I will be operating a shower for one person everyday and a second shower for occasional visitors.  The cost is aprox. R6 000.00 ($700.00).  Much the same as a conventional geyser.

Looks like an easy decision to make!



So What’s the Problem With Eskom Power?

We’ve all been grumbling in recent years at Eskom’s unreliable provision of electricity and are aghast at recent tariff increases.  Brace yourselves; Eskom is targeting an average annual increases of around 15% for the next five years.  The rate you per kWh depends on how much you use.

Figures from ESKOM website

Yet compared to global consumers our electricity bills are cheap.  Europeans for example are paying 4 times as much.

Coal is the most polluting energy source on the planet, and the main cause of the world’s CO2 emissions. (In addition it spews out nitrous oxide (N20), hydrofluorocarbons (CFCs, HCFCs, and HFCs) and methane (CH4). These emissions trap the sun’s heat and warm the planet, adding to the earth’s natural greenhouse effect. Coal ash, the solid waste produced contains large quantities of toxic metals, including mercury, arsenic, beryllium, cadmium, chromium, nickel, and selenium.

South Africa is the world’s fifth largest producer of coal, and is the sixth largest consumer on the planet.

The reality though is that the price we pay does not reflect our real cost.  South Africa’s addiction to coal generated electricity (only 1% of our electricity is coming from renewable resources) has other externalised costs including the following:

  • Acid mine drainage
  • Air pollution
  • Polluted water, massive use of water in production
  • Tunnels causing instability
  • Coal miners and local communities health and high mortality rate
  • Environment and eco-system degradation from the physical process of extracting the coal
  • Long term environment and eco-system degradation as a consequence of the greenhouse gases produced.

The University of Pretoria’s Business Enterprises unit has just released a report entitled The True Cost of Coal which clearly outlines the impact of continuing on this path.  The projected externalised costs (the ones that don’t appear on your utility bill) for the proposed new Kusile mine alone are a whopping R60.6 billion (766,656,000.00 USD) a year! The same report outlines the benefits of the transition to renewables, including far greater job creation and potentially faster provision to communities who are as yet not connected to the grid.  There are still 10 million South Africans without power (nearly 20% of us) and the technology is here to do it clean and safely.

But….How Much Will it Cost the Average Household to go Solar?

Before answering that question I urge you to look at your current energy costs.  Scrutinize your electricity bill.  Look at how many Kwh you are currently using.  The Eskom table above could be a little misleading as my family is currently paying R1.02 (0.12 USD) per kWh. Calculate what you will be paying based on a 15% annual increase over the next say 10 – 15 years.  Try not to fall off your chair in a dead faint!

Eskom have a nifty calculator on their website that allows you to drop in your current kWh consumption and it shows you what you are paying and how much you will pay next year.  Go to http://www.eskom.co.za/c/53/tariffs-and-charges/ and click on the residential tariff comparison tool.

I worked out that if my family were to continue in our current very non-green house with our current shocking consumption of 1664 kWh per month our electricity spend over the next 10 years   would    be in the region of R694 995.93 (80367 USD).  Over the next 13 years    R1 236 697.00 (143 013.00 USD). Your own calculation may well provide similar impetus to explore alternatives! So clearly ‘dirty energy’ is costing us at all levels, but it still boils down to ‘what can I afford now’?

For several years I’ve had a minor obsession with the notion of ‘getting off the grid’.  I would ask vendors at Sustainability Expo’s and the like “how much for a family of 5 to set up to get off the grid”?  Five years ago the response would be a sorrowful shake of the head and responses like “maybe just aim to get your water heated and supply your lights”.  If I pushed the numbers ranged around the 1 Million Rand (116 000.00 USD) mark.  Fortunately the cost of photovoltaic (PV) cells is falling fast and some say that they will be at grid parity with Eskom by 2015.  (David Lishitz: Our Power Station).

