Passive Design

A fundamental element of sustainability is the adoption of passive design principles. By responding to the climate and local conditions, free natural resources (sun, wind and shade) can be used to heat, cool and light spaces.

Passive design works with these natural resources, embracing the specific location and conditions of the site. Buildings are purposely oriented to respond to the movement of the sun and the wind. In addition, the building is designed to take advantage of the daylight and the change in seasons. Passive design seeks to ensure a building is naturally cooler in summer and warmer in winter, reducing reliance on artificial heating and cooling and improving a building’s energy efficiency.

Passive design strategies are important in helping to create sustainable building solutions. Key passive design principles include:

Orientation

The orientation of a building as well as its placement on the site plays a critical role in the passive design process. Managing the amount of sun a building receives (whether to achieve cooling or heating) as well as considering access to views and cooling breezes are all part of the process. Site location and orientation are factors that are considered at very beginning of the design process, to ensure that the building effectively responds to its unique site and context.

Ventilation

Designing to take advantage of passive ventilation, particularly in subtropical climates includes maximising the building’s exposure to cooling breezes and ensuring there a good air flow paths through the building. A key to encouraging and controlling natural ventilation is through the orientation and placement of doors and windows; using differences in air pressure to move air through the building. The combination of natural ventilation in conjunction with a fan running on renewable energy can help to move air and cool spaces on hot days.

Shading and Daylighting

Shading and ventilation strategies work to keep the building cool . Strategically shading windows and openings can help to control and minimise solar heat gain. Shading can be achieved with design elements such as awnings and eaves tailored for the path of the sun across the seasons or with landscape design elements such as deciduous trees. Overshadowing from neighbouring buildings and trees is also considered.

Thermal Mass and Insulation

The construction materials used directly impact the way heat is absorbed, stored and distributed within a building. Combined with properly insulated walls and ceilings, well chosen building materials will reduce the need for mechanical and electrical heating and cooling systems. For example, dense materials such as brick and concrete absorb heat. Thoughtful designing with thermal mass enables us to control how heat is stored and released; keeping the heat inside or outside as needed.

Building Size and Passive Design

When considering larger buildings (including larger homes) it is critical to ensure passive design is at the forefront of the design. Design elements including site orientation and building materials become critical. Incorporating shading and choosing insulation that does more than simply meeting minimum requirement is essential.