Energy makeover- retrofit case #2

sprayfoam

This 2 bedroom unit is undergoing 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. We’ll have to wait awhile before we get new figures to compare the before and after effect.

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 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.

sprayfoam 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 heat pump space heater/ cooler.

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. They are still in place and the plan for now is to install heavy curtains and pelmets.

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

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