I’ve been researching options, talking to vendors and doing some sums.  I recommend that you talk to   www.solarsunsa.co.za   who will walk your through the minefield of technicalities to help you understand your options.  Please beware of the plethora of inferior imports.

I’ve worked my calculations based on an annual consumption of 6694 kWh which is feasible if you make some changes.  For example, just switching to a solar geyser or heat pump can reduce your use by 40%.  (Note:  I plan to post a lot more all options to reduce energy consumption, including the hotly debated solar geyser vs heatpumps issue!).

The bottom line:   to get 97% off the grid your costs (panels, inverters, batteries, display screen, controllers, installation/labour etc.) from a reputable provider will cost approximately R340 000.00 (39317.92 USD).

I know, I know!!!  It’s a massive amount of money but if you plan to be in your home for a while you will get your money back by year 13.5 and thereafter you are laughing.  Remember the 15% increases we are promised? The scenario in the previous paragraph plays out like this:

So sadly, it’s clear at this point that only the wealthy can afford to make the investment (and benefit from the longer term payback) but is this not true of most investments?  Perhaps this is the way to view the opportunity?  My sense is that if industry, government and private households just get this thing started volumes will drive costs in the right direction, enabling more and more people access, encouraging further price reductions etc.  What will also create incentive is the ability to ‘sell back’ our excess energy when we have more than we need.  This is standard in other first world countries so fingers crossed we will catch up soon.

So, if you’ve got the means to make this investment and want to look at the viability for yourselves where to start?

Designing Your Solar System

Assuming you have already reduced your energy usage via the usual switch to LED’s, energy efficient appliances, solar geysers/heatpumps, general energy conscious living etc. start talking to vendors in the industry about how they would put together a system for you and what the costs would be based on your kWh consumption. Ask for a range of quotes to take you from 60% – 95% ‘off the grid’.

Battery Enclosure

You need to have a place to put your panels, and batteries, display screen and converters etc. That all needs to be planned for and a good specialist should advise.  You will need an outside cupboard that is well ventilated.

Most vital to the success of the technology will be the amount of sun you are in a position to harvest.If you are concerned that your intended roof/wall/garden space gets too much shade you

Solar Pathfinder

can ask you vendor to install a Solar Path Finder to calculate how many kWh of energy you will be able to harvest at all months of the year. The first design of our Gorgeous Green House had the panels positioned in the shade of an ancient Albizia adianthifolia (Flat Crown tree), not good! Trevor Wheeler www.solarsunsa.co.za  climbed up on our roof to put the Solar Path Finder in 3 places to take readings for us so we are now confident that our roof now facing North East is going to be right.

Don’t be put off if your are retrofitting and you roof line is wrong.   One can get creative and brackets can be used to place them just about anywhere as the link shows:  http://www.youtube.com/watch?v=vC-Xb3uaTk0

IOL Business Report SA Time: Fri Oct 05 2012 11:21:33 GMT+0200 (South Africa Standard Time) http://www.greenpeace.org/africa/en/News/news/The-True-Cost-of-Coal/

(http://www.precaution.org/lib/08/prn_is_coal_green.081106.htm) ( World Coal Association. 2010. Coal Statistics. http://www.worldcoal.org/resources/coal-statistics/

Gorgeous Green Architectural Design


Several years ago when I started talking about my dream of building a ‘green house’ a friend said “oh I saw one of those … a kind of hobbit house…really ugly”  So the first misconception to clear up is that green design has nothing to do with the aesthetics of the house!  Whatever your taste (hobbit-like or otherwise) one can incorporate green design principles.  Essentially it means building in harmony with the natural environment and cooperating instead of fighting with the regional climate.  Green building takes a passive approach which requires less energy to run once the building is erected. It’s also know as bioclimatic design, eco-design, eco-friendly architecture, earth-friendly architecture, environmental architecture and natural architecture.

This post will focus on the design of the building itself, not the technology or specific materials to be used.  I will cover those aspects separately.

