Michael and Kathryn Brenssell own Vistalite Otago – E13 Performance Windows, a Dunedin-based business that’s carved a niche for providing homeowners around the country with thermally efficient triple-glazed window solutions.

So when it came to building their dream holiday home in Wanaka, it came as no surprise that the Brenssells were keen to incorporate as much of that thermally effective joinery as possible.

“The home doubles as a holiday retreat and a showhome,” says Michael Brensell.

“It allows us to test products such as thermally broken sliding doors in-situ and showcase them to potential clients.”

There’s certainly ample scope for that here.

The west-facing living spaces have a 90% glass area to make the most of the magnificent views on offer.

Jamie Waller is manager of E13 Performance Windows.

“All those larger-than-life windows and doors means special attention must be given to thermal efficiency.”
Particularly in a region where temperatures fluctuate from a chilly minus ten to a balmy 35.

Sustainability and thermal efficiency were key factors behind the home’s design (along with the views, of course).

Matt Jeffery, from Johnston Architects, picks up the story.

“The house is specifically tailored to passively provide warmth in winter and stay cool in summer – we oriented the building to minimise the amount of energy needed to heat and cool spaces.”

Windows to the north, south and east were reduced or largely eliminated in favour of solid walls.

The west is where the views are, and it’s here that the triple glazing comes into its own.

The Pacific Thermal system from Altus was used throughout the home.

Floor to ceiling triple glazing in the living spaces has the double benefit of capturing all that stunning scenery, while allowing natural sunlight to penetrate deep into the home during those cold winter months.

“We used broad eaves to block high sun angles and provide much needed shade during summer,” Matt Jeffrey says.

“At the same time, these eaves still allow lower sun angles in winter to warm up the home.”

Eurostacker doors measuring an impressive 2400mm high by 7200mm wide provide a seamless flow from the living spaces to the exterior of the house.

“The joinery behaves less like a door and more like a moveable wall,” Jamie Waller says.

Euroslider doors achieve that same easy indoor/outdoor flow from the bedrooms.

The Eurostackers and Eurosliders are complemented by a custom, hot rolled, thermally broken main entry door and thermally broken sash windows and hinged doors, which are also used within the house to extend sightlines down the main circulation axis between the living and bedroom spaces.

Overall thermal efficiency is given a boost by the home’s Structurally Insulated Panel System (SIPS) and the decision to go with glulam timber portal frames (as opposed to steel) to reduce thermal bridging.

The exterior timber framed walls are thicker than usual too; at 140mm there’s more room for insulation.

Floors also play their part in creating a comfortable year-round environment. The concrete floor slabs sit on high performance XPS insulation and incorporate thermal breaks to the perimeter walls to reduce heat loss.

When it came to achieving the almost completely glazed western façade, Matt Jeffrey points out that collaboration between Johnston Architects and the team at E13 was key.

“Although we were responsible for the design, we relied heavily on E13’s wealth of product knowledge and experience.”

Jamie Waller says that with the right design and the right products, homeowners really can have the best of both worlds.

“Projects wanting the best views can often end up having their thermal performance compromised,” he says.

“But with the right design and joinery, you can achieve both.”

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