Monday, October 20, 2014

New Technology Renewable Energy System:

Wow!  I just had a 2 hr conversation with Bruce Gray.  It was at a presentation organized by Terrell Wong and Kathy Garneu, here in Toronto.  Bruce is the inventor and founder of a disruptive technology called Sunpump, (see located in Vancouver.  They have a new heating and cooling technology that blows everything else right out of the water.
It is a major shift to a new way of the using the very familiar vapour compression cycle.  We're all familiar with the mini split heat pump.  They have been around quite some time, and over the years, their efficiencies have improved.  In the last month or so Mitsubishi released (in Canada) their FH09 mini split heat pump with a SEER rating of 30.5.  That is news in itself!  But tonight, I learned about something even better.
This is a heat pump combined with a solar thermal panel - but there is no glycol, and no water.  The thermal panel hosts refrigerant.  In addition, there is no outdoor fan.  The thermal panel sits on the roof or on the wall, and exchanges heat with the sun and the environment, without any moving parts on the outside of the building.  The panel is a solid plate of aluminum with many small channels running through it.  This configuration is classically difficult to produce - but the company has overcome this challenge with the employment of 3D printing, so the panel is not two sheets stamped and brazed or somehow fused together.  It is a monolithic plate.  It is anodized to be blackish, and has a hydrophobic coating on it.  What is amazing about this whole concept is a number of things - and I feel dumb for not having thought of it - but the elegance of the whole configuration is just wonderful.  Unlike regular evacuated tube or flat plate solar panel systems, there is no stagnation, no drain-back, no thick lines to the roof (the copper lines are 1/4" and 3/8" dia), no freezing, no glycol, no pump, no fan, no nothing.  The system is very economical to purchase because there are so few moving parts.  The only moving part is the compressor rotor and perhaps a valve.  But efficiencies are huge!  Studies show that installed COPs of mini splits are about 2.5 and groundsource heat pump systems, 3.5.  This new technology has a COP of about 7 or 8, in the installed condition, and I think these numbers are not exaggerated.  If you are a little familiar with heat pumps and heat transfer, you'll see why.  Even evacuated tube solar panels have working fluids (water, glycol) that struggle to take heat from an environment that is say -5 or colder outside.  But when you have direct exchange with the R410a refrigerant, which is operating at much lower temperatures, you can extract heat from much colder ambient conditions.  In addition, because there is no fan, there is no bulk movement of air over the heat exchanger (in this case the panel - in a regular mini split outdoor unit, it is a finned heat exchanger).  This means there is no freezing of moisture on the heat exchanger, and a significant portion of the heat exchange is carried out via radiation.  To top it off, the company also offers these panels with PV cells grafted onto one side - so you can get electricity (just like a standard PV panel) as well as heat.  There are numerous hybrid panels on the market, including PV with Air, PV with water/glycol - but this is PV with R410A refrigerant.  This is a big step forward.  And, finally, the system's output side seems available in more than one configuration (which was always something I hated about mini-splits - their lack of ability to have a hot water output at a good price).  Sunpump offers their units with hot water outputs as well as straight refrigerant outputs - so their systems can work with hydronics as well as air-based HVAC systems.  BTW, the system cools as well as heats.
Costing is only about $1/watt of total output - I believe this includes the panels, accessories, and heat pump.  This means the system is cheaper than many many systems out there, and I think will even compete with the low price of natural gas in North America.  Apparently they intend to compete on installation costs with electric baseboard heating!
The company is well developed already, has sold much product, and has CSA approvals on their products also.  And the panels produce some 7 to 8 times as much energy as regular solar PV panels today produce (!!! - I know !).    They also have partnered with a financing company so builders can have these panels for ZERO dollars down - the company recoups the money by having the consumer pay their energy bill savings towards the loan.
So, this is the biggest, baddest news out there in the world of energy systems.  Absolutely must look into this for every project, not even just low energy buildings.  Remember the panels work at all hours of the day, (the thermal aspect of them), and on all sides of the house - they are about twice as productive on the south side, but even on the north side, they perform well compared to other heat pump systems.