My house is in Durban South Africa.  We have an average of 320 days of sunshine a year. Temperatures range from 16 to 25º C in winter and  23 to 33º C in summer.  However, before you consider relocating, the warm Mozambique current flowing along our coast and summer rainfall means we also experience high humidity which can be quite debilitating from December to March.  So here is what we have briefed the architect to design into the house:


We want light (lots of) but not direct sunlight which would heat up the house and require us to put in energy guzzling air-conditioners so one of the easiest things to do is install tinted windowsCross ventilation is also a vital consideration.  Windows were planned so that each room would have opening windows on opposite sides of the room.  The most challenging areas were the downstairs bedrooms which open onto the passage .  Tricky to get cross ventilation as you can see from the drawing below.

Bedrooms tricky for cross ventilation. Pond has low opening windows to draw in cool air

We did three things; firstly designed opening windows above the doors and small high windows (second floor not in view) that open up into the passage.  The passage windows slide sideways rather than level in our out so there are no unattractive or dangerous protrusions in to the passage.


Secondly we have put whirly birds into the roof of the passageway to draw the warm air up and out of the house. These are fantastic low tech gadgets that are used a lot in factories but surprisingly not in residential properties.  The third thing we did was put opening windows at ground level next to the pond to draw in the cool air as it crosses the water.  Thanks for this great tip Greg Seymour greg@go-green-consult.com


Sun pouring into a building is a costly thing to mitigate. Passive solar cooling eliminates the need for air conditioning. The image at the top of the  page shows the house as it faces North.  In Durban this is the hottest elevation.  Fixed louvres will cut the sun’s strength considerably without blocking light.  The verandahs are wide so that even in winter when the sun is lower  it won’t penetrate into the house.  Elsewhere on the building are ‘eyebrows’ to shade windows.  Best of all (though not strictly a design feature) are trees and shrubs next to the building.  Many are deciduous so in summer they are full of leaves when most shade is wanted and in winter the drop their leaves when a bit more warmth is welcome.


Example of roof garden with plants I will also use

A study undertaken by Canadian researchers found that green roof habitats were very effective in reducing a building’s energy demands.   The results show that a conventional roof absorbs solar radiation during the day, creating a high daily energy demand for cooling internal air spaces. In  contrast, the growing medium and plants of a green roof habitat reduce the heat flow through  the roof by providing shading, insulation, and evaporative cooling (shown in green below). It was found that the green roof habitat reduced the daily energy demand for cooling by a whopping 95%!!  (If you’re interested in the tech stuff that’s from 19.3  kWh or 7,080 British Thermal Unit (BTU) per m2 for a building under a conventional roof to 0.9 kWh or 324 BTU per m2 for a building under a green roof habitat). Thermal mass is the term given to material (usually concrete or stone) which will absorb heat and prevent its entry into the home.  Although there are eco-negatives associated with concrete because  of it production processes judicious use can swing its rating into a green category.  In our house concrete (a lot)  has been required to build the base for the roof garden.  Its payoff though is immense at  many levels.  More to follow on the wider range of green roof benefits and how to actually construct your own.


Albizia shading area of roof originally allocated for roof panel

Ensure you plan carefully for the location of your solar panels.  We were quite ignorant of how many we needed (24!) and initially made provision for only 8 on a section that also gets much shade from an ancient and huge Albizia adianthifolia.  Our main roof was pitched – but the wrong way – which has led to delays with approval of plans as we’ve had to switch the pitch direction to accommodate the panels.  In Durban one cannot make changes during the build without the risk of inspectors shutting down construction while you wade through approval bureaucracy so best to get it right up front.  We’ve had expert help from Trevor Wheeler of  http://www.solarsunsa.co.za/  and I strongly advise you get your solar needs properly specified from a specialist before you submit your plans.  More posts to follow on the process of determining what your solar needs are.

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