Why we design beyond the Building Code -
At Alter Architecture, we believe a house built to the minimum legal standard is just that — the minimum. It's the lowest bar a home is legally allowed to clear, and it isn't a guarantee of a warm, healthy, or efficient home.
Alter Architecture is built around a passion for performance: designing and detailing homes that work harder for the people living in them, long after the Code Compliance Certificate is issued.
We use performance standards such as Passive House and Homestar to guide us.
Passive House (Passivhaus)
Passive House is an international building performance standard, originating in Germany, focused on ultra-low energy use and consistent indoor comfort. Rather than prescribing particular materials or a look, it sets rigorous, measurable performance targets for heating and cooling demand, total energy use, and airtightness — and lets the designer choose how to get there.
A genuine Passive House can use up to 90% less energy for heating and cooling than a conventional home, while keeping the internal temperature stable and comfortable year-round, in winter and summer alike.
The five pillars of Passive House design:
Insulation
Continuous, high levels of insulation across the walls, roof and floor slab dramatically reduce the amount of heat that escapes in winter or enters in summer, cutting the energy needed for heating and cooling.
Airtight Construction
The building envelope is sealed to a very high standard, eliminating unplanned gaps and cracks that let warm air leak out and cold, moist air leak in. This isn't about living in a sealed box — it's about controlling where air enters and leaves the building, rather than leaving it to chance.
High-performance windows and doors
Double- or triple-glazed windows with insulated, well-sealed frames are one of the most important components in a Passive House. Correctly specified and positioned glazing also allows useful winter sun in while limiting unwanted summer heat gain.
Thermal-bridge-free detailing
Junctions, corners, and penetrations — anywhere materials meet or structure passes through the envelope — are carefully designed to avoid "thermal bridges," localised paths where heat escapes faster than through the surrounding wall or roof. Left unaddressed, these details can undermine an otherwise excellent insulation and airtightness strategy, and are also common locations for condensation and mould.
Heat recovery ventilation (HRV)
Because a Passive House is built airtight, fresh air is supplied mechanically rather than through gaps and draughts. A heat recovery ventilation system continuously exchanges stale indoor air for fresh outdoor air, recovering most of the heat from the outgoing air in the process. The result is a constant supply of fresh, filtered air without the energy cost — or the mould and condensation risk — of a leaky building.
Homestar: New Zealand's own home rating tool
Homestar is a New Zealand-specific rating tool, that assesses the health, efficiency, warmth and sustainability of homes against criteria developed for our climate and construction methods.
Unlike Passive House, which is a single rigorous international performance standard, Homestar is a graded rating system. Homes are independently assessed and awarded a rating from 6 to 10 stars — the higher the number of stars, the better the home performs across categories including energy efficiency, warmth, water use, healthy materials, and reduced carbon footprint. Any home that achieves a Homestar rating is, by definition, performing above the current Building Code, because a 6-Homestar rating is set as a mandatory floor above Code minimums.
Homestar looks at a home holistically rather than focusing on a single metric. Energy modelling is used at the design stage to test and refine decisions around insulation levels, glazing specification, and ventilation, so that trade-offs are understood and optimised before construction begins — much like the Passive House design process, though assessed against a different set of criteria and are graded, rather than a pass/fail, outcome.
Passive House vs Homestar: which is right for your project?
These two standards aren't in competition —many of the underlying principles (insulation, airtightness, ventilation, glazing performance) overlap. The right choice depends on your goals, site, and budget:
Homestar suits clients who want a warmer, healthier, more efficient home than the Building Code requires, verified against a New Zealand-specific graded standard, with a flexible range of achievable levels (6 through 10 stars).
Passive House suits clients who want the most rigorous, internationally recognised performance outcome available — near-total control over indoor comfort and very low energy bills — verified through detailed energy modelling and third-party certification.
Both approaches move a home well beyond what the Building Code requires, and both are grounded in the same building science: insulate well, seal the envelope, get the glazing right, eliminate thermal bridges, and ventilate properly.
How Alter Architecture can help
With a genuine passion for performance-driven design, we design every project — whatever standard it's ultimately assessed against — with these building science fundamentals in mind. Whether you're chasing full Passive House certification, a specific Homestar rating, or simply want a home that performs meaningfully better than Code minimum without formal certification, we can guide you through what that means for your design, your site, and your budget.
Get in touch to talk about what building better could look like for your next project.