BETTER DETAILED DESIGN + DOCUMENTATION
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 detailed design and documentation stages:
Select double glazed windows - Good quality double glazed windows make a big difference to reducing heating and cooling energy consumption and improving energy ratings. Windows are the weak spot for heat gain and loss in a building. Windows are rated by their U value which is the rate at which heat can travel through them. This is the inverse of the resistance R value used for walls (U=1/R or R=1/U) so a typical single glazed window U value of 6 is equivalent to a R value of 0.17. A typical double glazed window U value of 3.5 is equivalent to a R value of 0.29.
Also avoid fully fixed glass windows. Ensure there is an openable component to each window. Think about the appropriate window opening mechanism to encourage use of the window.
Including heavy thermal mass such as concrete or tiled floors in a space where the winter sun can strike the mass will also help.
Shade to keep summer sun out but allow full winter sun in. Place shading high enough above the header of the window or sliding door to ensure it is not creating permanent shade on the glass during winter. This is a more common than not mistake with fixed shading. 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. It is worth remembering the impact that fixed shading can have on the daylight levels within an adjoining room. For more details on shading LID can undertake shading analysis - contact us at Alternatively refer to
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. Good quality double glazed windows make a big difference. Including heavy thermal mass such as concrete or tiled floors in a space where the winter sun can strike the mass will also help.
Building sealing -
Downlights should be LED IC (Insulation Contact) type, allowing for insulation to be directly installed over the downlight fitting itself (as per manufacturer’s instructions). This will reduce the heat losses and gains through gaps in ceiling insulations. IC rated products are available at comparative prices to non-IC rated LED downlights. IC is possible for LED downlights as these run cooler and more efficiently than previous traditional halogen type downlights.
No power, data points etc. will be installed on external walls where insulation removal for electrical safety would compromise the external wall envelope. Alternatively, if installed, acoustic fire rated wall boxes will be installed behind these power and data points.
Select low VOC materials
Modern construction products over the last 40 years have given us more choice and variety of inexpensive, cool materials, but with this has often come more hybrid materials that incorporate potentially harmful glues and synthetic products. These products often emit harmful fumes known generally as Volatile Organic Compounds (VOCs) and they potentially cause harm to building occupants.
As we seek to have more energy efficient buildings, we are sealing our building better. With this comes the risk that VOCs will not be flushed out of rooms. In response we need to either be very diligent on good ventilation, or ensure we only specify materials that have low or very low VOC levels. For the optimum outcome we should incorporate excellent easy to operate ventilation and low VOC materials.
Remember domestic reverse cycle air-conditioners generally do not ventilate a building. Nor do fixed glass window panes, despite them offering an uninterrupted view.
Internal use products that typically include VOCs. Low VOC options are available for all products if you search – see comments below:
- Glues, adhesives (Low VOC versions available from Bunnings and other suppliers)
- Paints (Low VOC versions common at all paint stores)
- MDF or plywood joinery board (Zero VOC emissions E0 board is common industry board)
- Carpets, carpet tiles (Low VOC versions available)
- Floor boards (Low VOC versions available)
- Floor coatings (Low VOC versions available)
Efficient lighting - Good quality LED residential downlights at 6W now provide better lighting output than 50W halogens so generally make this target easy to achieve. But check the appearance of the light produced by the daylight or warm rated lights. Motion sensors and smart circuit switching can further improve energy efficiency of lighting installations.
Light coloured roofing - building roof colour is to be light – medium colour (as per the BCA definitions) rather than dark to help mitigate the effects of the Urban Heat Island effect.
Best practice projects free standing dwellings, townhouses, communities and apartment developments.