I discussed groundsource with Bruce as well.  He said their testing showed ground source loops to eventually degrade in their heat transfer capability due to freezing and shifting of the soils around the pipes - but the performance potential is ultimately limited by the working fluid.  There have been what are called direct exchange systems in the past, in which refrigerant is passed directly into copper pipes in the ground - but the copper seemed to be unreliable and developed leaks, etc.  (I 've heard also of the difficulties in these systems).  One great advantage of the groundsource system is that they tend to store the summer's heat in the ground, and then, later, store the winter's cold in the ground as well, reducing both heating loads and summer air conditioning loads.  This system does not have an inherent storage aspect like the groundsource, but the simplicity and greatly increased efficiencies seem to me to make things much more worthwhile with these thermal panels - ultimately groundsource is has some environmental issues and is really quite expensive, as well, and involves a fair bit of plumbing and pumping.  This system does away with that.  Storage can be added to the system of course, with the use of a water/ice tank.
So - it is not often I am impressed with a new product - but this is one of those times.  The concept is absolutely fantastic, and the product appears to have great potential.
Actually, I was badly conflicted in writing this article.  They are currently in explosive growth mode, so production is very tight and it may be hard to get one right now - but of course, I want one, so I didn't really want to tell everyone about it - but hey - must do the right thing......and tell you all.

Have at it!

Wednesday, August 20, 2014

What Engineers Should be Doing

Sure, I'm building this net-zero passive house.  It is taking too long because I want to put so much into it, and because I'm also busy trying to earn some money to keep things working in the family, in the project.

But recently one of my engineer colleagues, Lukas Vos, left Toronto to seek out a deeper meaning - he's actually been seeking for some time, but he went to northern Europe, took a bunch of photos (here and he's constantly out there learning about our world so he can make a difference in it.  I was reading his stuff and I realized, that I have so far to go!

So I asked myself:  What should an engineer be doing in this world, at this time?  Do a google search and you come up with basically nothing.  For some time now, I've been learning and learning about the technical aspects of how to build a house that is nearly self-sustaining.  The answer can be summed up simply:

  1. Build a net-zero energy Passive House.  - This has been my focus, but it leaves three major aspects of sustaining our present human lives unaccounted for:  Food, Water, and Waste (I'm assuming everyone already has enough sex and oxygen - for now).  So for these other 3 aspects, I have also been learning about:
  2. Food:  Design and build a permaculture garden/farm - see Geof Lawton Videos for more on this.
    consider including aquaponics
  3. Water:  See # 2, but also use rainwater collection, filtration, and a recirculating shower
  4. Waste:  implement Eco-sanitation - see the current eco-sanitation project in Haiti - basically harvest human waste for the incredible resources it offers - this is simple and useful
These 4 points, as best as I can tell are the basic directions we must all move towards.  I'm slowly figuring out that what an engineer should be doing is basically becoming an expert in the above, then going out into the world to help others achieve...the above - in the most ecological way possible.  Life's work, here I come.

Tuesday, July 15, 2014

Green Plumbing Design and Urine

Pic of the house - nothing to do with this blog post.

Well, maybe I was the last to know.  Our wonderful urine is a fantastic resource we have been wasting!
Its a bit late to incorporate this into our house project, but with a little reconfiguration, we can make some big improvements.
Basically, the thing we need to do is collect our urine - not throw it away.  It is full of excellent nutrients plants love - like nitrogen and phosphorous - and it carries these nutrients in forms easily accessible to plants.  Addiing urine to plants can double their yield, says Patrick Makhosi from Uganda.  Our urine is sterile for some 24 hours after pissing - after which time, the urea begins turning into ammonia, and that pee smell starts to waft out.  We can apply it to plants diluted.  Heck lots of details on the internet, like here:

