Extract of Part Three
Design Elements
of the Residential Design CODES of Western Australia


3.9 ELEMENT 9 – DESIGN FOR CLIMATE

Energy Conservation and Comfortable Living

  • The sun is further north in winter than in summer, and its angle is much lower. This means that a simple, properly calculated, north-facing roof overhang will allow the winter sun in and keep the summer sun out.
  • Dwellings should be laid out so that at least one living area (preferably the one used most of the day) faces north or within 15 degrees of north. An outdoor living area is also best located on the north side of the dwelling.
  • Pergolas with removable awnings or deciduous vines can be designed to provide solar access for desired times in the winter while excluding solar access for desired times in summer. So will pergolas with correctly angled blades, called solar pergolas.
  • The sun is most fierce in summer in the afternoon. At this time it comes from the west or west-south-west, so areas of glass facing in that direction should be avoided. Protect the dwelling with trees or vines (preferably deciduous, so as to allow in the sun in winter), pergolas or verandahs.
  • The morning sun comes more directly from the east in summer, but will generally have moved to the north and then west before the ambient temperature rises. Therefore east facingwalls are not as critical as west facing, but the use of glass should still be kept to a minimum, unless screened.
  • The sun never hits the south face of a dwelling in winter: large areas of glass on the south will allow heat to escape in winter.
  • Cooling breezes in summer come to the Swan Coastal Plain from the south-west; design should allow for letting these in while protecting windows from the sun, and avoiding crowding shrubs so close that they will hinder breezes.

    All of these factors need to be verified for their relevance to other regions. For example, sun angles vary significantly with latitude, and the time and direction of cooling breezes varies with proximity to the ocean and other factors. In the hot humid regions thorough ventilation (and hence space around buildings) and shade are more important than solar penetration in winter.

    Achieving Solar Access on Site

    The shape and orientation of lots sometimes make it difficult to achieve optimum layout of a development. Sometimes this may also conflict with the principle of dwellings facing the street. Often a compromise will have to be made.

    It should be Council practice to assist where necessary by making concessions in particular cases, especially by modifying side setbacks to allow solaraccess, provided that neighbours’ privacy or solar access is not affected. These concessions may include building up to a side boundary.

    In other cases, the only available private north-facing open space may be within the street setback area. The Codes recognise this, for example by modifying the provision for fencing in the street setback area to allow for private outdoor living space.

    Protecting Solar Access for Neighbouring Properties

    Development should be designed so that it does not seriously affect solar access for neighbours. In most cases, this means avoiding very tall walls close to southern boundaries, so that excessive shadows are not cast across the north-facing areas adjacent. In some cases, overshadowing by west or east-facing walls may also be important.

    As with overlooking, but even more so, the potential for a building to overshadow a neighbouring site, or be overshadowed itself, varies enormously from case to case.