Heating and cooling an older brick veneer home

Brick veneer means a timber-framed house with a single skin of brick outside, a cavity between the two and plasterboard inside. Through the post-war decades and the 1970s it became a standard way to build across Melbourne's west. The Hobsons Bay planning scheme notes that post-war industrial and residential growth transformed Altona and Laverton, and much of Hoppers Crossing dates from the 1970s and 1980s.

The brick looks solid but does little for comfort. Many homes of that era were built with little or no wall insulation, thin ceiling batts that have since settled or been disturbed, single-glazed timber or aluminium windows, and timber floors over a ventilated subfloor. Altona's special character areas exist to protect intact post-war brick and weatherboard homes from exactly that period.

Before choosing a system, look at what's letting heat in and out. A ceiling bare in patches, a gap under every door and floorboards breathing cold subfloor air can make a well-sized unit seem too small. Fixing them often lets a smaller system do the job, and every system works better in a tighter house.

Work in the ceiling needs care around old wiring and downlights, and insulation shouldn't be packed over downlights or their transformers. Energy Safe Victoria advises owners of houses over 30 years old to have their wiring checked by a licensed electrician, and that's worth doing before anyone starts crawling through the roof.

Many of these homes still have a gas wall heater in the lounge or a ducted gas heater under the floor, and many have permanent wall vents. Some of those vents are there to give gas appliances the air they need.

Energy Safe Victoria warns that renovating or weather-sealing a home that still has an open-flued gas heater may change the ventilation needed to clear carbon monoxide, which could trap dangerous CO inside, and it says open-flued heaters spill CO more easily than other types. Before blocking vents, replacing windows or draught-proofing, have a licensed gasfitter check the heater and its ventilation.

If you're retiring the gas heater, a licensed gasfitter should disconnect and cap it. The vents it relied on can then be reviewed.

Wall-hung split systems suit most older brick veneers. They need no roof space, each room is controlled on its own, and a split in the living area plus one or two in bedrooms covers what most households use. Victorians typically use more energy for heating than cooling, and Laverton's July mean minimum is 5.2 °C, so choose units on their Cold zone heating performance, not just the cooling figure.

Ducted reverse-cycle can work, but these homes often have low-pitched tiled roofs with tight access, which makes placing an indoor unit and running ducts well harder. Have the roof space looked at before you settle on the idea. A multi-head split, with one outdoor unit feeding several rooms, is a middle path where there's only one good spot outside.

Wide side setbacks, common on post-war blocks in Altona, usually leave room for outdoor units along the side of the house, out of sight of the street. In a special character area, ask your council whether anything visible from the street needs a permit.

A 1970s or 1980s gas ducted heater often sits under the house, with floor outlets in each room and ducts through the subfloor. After decades down there, those ducts may be uninsulated, crushed, disconnected or chewed.

Floor outlets are good for heating, but cold air pools on the floor and doesn't spread, so under-floor ducts rarely suit reverse-cycle cooling. YourHome says ducts should be insulated to at least R1.5 with sealed joints. A move from gas ducted to reverse-cycle usually means new ceiling ducts or wall units, with the old floor outlets sealed.

Owner-occupiers aren't required to switch gas space heating to electric. If you're keeping the gas heater for now, a duct check is still worthwhile, because a leaking subfloor duct heats the ground under the house instead of the bedrooms.

Older homes often still have the original switchboard, sometimes with ceramic fuses and no safety switches, or a board added to over the years with no spare space. A new reverse-cycle system needs its own circuit and a lockable isolating switch next to the outdoor unit, so the board needs room for it.

Energy Safe Victoria notes that the Wiring Rules require additional safety switch protection when an existing installation is altered, and a replacement switchboard needs safety switches on every final sub-circuit. If the board is an old fuse board, upgrading it is often the cleanest path. That's prescribed work, and the power can't go back on to the new board until a licensed electrical inspector has inspected it.

Old switchboards can also contain asbestos. WorkSafe Victoria lists switchboards and their backing boards as a typical location for asbestos in buildings built or renovated before the late 1980s, so leave the board alone and let the electrician assess it.

For most older brick veneers, a sensible order is to have the switchboard and wiring checked, get any gas heater assessed, fix the worst insulation gaps and draughts, then size the heating and cooling for the house as it will be. Doing it the other way round tends to buy more system than the house needs.

Look at existing units at the same time. The Victorian Government says a reverse-cycle system more than 15 years old will typically use more than three times the energy of a modern one, so an early split in the lounge is worth reassessing while the rest of the plan comes together.