So back to plumbing.  The big deal is that while urine is great for plants, it is bad for rivers and lakes - giving rise to algal blooms, which can spell death for the other animals and plants in the waterways.  Urine's nutrients are difficult to remove from the sewage once it is in there - so the best thing to do is to plumb our houses and buildings to separate it at the source - And now, looking at our plumbing fixtures, we can only conclude that as a society, we are embarrasingly primitive - All the time I was made fun of in school for talking about our bodily fluids, but who knew!  There is no urine separation!, and there is no proper urinal for women!  Meanwhile we are polluting our waters like idiots.  We should all be pissed that our scientific and other leaders led us so far astray.
A long time ago, before I ever designed my first house, I wanted to have a washroom with two toilets.  It was not for separation of urine from poop - it was because so much productive talk was happening while I was on the John - so I figured I might as well invite the person to join me, except it wouldn't be fair if they didn't have a toilet, too.  But now I see a much more acceptable reason for having this feature in a house.  The one toilet dedicated for urine would be such that our ratio of water to pee was between 15 and 30,  to 1.  Then we don't really have to add the water later.  The whole thing would go to a P-trap, then to plastic tank in the basement or somesuch, which could then feed the garden  - hopefully with gravity feed. - I'm sure there will be people who tell me this is not a hygienic system - I'm all ears.

All the while we haven't even started talking crap.  Next time?

Saturday, May 10, 2014

100 in 1 Day Toronto

What if hundreds of people united, each putting in place the changes they wish to see in their city, all on the same day?
On 7 June 2014, for the first time-ever, Toronto will host 100 in 1 Day.
This citizen-driven festival will unite people across the city to make Toronto a better place by creating acts of urban change.
These acts, or interventions, have the potential to raise awareness of urban and social issues, inspire ideas, and motivate leaders to consider new approaches to old problems.
From 2-4 pm, we will be hosting Net Zero Passive House Tour
We invite the community to come and see what we've done with our house project to minimize our ecological footprint. The design directly targets net zero energy and passive house certification and aims to achieve this at no cost premium. The tour will include a presentation of features and strategies to make the most of every opportunity to improve performance, comfort, function, and versatility. 
Note: As the house is currently under construction, the tour will not be suitable for children and those with mobility challenges.
Do you have an idea for making Toronto a better place? Share it here:

Tuesday, February 4, 2014

Smells, Moisture, CO2 and Indoor Air Quality in Tight Houses

In past blog posts, I've noted various areas in which we are in a technological revolution - including lighting, renewable energy, energy storage, not to mention high performance buildings and windows..

But smells!  The science of smelling/sniffing is definitely in its infancy, but the potential for advancement to yield results is huge.  I looked into this just today because I've been working on our ventilation system, and we happened to install the PAUL Novus 300 HRV (probably the most efficient machine on the market).  But effective and efficient ventilation goes well beyond the heat recovery efficiency.  The energy demands of the ventilation strategy have a lot to do with sensing and control.  (And this was the main reason we chose the Novus. It allows up to 4 channels of control.  )

The ventilator should slow down when users are not occupying the house, or windows are open, should ramp up when users are having vigorous activity in the house, or there are a lot of people in the house, and should operate with a big imbalance if there is a vented dryer in operation or a vented kitchen range hood.  What if 6 people took a crap nearly at the same time?  The indoor air quality could be very poor for a while.
So, to minimize energy demands and maximize effective provision of fresh air to house, I would consider sensing the following, in order of importance with first items most important;

  1. CO2
  2. moisture
  3. Pressures inside and out
  4. windows and doors
  5. smells (!)
(this listing is not including the CO sensor - which could be important if you have gas appliances).

Using CO2 sensing, one could minimize the delivery of fresh air to the house and not over-ventilate.  It would also take into account the presence of more or less people and plants, and probably even fires.  CO2 sensors on the market for HVAC applications (there are also lots for greenhouse applications) are about $300 with NDIR (recommended) sensing systems).  Companies like Honeywell, GE, Senseair all make them).  You can get desktop CO2 monitors on Amazon for about $150.

