PASSIVE DESIGN


Passive design is design that does not require mechanical heating or cooling. Homes that are passively designed take advantage of natural energy flows to maintain thermal comfort.
Incorporating the principles of passive design in your home:
Building envelope is a term used to describe the roof, walls, windows, floors and internal walls of a home. The envelope controls heat gain in summer and heat loss in winter.
Its performance in modifying or filtering climatic extremes is greatly improved by passive design.
Well designed envelopes maximise cooling air movement and exclude sun in summer. In winter, they trap and store heat from the sun and minimise heat loss to the external environment.
The fundamental principles of passive design, explained above are relatively simple but they must be applied to a vast range of climates, house types and construction systems in Australia.


DESIGN FOR CLIMATE

CHOOSING A SITE
Choosing an appropriate site, or existing home, and developing it to make the most of its natural attributes will yield significant economic, lifestyle and environmental benefits.
The usual stages of choosing a site:

ORIENTATION
A home that is well positioned on its site delivers significant lifestyle and environmental benefits. Correct orientation assists passive heating and cooling, resulting in improved comfort and decreased energy bills.

PRINCIPLES OF GOOD ORIENTATION

PASSIVE SOLAR HEATING

Passive solar heating is about keeping the summer sun out and letting the winter sun in. It is the least expensive way to heat your home.

Passive solar houses can look like any other home but they are more comfortable to live in and cost less to run.

PASSIVE COOLING

Passive cooling is the least expensive means of cooling your home. It is appropriate for all Australian climates. Four key approaches should be examined:


INSULATION

Insulation is an essential component of passive design.
It improves building envelope performance by minimising heat loss and heat gain through walls, roof and floors.



THERMAL MASS

Externally insulated, dense materials like concrete, bricks and other masonry are used in passive design to absorb, store and re-release thermal energy. This moderates internal temperatures by averaging day/night (diurnal) extremes, therefore increasing comfort and reducing energy costs.



GLAZING

Windows and glazing are a very important component of passive design because heat loss and gain in a well insulated home occurs mostly through the windows.

With good passive design, this is used to advantage by trapping winter heat whilst excluding summer sun. Cooling breezes and air movement are encouraged in summer and cold winter winds are excluded.

WERS

The Window Energy Rating Scheme (WERS) is a system for rating both the glass and the frame performance of windows in reducing heat loss and heat gain. WERS will help you to determine whether heating, cooling or both are more important in your climate. It assists you in choosing the most energy-efficient windows for your home and climate.

SHADING

Shading of glass is a critical consideration in passive design. Unprotected glass is the single greatest source of heat gain in a well insulated home. Shading requirements vary according to climate and house orientation.

In climates where winter heating is required, shading devices should exclude summer sun but allow full winter sun to penetrate. This is most simply achieved on north facing walls. East and west facing windows require different shading solutions to north facing windows.

In climates where no heating is required, shading of the whole home and outdoor spaces will improve comfort and save energy.



RATING TOOLS

A range of specific purpose modeling and rating tools has been developed to rate aspects of building performance for Australian conditions.




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