A Semi in Ottawa goes Passive House

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Door #3 – Room for improvement

There is a lot of room for improvement in the way currently buildings are built. Just a few months ago the new Rideau Centre expansion opened in Ottawa with a lot of new fancy stores. There is a huge glazed area with single glazed curtain wall facing Rideau Street. When I first saw this, I was shocked –  to say the least. Imagine the heat loss in the winter, when it is -35ºC outside. Probably some fancy energy modelling software made up for that loss at another location in the building, but imagine how much energy could be saved, if insulated, double (or triple) pane glass would have been used.


Door #2 – Passivhaus explained…


…by Adam Cohen.

Worthwhile watching, only 60 seconds long. Attending one of Adam’s presentations I learned that the passive house concept had made it to North America.

Door #1 – net-zero

Solar panel on a red roof reflecting the sun and the cloudless blue sky

There is a lot of buzz about net-zero energy buildings (NZEB). Buildings that only use as much energy  on an annual basis as is roughly generated on site. In my opinion the talk about net-zero is really a distraction. Theoretically any house – your house – could be transformed to net-zero if you install enough solar panels on your roof or in your backyard – if your roof is large enough that is.  But will that really reduce our energy demand, reduce the amount of power that needs to be generated in Canada? On cold and dark winter night, when the energy demand is probably very high, the sun isn’t shining, so the grid must still provide at the time of peak demand.

And of course all that technology that you have to install comes at a price. There was an interesting feature on this on CBC a few weeks ago. It was estimated that a NZEB would cost 15% more. I wouldn’t really want to pay that much extra for my new house either and energy in Canada its still too cheap to make this an interesting calculation.

But if you want to turn a Passive House into net-zero it starts to make sense, after already reducing the heating load by almost 90% , only a small amount of solar panels are required, much cheaper. And the house will provide superior comfort – very hard to put a price on that.


Advent Calendar


advenrWell, I have been very quiet on this blog and it has been a long time since my last post – somehow I lost momentum and my excitement about my project was affected from the process of getting a demolition and building permit: I am still trying to get all the utilities disconnected, very lengthy process, I had to get a hazardous materials report done, I got word from the city that my parking spots were not compliant with the zoning, so I need to make some changes to the design – thankfully I am my own client – so I can only get mad at myself to have missed that.

But it is almost December and we had the first snow fall already here in Ottawa. Last Sunday was  the first advent with one candle lit on our “Adventskranz”, a German custom to mark the four Sundays before Christmas. In the past we also always had an advent calendar for my kids – often home made with little presents or candy. Now my kids are older – so they are out of luck this year. But I will have one for you – the first Passive House Advent Calendar, with 24 posts until Christmas. Everyday you will learn something about my project or passive house – I hope it will be interesting for everyone. And it will force me to overcome my writers blog…

A Logo and Comfort

My daughters ringette team is looking for sponsors for the upcoming season. So I decided to be a sponsor and get my logo on their shirts, that they will be wearing from now on until March. Hopefully that will get me some additional attention. But what logo?? I spend a day with Illustrator and came up with one.


I got some input from my friend who is coordinating the fundraising and is not an architect or designer. Which is probably a good thing. She was wondering if I could add an explanation of Passive House to the logo in 3-5 words. Because there are a lot of people that don’t know what that means. HA! Not that easy. I asked if I could get half the shirt to explain that a Passive House is a super-insulated building, very airtight, you can basically heat it with the equivalent of your toaster, it has triple glazed windows, it doesn’t need an air-conditioner, it is quiet, it provides comfortable living throughout the entire year, it has superior air quality, especially beneficial for people with allergies, it is affordable, it is the most rigorous green building standard in the world, it can be applied for renovations….well by now I might have covered the entire t-shirt… And even for the sake of saving the planet – every sponsor gets the same amount of space.

While trying to come up with a three word definition for Passive House, one quality of this building standard came up most: COMFORT. And this might get your attention even more than energy efficiency: A Passive House is really comfortable to live in.

I will quote British architect Elrond Burrell and his post Passivhaus; Comfort, Comfort, Comfort, Energy Efficiency  on his excellent blog to try to explain this.

“….energy efficiency is actually only part of passivhaus. People don’t often realize that the Passivhaus Standard is also a rigorous comfort standard that ensures a building is free from drafts, free from cold spots, free from excessive over heating and provided with a constant supply of fresh clean air. And it does so with the minimum amount of energy.”