Moisture sensing is important to protect the building contents, but more importantly to protect the structure, and prevent mould formation, etc.  But don't forget to protect houses from dry conditions also - moulds wont' grow, but anything made of wood will shrink and crack - very low humidity is just as bad as high humidity.

Pressure sensing would compensate for any other exhaust fans as well as open and closed windows.

Smells! - what if someone were to be using a harsh paint, or a cleaner, or indeed, the washrooms.  The science of gas analysis (all smells are due to gases in the local atmosphere) applied to smells has incredible implications.  For example, this company says they can make electronic sniffers that can detect pathogens in the air - this means one could potentially detect a virus in the air in one's house, and record that event in a log.  By smell detection, the house could 'know' when the washroom was being used, or when cooking was being done, or when there was a fire, or when laundry is being done, or when mould was growing in the walls (!), when animals have nested inside the attic, perhaps, or when the outdoor air is more polluted than the indoor air.
There is much to read online regarding electronic noses.  The process of technological smelling involves 3 steps:  acquiring a standardized sample, detecting the chemicals in the sample, and analyzing what was detected.  This last part involves a fair bit of software, including databases - because various odor events are logged as a certain configuration of results form the gas chromatography or whatever detection method was used. - the device needs to learn and grow its knowledge to be effective.

All the above is another way for me to feel good about all the low voltage wiring we've been putting into our house - we'll have the built-in ability to employ sensors all over the house because of this, and things are telling me the future of buildings will have a lot to do with sensing.

Thursday, January 30, 2014

How Best to Plumb a Drain Water Heat Recovery System

If you are not sure what a drain water heat exchanger is, google it or read the following:

Here's a couple pics of our installation:

Below I summarize salient points on this concept/product, and then give my thoughts.
  1. Cost is $500 to $1200 for the item.  Installation is extra.
  2. Go with the largest diameter and longest exchanger you can fit into your plumbing, assuming a vertical installation.  There are horizontal ones available from , in which case, I'm not really sure - but I think they have just the one size.  Leave at least a 12" (0.3m) of straight drain pipe above the exchanger to smooth out the flow.  You can see we've done this, and we've used 4" pipe
  3. It is still worthwhile to pump shower drains in the basement back up so they can drain into the heat exchanger.  Cost of these Gulper pumps with a kind of control that senses the water level in the drain is something like $300.
  4. Gather all your drains to one place, if possible.  In our case, we've done this with all the shower drains in the house, which all happen to be clustered together in the building.
  5. Savings of some 50% on water heating energy are possible depending on how things are plumbed in the house and cost of energy.
  6. Hot water recovery times can be dramatically improved - this, to me, is a very sure sign of energy being saved.
  7. The design requires a double walled heat exchanger - in other words, there must be an air space between the copper pipe carrying the drain water, and the copper pipe carrying the potable water - this severely limits the efficiency of the unit, and increases the costs - more on this later.
  8. Gravity film - surface tension effects cause the drain water to stick to the drain walls in a thin film - this is why heat exchange is arranged at the surface of the drain pipe.
  9. Simple payback periods range from 2 years to 10 years.
My Thoughts:

Leaving water in the Bathtub  One comment I've read is this:  Recover your 'waste' hot water heat by just leaving the shower water in the bathtub and letting it cool to room temperature before allowing it to drain away.  This is an excellent measure, and no cost to install, but it has some issues:   - first, it adds moisture to the house - good thing in winter, probably,  not so good in summer.  2nd, only possible with bathtubs, showers can't hold much water.  3rd, ring around the tub, 4th, it gets difficult to have multiple showers in a short period of time - such as on busy mornings with a family of 4, and 5th, don't assume it is 100% heat recovery.  The water in the tub cools only to room temperature, which is almost the halfway-point from the cold water inlet temperature to the 40deg C or so needed for a shower/bath.  So heat recovery is something like 60%, similar to a good drainwater heat recovery installation.

