Using permaculture ethics & design principles to transform an old energy guzzling bungalow into a showcase of sustainable design. It's about energy cycling, building community, self-reliance,creatively using & reusing materials... all without spending heaps of money.

Friday, February 27, 2009

Energy Rating

Principle 2: Catch and Store Energy

As part of the building permit application process I needed to get an Energy Assessment of the house design. The architectual drawings were submitted to an Accredited Rater who uses House Energy Rating tools like FirstRate to give an energy rating to a house. In Victoria any new house or renovation needs to receive a rating of 5 stars or better in order to be appoved by council.

The house design received an Energy Rating of 6 stars, the maximum rating available with software used.

FirstRate report summary

With the plans a list of design details was also supplied which help to elaborate on the drawings which is listed below.

Design Details for Energy Assessment

The development includes the relocation and rebuild of an existing 3 room timber structure (to become 3 bedrooms) with a new construction of Living/Dining/Kitchen plus Bathroom. The Living/Dining/Kitchen is an open plan design with thermal mass from the insulated concrete slab. This area has seals to external doors, and an airlock through the main internal traffic area. Bedroom 3 has a door seal.

The information below refers to this plan

Roof Construction R 6.5 summer, R 5.1 winter (using AirCell info)
Generally- a plywood box beam structure with “sprung” corrugated iron roofing. The roof space is 450mm deep, and has 2 roof ventilators. The RFL (reflective foil laminate) is AirCell Glareshield fitted under the timber battens to ensure effective reflective capacity (min. air space 45mm). There is no thermal bridging between roof iron and RFL. Ceiling insulation is R4.0 polybatts, fitted in 2 layers to ensure no edge gaps in laying.

Walls R 4.5 (assuming AirCell info is correct)
External walls are all timber framed 100mm nominal. All wall cladding is corrugated iron fixed to timber battens fixed over AirCell RFL onto studs. Again, a guaranteed minimum air space of 45mm is established (allows summer heat to discharge vertically). Wall batts R2.5 Polybatts fitted between studs. Internal lining is 9mm plywood (perhaps another R0.5?). Doors and windows to the Living area have draft seals. Bedroom windows do not.

Windows to the Living/Dining/Kitchen open area are all double glazed (12mm airspace, argon gassed, Low-E external glass). These windows are fitted with pelmets. All other windows are single glazing only (some laminated, e.g. greenhouse). All windows are planned to be fitted with curtains. Window frames to be made from timber.

Concrete slab-on-ground to Living/Dining area has an area of 30m2. This is a raised slab (Urban Flood Zone overlay) with 15mm styrene board edge insulation from the base of the strip footing (500 below GL) to within 75mm of the Floor Level (75mm termite inspection area). The styrene board is externally protected by a layer of cement sheet, to avoid physical damage. Timber floors are enclosed to restrict (but not eliminate) sub-floor air flow, and are all fitted with a RFL of AirCell Permifloor 500. The product information suggests an enclosed timber floor can exepect a R 1.6 for heat flow in, R 3.0 for heat flow out (winter).

Hot Water Service
An Edwards 300litre gas boosted solar hot water service is proposed. This is located on the north facing 30o elevation roof of the Bathroom/Greenhouse. This is close to hot water demand areas.

Roof Drainage
All rainwater is collected on site. Tanks T1 (7,000litres) and T2 (22,500litres) are shown on the Floor Plan. A further tank of 22,500litres is a possibility after reviewing rainwater collection patterns over the coming 5 years. Tank T1 is proposed on a brick tank stand with a cellar underneath.

Cellar and Cool Cupboard
This cellar will have a floor 1.5m below Ground level. The above ground walls portion will have ventilation louvers, and these covered in vines within the first year (evergreen). The vines will filter the air flowing through. A 400mm air duct will connect the base of the cellar with a Food Cupboard in the Kitchen. This will allow cool air to feed the cupboard, and then to a roof ventilator. This will allow cool storage for fruit and vegetables (reduction of Frige load). The refrigerator is located in a recess with a bulkhead, vented to the roof space for heat discharge in summer. A manual vent control (flap with cord) is in the kitchen.

All stormwater is retained on site and discharged into swales to allow local wet spots of different food production.

