When driving past new building developments, particularly residential, one sees remarkably little evidence of solar or heat pumps being installed as part of the energy efficient policies required under SANS10400-XA.
Shiny examples in the commercial property sector are frequently published, with accolades and commendations being sought in Green Building Competitions.
In the domestic sector, the focus towards keeping costs down, results in SANS 10400 – XA being ignored either deliberately or through negligence, or indeed through arrangements with building inspectors.
SANS 10400-XA and in particular XA2 states that not more than 50% of domestic hot water should be supplied by means of electrical resistance heating.
Simple enough to understand in principal, but how does one actually interpret it? With no clear guidelines or indeed rules as to how it should be interpreted the opportunity to ignore it is obvious, and developer additional costs for energy efficiency can be ignored.
The general guidelines that electric resistance geysers use for 40%-60% of a typical homes electricity bills is not accurate enough, particularly when average electricity consumption across homes can include low income homes that do not even have electric geysers.
Hot water consumption of 50 litres per day, (as previously referred to by Eskom) is equally misleading. Is that geyser hot water or hot water from the showerhead that has been mixed with cold water?
A common sense approach is to understand the amount of electricity used in heating hot water for washing, and to estimate the amount of hot water used for washing by all the occupants in the home over 24 hours.
Using the specific heat of water formula, 1 kWh is used for heating 36 litres to 40 °C, taking average cold water temperatures. 40 °C is the typical temperature that is comfortable for washing.
The shower will use 16 litres per minute, some with larger showerheads much more. Adding the minutes together that everyone spends in the shower in 24 hours, and dividing the total by 36 litres gives you the approximate kWh consumption per day.
Converting the required kWh saving into solar is a question of looking at the deemed kWh output of a solar water heater, and comparing. Where no kWh output is given, a ‘Q’ factor performance figure at 20 MJ m2 pd (as provided by the SABS) can be divided by 3,6 to get the deemed kWh output. For heat pumps the kWh output and COP provides the guideline. Gas is more complicated.
Meeting the minimum requirements under SANS10400- XA arguably is missing the point.
- Consumer renewables and energy efficiency are now so competitively priced when compared to the price of electricity, that the payback on the investment can be as little as 2 or 3 years (some systems are considerably more).
- The return on investment for the homeowner will be better and more certain than any investment in the stock market, and over 10 or 20 years nothing else will come close.
However the additional cost of consumer renewables still presents a problem to the builder developer. They want to keep their costs as low as possible, and to sell the development with the maximum ROI on their capital invested.
So not surprisingly 4 years after the SANS 10400-XA rules were implemented, they are still being ignored.
Are there compromises or other initiatives that can bridge the problem? One solution would be for the mortgage lenders to insist that the new buildings comply with SANS 10400- XA. Discounts from mortgage lenders for green homes that meet the requirements would be a motivation.
Builders that installed solar ready geysers would cost almost nothing more, but would enable the new homeowner to choose a solar system of their choice at lower costs. Likewise a larger solar ready electric geyser, say of 200l rather than 150l would be beneficial.
In the interim as with so many good intended rules, which would be rigorously complied with in Northern Europe, they will be ignored in Southern Africa, and only the consumer will take the initiative and in their own time.