Efficiency:  The best units are limited to something like 60% efficiency - measured in terms of inlet and outlet water temperatures. Industrial heat exchangers are good for over 90%.  Even over 95% in some cases. A much more 'effective' design, would be to simply have a copper drain pipe inside of another larger, plastic pipe filled with the pressurized, cold water.  This would increase heat exchange efficiencies a lot (to probably above 80%, easily more), and reduce the cost of the units greatly as well, and also reduce the pressure drop incurred by the units we use today.  Given the huge potential for energy saving across a nation like Canada, one would think it is possibly worth the very small contamination risk - after all, if ever there were a leak, the pressurized water would go into the drain, not the other way around, and it would be fairly easy to detect - just check the water meter while all fixtures are off - perhaps an annual check would be worthwhile.  Imagine - if we could recover 95% of the energy used to heat hot water for bathing, small electric point-of-use hot water heaters would be so much more viable (read my post on POU Hot Water) - they could be built right in to shower fixtures, and this could lead to all sorts of interesting plumbing configurations (just plumb one line, for example - no need for both hot and cold?).  I can see Doc saying "What, are we in the Dark Ages?!".

Alternative Strategy: One way around this is to avoid the issue altogether.  Instead of directing reclaimed heat to the DHW system, transfer it to the space heating system instead - ie to a non-potable heat sink - such as a hydronic heating component, or direct to refrigerant in a heat-pump system.  This avoid the water contamination issue, and can recover much closer to 100% of the energy used for heating water.  Sadly, I know of nothing on the market that does this as yet, but it would be very easy to build something - a coaxial pipe heat exchanger is all you would need.
Another thing not being explored - use heat pipes to do the heat exchange work - this would probably increase the options for horizontal exchangers.
And yet another approach involves using an auxiliary tank and a pump - so we recover heat even from processes like clotheswashing and dishwashing, in which the hot drainwater is not expelled at the same time cold water is being drawn in.  Here is a link to one company to doing this:

Installation:  You can see there is a lot of copper in these things - the one pictured was a good 60 lb.  We came up with a simple way to mount the item effectively.  We used a 4" water closet flange.  We removed the small groove inside this flange so the 4" ABS pipe could be passed right through.  This is basically creating a bulkhead fitting on your pipe - but there is no break in the pipe.  Glue it on with solvent, and then mount to a couple of wood runners.  Makes a good support.  Notice also we've installed unions around the exchanger - this will let us more easily check its insides from time to time and clear out any build-up.

Water Pressure Losses from Drainwater Heat Exchangers:  Something not mentioned too often:  What about the pressure losses?  The one we chose to install uses a single 3/4" copper tube (about 60 feet of it) wrapped around the 4" drain.  In choosing a product, it is a matter of heat exchange performance and this is measured by the Canadian government testing apparatus, so after finding units that perform well, we looked for designs that retain water pressure the most, and most robust.  So how to plumb in order to retain water pressure?  If you have high water pressure, this may not be an issue, but keep in mind, water pressure is not free.  Someone, somewhere, must provide it, and I feel we must always think of our buildings as 'off-grid', so we want to minimize energy losses at every opportunity.  Therefore, buy a unit that performs just as well, but results in the least pressure loss.  then, I would plumb everything through it.  After all, we heat a lot of water to just room temperature via space heating - it sits there in the toilet, in the pipes, etc.  But to recover that heat using the drainwater heat exchanger, the cold side must flow - therefore, as per manufacturer recommendations, just plumb everything through it - I would still provide a small line to a drinking water fountain or icemaker, however.

