In the era of skyrocketing energy bills and concerns around climate change, there is a soaring demand for residential renovations that improve building performance.
Here’s what you need to know.
Context is Key
According to researchers, Australia has some of the world’s most inefficient homes. Some have even described many older homes as little more than “glorified tents”. As more groups like ASBEC and the Energy Efficiency Council draw attention to this problem, the market is growing for renovations to improve existing homes.
Factors influencing the demand for improvements include the gradual emergence of home energy rating schemes for existing dwellings, such as the Residential Efficiency Scorecard. Another push-factor is that buyers are increasingly willing to pay more for a property promising good thermal comfort and low operational energy bills.
Director of Ovens and King Builders, Lachlan Gales, says the federal government’s COVID-19 stimulus program, HomeBuilder, has led to increased demand for major renovations. Most people who reach out to him to renovate their homes understand the importance of thermal comfort and low energy bills, and they wish to achieve it.
“People tend to make renovation decisions about what is most important to them. Thermal comfort is a priority for many. Some want to lower running costs through energy efficiency, while others are particularly aware of climate change and want to make a small contribution to lowering carbon emissions [from energy use].”
Another demand factor is the number of people moving out of the major capital cities and into regional areas. Gales explains this affects property prices in regional towns and cities, so people who own homes can undertake substantial renovations without over-capitalising on the home’s value.
Subsidies and Other Support
A number of programs are also driving demand, including the Victorian Energy Saver Upgrades program, the ACT’s Energy Efficiency Improvement Scheme, South Australia’s Residential Energy Efficiency Scheme (REES), the NSW Government’s Energy Saver Certificate (ESC) Scheme. Some local councils are also offering schemes in many states.
ESCs, REES and the Victorian program make discounted products available. Each project that improves energy efficiency generates energy savings certificates that the project delivery partner then sells. The financial return on the certificates is written off against the project cost as a discount for the client.
How it is Done in Multi-Res
Founder and Senior Sustainability Consultant at Green Moves Danielle King is an accredited energy auditor and assessor working across both residential and commercial projects.
King says that there are several types of projects that can generate significant savings for multi-residential buildings. They include LED lighting retrofits, solar PV installation, and more efficient pool pumps. Many buildings could also swap out centralised conventional gas-fired or electric-coil hot water systems for individual heat pump units. This can pay off in energy savings, as individual units mean individual bills, rather than the common practice of splitting the total bill for a central system between lot owners.
Addressing the thermal comfort aspect for apartments might mean the strata body deciding on upgrading glazing from single-glazing to double-glazing, adding shading to the exterior on summer sun-exposed elevations, or improving the building façade and insulation.
“There are products available that allow you to build another skin around the building,” King explains. However, one must keep in mind these projects are more technically challenging, King says. In general, they would require a crane and careful staging to minimise disruption for occupants, King adds.
If upgrading windows by replacement to glazing with a high WERS rating is not a suitable option, King points to secondary glazing products and window films that are available. Their installation does not require working at heights.
HVAC is another potential upgrade. This could mean installing reverse cycle air conditioning units with a high Energy Star rating in combination with ceiling fans in bedrooms and living areas.
King also says that builders should consider the specific climate zone conditions from the outset and select products accordingly.
The payoff for owners of upgrades includes adding capital value to the properties, running cost savings, improved energy and thermal performance, and increased resilience in extremely hot or cold weather.
What Benchmarking Tools Exist
The rating systems that can be used to benchmark dwelling performance in multi-residential are the NABERS rating system for common areas and either the NatHERS rating system or the Residential Efficiency Scorecard for individual apartments. While NatHERS rates the building shell (heating and cooling thermal efficiency), the RES also includes the efficiency of the fixed appliances (hot water, heating and cooling, lighting).
NatHERS and RES are also used for rating detached dwellings. NatHERS is generally used for new builds to verify the plans will meet the energy performance requirements of the National Construction Code. RES, on the other hand, is applicable to existing dwellings. King says an assessment can cost between $330 and $500, depending on the home’s size.
The rating process examines passive performance factors, including ceiling and wall insulation, glazing, lighting and whether the slab is insulated. Active systems, such as pools, spas and the hot water system, are also factored in.
The Scorecard report gives a rating out of 10 overall for performance and indicates the cost to run the house and the comfort levels in both hot and cold weather. It also sets out the main issues and potential solutions.
King recommends getting the assessment done during the planning stages of either a renovation or a new build. That is when a builder or homeowner has the lowest-cost opportunity to improve energy efficiency decisions.
She points out that during a renovation like an extension or re-cladding, a builder will usually need to install insulation and heating and cooling. So, going the additional step to identify any major issues and optimise the energy efficiency and thermal performance is logical. King has developed a range of information resources builders can access to guide project planning and delivery.
How to Improve Detached Dwellings
Gales says bringing more light into a home is often a priority. This might mean the client wants large windows. However, if these are on a sun-exposed elevation, they can create a comfort problem. The solution is to use double-glazing, triple-glazing, and look for thermally-broken aluminium framing, aluminium-timber composites, uPVC framing or similar.
“The best advantage for performance is to spend money on the windows—they are always the weakest link in the wall fabric,” Gales says.
He now specifies double-glazing as standard for all projects and is increasingly specifying triple-glazing manufactured to European Passiv Haus standards.
Focus on Detail Delivers Performance Gains
Ovens and King are accredited Passive House builders, and Gales says many of those techniques can be used in renovations. These include installing building membranes, slab insulation, and taping in projects, for instance, building extensions.
Taping joints and around window installations in any renovation is a win for comfort, as it reduces air leakage. Quality of workmanship also matters. Gales uses a thermal camera to check insulation installation, and if there are gaps, the subcontractor gets a call-back to fix them.
At the very start, builders should consider the fine-grain detail of the home’s climate zone, and this should inform plans. No-cost ways to achieve better performance can be incorporated into the design, such as orientation, shading, and width of eaves.
“Those are the first, bare-bones things to do,” Gales says. “Make good decisions from the outset.”
Solar PV is now expected on most homes, Gales says, which has led to a shift away from gas-fired hot water systems to electric. The conventional coil cylinder is now making way for the highly-efficient heat-pump hot water system, powered by rooftop solar.
For builders starting down the path, taking time to look into products and suppliers is key. Small details matter, for example, producing exhaust fans that have built-in draught stoppers. Gales also says to choose trades that are focused on quality craft.
“Energy efficiency is not necessarily more expensive [to achieve]. Where we struggle is when we ignore local conditions and don’t take advantage of them. For some people, it’s a change of mindset.”