Insulated tray slab foundation

This is the insulated tray into which our structural concrete slab will be poured. This is the cosy foundation of our new home!

The last week has flown by as we've happily watched our house start to take shape. Last Wednesday we received our first insulation shipment from StyroRail. The first shipment of foam is for the insulated tray that will hold our structural slab. The foam is called SRP 400 and is a high density expanded polystyrene with a compressive strength of 40 PSI (aka strong enough to hold up our house). StyroRail shipped all of the pieces of the insulation tray cut to size, so aside from cutting holes to pass the plumbing through there was no cutting or waste on site!

Our tray insulation being delivered by StyroRail.

Before I get too far, I should explain what had to happen before the foam went into the hole. After installing the ground loop we backfilled with 6" of stonedust to protect the loop and create good contact with it. It was then time for the underground plumbing and electrical preps, which were very cleanly executed by Ackland Plumbing and Portage Electric. Then 12" of additional fill were laid in two lifts. Each time fill was added it was compacted to provide the bearing strength we need to support the house. The last pass levelled the gravel pad to within about an inch of level all over, simplifying the installation of the foam.

At last it was time for the foam. After laying the first few pieces we noticed that even though the gravel was nearly level there were still voids under some of the pieces. In order to get as close to perfection as possible we decided to use some extra stone dust to fill the voids and truly line up the foam blocks. It worked like a charm, and with only 2 days of work the team from Cornelis Grey had all the pieces in place, secured with straps and foam and gravel ballast.

Now that's a straight edge. Good job team!

Next steps are to install the frost skirt and drain tile around the perimeter of the tray, after which we will backfill over them to provide extra support to hold everything in place. We will then lay the 6 mil poly vapour barrier and rebar into the tray prior to pouring concrete early next week!
This stage has been really exciting to watch as I think it really showcases how smooth and clean the process can be when well planned. The whole team is doing a great job so far. I can already picture the concrete slab nestled nicely into its insulated tray, safe and warm and comfortable. The robustness of our building shell starts with this foundation, and it's off to a great start. 

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Ground Source Geo-Loop

Today felt like the first day of actual construction! After a lot of delay, digging, waiting and watching, today marked the first time I actually put on my boots and climbed down into the hole in the ground to start building our passive house. The first step: installing the ground source loop.

The ground source loop is 600 feet of high density polyethylene pipe installed in a continous loop 18" below our insulated foundation. The loop will eventually be filled with a brine or glycol solution and connected to a heat exchanger in our mechanical room. A small pump in the heat exchanger will move the liquid around the loop, picking up free heat from the ground in winter and free coolth in summer and using it to temper the incoming fresh air in our ventilation system. This gives us all sorts of wonderful benefits:

  • the HRV's efficiency will be maximized in even the coldest winters
  • no defrost cycle will be required to protect the HRV's core, as the ground source heat will provide enough pre-heat
  • the incoming air in the summer will be cooled and dehumidifed
  • the size of post-heater for adding the balance of the required heat for the house is minimized

In plainer terms, the ground loop makes heating easier in winter and cooling easier in summer!

The pipe we used is from GeoSmart Energy. It was quite easy to work with, even with the cooler air temperatures this morning. We ran the loops with roughly 2 foot spacing between them. Given the opportunity, an ideal install would likely use greater spacing and a deeper installed depth — to counter this we've installed more length than is propbably required. The spacing and depth are determined in part by the constrictions of our infill site, the size of our footprint, and cost. Going deeper is expensive (not only the digging, but the fill to bring the level back up for the foundation). The original design called for installation 36" below the foundation insulation, but by reducing this to 18" we saved over $4000 in compacted fill and labour. Definitely the right call.

We will be connecting the loop to the Zehnder ComfoFond, which plays very nicely with the ComfoAir 350 we have planned. The two units have been designed to communicate and work together well. I'm happy to stick with one manufacturer for all of the pieces of this heat exchange/ventilation system, which definitely has it's perks when it comes to maintenance and warranty.

I'm looking forward to connecting and filling the loop, but that will have to wait until the mechanical system is installled (which is still months away). Once we do, we will be able to play with the flow rates through the loop to optimize the amount of energy we are able to pull from the ground.

Next up we will be installing the engineered fill and all of the sub-slab plumbing and electrical. We are also looking forward to our first big shipment of insulation from StyroRail on Wednesday!

Pre-fab no more

We’ve thrown the towel in with our pre-fab builder. The red flags have been flying for a while now. We’ve finally decided that we would feel more comfortable building the good old fashioned way — with site framing. 

Despite this setback, we're feeling much more comfortable with where the build is headed. With tried and tested techniques and builders. We’ve got several enthusiastic and experienced builders anxious to join our team. Mark has had to redesign our wall panels so that they can now be built on site (rather than the factory), using updated modern framing methods. His new wall system is pretty exciting. One in which he might actually like even more than before! He will write a post about it, because it’s worth writing about. Something new that can open up the doors for blah blah blah… (I say blah, but it’s very fascinating. Blah is because I’m not sure how to explain it.)

Now the ball is back in our court. We’ve got structural engineer looking at the new wall system. He should be giving us his feedback and stamp this week so we can finally get the city all of the drawings it needs to issue our permit. Quelle relief that will be.

This is what comfort looks like

Mark has been doing ‘thermal bridge calculations’ on our house. With Passivhaus, the goal is to make the building as air-tight and insulated as possible. Weaknesses often lie in the details —where differing materials connect or gaps occur. Obviously we don’t want any weaknesses. We want a fortress of thermal resistance, which is exactly what Mark’s models are showing.