Sunday, December 15, 2013

Low and High Voltage CAN go in the Same Box

All our lights are low-voltage.  I looked for boxes for the switches, but I was surprised to find the plastic LV boxes were expensive, and in my view, not that great.  I searched for a steel box and found one!  It is the Hubble product pictured below, the price is reasonable, (less than the LV mud-ring boxes) and the divider is removable (additional $1 for the divider), so the box can accommodate both regular household voltage and low voltage in the same double-gang box.  We used double-gang boxes for all our switches and plugs in the house - (almost all).  Most will have a CAT6 cable and an 18g. cable in the LV side, plus whatever goes on in the household current side.  From these, we can eliminate power adapters in the house by providing LV direct from the plug, and we also can use any 12V devices, and have DC lamps (so DC power direct to LED COB lamps).  DC-DC boost or buck pucks are available online now for about $5, so you can get almost any voltage you want by placing it in the box (we are supplying 28V), and it would remain within the electrical code rules as long the voltage remains below class 2 wiring limits.  In addition, every plug location becomes a data/voice/LV/automation/sensing/instrumentation node as well, without adding additional boxes all over the place.  So we can have things like motion sensing that controls things far away from the box, microphones, speakers, bluetooth, wifi, fire sensing, temperature, humidity, etc.
In many of the switch locations, there is no household current component, so the whole 2-gang box is for LV.

There are virtually no octagonal boxes in our project - Just one, actually in the utility room because I wanted to have a different source of lighting while the LV lighting system was being worked on.
You can see the LV wires come from above the plywood - they were incorporated into the acoustic floor assy above.  This could be done with 115V also, but you would likely need for it to be in conduit depending on the acoustic floor thickness.

Exterior Cladding is Finally Going Up

The exterior cladding is finally coming together, but its hard to photograph due to scaffolding, and the difficulty of getting a good camera angle.
We've made so many changes to the project it is no longer funny, so I've figured out now that one way to avoid changes is to build it fast!  Everyone seems very unwilling to change things once the money is spent and the construction complete.  Sadly, that is not our current situation!

Here's a rendering of what we are doing:

I offered to go up there and paint the roof white (because we both felt we chose the wrong colour shingles for it), but she's not keen on the white idea, so the brownish mistake will remain.  I find the house pleasing, though it is simple.

And here's a pic of the cladding going up:

Removable Basement Floors and Interior or Exterior Insulation Placement

A basic decision that one faces early in the design of a super-insulated building is the strategic choice of interior/exterior insulation placement and thermal mass.  This a strategic decision because it has far-reaching implications and ripple effects.  Think of the building as a shell on all sides, including the parts in the ground.  If we are designing an airtight envelope without thermal bridging, then we want to avoid having some of the insulation inside, and some on the outside - it can be done, but this frequently leads to thermal bridges and sealing problems.  For example, if we have insulation under the footings, (this being outside the structure of the shell), but then we want to have insulation inside the basement walls, how to connect the insulation under the footings to the insulation inside the basement?  The problem is there because in general, insulation materials are weak and soft, while structural materials are hard, but conduct heat.  To simplify the design and construction greatly, and improve the effectiveness of the insulation system, work to have all the insulation either outside the shell, or inside the structural shell.  Cross-overs are to be avoided.  In our case, we decided to place all the insulation inside the shell, and forego the thermal mass benefits - I believe thermal mass benefits are less well proven than insulation benefits, and that 'thermal' mass can be achieved without 'mass' (for ex. by the use of water - a very thermally massive material without much mass, that can be moved around).  
SO, here are more photos of our basement floors - they are above all of our interior insulation (about R55, or 15" of Roxul) above our basement concrete slab.  As posted earlier, they are removable, and they are a common material - regular construction lumber 2x12.  which means we can remove and replace pieces, but we can also remove and look underneath.  We're currently pretty happy with these floors, and the system feels very solid to walk on - as if the floors were resting directly on concrete.  It turns out the wood has shrunken a little in the 2 months since we installed it - but only the pieces that were wetter.  those nice planks in the 2nd photo have not shrunken at all.
Some astute observers have commented that the floors will allow moist interior air to go into the spaces below the slabs.  What will happen to this moist air when it reaches the cold concrete some 17" below?  Well, we have Tyvek under the floor boards in one area to prevent this bulk movement of air, but most of the floor is left without any kind of air barrier.  Since it is removable, we can make a correction if this turns out to be an issue, but I have a feeling the issue is fairly minor for a couple of reasons.  If we think of regular basements, many have no insulation under the concrete floors, and they are perhaps a bit damp on muggy, hot summer days, but often this problem is short lived in the Toronto climate.  In our case, there is a floor assembly blocking the bulk movement of air to some degree, and in addition, the space beneath our floors may be warm for much of the summer due to our under-floor (sub-slab) heat storage strategy.  This raises the temperature of the basement concrete slab right when the chances of hot moist air condensing on it may be highest, which should reduce that whole issue quite a bit.

