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Casa Pasiva: a super-efficient laneway home

with 3 comments

Casa Pasiva, still under construction

Casa Pasiva, still under construction

I payed a quick visit to Casa Pasiva, a new laneway house on east 15th in Vancouver.

The house sits in the back of a lot graced by a large heritage house. The owners have decided to renovate the old house and turn it into rental accommodation, while they themselves move into the smaller laneway house.

The old house is treated with new insulation added to the outside, and better windows. The old wooden houses of Vancouver will never be super energy efficient, but their performance can be improved quite a bit. What I saw convinced me that heritage character and energy efficiency are quite compatible.

The heritage house under renovation, showing the added insulation

The heritage house under renovation, showing the added insulation

The laneway house itself is built according to PassivHaus principles. The house has triple-glazed windows (assembled in BC), double-layer insulation, and an air-tight envelope that is coupled with a high efficiency heat exchange ventilation system (for a minimum of about three air changes per hour). Fresh outside air is brought into the living areas (bedroom, living room) and vented off the washroom and kitchen. But it’s also possible to open the windows and bring in fresh air; the house is designed for good cross-flow natural ventilation. There is also a small green roof.  What made the visit fun is that it is still under construction; all the working guts are visible.

Because of the orientation of the lot, the laneway house faces north and is shaded much of the day, unfortunately. This results in a thermal performance just shy of PassivHaus standard: an expected load of 18 kWh per square meter per year (the standard is 15). At about 7.5 cent per kWh in vancouver, that would mean a total cost of maybe $135 to heat the house – per year!

The lungs of the house: a combined ventilation/heat exchanger with over 90% efficiency.

The lungs of the house: a combined ventilation/heat exchanger with over 90% efficiency.

The design of the little house (well, it’s a bit over 100 square meters, or 1000 square feet) was also very interesting. There is the usual architectural considerations, sure; but for a geek like me, what’s fun is discussing how the thermal performance is simulated for various weather/occupancy scenarios and the design (size and location of windows, for instance) tweaked for optimum performance.

Air ducts, water, and lots of wiring: the working guts exposed.  And insulation to be added!

Air ducts, water, and lots of wiring: the working guts exposed. More insulation to be added!

It’s pretty gratifying to see this kind of construction happening here. There ought to be many more; that would make some unit costs for things like windows and heat exchanger go down. But more importantly, to have numerous energy eficent houses would result in a much lower need for power, so reducing greenhouse gas emissions (and the need for power projects like Site C). Seeking “negawatts” – that is, looking for energy efficiencies – is still the cheapest source of power.

 

But I feel even more encouraged by seeing the heritage house being well pampered and insulated. There is a lot of housing stock in the Greater Vancouver that could use a performance overhaul, instead of a demolition. How about bringing back the program to subsidize residential energy efficiency improvements? That would spur change and create jobs. Just sayin’.

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Written by enviropaul

November 9, 2014 at 6:05 pm

3 Responses

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  1. I agree – conserving is definitely the best source of energy.

    I’m interested in the old house upgrade. Do you know what type of insulation in being applied? Is it mineral based or organic? Did they also blow insulation into the wall cavities before applying the ‘outsulation’? I understand that fairly good performance can be achieved in these old places with blown in stabilized cellulose.

    In any event, thanks for the update on what’s going on on the local scene.

    Brent

    November 10, 2014 at 11:35 pm

  2. Hi Brent, we used ROXUL Comfoboard on the outside of the sheathing. Also, the insulation inside the walls was replaced with a Roxul Batt product. Feel free to contact us if you have any further questions on this Reno. Thx, Alex. http://www.markenprojects.com

    Alex

    November 16, 2014 at 10:45 am

  3. […] to boost thermal performance. As Paul Richard, one of the visitors to the open house stated in his blog, “What I saw convinced me that heritage character and energy efficiency are quite compatible.” […]


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