The image above is a thermal bridge calculation on where our walls meet the slab. By all accounts, it looks excellent. Uniform heat distribution throughout. The inside sits at a comfortable 20•C and the outside at 0•C. If we had any gaps or weaknesses you’d see the warmer colours leaching their way out to the exterior. Instead, we have magical, rainbow coloured walls :)

Going off-grid in the city

Elon Musk announcing the Tesla Home Battery. Image courtesy of GeekyGadgets.

Elon Musk announcing the Tesla Home Battery. Image courtesy of GeekyGadgets.

There are three utilities that conventional urban homes take advantage of: electricity, gas and water/sewage. Going completely off-grid would imply ditching all three. But primarily, when the term “off-grid” is thrown around, it addresses the electrical grid.

Electricity

It’s incredibly frustrating to open up a hydro (electricity) bill. Half the cost is for delivery and fees alone. We already pay some seriously high rates for electricity in Ontario, which are only set to skyrocket in the near-future by as much as 40%. So much of our energy is nuclear, supplied by ageing power stations and is delivered via grids and infrastructure established half a century ago. There’s no shortage of uncertainty. Sure would be nice to go completely off-grid — to smugly sigh and sit back as the politicians and utility companies mess about. 

Alas. We will be plugging in to the grid. For the following reasons:

  1. Capital costs. The grid is right at our door step and so the costs to connect are fairly minimal compared what they would be if we were to set ourselves up off-grid. If we were in the country, going off-grid would be a no-brainer, since the cost to connect would be significantly higher.
  2. Space. Even though our energy requirements will be 80-90% less than an average home, we would still require a decent-sized array of solar panels to power it. This can be tricky on a small, urban site.
  3. Storage. Solar panels only produce energy when there’s sun. But we often demand energy when there is no sun. The supply does not always keep up with the demand, and visa versa. So there has to be a storage solution. From what I understand, the storage process is inefficient— lots of energy gets lost in the process. 

Planning for the future.

There is hope that we will be able to go off-grid (or at least become partially self-sustainable) in the near future. Tesla is set to announce their home battery technology at the end of the month. We are anxiously awaiting the details. According to theverge.com

“The technology promises to store things like solar energy or potentially a mix of that and cheap electricity during off-peak hours, helping keeping state power grids balanced and trim bills by 20 to 30 percent for some customers.”

That would solve our storage issues. The space for our solar panels has been ear-marked for the roof of the garage that Mark has designed in to the master plan. The capital costs would definitely be the largest obstacle to overcome. Government incentive programs would go a long way here. 

Mark has been coveting a Tesla car since its debut. And now the Tesla house.

What about those other utilities?

Gas. We will be fossil-fuel independent. Hooray! We won’t be bringing a gas line in to our house. We won’t need gas for heat or hot water. For water, we are going with an efficient electric heat-pump hot water tank. 

Water and sewage. It just makes sense to connect to water and sewage in the city — to guarantee clean drinking water and treatment of waste water. I don’t think that the building code, nor the city, would even permit otherwise. What doesn’t make sense is that we flush our toilets and water our lawns with clean drinking water. Our house will be grey-water-ready. We don’t have the capital to get it going yet, but we don’t want to preclude it. What this means is that one day, we will be able to flush our toilets with used bath water instead of clean drinking water.

In short, we won't be going off-grid. We'll be 1/3, with a lofty potential for 2 out of 3. We’ll take it. And do everything we can to future-proof our home against rising energy prices.

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Gaulhofer windows

gaulhofer passivhaus windows

Windows are especially important in order for us to obtain Passivhaus certification in this climate. They've got to be the bees knees. And they are. We decided to go with Gaulhofer simply because they have been tried and tested. Mark has heard nothing but positive reviews on the windows themselves as well as the service and install. These babies are Austrian-made marvels that will be be a joy to use and last a life time. They are rock solid. 

We have been working with Adrian from Hermann Timber Frame Homes. He emigrated from Austria, started a family business of building homes, and became frustrated by the lack of quality windows and hardware options available in Canada. So they started importing European building products. He's one of a handful of reps now in North America bringing these windows over.

The windows represent a rather large chunk of our budget. Doors and windows will be coming in at around $50k, without install. Yikes. Sure hope our building permit comes through, along with the preliminary modelling because those windows are now set in stone. We jumped ahead and ordered them because Gaulhofer was offering a bit of a promotion — their UPVC window line, with upgraded aluminum cladding at no additional charge. It's good that we jumped ahead too so that we're not waiting for them to arrive from across the Atlantic, which can take a good 2-3 months...

We're invested now. No turning back.

Passive House in The New York Times

Pablo Enriquez for The New York Times

Pablo Enriquez for The New York Times

There was an article published last week called The Passive House in New York. It really goes to show that the ball is rolling here in North America. I'm impressed by the mayor's initiative over there. It looks like they are poised to be at the forefront of the movement in the US.

It can be argued that Ottawa is leading the way here in Canada. Mark is currently working as the Passive House/Passivhaus (US/German) designer on a multi-unit community housing project here in Ottawa. He's working with Salus and CSV. If it achieves certification, it will be Canada's first multi-unit Passivhaus building. And how wonderful that it's 'supportive housing' and doesn't have developers thinking about how much more they can be charging for rent (as in the NYT article). He's working on another Passive House set for build this summer over in Chelsea. And there are a number of other projects in the works, by other fine folks, as well. Our project will be the first in Ottawa to actually gain certification (if we get it).

Now if only we could work on really bringing prices down. With all this momentum, a factory in China has opened up to manufacture Passivhaus-certified windows. Surely that will help. China is actually setting itself up to be the world-leader when it comes to Passivhaus builds. The factory to make these windows will be built to Passivhaus standards, becoming the world's first factory. They also have a giant hotel in the works. China doing China's thing. There's an economic drive now behind Passivhaus, which will hopefully benefit more of us in the near future.

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