Good environmental design and green buildings have been around for centuries. To the ancients, all matter was composed of the four elements of fire, earth, air and water, in varying proportions. Today, the key to understanding good environmental design is in thinking about these four classical elements and how they interact with your home and the planet at large
With the latest series of Big Brother promoting their ‘green’ theme, it is safe to say that most Australians, even the younger generation, have an awareness of environmental concerns. This awareness is shifting from household utilities to the design of homes. Many are now searching for answers well beyond the household garbage recycling protocol.
From an architect’s perspective, environmental design is very simple; good architects practise environmental design most days of their working lives. Environmentally responsible/responsive design is simply integral to good design. Judging by the arrival of the Big Brother ‘green house’, we should all know that energy-efficient buildings can save money as well as helping the environment.
The initial approach to green design should always be to look for the simple and effective solution first and not to develop an over reliance on mechanical gadgetry or expensive secondary systems. Architects call this ‘passive design’ — letting the building do the work for you without flicking a switch.
Any home can be designed to be energy efficient and existing homes can be modified to improve their energy efficiency through both ‘passive’ and ‘active’ design techniques. Following are some ways that energy-efficient passive design measures can be implemented in the home.
Passive design
This refers to heating and cooling that occurs naturally, without having to rely on mechanical devices such as heaters or air-conditioners to artificially control internal conditions.
The first step in a passive design approach is good siting or positioning of the building; generally a north-facing aspect will allow for greater control over sun penetration. It is also important to take advantage of prevailing breezes and shelter from strong, cold winter winds or hot summer winds and to respond to seasonal changes. This information can be gathered from a combination of local knowledge and from the Bureau of Meteorology.
If your house is already built, you may not have any control over the siting of your home, however you may have control over the placement of appropriate openings, installation of shading devices, or perhaps even a passively designed home extension.
1) Fire (sun/heat/shading)
The sun is our most powerful energy source. Sunlight, or solar energy, can be used for heating, lighting and cooling homes and other buildings. Often passive design is referred to as ‘passive solar design’ for its reliance on the sun’s energy for the heating and cooling of buildings.
To take advantage of the sun, as many windows as possible should face north. The most effective strategy in summer is to keep the sun out before it enters the house. If openings are left unshaded, heat gain may be considerable and it is more difficult to reduce the heat once it’s trapped inside the building.
The windows and their position in the home can make a large difference to the home’s energy efficiency. Windows that face to the east or the west should be shaded using awnings or shutters, while north-facing windows should be shaded with systems that still allow the winter sun to penetrate the home.
Figures 1 & 2 or 2a :
Awnings with carefully angled timber louvres can let in winter sun and block out summer sun.
Shutters or a well-positioned deciduous tree can also be useful in keeping out the sun. The last resort should be curtains because the heat will already be inside the building and more difficult to remove. However, for the colder months, heavy curtains, preferably with pelmets, will greatly reduce heat loss.
Figures 3:
Position trees to block out the sun.
Wherever possible, use the passive design approach of allowing natural light into your home through window and door openings. Where this is not possible, skylights can be used in darker areas of the home that may otherwise require artificial lighting. Typically, many project homes have deep floorplans that don’t admit enough natural light.
Figures 4 & 5:
Skylights are great in dark areas. Large custom-designed skylights can dramatically light internal areas. Operable skylights let out the heat.
2) Earth (thermal mass)
In the winter, sun needs to penetrate the home as deep as possible into the plan, preferably onto a hard surface or heat sink (thermal mass) to trap and retain the heat throughout the day and into the night. One of the most thermally efficient flooring methods can be concrete coupled with the ground (slab on-ground) together with appropriate solar treatment. Alternatively, the floor as well as the roof and walls may be insulated to reduce heat loss.
Figure 6:
Exposed concrete or tile-covered floors are good ‘heat sinks’, while timber-framed doors and windows reduce heat loss.
If your home is well insulated, it can be up to five degrees warmer in winter and 10 degrees cooler in summer. When choosing insulation, you should look at its R value. The higher the R value, the better the insulating effect. Think of insulation as the woolly jumper you put on in winter to help your body (thermal mass) retain heat.
Old doors and windows and un-insulated homes often suffer from dramatic heat loss. Sealing gaps, installing weather seals or replacing windows/doors if necessary will reduce heat loss. Solid timber-framed doors and windows have better thermal properties as aluminium is a good heat conductor, allowing more heat gain and loss.
3) Wind (ventilation)
To cool the house, it is important to be able to remove the heat quickly through the use of ‘cross-ventilation’ or the ‘stack-effect’.
The effectiveness of natural ventilation depends on the ability for cross ventilation, that is, the natural flow of fresh air through a room. For effective cross ventilation, windows should be located as close as possible to or opposite each other. Louvres also assist in speeding up cross ventilation.
Figure 7:
Louvres can increase and direct airflow.
Good ventilation also depends on the potential to release heat that is rising through openings in the roof or upper-level windows. When the house is hotter inside than out, this establishes a pressure differential causing buoyant indoor air – the phenomenon is known as the ‘stack effect’. Because of the temperature differential, pressure increases with height, forcing the air out of openings such as operable skylights or whirly birds. Conversely, the stack effect can also be used to distribute warm air throughout the building.
Wind speed and the moisture content in the air affect temperature. Evaporative cooling can be used as an effective passive design technique. Ponds combined with breezes can carry cooler air through the house.
Figure 8 or 8a:
Ponds located outside the main living area can send cool breezes through the house.
4) Water
Water is becoming increasingly precious, with droughts lasting longer and higher demand being placed on our water supplies. As well as considering reducing water usage by using appliances with high-efficiency ratings, installing tanks to catch rainwater that can then be used for things such as flushing the toilet or watering the garden can also be useful. Installing grey water systems or recycling systems that can re-use water from sources such as the washing machine and hand basins is also possible. But remember the passive design techniques and try to gravity feed water whenever possible, and consider using header tanks if necessary.
Last, when it comes to materials, try to choose natural renewable resources that burn as few fossil fuels as possible during production and have the greatest longevity. Having to demolish a poorly designed home, constructed of inferior materials, is one of the worst forms of environmental vandalism.
Environmental building design makes sense; it is simple to understand and Australians have the ability to understand and apply ‘green’ thinking due to our practical nature. After all, we have been practising it for hundreds of years.
Figure 9:
An Aussie wind-powered water pump, supplying drinking water without the use of fossil fuels.
With endless hours on their hands and a bicycle-powered washing machine, the contestants and viewers of Big Brother must surely be thinking green — but has the crucial leap been made?
“Be assured the future is not a time zone to which we are heedlessly going, it is a condition we are consciously creating.” — Jack Greenland, Foundations of Architectural Science.
Images by Jamie North of Pardalote.
For more information contact
Zugai Strudwick Architects Pty Ltd
02 6684 8017
or visit
www.zsarchitects.com.au.
