Energy &
Sustainability
The cheapest energy is the energy you never need. Passive design strategies — pursued before any technology decision — are the foundation of a building that performs well and costs less to run. NCC 2022 has raised the bar; here is how to meet it and go further.
Passive design works with climate rather than against it. These strategies should be embedded in the brief and resolved in Stage 1 — before layout, before fenestration, before materials. They cannot be retrofitted cheaply.
In the southern hemisphere, the primary living spaces should face north. North-facing rooms receive winter sun when the sun is low in the sky, and are easily shaded from summer sun when it is high. East faces receive morning sun (manageable). West faces receive afternoon sun in summer (problematic — hard to shade, high heat load). South faces receive no direct sun in winter.
Site constraints often prevent ideal orientation — an east-west street, heritage setback requirements, or a retained tree. Good design finds ways to capture solar access despite these constraints. Early site analysis is critical.
North-facing glazing can be shaded simply and effectively with a fixed horizontal eave or pergola. The geometry is straightforward: summer sun angle is high (block it), winter sun angle is low (let it in). Eave depth is calculated from the window head height and the critical sun angles for your latitude.
East and west glazing cannot be shaded with horizontal elements — the sun is too low. Vertical fins, deep reveals, or external screens are required. Reducing east and west glazing is often the more effective strategy.
External shading is always more effective than internal blinds. Once solar radiation penetrates glazing it becomes heat. External shading prevents that radiation entering the building envelope.
Cross ventilation — air moving through the building from inlet to outlet — allows the building to be cooled without mechanical assistance during mild weather. It requires openings on opposite sides of the building aligned with prevailing winds.
Layout decisions made in Stage 1 determine whether cross ventilation is possible. An open plan facilitates air flow; a series of closed rooms does not. Ceiling height, operable high-level windows, and stair voids can all contribute to stack effect ventilation where cross ventilation is not possible.
Thermal mass — concrete slabs, masonry walls, rammed earth — absorbs heat during the day and releases it at night. It moderates temperature swings, making buildings more comfortable in climates with large diurnal temperature variation (hot days, cool nights).
Thermal mass only works if it is exposed to the interior and insulated from the exterior. A concrete slab covered in carpet and insulated with rugs provides no thermal mass benefit. Polished concrete or tiles on a slab, with insulation in the sub-floor or on the external face of slab edge beams, is the correct approach.
In climates that are hot and humid with little diurnal variation (northern Queensland), thermal mass is less beneficial — the building never cools enough at night to discharge stored heat.
Insulation reduces heat transfer through the building envelope. The most important locations are the ceiling (heat rises — ceiling insulation is highest impact), external walls, and under suspended floors. Slab edge insulation is frequently omitted and frequently responsible for thermal bridging.
NCC 2022 specifies minimum R-values for each building element by climate zone. These are minimums — going beyond them typically provides better energy performance than the NatHERS model predicts because it reduces moisture-related issues and infiltration.
Insulation continuity — no gaps, no compressions, no thermal bridges through structure — matters as much as the R-value specified. A well-specified insulation system poorly installed performs like a lower-rated system.
Glazing is the weakest element in any building envelope. The two key performance metrics are U-value (heat transfer — lower is better) and SHGC (solar heat gain coefficient — how much solar radiation passes through). The right SHGC depends on orientation and climate: high SHGC on north faces captures winter sun; low SHGC on east and west faces reduces unwanted solar gain.
Double glazing is now the minimum for most climate zones under NCC 2022. Triple glazing is increasingly cost-effective where heating loads are significant. Low-e coatings on the inner surface of the outer pane improve U-value without significantly affecting visible light transmission.
Frame performance matters too. Aluminium frames conduct heat readily. Thermally broken aluminium frames or timber frames significantly reduce heat transfer at the frame.
All-electric buildings — no gas — are now standard practice for new construction. Gas reticulation infrastructure costs are rarely justified, and the operating cost of gas appliances is rising relative to electricity as the grid decarbonises.
performance
from the start.
Energy performance is a design decision, not a compliance exercise. We integrate passive design and active systems thinking from Stage 1 so your building performs — not just passes.