Any building (whether it be a house,
a school, a supermarket or other structure altogether) that is truly
energy efficient, comfortable, (relatively) affordable and ecological
at the same time can be classified as passive construction. Keep in
mind that ‘Passive House’ is not a brand name, but rather a
construction concept that can be applied by any builder or supplier
focusing on energy-efficient designs.
Eco buildings are not a
new concept to South Africans, and passive houses (also called green
buildings and eco homes) have taken this quite a few steps further,
depending on which region of the country it is required. For example,
a certain passive structure in an arid region (like Kimberley or
Upington) was designed with operable screens surrounding the home's
courtyard, allowing summer winds to ventilate the house when opened.
On the same property, a conservatory with glazed stacking doors acts
as a thermal heat collector during winter days. At night, blinds or
curtains are closed to make any heat that has been collected in the
concrete floors during the day radiate into the living areas and
In short, passive
houses require a fraction of the energy used by traditional designs
to heat and cool, which makes them a most welcome addition in South
Africa, where electricity is among the most expensive in the world.
Four principles of
passive design in South Africa
Overhangs and screens can be used to block direct sun in summer.
Deciduous vegetation can also be used to shade parts of the building
and lower the temperature of the micro-climate in summer and allow
light through in winter.
When windows are placed at opposite ends of a room at different
heights and sizes to create a draft, cross-ventilation is achieved.
Windows can also be placed in relation to prevailing winds, which
will cool a building down in summer and ensure a well-sealed
structure in winter.
It’s important to choose materials that have a high insulation
value and can also absorb and release heat when necessary.
As South Africa enjoys lots of sunshine and clear skies during the
day, this presents the ideal opportunity to use natural light through
well-placed windows to light up indoor spaces during the day without
having to use electricity.
The pros and cons of
Eco homes are
definitely improving the quality of life for homeowners almost
everywhere, but what advantages (and perhaps more importantly,
disadvantages) do they pose?
Green building construction offers a healthy
and comfortable living environment without higher heating or cooling
Thicker walls that offer more heat retention.
Insulation creates a sound barrier for more
quiet indoor spaces.
It can be beautifully integrated with hot-water
Due to the controlled ventilation, there is no
condensation or mould.
Lower operating costs.
Independence from fossil fuels.
It’s a sure investment in the future.
It can be an expensive initial investment.
The initial costs can be even higher (between
10% and 30%) for new or renovated constructions.
Some locations require more insulation than
others for ample heating and cooling, which means there's no "one
price/system fits all".
Additional heating and/or cooling systems may
be needed as backup in case of extreme seasonal conditions.
Occupants need to learn how to operate
Passive houses or other
structures can be seen as the next step in green building due to
their environmentally friendly criteria, such as:
Passive house buildings allow for heating and
cooling-related energy savings of up to 90% compared to other
building types. When it comes to heating oil, green buildings use
less than 1.5 litres per square metre of living space per year, which
is considerably less than for your average low-energy structure.
Similar energy savings have been demonstrated in countries with
warmer climates, like South Africa, where the buildings require more
energy for cooling than for heating.
Windows with excellent insulation properties,
as well as a building shell consisting of good insulated exterior
walls, roofs and floor slabs, help to keep the heat out during summer
– and in during winter.
A ventilation system is also put in place to
consistently provide fresh air for enhanced quality without causing
Costs of passive
houses in South Africa
Searching for a “one
price fits all” when it comes to eco houses, both in South Africa
and abroad, is like asking how long is a piece of string: there are
multiple answers as costs are all project-specific dependant on the
process, size and complexity/simplicity of the brief and design, self
involvement or not, etc. However, what we can do is study examples,
such as the passive energy-efficient house in Pretoria that, thanks
to its insulation properties, has an annual heating cost of
approximately R567 (working at a kWh rate of R1,20).
Compare this to a
standard, low-income house that doesn’t present all the
energy-efficient properties as the previous one and has an annual
heating cost of R4,082.
Scope out builders and eco-friendly suppliers focused on
environmentally friendly structures and passive houses in South
Africa to find out what your required ‘green’ house will cost.
How homify can help
Don’t forget that
homify has an ever-growing list of housing examples that not only
includes passive homes, but also prefabricated structures, modular
buildings, single-family residences, log cabins, wooden houses and many more.
We also provide a list of professionals such as architects,
interior designers and builders working throughout South Africa to
help make your search for the best expert so much easier.