The standard for airtightness (0.6 air changes per hour) makes the house completely draft-free. Since the windows are so good, designed to have interior surfaces that are within 3°C of interior temperature, there are no cold drafts off the glass like there are in most conventional houses. (That’s why typically in your house duct vents are placed under windows, to counteract this). It also means there are no cold spots.

“Windows that are much colder than the room temperature are also uncomfortable because we experience them as cold spots. The glass acts like a radiator in reverse, drawing warmth away from our body. And the reverse is true in summer; the glass acts like a radiator adding unwanted heat into the room. The effect of this is a band of discomfort around the perimeter of a room where convection currents and cold spots make the space too uncomfortable to enjoy and make use of.”

Of course in such an airtight building you need to provide fresh air.

“The Passivhaus standard requires that the ventilation system provide 30m3 of fresh air, every hour, for every person in the building. This can be provided all year round by a mechanical ventilation system with heat recovery so there are no uncomfortable cold draughts from the ventilation. Alternatively it can be provided by ’natural ventilation’ in summer and mechanical ventilation with heat recovery for the rest of the year.”

This is one of the reasons I really like Passive House. Everyone can design a net-zero building by adding enough solar panels on the roof or adding an expensive geo-thermal system. But the house might still be drafty, have cold spots in the winter and overheat in the summer due to too many south facing windows.

Or imagine you renovate your house and add a nice new extension for a family room in the back. I came to the house of a friend of mine for the first time, they live in a very nice neighbourhood in Ottawa, they renovated their house, upgraded the kitchen and did an addition in the back. I really liked it, I walked around, looked at every thing (like architects do) and commented on the great new family room with a window seat overlooking the backyard. She said: “Yes, it is great, but we can’t really use it in the winter, it is too cold next to the window.” Well that is terrible! And really shouldn’t happen. If people ask me how expensive it is to build a Passive House, I like to bring up this example, because that really is expensive to build a space that is not comfortable to  live in year round.

And if you happen to see a ringette team with my logo at an arena around Ontario, why don’t you ask the girls if they know what a Passive House is? And if you are willing to sponsor the team let me know, there is still room on the shirts as I didn’t add any explanation to my logo.




What is this?
Cross Laminated Timber or short CLT has been developed in Europe in the 90s.  They are solid wood panels for walls, floors and roofs, massive plywood if you like.  Each panel consists of several layers of lumber boards stacked in alternating directions, glued and pressed to form a solid, straight, rectangular panel. They are delivered on the construction site including door and window openings and I have been told, that my building can be assembled in a few days. But there is a lot of concern out there, that it is expensive…
So are there advantages to traditional stick build walls?

One of the challenges in Passive House construction is the required airtight construction. To achieve this with built walls built from wood studs, a lot of things have to happen to get it airtight and the wall consist of many layers, which can get complicated at the junctions of wall-roof or wall-floor.


Compare this to a CLT wall assembly: the wood does a lot of things: it is the airtight layer, the vapor retarder, the interior finishes and the installation layer and reduces the number of layers that have to be put together.


Add the simpler wall assembly to the speed of construction – I really believe that there should not be any additional cost to the project due to the CLT construction.




So is this only for single family homes and smaller projects? Definitely not, there are built examples using CLT, mostly on the West Coast. If you are interested there are two of my favorite projects described by a former Carleton professor in this article.


It has been a while since I have written my last post – I was busy with a visit from our oldest son before he heading to his last year of university, Labour Day weekend camping  with glorious weather and getting used to the back to school routine again.

But I have been pretty busy working on my project on all kind of things that aren’t special to a passive house project: Getting a survey done – it is required for the building permit application and will be the base for the drainage and grading plan.
It turned out the soil on my new property is really crappy, I had to get a geotechnical report done and and hire a structural engineer to design a structural slab on helical piles (yes!). This was a bit worrisome at first, but it looks like the engineers came up with an economical solution. It will pose some challenges on the thermal bridge free design, but more on that later.

I have decided to get the house built out of Cross Laminated Timber – short CLT. This has been used in Europe for some time and is getting more popular in North America as well. CLT is a solid wood wall panel, that arrives pre-cut on site and all the pieces can be assembled in a few days. For me the main selling point was that the quality control to get an airtight building envelope is way easier compared to walls built on site out of a bunch of wooden studs. My CLT will come from Germany – of course you might think – I will write something on CLT in the coming days and explain why…
I have send my drawings to the manufacturer on Friday, as they will do the structural design for the CLT shell. So hopefully I am on track for a building permit ( and demolition permit!) application in October. As I really want to demo the existing house before the winter.