Grey water
A worm farm attached to a reed bed will treat all grey water on site. The discharged liquid will feed the existing (and proposed) fruit trees.

Existing deciduous trees on the north provide winter solar access and summer shade. Additional deciduous fruit trees are planned to the west. Deciduous vines are also planned for summer living area shading (north pergola to deck).

The immediate power supply will be the existing mains connection. An option of grid-connected PV power is a serious future consideration (so not in this assessment).

Heating (winter)
A small gas space heater (wall vented) will complement the passive solar heating.

The dwelling will not need any air conditioning. Pedestal fans will assist air movement in very hot weather. Good cross ventilation will allow doors to be lefy open for cooling assistance. Fly screens to doors.

Sunday, February 22, 2009


Principle 3: Obtain a yield

About a day and a half work was involved in milling up the Red Gum and Lightwood on site. I employed the services of a mobile miller by the name of Mal who used a portable sawmill to cut the timber into planks and slabs.

The slabs were quite an effort to move. It took 4 blokes just to lift one end of a Red Gum slab to get it onto a trailer for drying off site. Metal pipe was used to help roll it into place.

Because we are in mid-summer here in Australia, it was suggested by Mal that the timber be stacked on flat ground with no air gaps and be covered. This helps to reduce the speed at which the timber dries. When timber dries too quickly it twists / bends / warps / cracks and becomes very difficult to use for building. When the weather cools down and the rains start, Mal suggested that the timber is re-stacked with wooden spacers (about 10mm high and 300mm apart) to allow it to air dry. As a general rule of thumb it timber takes about a year per inch (25mm) to air dry. So it will be quite a while before the timber is ready to use.

The reward for our efforts was about 40 x 3m planks (40mm x 200mm) and 20 x 1.5m planks (40mm x 200mm). We also got 10 slabs which are about 3.5m long (60mm x approx. 900mm wide). The milling cost was about AU$900.

The plan is to use the planks for decking in a year or so, and the offcuts for stairs and benches. A slab may be used for a kitchen bench down the track. That will help justify the cost of milling the timber, and I have a stack of slabs left over which may be sold or used to make furniture.

Peter manoeuvring a log onto blocks using a crowbar with the ute (pick-up) pulling the log using a chain

Mal cutting planks using the LewiSaw

LewiSaw in action cutting a 40mm x 200mm plank

Milling the top part of the log in preparation for slabbing

Mal works the LewiSaw with a slabbing attachment (a giant chainsaw)

Red Gum slabs fresh off the log

Mal mills up the Lightwood experiment while Peter watches

The milled Lightwood

Friday, February 13, 2009

Preparing to mill

Principle 9: Use small and slow solutions

Peter was pretty keen to take some of the Lightwood (Acacia Implexa), which is native to Tallarook ranges, to the Tarcombe Road house site. Peter has been interested in how the timber performs in extreme conditions and loves the finish of it. He believes that it would be good for joinery, as it tends not to bend or split. These logs are all dried and collected from the property where he lives.

Our mission here is to move some rather large logs from a very steep site, to the house site some 12km away, with some pretty basic equipment. Since the Red Gum is going to milled up on the house site it seemed like a good opportunity to experiment with some other timbers.

It took most of the day to move seven logs to the site. Let's hope that the timber comes up okay. If is doesn't then I guess we have wasted some time, but not much money, and will learn some lessons. If it does work out, then we have discovered a fanstastic renewable resource available locally, and have some nice joinery timber to work with on the house and other projects.

Rolling up a log onto the trailer using steel pipes tied together at the top

Pulling a large log up onto a trailer using a small hand winch and rollers

The hand winch in action

Pulling a log off the trailer using a chain fixed to a tree and driving the vehicle forward

Lightwood in forground and Red Gum logs in background in preparation for milling on site

You might notice the yellow tinge to the last photo. This is because of the nearby bushfires which have decimated the towns of Kinglake, Strathewen and Marysville in central Victoria. The project has been delayed because of the threat to towns nearby as the miller is in one of the CFA strike teams. Milling cannot be done on days of total fire ban, which there are many at this time of year.

Other logs from around the Red Gum were moved with friend Conrad (Student from the Central Victorian PDC) using branches as levers, and rolling them to more suitable positions nearby. The idea is that one the mill is set up, logs will roll into place, where they can be cut to size and stacked.

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