25 Lanark Street
East Brunswick
Victoria 3057
tel: 03 9386 3700

Renovation to 1930’s duplex in Surrey Hills, Melbourne.

In this extensive renovation, the clients, a young couple required a solar efficient 2 bedroom home with large living areas, 2 separate studies and 2 bathrooms. Their brief was to incorporate the latest technology in solar efficient design, water collection, greywater system, PV grid interactive power system, low toxicity finishes and use of forest friendly timber products.

The site is a long block 48metres by 10metres wide, running east/ west. There were limitations to north access due to the duplex nature of the existing building and the neighbours’ party walls and future extension.

Solution
The existing home was a maze of small pokey rooms. The rear of the building was removed and the front living room converted to a master bedroom with ensuite attached. Only 2 rooms remained intact by the completion of the project. The owners were keen to maintain the streetscape and the connection to the neighbouring duplex, which was achieved and can be seen in photographs. The design incorporates the use of courtyards on the north face to maximize solar gain with extensive double glazed roof glazing over the dining/ living area. The extension was built with a suspended concrete slab for thermal mass and the party wall is built from AAC blockwork. The living room has a basement below to accommodate battery room, storage, dog shower and cellar. Maximum cross flow ventilation was achieved with carefully positioned windows and a window positioned above the stairs to create a thermal chimney/ venturi effect. The open plan nature of the kitchen, dining and living spaces opening onto an external north facing deck and internal courtyard are very conducive to a relaxed lifestyle. The north facing deck is protected by a shade sail in summer, which is removed in winter to allow maximum solar penetration into the building. The pitch of the north facing roof had to accommodate solar panels and a solar hot water service.

Planning Controls
Fortunately the site was not subject to Planning restrictions due to the size of the block and there were no planning overlays at the time.Cladding: The external walls are a combination of rendered fibre cement sheet and AAC blockwork. Both products were chosen for their low embodied energy and in the case of the AAC blockwork its inherent insulation properties and its fire rating for a boundary wall. The unique nature of AAC also contributes to some thermal mass.

Recycled materials
Wherever possible existing timber frame was reused, flooring salvaged and reused, the gas heating system was serviced and retained. Bricks were salvaged from the garage that was demolished, cleaned and reused in the basement walls and base brickwork. All internal flooring to second story and overlay flooring to first floor and external decking are from recycled timbers. Internal timber posts were from recycled ash. Smorgons ARC steel was used for slab reinforcement which is 100% recycled and the concrete was GB Slag Blend used for its recycled content. Recycling bins were built into the back of the pantry unit with sliding doors to enable
easy removal of recycling. The kitchen also has a Kitchen King recycling system for compost and general garbage.

Thermal Mass & Insulation
The new rear first story is constructed with a suspended concrete slab with existing brick walls at front retained. The AAC walls in the dining area also provide thermal mass.Wool/ polyester batts were installed in the walls and ceiling: R1.5 to walls and R3.0 to ceiling Astrofoil was used as roof blanket due to its excellent reflective properties, increasing the R rating by up to R2.0 50mm thick RMAX L grade (R1.0) min slab insulation was used to the underside of the entire suspended slab.

Glazing
All windows and glazed doors were double glazed. Roof glazing was argon filled with a Low E coating on the inside face with a 12mm spacer bar to increase its R value and to minimize losses. There are no west facing windows to the new extension.

Shading
The Roof Glazing is shaded by Auto spring loaded rollers and the north facing courtyard and deck are shaded by sail shades made from acrylic canvas. As the roof glazing can lead to serious overheating in summer, we experimented with a unique method of using a version of Astrofoil on the outside. This should reduce heat gain by up to 95% in summer. The PV panels on the roof will provide significant heat reductions too.

Ventilation
Maximum usage of cross flow ventilation has been provided in window placement and by the majority of windows utilising casement mechanisms which increase the size of the openable Space and a window above the stair well creates a thermal chimney effect.