The Design

Designing is sometimes easy and fun and sometimes very hard. In university we spend long days in studio working on our projects, usually we didn’t sleep at all the night before the deadline. In the morning we had to hang our drawings / plans / sketches / models for the dreaded critique by our teachers. Then you had to present your design  and it felt like turning your inside out in front of everyone, all that in a very tired and exhausted state of mind. Some of the professors were nice and understanding, tried to get something positive out of any project.
My favorite prof was a chainsmoker, his burning cigarette in his fingers, he was pointing out things over the model with the ash becoming longer and longer – until someone in the last minutes protected the precious work, often made out of white cardboard,  holding a small plate under the falling ash. We were too terrified to point it out to him.
One of the less supportive professors asked one of my friends after her presentation:”Can you cook?” – she wasn’t sure what to say, as it was in no way related to her work, so she hesitantly said:”Yes, a bit.” – His answer:”Why don’t you go home and cook!”

I have been working on the design for some time now, and want to share it here with my readers – hoping for some feedback….

Each side of the semi will be a three bedroom house with a nice kitchen / dining / living area on the ground floor. I have to stay within the setbacks of the zoning and provide one parking spot per unit. Those take up a lot of space in the front. I am lucky as my backyard is South facing, ideal for solar heat gain during the winter.






Can you see yourself moving in? Sorry for only showing the floor plans – elevations and 3D views to follow later. Comments are welcome – already got some regarding my angled walls….might think about that – and by the way: I can cook!!

Green Design

There are a lot of green, sustainable, energy-efficient building standards out there: LEED, Green Globes, Energy Star, Living Building Challenge. So why do I really like Passivhaus?


The passive house standard is all about the building, and as an architect that is where I can have the most impact. One of the main focus is on the building envelope: super insulated without thermal bridging and air tight. And this standard gives the architect the control over the design and the energy performance. The building has to be designed to use very little heating energy, how can that be done? As the designer I can select the orientation on the site, the shape of the building, the orientation of the rooms in the building, the location of the windows. Adding a big window on the North side – the software tells you right away that this increases your heat demand. So you add large windows on the South – this is good for the winter, but you have to provide shading in the summer, so the building doesn’t overheat. With passive house design, you exactly know how much energy will be required to heat and cool the building, and this has been proven and tested in many, many built projects. So the heatings system can be very, very small – a toaster or hairdryer for a small single family home. And there is no way to cheat – every single component of the building has to be optimized – no way to make up for leaky windows with bike racks or recycled carpet (sorry LEED).

And with the Passive House software the designer is in the driver’s seat – it really can be a design tool to help to improve the energy performance of the project.  The building is designed to only use a known, very small amount of energy: 15kWh/m2. Not like it is usually done: the building gets designed and then the engineers take a very complicated energy modelling software to determine the heating and cooling loads and then they dimension their units. Often they come back and tell us architects, that we have to double the size of the mechanical rooms or penthouses….ok, maybe not double, but they always need more space….

The other thing that really stuck with taking the Passive House designer course was, that I didn’t learn that much new. That sounds really vain, but it is the truth. The way heat travels through walls, windows and roofs hasn’t changed in the last 50 years. Physics always remained the same…In Architecture school we learned about building physics, one of the least favourited subjects – you had to study hard to pass the exam and we thought of it as rather boring. We had to review drawings showing nasty details of thermal bridges and mould developing on the inside walls. And then sketch a solution. It was hard and not very exciting. We wanted to design cool buildings, museums and airports! So we chose to neglect the building physics….after all it was the 80s and deconstructivist architecture was all the rage.


Daniel Libeskind

So it is no wonder that the “father” of the Passivhaus concept and founder of the Passivhaus Institute in Germany is not an architect, he is a physicist. He wrote his doctoral thesis on thermal simulation of buildings and built the first Passivhaus in 1991.


Passivhaus Darmstadt Kranichstein



Haus ≠ House

All architects like pretty pictures and cool designs! My husband used to spend a small fortune on architecture books, today we can spend hours on the internet looking at cool projects.  Passive Houses come in all shapes, sizes and styles. Haus is not only House.

Single family houses

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Office buildings












Soon I can add a Semi in Ottawa to this list. I was working on the design the last couple of days and and I hope to post something about MY project soon….

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