Around a decade ago, New Zealand–based architect Rafe Maclean designed a house. “We thought it was going to be thermally quite good and efficient. Then it was built and the clients moved in, and they gave me some very direct feedback: It was such an energy-hungry house to keep warm,” recalls Rafe. “It hit a nerve, and it got me thinking, ‘How can I school myself here? I need to do better.’”

$33,230 Site Administration, Insurance, & Builders Margin	$146,767 Labor Costs	$11,076 Scaffolding
$6,923 Excavation	$17,307 Structural Steel	$49,845 Structural Insulated Panels
$26,307 Exterior Windows & Doors	$27,000 Roof & Wall Cladding	$21,461 Electrical
$4,846 Light Fittings	$22,153 Plumbing & Drainage	$6,231 Plumbing Fittings
$56,768 Interior Cabinetry	$4,154 Tile	$13,154 Mechanical Heat Recovery Ventilation System
$33,230 Access Steps & Entry Portal	$9,692 Painting
Grand Total: $490,144

Rafe started studying passive house principles, and he went on to become certified as a Passive House designer by the Passivhaus Institut in Darmstadt, Germany. Then in 2015, the architect designed the first certified Passive House on the South Island of New Zealand, called the George House.

Perhaps it should come as no surprise that three years later, Rafe built a certified Passive House for himself and his family in Dunedin, after realizing that their current rental was exacerbating the respiratory health of two family members.

A Passive House achieves a rigorous level of energy efficiency through five interrelated principles: continuous insulation without thermal bridging, an airtight building envelope, high-performance windows and doors, a ventilation system for heat or moisture recovery, and minimal need for space conditioning. The design process involves a lot of number crunching, which appealed to Rafe off the bat. “It was all mathematics and physics,” says Rafe. “And that hit a note with me.”

Rafe’s build started with a tight budget and a challenging lot. “It was pretty rough,” Rafe recalls. “It’s on a steep hill. It’s got a council wastewater drain going through it. Really bad soil. Existing trees. Access was impossible. And so, we got it for a very good price because no one else wanted it.” The site also limited the size of the new home, which tops out at 1,506 square feet for the family of four. Construction finished in 2018, and the budget totaled $708,000 NZD, or around $490,144 USD.

Construction necessitated removing only one tree on the site, and Rafe sited the home to take advantage of the rest. “We think of it as a tree house in the bush,” says Rafe. To that end, he made sure to preserve an existing native Kōwhai tree. “They’re quite precious; if you’ve got one growing, you can’t cut it down,” says the architect—and he framed a view of the tree with the living room window.

Kōwhai trees bloom with yellow flowers, and Rafe initially wanted the home’s exterior to echo this color. “But the feedback from the family was that, ‘We don't want to live in the yellow house,’” says Rafe with a laugh. The compromise was to wrap the exterior in corrugated steel (which is not only economical, but also shimmers depending on the light) and then accent the design with yellow trim inside and out.

The interior material palette is simple, with plywood walls and ceilings, white floors, and a kitchen backsplash and counters made from stainless steel. In addition to a combined living/dining/kitchen space, the compact plan includes three bedrooms, three bathrooms, and an office. The children’s rooms have mezzanine beds suspended above closets to save space, and a second-story common area functions as their own living room.

Rafe’s goal was to “prioritize usable space” and “cut out hallway space as much as possible,” he says. “So, if there was a corridor, what else could that be used for?”

These days, Rafe’s studio has five more passive houses in the works, as well as a passive apartment building. “I think it’s really important that we do the best buildings that we can, with the knowledge that we have, because these buildings get passed on to the next generation,” says Rafe. To not do so just kicks the problem down the road. “It’s a delayed investment,” says the architect.

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A Maui Couple Build an Off-Grid Tiny Home For $45K

Project Credits:

Architecture: Rafe Maclean Architects / @rafemacleanarchitects

Builder: Stevenson & Williams

Structural Engineer: eZed Ltd

Landscape, Lighting, and Interior Design: Rafe Maclean Architects

Cabinetry Design: Rafe Maclean Architects