As one can see from the image above, things are progressing along nicely. The external Fibre Cement cladding is nearing completion to the first floor, all windows are installed and some internal works have commenced. On the second floor roof a photo voltaic solar array is just visible above the roof sheeting.
The solar array, below, is a grid connected 3 kW system which we believe should look after all of the household power needs, making the house a genuine zero carbon or carbon neutral house.
The panels have perfect due north exposure and are mounted on support frames to bring them up to the optimal solar angle for Sydney's latitude, thus ensuring they generate the most energy possible.
An important but often overlooked aspect of good passive design is ensuring that a house is well insulated. Insulation products are available in various 'R' values. An R value represents the thermal resistance of the particular insulation product. So in theory the higher the R value, the greater the insulating properties.
However achieving a well insulated building envelope is not just a case of using the highest R value you can find. It is possible to have too much insulation. Insulation works on trapping air between the fibres, so good loft is required for the insulation to work properly. If insulation is squashed into a wall of roof to make it fit, then the insulation will not loft and won't perform to its optimum. If you don't get the full insulating value from your insulation product then you are simply wasting money.
Also, when creating a well insulated building envelope it is critical to provide adequate ventilation to roof spaces and wall cavities. It you don't, then you will create a moist and damp environment which will become a breeding ground for unhealthy moulds.
Above and below are the insulation product and installation that we typically use. We always choose to use polyester insulation because it very safe to handle when installing (it is just like installing fluffy pillows), contains no formaldehyde unlike most glass fibre insulation and is made from recycled materials such as PET bottles.
Something that we are big on is trying to re-use heat and energy twice. In the case of the ducting and fan in the image below, this is not air conditioning. The simple fan and duct system transfers warmed or cooled air from one part of the house to another. So in the case of winter, a well heated living space will create and element of 'wasted' heat which we duct off and transfer to the second floor bedrooms. Those bedrooms are there fore heated virtually for free. The fan uses less energy than a single light globe and is linked to a thermostat which controls the temperature
Most people fail to realise how much heat loss or heat gain occurs through the glass in their windows. Most windows as standard have nothing more than 3mm thick glass which has no more insulating value than cling film!. In our opinion, upgrading the glass in windows is one of the most important aspects of green building.
The first step up from standard glass is to install what is called a 'Low E' coated glass. This has an efficiency improvement of around 40% over standard glass. The next step up would be to double glass your windows.
In the case of this house, we have used a Low E coated glass, below, because it provides a great combination of cost and performance for a temperate climate such as Sydney.
We simply love the look of this shot. The cladding, roof line, exposed roofing timbers and shadows.