Perth builds in one of the more forgiving climates in Australia: long dry summers, short mild winters, high sun all year and a dependable afternoon sea breeze near the coast. It is also easy to build a house here that runs the air conditioner from November to March. The difference is almost never the appliances — it is orientation, shading and the building fabric, all settled before anything is drawn.
This page explains what energy-efficient home design actually involves in Perth, and how to tell whether the architect you are speaking with genuinely designs for performance.
Efficiency is decided early, not specified later
By the time drawings reach the approval stage, most of the performance of the house is already locked in. Orientation, window placement and how much glass faces east and west are design decisions. Insulation and glazing specifications are shopping decisions that follow.
That is why we treat the first fortnight as the important one. Site, orientation and the broad shape of the plan get tested while they are still cheap to change. After that, the design is mostly documenting what has been decided.
What we look at, in order
Orientation and room placement. Living areas take the northern arc where the block allows; bedrooms, bathrooms and utility spaces absorb the harsher east and west sun. On a narrow infill lot the ideal orientation is rarely available, so the design works with what the site gives you.
Shading, calculated rather than guessed. Eaves, deep reveals, screens, shutters, pergolas and deciduous planting are sized against the actual sun angles for your latitude, so summer sun is blocked and winter sun still lands inside. Fixed shading chosen by eye is one of the most common reasons a new Perth home underperforms its drawings.
Glazing that earns its place. Glass is where heat moves fastest in both directions. Size, position and glass specification are chosen together with shading — a large west-facing window is a very different proposition from a large north-facing one.
Thermal mass, used with care. Slab and masonry store heat and release it slowly. In Perth that helps when it is shaded correctly and paired with night ventilation, and works against you when it sits in unshaded summer sun.
Airflow and night purging. Cross ventilation, openable high-level windows and a plan that lets air travel through it rather than around it. On still nights, in smoke-prone periods and in the hills, ceiling fans and mechanical ventilation carry the load.
The fabric of the building. Insulation, draught sealing, wall and roof construction and window frames do the quiet work. They are the cheapest place to spend money early and the most expensive place to fix later.
Systems, sized last. Heating and cooling equipment is the last decision, and it is much smaller when the first six are right.
How to tell whether a practice really designs for performance
Four questions separate a practice that designs for energy performance from one that specifies it at the end:
- Will performance be modelled during design, not just documented at approval? Modelling early changes the design; modelling late only reports it.
- How would you handle a west-facing living area on my block? This is the hard problem on most Perth lots, and the answer tells you whether you are talking to someone who has solved it.
- Can I see completed projects, and what do you know about how they perform in summer? Real projects, ideally ones you can visit or clients you can speak to.
- Who details the airtightness and insulation junctions, and who checks them on site? Performance is lost at junctions and penetrations, not in the middle of a wall.
If the answers stay general, the design probably will too.
Perth metro and regional WA are not the same brief
Both are in the same climate zone, but the constraints differ. Metro projects deal with infill, narrow lots, subdivision patterns and established streetscapes. Regional projects add distance, trade availability, bushfire considerations, water and power limits and, in many towns, heritage context. The principles are the same; the weighting is not. We work in both and design for the conditions in front of us — the climate considerations for regional sites are set out in our guide to passive house and energy-efficient design in regional WA.
What it costs, honestly
A high-performance envelope costs more up front, and the extra spend is uneven — some measures pay for themselves, others are a comfort choice. The only figure worth trusting is one modelled for your site, your block and your household. Anyone quoting a percentage uplift before looking at your plan is guessing.
Frequently asked questions
Does an energy-efficient home need to be certified to perform well? No. Certification is a formal verification process, separate from whether the design performs. Many projects sensibly adopt the principles without the paperwork. If certification matters to you, confirm the current requirements with a certified designer before you commit, because they change.
Can an existing Perth home be improved? Often yes. Airtightness and draughts, glazing, shading and insulation are usually the first places to look. It is more piecemeal than a new build and works best with a staged plan.
Will energy measures slow down my planning approval? No. Thermal performance is assessed as part of the building approval process, and the planning side deals with setbacks, site cover, overshadowing and privacy. Both are documented in the same set of drawings and reports.
Is a bigger air conditioner a simpler answer? It is the most expensive one over the life of the house, and it does nothing for the rooms that are uncomfortable in the late afternoon.
Where we work
Office of Regional Architecture is an accredited architectural practice, and we model thermal performance during design using Hero, accredited NatHERS compliance software — run while orientation, glazing and shading can still be changed, rather than only at approval. We do not hold NatHERS assessor certification ourselves. Our head office is in Perth, and we design new homes, renovations and additions across the Perth metro area — including the hills and the coastal suburbs — while continuing to serve clients throughout regional Western Australia. Our work spans residential, community, commercial, heritage and landscape projects, and sustainability runs through all of it: lower carbon, lower resource use and better outcomes for the site.
If you are planning a new home or a significant renovation in Perth and want comfort that does not depend on running the air conditioner all summer, talk to us early. The most useful conversations happen before you buy the block or finalise the brief. For a broader look at how we approach comfort and sustainability in the city, see our guide to climate-responsive and sustainable home design in Perth.