Playtime front and centre

When it came to extending their house to fit their family, creating kid-friendly spaces with playful details was just as important to this Melbourne couple as achieving an energy efficient, light-filled home.

The motivation for Carol and Andrew’s renovation and second-storey extension to their 1920s Californian bungalow in the Melbourne suburb of Northcote is a common one – having moved in with one small baby, several years later they were a family of five and needed more space. However, the priorities and the rigorous commitment to energy efficiency and passive thermal performance they brought to the project set it apart from most.

“The brief focused on the house being a bit fun and quirky for the kids, as well as on sustainability and improving the existing envelope as much as possible,” explains their designer Penny Guild of Guild Architects. “Often, an upper level extension houses a parents’ retreat, but here it was all about a family home with three new bedrooms and an extra play area for the kids upstairs – with a walkway above the stair void and hidden hatches connecting the bedrooms via the roof space. It made it a fun project.”

Another important driver for the design was the need to admit more light into the existing living space, without making drastic changes to the structure. Penny removed the central study that is a common feature of bungalows of this era, and opened up the hallway into a double-height void; cleverly located windows, the open treads of the staircase and deliberate spaces between floor boards on the landing all help admit winter sun deep into the dark south side of the house. “We used heat shifters and ceiling fans to offset the heating stratification you can get with voids like this,” says Penny: the warm air is directed into the tiny laundry where clothes airers hang from the ceiling.

It was a challenge to design the upper level extension to minimise its bulk when viewed from the street while still maintaining the original home’s three-metre ceilings, and the concept went through several iterations. The original ridgeline was retained at the front of the house, behind which a small flat section of roof sets the main height of the second storey back a little further. “I tapered the new roof in a little at the sides to reduce bulk,” says Penny. “It made the internal spaces more fun for kids’ bedrooms too. You can create interesting spaces with angles.”

Another favourite feature of the house is the large integrated fish tank in the wall between the hallway and the dining room. “It started as a joke,” laughs Penny. “We were conscious of the fact that there was no thermal mass in the house, and it’s difficult and expensive to retrofit. As Andrew is a marine biology teacher and has always kept fish, I suggested we install an aquarium because water can be excellent thermal mass.” Although the aquarium is currently heated to house tropical fish and thus doesn’t function as thermal mass, it could be adapted to do so in the future – and in the meantime, it’s a striking design element and helps bring light into the dining area.

Upstairs, the problem of lack of thermal mass was addressed through the use of phase change material (PCM) in the ceilings to help moderate the internal temperature. “I’d been reading about it, and it seemed too good not to include, though it’s expensive,” says Carol. It was something of a leap of faith, as it’s a relatively new product for residential use and they were unable to experience it ‘in situ’. But Penny was supportive, explaining that “one of the good things about PCM is that unlike insulation, it doesn’t matter if there are gaps between the pieces of phase change blanket. The supplier calculates the optimal amount of material, and you just squeeze it in wherever it will fit above the ceiling and in the upper walls.” [See page 72 in Sanctuary 42 for a phase change material product review.]

Andrew and Carol’s quest for a “really energy efficient, passive thermal house” also involved careful attention to cross ventilation, shading and insulation. The existing house was retrofitted with underfloor and blow-in wall insulation. Upstairs, a variety of fixed and adjustable shading including fixed louvres, eaves, and roof windows with integrated honeycomb and blockout blinds ensures optimum summer shading and winter sunlight. Downstairs, an existing pergola to the north was extended and is fitted with Vergola adjustable roof louvres. Closed, the roof provides an outdoor living space protected from the rain; the louvres can be adjusted to regulate solar access to the interior as needed.

And while the family has not gone off gas yet, they put in a circuit for the induction cooktop they plan to install, and a full energy transition is very much on the cards for the future. “Carol and Andrew opted to retain the existing gas-boosted solar hot water system, as it wasn’t that old and had plenty of life left,” explains Penny.

“However, they took the opportunity to install the larger hydronic heating panels that they’ll need when they upgrade from gas to a heat pump for their hydronic heating down the track.” Air-to-water heat pumps operate at a lower temperature than a boiler and consequently larger panels are required to provide correct comfort.

The result of the clients’ and the designer’s commitment to the project is a collection of practical, inviting spaces in which Carol’s cherished indoor plants now have sufficient light to thrive everywhere.
Perhaps most importantly, “the kids love it”, she says. “We wanted them to enjoy it and be part of caring for the house, learning to ‘sail’ it for its best performance.”

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