‘No Expense Spared’ On NZ’s First Passivhaus EnerPHit Rebuild, Now Selling – Stuff.co.nz

Certified Passive Houses have captured a lot of attention in recent years, being the “ultimate” in energy efficiency, but they are not limited to new builds.

Sang Architects has just completed New Zealand’s first Passivhaus EnerPHit rebuild, and the 344 square-metre Piha house has been listed for sale – there is an additional 123 square metres of decking, including a lanai.

But this was no ordinary renovation, says listing agent Corey Knapp of Premium Real Estate Group: “The house was gutted right back to the bare concrete shell – it’s a total rebuild to certified Passivhaus EnerPHit standard.”

The project, designed by architect Darryl Sang, son of the late architect Ron Sang, and built by certified Passive House builder Terry Bryers, is also significant for its “no expense spared” approach. A build cost of around $13,000 per square metre was mentioned.

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“The owners didn’t have a budget in mind,” says Knapp. “Everything is bespoke and hand-made.”

And it’s the combination of the fabulous view, Passivhaus benefits and beautiful interior that make the house stand out. The owners say the guiding principal behind the project was to build “the most healthy, comfortable and high-quality home possible”.

“The objectives were achieved with state-of-the-art computer modelling by Environmental Engineering and benchmarked to the most prestigious German ‘green building’ standards.

“Every material was meticulously considered with an emphasis on quality and longevity. Most of the money has been spent where you don’t see it, but where you will enjoy it with all of your other senses.”

In a nutshell, the building envelope, with its double-glazed German SmartWin joinery, is completely airtight, and there is a mechanical ventilation system that controls the air quality and climate for optimum comfort. Fresh air from the outside is delivered into each room of the house, and stale air is extracted from every room, with an emphasis on extraction from the bathrooms, kitchen and laundry.

“The entire volume of air in the house is replaced with fresh southern ocean air 7.5 times every day,” say the owners.

Being able to control the humidity means the normal Auckland humidity in summer (80 to 90 per cent) can be maintained at less than 60 per cent, which makes for a more comfortable living environment and helps prevent the growth of mould.

The house and roof are insulated on the outside, and the walls are solid concrete so sounds from the outside are minimised.

All the internal walls and floors separating bedrooms from living, bathroom and garage areas are solid concrete. And all penetrations have been soundproofed. Inter-tenancy sound standards were applied to key internal walls.

The thermal mass of the concrete also ensures the house acts as a giant radiator.

“When all the surfaces in a house are the same constant temperature, your body reads this as comfort,” the owners say. “Once the entire mass of concrete is at the desired set temperature it takes a lot of energy to move it from that value. What this means is that the house will feel instantly cool when stepping in on hot summer days and instantly warm on cold winter days without even adjusting the air temperature.”

The water heating is achieved with a combination of direct solar, heat pump and a backup gas califont. The solar and heatpump will cover the majority of use at minimal power consumption and the gas califont ensures unlimited hot water during high use times.

The property has an artestian bore providing fresh water, plus rainwater is harvested and stored for use in toilets, hoses and irrigation.

Aesthetics have not been compromised – the house features beautiful cedar sarking, and custom internal wall panelling designed by Herbst Architects.

The KXN steel kitchen by IMO has a solid stainless steel floating work bench and a solid oak island. The cabinetry is powdercoated with a custom matte black finish that’s resistant to finger marking.

Knapp says the house has already caught the attention of social media influencers, wanting to post on their pages.

But he won’t be drawn on a sale figure – the agency is inviting “expressions of interest”.