Concrete plays large part in passive heating of Wanaka home  
A challenging wedge shaped section overlooking Lake Wanaka and bordered by two suburban streets was what Condon Scott Architects was presented with by their clients, along with instructions to design a family holiday home that would indulge in the extensive mountain and lake views. The home incorporates two very different pavilions, a connecting structure, a series of outdoor spaces to enjoy the view while being sheltered from the prevailing lake winds, and some impressive off the form concrete features using a rough sawn formwork  to cast insitu a specialised concrete mix from Firth. 

“To create a home that blends privacy with openness, we designed a structure incorporating two quite different pavilions connected by a linking gallery space,” explains Barry.  
From the street the southern facade is curved and striking with no windows or openings. This curves around allowing for a transition around the wedge-like shape of the site. Behind it a glazed gallery area leads to the contrasting northern pavilion with its eaves jutting towards the sky. Beneath the eaves there is a wall of glazing designed to take advantage of the spectacular lake and views across to the Buchanan Range.  This is in direct contrast to the southern facade that is closed, dark in tone and dominated by its vertical cedar cladding.  

“The client had seen another house by Condon Scott Architects and liked certain aspects of the design,” says Barry. “They gave us an outline of the design elements they liked and then left it in our hands to design a home that incorporated them. It was our design intention to connect with the environs, yet create privacy, that led to this house of two halves.” 

The interior of the house includes the continuation of the use of exterior materials, including vertical cedar and board form concrete, to the inside. The living space is configured around a courtyard adjacent to the gallery area, with the body of the house providing both a windbreak and a visual barrier to the south and street front. From here the lake and peaks are visible through the house, allowing for a sheltered area still connected to, and defined by, the surroundings.  
The outdoor fire is also surrounded by board form concrete which easily becomes one with the inside by opening the corner aluminium sliders to merge indoors and out.

When it came to the materials they preferred for their new holiday home, the clients left Condon Scott to make the right choices. “The client wasn’t specific about which materials they wished to use in the house,  but they wanted an overall look that was clean and contemporary. We felt that the exposed board marked concrete has a strong materiality that would ground the house and give a sense of substance,” says Barry.     
When asked how much the use of concrete helped with the thermal mass,  insulation capacity and passive solar design of the house Barry says, “Often simple design considerations can have the most impact from a sustainability perspective. Wanaka has extreme seasons, cold in winter and very hot in summer with off-shore lake winds. We developed the house design in response to climatic conditions, e.g. orientating the house to the sun correctly, considering shading and with high levels of insulation. As part of this we also incorporated  heat  sinks for passive solar gain through the use of concrete. As an excellent thermal mass, concrete plays a large part in the passive heating aspect of our designs.” 

“Nigel Lock, the builder used on this home, liaised with Firth closely for direction on the required concrete strengths to meet the design specifics for the various areas of the house,” adds Barry. “This included the foundations, the concrete slab, the in-situ board form concrete and the Decorative Concrete driveway (standard exposed aggregate with a small amount of black oxide).”  

“It’s these types of design decisions that are relatively inexpensive to include at the design stage but are choices that make a significant impact on the long-term experience of the house, and a notable decrease in the need for mechanical heating,” says Barry.  

Customer: NLB Builders

Architect: Condon Scott Architects 

Location: Lake Wanaka 

Product: Decorative Concrete, Certified Concrete®, and in-situ board form concrete