12 Dec Fabulous Flamborough – a case study
How to design and construct a passive solar, energy efficient home on a budget for the western Perth climate of Doubleview.
We were approached by our client in late May 2016. The brief was to design a small 3 x 1, two storey passive solar home to a modest budget. The block is a smaller subdivided lot, flat and on sandy soil.
Due to the budget we chose mainstream, cost effective materials such as a concrete slab on ground with insulated double brickwork to the ground floor where the living area is to be located. The thermal mass will help offset heat gain in summer and heat loss in winter. The upper floor will be constructed in timber frame work, the suspended floor will be sound insulated and the external walls will have R2.5 batt insulation. Due to the lack of thermal mass to the upper floor, airflow becomes imperative, therefore consideration has been given to windows placement, size & function. The breezeways will help cool the thermal mass on the ground floor as well as flush the upper floor of the heat that will slowly accumulate throughout the day in the heat of summer.
Glazing is minimal to the eastern and western elevations and we have nominated Low-E glass here for protection whilst single, clear glass has been nominated for the northern aspect of the living to maximise the solar ingress in winter. The living area northern glazing will be protected internally by ceiling to floor drapes located behind a ceiling mounted pelmet. A salvaged timber pergola will have a deciduous vine growing over it protecting the northern glass externally in summer.
The door between the entry and the living area in this home will have a significant bearing on the passive solar performance in that it isolates the stairwell from the living areas. Keeping the door closed in winter will prevent heat disappearing up the stair well. Keeping the door open in summer will help flush the heat up and out the windows on the upper floor.
In terms of the bigger picture – the community – this home will help reduce the heat island effect through the use of a steel roof instead of tiles. The roof cover will cool down as soon as the sun sets- not add heat load to the roof volume nor the atmosphere like a tiled roof will. Just like a clay pot keeps baking its content after it has been taken out of the oven a tiled roof will keep radiate heat hours after the sun has set! We have nominated an R4.0 ceiling insulation in the roof and Anticon to under the roof cover for extra protection.
Water usage: There will be a rainwater tank feeding the laundry and WC’s. A grey water system will feed the garden throughout the year via a subsurface drip irrigation system. Water will be collected from the laundry, shower and vanity. A Caroma WC with integrated hand basin has been nominated for the Powder.
Energy Efficiency: Our client will add a photo voltaic system on the roof which will be accompanied by a storage battery in the future. Room has been added in the Laundry for a wall mounted battery. For water heating we have decided on a heat pump due to the limited roof space.
In terms of landscaping our clients have minimised paving by using a ground cover dispersed throughout the carport and driveway- this not only softens the landscape but will also soak up storm water and minimise run-off to soak wells. Furthermore the ground cover will greatly help with keeping the homes walls and windows cooler. To protect the eastern and western walls we are proposing foliage- mature evergreens to keep the morning and afternoon sun off the walls.
Some additional information – the home has been designed with recessed door sills as well as wider doors and passageways for accessibility. Consideration has also been given to minimise volatile organic compound (VOC) off-gassing by using low/no VOC paints and furnishings, to create a healthy living environment. The garden will be designed as mentioned earlier to help protect the home against the harsh summer sun but also to provide our client with edibles such as vegetables and fruit. There will also be a chook pen and a composting station.
Our client came to us with a strong sense and good knowledge about sustainable living, having actively studied this subject for some time. The home was never meant to be an architectural statement but a comfortable home and together we think we have come up with a modest home that will serve her well. The process so far has been most enjoyable and due to our client’s knowledge and decisiveness we believe we are ready to start on site in the first quarter of the New Year.