BETTER CONCEPT DESIGN
Delivering an energy efficient and sustainable building relies on addressing many considerations during the design and construction of a project. At different stages there are different relevant considerations that together make up a complete sustainability response.
The following are key basics to consider at the concept design stage:
Passive design is the concept of designing to work with the local climate, to reduce the need for mechanical heating, cooling and ventilation. Appropriate room placement, window locations, size, openability and shading are all key considerations in passive design. For more see the Australian government Your Home free publication https://www.yourhome.gov.au › passive-design
In Melbourne the starting point for passive design for residential dwellings involves placing the living rooms on the north side of dwellings with glazing designed to capture the lower angle winter sun to heat these rooms 'passively' ie with a reduced need for mechanical heating. Service rooms or bedrooms have less need for daytime winter heating so are better placed on the elevations less able to gather winter solar heating.
For more rigorous design approach, consider passive house principles - appliable to all building types.
Optimise Window placement. Windows are the weak spot for heat gain and loss in a building – they are effectively a hole in the wall. A typical wall might have an insulation resistance to heat flow R value of 2.5. A typical single glazed window might have a resistance to heat flow of R0.17 and a typical double glazed window might have a resistance to heat flow of 0.29.
Breeze paths and natural ventilation opportunities from windows. Think about breeze paths (max 10-15m) through a space with limited turns or obstructions. Avoid fully fixed glass windows. Ensure there is an openable component to each window. Think about the appropriate window opening mechanism to encourage easy use of the window.
Shade rules for summer and winter. Smart fixed shading works with the different sun altitudes during the day in summer and winter, to allow winter sun into the dwelling while keeping the higher summer sun out. Poor shading that keeps out winter sun negatively impacts residential energy ratings in Melbourne.
Adjustable external shading can be the optimum shading as it can be adjusted for the conditions. However if a client is unlikely to adjust external shading on a regular basis it might not be effective.
Internal adjustable blinds are much less effective than external shading as the heat is kept out of the house by external blinds, but still allowed in by internal blinds.
Effective shading is one of the more difficult design challenges, particularly for east and west facing windows. South facing shading is unnecessary, but often included on buildings for decoration!
It is worth remembering the impact that fixed shading can have on the daylight levels within an adjoining room.
For more details on shading refer to https://www.yourhome.gov.au/passive-design/shading
Energy ratings as a design tool - Maximising energy efficiency of the building fabric - ie the walls, floors, ceiling roof and windows. After optimising a building for passive design the focus should be to maximise the energy rating. Undertake a preliminary energy rating to use the energy rating as a design tool rather than just a certification tool when it is too late to benefit the design!
Trees and vegetation - are critical for so many reasons. Plan to include substantial vegetation (ideally shade producing trees) in projects. Trees and vegetation provide:
Habitat for wildlife, and potentially supporting maintaining biodiversity
Shade - protection of people and surfaces from direct sun
Active cooling via the process of transpiration (the process of water movement through a plant and evaporation from leaves, stems and flowers)
Improved air quality and oxygen generation
Documented psychological benefits to people
Water Sensitive Urban Design benefits that allow filtering pollutants out of water run-off from hard or paved surfaces.
Best practice projects - free standing dwellings, townhouses, communities and apartment developments.