Jonathan Kearns of Kearns Mancini Architects, describes how he tackled a high performance retrofit of a century-old building.
Interview with Jonathan Kearns
Originally from Dublin and a keen environmentalist, Jonathan emigrated to Toronto in 1975. He became an architect and by 2008 was looking to incorporate his interest in sustainability into his designs. This led him to take the Passivhaus training, with his first project using this methodology being the Reach Guesthouse renovation.
Reach Guesthouse was an experimental exercise
Located two hours east of Toronto in Prince Edward County, Jonathan took on a late 1800s post and beam farmhouse. At around 1700 square feet it had a ground floor with smaller upper floor.
“And so, that project became my learning tool and sort of an experimental exercise in how to renovate an older building and draw all the best qualities out of it while at the same time enabling it to be superbly energy efficient.”
Renovations tend to be more tricky than new builds
Jonathan explains that the Passivhaus training that was developed for new buildings hadn't entirely prepared him for the task. It took a period of stripping away and demolishing the worst parts of the house to establish whether it would even be worth renovating, but the more raw structure that they uncovered, the more they realised that they could end up with something very interesting and unique.
A friend of Jonathan's was an artist who in his free periods would also do some construction work. He moved to the site to carry out the selective demolition, using his artistic eye and considered approach to decide what would be worth keeping. This approach did mean the time schedule became stretched, but Jonathan considers it to have been time well spent.
The house was enveloped in Structurally Insulated Panel cladding
Jonathan worked with a local contractor specialising in Passivhaus home projects, who built modular pre-fabricated components in his shop in the local town.
Using 12 inches of SIPs cladding as an insulated jacket to the building, they were able to create a house form very similar to the original. Jonathan describes it as being somewhat surreal to cross from the entirely white exterior through to the contrasting original woodwork inside.
Later additions to the original farmhouse had been poorly built, so they chose to demolish them but use the same foundation to construct a kitchen / dining space on the back of the house.
“So, again, even within the house, you have a very nice contrast of the intimate, richly wooded finishes of the original house, and then you go through into the kitchen dining room and it’s a one-and-a-half storey high open cathedral ceilinged space that is painted white on the inside and is white on the outside and has larger windows that overlook the garden.”
Excluding the basement from the Passivhaus envelope was a painstaking process
With the basement being shallow and built of local stone, Jonathan says there wasn't much opportunity to incorporate it into the house, so lots of insulation had to be added to the underside of the floor to achieve an air seal.
As they wanted to keep the beautiful, original wooden floorboards, they lifted each one from the ground floor, recorded where they had come from, and preserved and set them aside until later. A layer of Oriented Strand Board (OSB) was laid, taped and sealed, with all the edges being sealed to the outside of the exterior cladding of the original house, so that when the house was wrapped with an air vapour barrier it could be taped to the edge of the floor. The original floorboards were then re-laid.
A particular challenge was the four posts of the house. To complete the air barrier they had to tape three or four inches vertically up each post and down to the floor membrane.
The next project will be a Passivhaus new build
“It makes me want to do new build more than renovation because with renovation, it’s a journey and you don’t know the route. You know what your objective is but you’re starting with something where you can’t see all of the challenges. So, it’s not until you get in and you strip away and you discover all the nuances, that only then can you really make the right decision, make the right design choice.
So, the renovation project really needs you as the architect and designer to be very hands-on and very engaged in the process all the way through. Whereas with a new build, you can really design, think out, calculate and detail every aspect of your new build before you start construction.”
Following Jonathan's renovation experience, he is now constructing a new Passivhaus guesthouse, called Endymion Guesthouse, which is also in Prince Edward County. Being a completely new build he has been able to site it facing south the way he wanted, and has chosen an ICF construction which could be built by a builder without much Passivhaus experience.
His approach to sustainability has changed
Jonathan says he has always liked the landscape and ecological approach to architecture. He went through periods of being very immersed in looking at photovoltaic panels, wind turbines and the use of geothermal for heating and cooling, but when he studied the Passivhaus methodology he realised they were all secondary to building the primary architectural enclosure to an extremely high performance level.
At the Reach Guesthouse, they have very low energy consumption in summer and winter months for heating and cooling, and the shoulder seasons quite often rely only on keeping the energy inside the building that has been generated by people and appliances.
Something Jonathan enjoys about Passivhaus is he feels it allows him the freedom to work with any material that is appropriate to the design, programme, location and landscape, whilst applying the science as stringently as possible.
Find out more
Visit the website of Kearns Mancini Architects
Read Lloyd Alter's Treehugger article about the Reach Guesthouse
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