From hovel to haven- retrofit case #2

burke st unit

This 1980ish 2 bedroom, brick veneer unit has undergone an energy makeover along the lines of a previous post on “energy freedom”. The previous tenant was spending $1300 a year on electricity and gas and it was terribly hot in summer and cold in winter.

Lights have been changed to LED except in the kitchen where there is a strip fluoro which has been retained, and some rooms that have compact fluoros.

A blower door test prior to any work showed a result of 18ACH50 (air changes per hour at 50 pascals) which is indicative that a lot of energy was being wasted through air leaks. To address this, fixed vents in the ceiling of the kitchen and laundry were removed and the holes repaired, caulking was done around the architraves and windows, draftstoppas were installed over the exhaust fans in the bathroom and kitchen, compression seals were fitted to the doors as well as bottom seals and the holes in the walls left over after the removal of gas heaters were filled with expanding foam. A repeat blower door test showed 9ACH50 – half what it was.

The unit is on a concrete slab so no floor insulation was possible. It is a brick veneer with one hardiplank wall in the garage- pictured above. Sprayfoam has been injected into the wall cavity through holes in the brickwork, or after removal of two boards in the garage.

sprayfoamsprayfoam brickwork

The holes are filled with mortar afterwards- seen in the middle of the picture above. The ceiling had existing fibreglass batts which are probably R2 but there were a few areas with no coverage at all. The gaps were filled then another layer of R3.5 earthwool roll was placed over the top, running perpendicular to the batts and covering the ceiling joists.

As mentioned before, an old gas wall furnace that was no longer in use was removed. It was just an eyesore as well as a source of air leaks. The newer gas heater was also removed, as were the gas hot water service that was aged and the gas cooktop and oven unit. With no gas appliances left, the meter was disconnected.

Efficient electric appliances have replaced all those gas ones- a Sanden heat pump HWS, new electric oven with induction cooktop and a the most efficient heat pump space heater/ cooler on the market- the Daikin US7.

The unit already had a solar PV system installed some years previously.

The windows are single glazed in cheap, non thermally broken, aluminium frames and are of the sliding type. In other words, they couldn’t be worse from an energy efficiency point of view. All but 3 windows have been improved with secondary glazing- acrylic sheet held in place with either magnetic strip for the smaller windows or with a timber bead for the larger ones. Three windows were left not done to allow easy cross ventilation. Bedroom and lounge windows had pelmets fitted, made with clear acrylic sheet, held in place with 2 bolts to the existing curtain railing.


The next tenant has moved in and should notice their energy bills are almost wiped out- but we’ll have to wait and see.

Below is a list of the costs involved:

Top up ceiling insulation (DIY labour) $1001

Sanden HWS (installed) $4162

Electrical work for new oven/ cooktop, HWS, wall insulation $1769

Weatherstripping materials (DIY labour) $161

Plumbing contractor (removing gas appliances, installing new toilet) $486

Secondary glazing (DIY labour) $1415

Daikin US7 (installed) $4150

Wall insulation $4631

LEDs and new fittings $187

Belling oven / cooktop $1800

Total cost $19,762

The benefits?

Saving on gas supply charges (annual) $291

Expected reduction in annual energy usage bills of $1000

Much greater comfort – priceless!

This Scorecard certificate shows the home now achieves a 10 star rating with a 6 star rating before the improvements were made. More info on the Scorecard tool is available Screen Shot 2018-01-28 at 2.42.41 PMhere. It reflects the expected costs in running a home after assessing the building shell and the fixed appliances used for heating, cooling and hot water. It does not consider the number or behaviour of occupants or other appliances.



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