Appliances and Services
The home is heated with a Brivas gas central heating system. No supplementary cooling is required for summer. The study has been provided with ceiling fans for airless days. The owners have selected a gas cooker, a Vestfrost 6 Star refrigerator which uses just1080watt-hours per day at 32degrees ambient temperature, 1/3 of the average use of a refrigerator which normally contributes to 25% of a houses energy consumption, a Miele G851 water efficient 4.5 Star dishwasher connected to the hot water tap and a Miele Novotronic W963 4 Star Galaxy award winning washing machine. No electric clothes dryer has been installed. A drying rack has been provided for passive drying of clothes internally.

Rainwater Harvesting
Two 4,500 litre water tanks, housed under the deck have been installed to supply showers, vanity basins, toilets, washing machine and laundry taps and hot water service. Town water is used for drinking in the kitchen only. There is a switch over from town supply to rainwater supply should the need be required by the appropriate check valves. Tanks are fed from all
roofs and augmented from town supply. A third tank of 13,500 litres has been installed in the garden at rear to handle the overflow. The pump is a Davey pump XP900H powered by the PV panels.

Greywater Collection
Grey water has been collected from all showers, basins, bath and washing machine. This supply will service toilet cisterns and garden taps as shown. Capacity of tank: 2,000 litres septic polyethylene with a Davey XP350 powered by the P.V’s.

Water Heating
Edwards LX 305 solar hot water unit was installed with 3 panels boosted by Bosch Instantaneous 18EHighflow gas unit. The electric element has been removed from the solar hot water service to reduce greenhouse gas emissions. It has been connected in series so as to only boost water temperature when it is actually required.

Timber Usage
All cabinet timber veneers were made from New Age Veneers, produced in Europe from refigured plantation poplar.All flooring is recycled ash or jarrah supplied from Shiver Me Timbers. External decking is recycled jarrah. External stairs are constructed from treated plantation pine. All framing is plantation pine. Internal stairs are constructed from recycled jarrah.Cedar windows and doors are sourced from Canada. A viable alternative to cedar for window joinery is not commercially available as yet. Whilst this cedar comes from old growth source, the plantations have a reasonable managed harvest program in place. Aluminium windows have very high embodied energy and PVC is a major health concern as dioxin is produced during its manufacture and it not recyclable.

Low Toxicity Finishes
The flooring was sealed with Feat Watson Floor Seal which is Tung Oil based. It has very low levels of di-isocyanate compared with 2 pack polyurethane finishes. The internal walls and ceilings were painted with Berger BreatheEasy paints and Murobonds Pentimento Limewash was used on feature walls. Due to the tight nature of a well designed and built passive solar design it is important to have as little indoor toxicity as possible.

Lighting
Surface mounted and pendant lights were selected exclusively to eliminate holes in the insulation necessitated by low voltage transformers. 98% of lights have compact fluorescent or circular fluorescent globes.

Landscaping
The clients are establishing an inner city permaculture based garden at the rear of the property and the internal courtyard utilizes low water usage planting and porous surfaces. The grey water system will be the sole source of water for the garden.

Photo Voltaic System
OPERATION OF SOLAR GRID BATTERY INTERACTIVE SINEWAVE INVERTER (20 only 75watt BP modules and 3kVA PSA inverter)Non essential loads (ie loads without battery backup) are wired as grid interactive.Essential loads are grouped in the switchboard and are wired to the inverter such that in the event of a main grid failure the inverter will drive these loads from batteries.
Typical essential loads would include, but not be limited to the following:
1/ Lights
2/ Water pumps
3/ Gas hot water electronics
4/ Alarm and intercom systems
5/ General Purpose Power outlets supplying computers.

NORMAL OPERATION with mains supply available. Night time with no solar power. All loads are running from the main grid supply. The inverter is in an idle state synchronised to the grid with a battery charger maintaining the batteries in a charged state for essential
systems.Day time with solar power.The solar power generated will raise the battery voltage above that set by the inverter battery
charger. The energy thus created is converted to 240 VAC and fed into the switchboard. If it is not used within the house it is fed back into the grid. A solar regulator is required for the sole purpose of protecting the batteries from overcharge in the event of the grid failing.

Main Grid Failure: The inverter must disconnect itself within 2 seconds from the grid. Essential loads then run off the battery supply.