Retrofit or Rebuild? A Design Charette with 8 Green Building Experts [video]

Bungalows in Old East York - Retrofit or rebuild

Chris Phillips:

Hi, my name is Chris Phillips and I’m the president of Greening Homes. Greening Homes is a renovations company whose mandate is to minimize our environmental impact on our projects as much as possible.

We’ve recently been retained on an exciting new project in East York [in Toronto, Canada]. It’s an attempt to reach Passive House standards on an East York bungalow, a 1950s existing building. And my role for this project is primarily acting as a project manager, keeping track of the budget, having an input on various materials going into the project, and also offering some of my expertise in building science and also sustainable building and design.

Steven Gray:

Hi, I’m Steven Gray. I’m one of the construction managers at Greening Homes. What’s really interesting about this project is the long-term outlook that the owners have, because they plan to occupy the house for the rest of their lives. We’re aiming to achieve Passive House standards, so this means an ultra-low energy demand for the house, so much so that you don’t even require a conventional heating system. This is achieved through super-high insulation levels, high-performance windows, a very tight building envelope, mechanical ventilation with heat recovery, and very efficient lighting systems and domestic hot water.


The Passive House standard is an incredible challenge, and it’s going to be up to Steven and the Greening Homes team to ensure that we build with extreme diligence, with extreme attention to detail.


At Greening Homes, we really like to be involved in the design process for our projects. We really feel that an integrated design process is the key to a successful, high-performance, high-quality building product at the end. For this project, we were able to participate in a design charette…


What is a design charette? Well, imagine that you as a client have an idea of something that you’d like to achieve, but you don’t know exactly what the steps are to achieve it. And a design charette is basically getting together a whole bunch of experts in the building, building field—so you’ve got your architects, your designers, your energy modellers, your constructor—and just laying out a whole bunch of different ideas out on the table, and letting those experts in the field discuss with each other, just different approaches to basically make that dream become reality. And that’s why a design charette, particularly for trying to achieve something like Passive House, is just so extremely important.

Andrew Hellebust (Client):

Hello, my name is Andrew Hellebust, and I live here with my wife, Maria Riedstra, and our two children: Eric, who’s 12, and Laila, who’s six. We’ve had this house for over… just over 10 years.

And as our son approaches teenagerdom, we thought it’d be good to have the second bedroom, or a third bedroom. Our basic requirements are not many; we want another bedroom, we want a little more space for a grand piano…


Basically, in this design charette, everything was out on the table. We don’t know exactly what the building envelope is going to be built out of, we don’t know what the walls are going to be built out of.


We have to consider these drawings still flexible, because this is the first time we’ve really gotten this expertise around the table to say that, I don’t know, we need more windows in the south or we need such and such an insulation.

Ashley Smith (Engineer):

You have a 50-year outlook for your building, which is kind of important to keep in mind of where we’re aiming at… that you want to minimize your energy use, that you want to include the intangible things in a building. They’re actually very tangible, they’re just unseen [laughs]… the emphasis on function and also carrying the cost, and you spoke a bunch about insulation and a little bit about drainage.


In this design charette, we talked about some really interesting state-of-the-art materials, super energy efficient materials, some even come in from abroad, Europe. We talked about vacuumed insulated window glazing, we talked about magnesium oxide structural insulated panels.

Greg Allen (Engineer):

So this was the first super-insulated, air-sealed, heat recovery ventilated building in the world [shows television screen to group].


Our experience with our panels as they are is that they, they’re covered in snow for some days, days at a time in the winter, and in the summer, there’s just more heat than we can ever use. So if we could actually favour a winter orientation that sheds snow, that’d be good.

Bob Abraham (Architect):

Existing, in the basement you see existing walls to remain are in grey, and walls to be demolished are dashed.


One thing I never felt was resolved in our project so far was how to insulate this building. The simple question of, you have this old building with brick walls… do you insulate on the inside, do you insulate on the outside?

Shervin Akhavi (Engineer):

So extending the insulation from the outside down to the bottom gives you also more space inside the basement.

Greg Labbe (Consultant):

It fixes the leak, it allows you to not do… it saves you a ton of money of having to redo the basement.


But you could still do it on the east side, if you can get permission from your neighbour to dig a trench on their property. Fill it with foam-in-place insulation, and then a layer of Hardie board on the outside with a narrow space behind the Hardie board. And manufacturers of foam-in-place insulation say that it’ll seal perfectly; it makes your air barrier, vapour barrier, everything all in one; just fill the entire cavity with it and that’s it.

Ed Marion (Passive House Consultant):

I’d been saying to everybody, I’m going to build the first Passive House in Canada, and I came back and started modelling, and it wasn’t long after that that I realized I wasn’t going to build the first Passive House in Canada, because it was almost cartoony, the amount of insulation I had to have… and insulant, there’s a fine line between what’s reasonable—maybe not even a fine line, a very well-defined line—and what’s going too far for the sake of procuring that certificate.


So Andrew, we’re going to be doing exterior insulation here, so I think definitely either removing or cutting back this attached garage wall is a great idea, because it’s going to allow us to run our insulation in a continuous layer all the way around your building.


Why did we choose Greening Homes? They know a lot about all sorts of building techniques and are up on the latest techniques to source things locally, to have the lowest greenhouse gas impact, and I think choosing them took the onus off us to research all the stuff and impose it on the builder, ’cause we’re confident that they would choose the right materials, that we didn’t have to go after them to choose ’em. And I really like that they have a well-educated team that is eager to participate in the design process.


One thing that was discussed extensively in the charette was whether this bedroom over the garage was a good idea. Bedrooms over garages are often a problem because they have five exterior faces, and so they’re often a problem to heat and there’s often a comfort issue with them being too cold. Another point that came up was that the cost of building this one room is gonna be, is gonna be quite high as compared to the rest of the house, so I think after the charette, Andrew and Maria decided that they didn’t need this extra space.


So there’s been some ideas in the past five minutes about, well, remove the garage and create better side-road access, remove that wall on the west side so that it can be moved back from the property line and how much do we need to retain, 50 percent, OK. You know, at a certain point, you’ve got a new house.


In the design charette we also discussed whether the renovations were so extensive that it would make more sense to entirely demolish the existing building and construct from new.


It’s something shocking, psychologically, about just throwing something away, but I think economically… economics isn’t always psychologically coherent.


Working with the existing housing stock, figuring out solutions with the existing housing stock is where we have to go collectively, because that’s where the big problem lies at every level: residential, commercial, industrial. But no one’s come up with the perfect way of doing that right now.


In my opinion, I would, I think we have a very sound, usable structure. The shape of it is good, it does a lot in terms of maximizing to the property line…


I know I’ve argued about the rebuild that makes some perhaps compelling urges about rebuilding but… and that’s kind of where my head is at, though my heart is really with the retrofit, and having done the retrofit and put money into it, I’m happy with the results; the house is super comfortable, and in the hands of a capable contractor, you will get there.


In the end we decided to, that it was worth keeping the existing structure, because it’s a sound masonry structure and that we would just build new from the second-storey level up.


We’re incredibly excited at Greening Homes to be working with a client who is committed to such an incredible standard such as Passive House, and allowing us to build for them a home that will last for their lifetime and be relevant for generations to come.

Final results

To see how the whole thing turned out, read about the finished home and the award Greening Homes Ltd. won for their role in the project.

You may also be interested in watching a short video (or reading our transcription) about Ottawa, Ontario’s Own Passive House»

video: GreeningHomes; image: Wikimedia Commons

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