A house many would consider a knockdown, rebuild has been given a new life as a snug, energy-efficient home by an ACT firm that say their science-based architecture model can be applied to existing housing stock across Australia.

Prior to the renovation, owners Kathryn and Rachel – who have requested their surnames be kept private – say the house was “always cold in winter and hot in summer”. They decided to upgrade it when they moved from Melbourne to Canberra with their teenage son in 2019. Kathryn had owned the house for years and while well situated – north-facing and opposite a park – it did not suit the family’s needs.

At first, the pair weren’t wedded to the idea of keeping the home. However, when their research led them to Light House Architecture and Science, Kathryn and Rachel, both archivists, were told it was the perfect candidate for an energy-efficient makeover.

The lounge room in Little Loft House before and after it was renovated

At the time, the home was 123m2 – with two bedrooms, one bath and a small study. With a 3.8-star energy rating, architect Duncan Hall says in addition to being “leaky”, it suffered from a progression of awkward, disjointed spaces, typical of many 1980s project homes. “The kitchen was old-school, disconnected from the dining area, and dark. The bedrooms were fine, the wet areas depressing. At the end of the house, the study/bedroom was small and poky.

“[But] it was solid structurally, in pretty good nick,” says Hall. “And it had clear potential. It sat comfortably in the streetscape and related well to the other homes in the street.”

The design team from Light House Architecture and Science focused on the home’s thermal performance and rearranged the floor plan, adding a 13m2 multipurpose room and creating better connections to the garden. Completed in 2020, the high-functioning, tightly sealed 136m2 home achieved a 7.7-star energy rating – on a budget of $400,000.

Light House owner and director, Jenny Edwards, is a building scientist, whose research and simulations inform the practice’s design approach. The Light House team takes on 35 projects a year – half are new builds – using scientific modelling to streamline processes to drive sustainability and affordability.

In the case of Little Loft House, one look at the plans told Edwards the house should be retained and upgraded. “Orientation is number one. Unless the house is structurally really bad, we would always encourage clients to renovate and extend.

“The savings and comfort improvements are very real.”

The backyard in Little Loft House before and after it was renovated

Built on an east-west access, the living room and bedrooms already enjoyed northern sun, but it was clear more could be achieved within a “smaller, smarter, sustainable” framework.

Hall sketched out the possibilities on the existing plan, noting the moments that arose from the sun’s progression through the house.

“It was one of the things we really enjoyed about the planning process,” says Rachel. “Duncan said you can have your morning tea here, lunch here and pre-dinner drinks here.”

“A good home can’t just be about energy efficiency. It has to feel and look like a joyful home,” insists Edwards. Her team’s process is holistic, beginning with a focus on passive solar features and draught-proofing, ditching gas for all-electric appliances, improving function and liveability by rearranging and improving the floor plan, then addressing water storage and landscaping.

In “leaky” Australian homes, draught sealing and insulating delivers “the best bang for your buck”, says Edwards. Between 46{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69}-61{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69} of a home’s heating energy can be lost and between 79{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69}-86{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69} of its heat gained through windows. All of the aluminium-framed single-glazed windows in Little Loft House were replaced by uPVC double-glazed windows with high solar transmission/low emissivity glass.

Insulation was bumped up too. “Pre-90s homes don’t have insulated walls,” says Edwards, but retrofitting is not expensive. “We took all the internal lining out and replaced it with new batts in the walls plus topped up the ceiling insulation – for less than $10,000.”

The internal envelope was also thoroughly sealed, and ceiling vents, ducts and downlights removed.

Taking the home all-electric was the next step – heating, hot water and cooking were all converted from gas to electric. There are now two reverse-cycle air split system air conditioning units, ceiling fans and a hot water pump. There’s electric under-floor heating in the new bathroom, all lighting is now LED, and the cooktop is induction.

Combined with the draught sealing, the switch to electric has reduced energy consumption by 69{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69}.

The family delights in the comfort and sense of intimacy that comes with temperature stability in the home. “It feels safe and calm and stable,” says Rachel.

They also loved the process. Light House presented good/better/best options to guide the selection of fixtures and fittings. “They’ve done all the research,” says Rachel. “Australian-made where possible, the best star ratings, a standard bathroom design for example. The model was very transparent.”

Hall’s plan has addressed flow and function. Sitting at one end of the east-west access, the once-poky study has been transformed with a pop-out addition that draws northern light and sunshine in. The loft space that inspired the project’s name sits suspended over a daybed. The room has a library wall and a desk. Now, a bench outside the window is a favoured spot for enjoying the garden.

The kitchen in Little Loft House before and after it was renovated and upgraded to improve its energy efficiency rating from 3.8 to 7.7.

A study nook, extra wardrobe space and extra toilet were other gains.

“I think the term I would use is ‘human scale’,” says Rachel. “It doesn’t feel overbearing and it’s not ostentatious. Duncan has come up with a design that encourages us to live in a comfortable but less cluttered way.”

The owners aren’t the only ones impressed with the project, which picked up two gongs in the 2021 ACT Institute of Architects Awards: the Derek Wrigley award for sustainable architecture and the Gene Willsford award for residential architecture – houses (alterations and additions).

Jenny Edwards says the Little Loft House project is a rejection of the “disposable” attitude to substandard housing. Instead, it uses standard construction materials to keep costs low while achieving thermal excellence – avoiding demolition and landfill.

“This gorgeous little house is 47{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69} smaller than the average new Canberra home and uses 80{49352ce17ba8b8c977b46090d4022735cbbf9c8d2a96e7181f87be9b36a1fd69} less energy,” says Edwards. The project cost – in “a very expensive construction market” – includes significant landscaping, rainwater tanks, all fixtures and fittings and appliances.

Her modelling shows the same approach would achieve better outcomes in every state of Australia.

“It’s not rocket science … it’s just good design and science, and fairly simple science at that.”