However, as there could be a small concern, we did place some sensors at the bottom of the floor insulation, in three locations.  The photo below shows a small pump with tubing, a water level sensor, and a temp/humidity sensor in the background.  The sensors are inexpensive devices for Arduino, and cost about $5 each.  The pump was from Princess auto and was about $20.  We had some problems with our basement floor pour - there was not enough slope in some areas, and during the big Toronto flood in July 2013, we noticed a little water in three locations on the floor, and so marked these spots and placed these little pumps to transfer the water to the sump pit.
Later on, as the systems become live, we will be able to report the fluctuations in temperature and humidity at the bottom of our basement floor assemblies.
We will also probably place sub-slab soil temperature sensors as well, one day...

Sunday, October 27, 2013

Cellulose vs Urethane Foams - Again

I've noticed that in much older posts I reported on costs of various types of insulations.  More on this here. We have now finalized our cellulose insulation contract with Greensaver - a not-for-profit in the Toronto area.  Costs for dense-packed cellulose insulation for walls seems to break down like this, at least on our project:

Walls:  4085 cubic feet, at 3.5lb/cf density = 14,300 lb cellulose, at 33 lb/bag, we need 433 bags at about $10ea. - so materials for the walls are $4330.

Attic:  4183cf at 2.0 lb/cf = about 8400 lb in the attic, or about $2550 worth of material.

Labour in the walls is about twice the material cost, and labour in the attic, about 70% of material costs.

Much thanks to Climatizer insulation of Toronto for providing a fantastic price on the material for our project!  (They've had a tour of our house and took a step to support us as a contribution toward green initiatives).  Here are the bags we will be using:

In the past I've noted that spray-foams are about 10x the costs of cellulose and the other fibrous insulations. There is a bit more to note regarding this issue, which has some impacts on the 10x difference.  I discovered this video on youtube: showing the use of pour foam - liquid foams that you pour into things.  This is very similar or the same stuff that is used in the spray foam process, (it is basically the same, but additives may differ).  The video points to Aeromarine Products, where you can purchase the foams right from the website.  You'll notice you can purchase about 500 cubic feet of 2# foam for about $3900 - which works out to $7.80/cf, or about 10.8 cents/sf-R.  This is still a lot more than cellulose, at $0.303/cf, or $0.0072/sf-R.  Something like 15x the cost on the materials.  Here is a place you can purchase spray-foam kits:, and they also give you the prices right online - I love it when they do this.  Here the price of spray foam on their largest kit works out to $14.3/cf - almost twice the price of the pour-foam.  This is some 30x the cost of cellulose, R for R (not accounting for the fact that cellulose takes about twice the space to achieve the same R levels - the value of space and the construction details required to build this space for cellulose are pretty variable - but then, we are also not accounting for the health and environmental footprints of the two materials, which are vastly different as well, with cellulose miles ahead on both accounts).  Note that labour costs are not included in the comparison, but given the labour portions noted above, we are still well ahead with cellulose.

Why is spray foam so much more expensive than the pour-foam?  Pressure vessels, and possibly additives - but mostly the pressure vessel/ hoses, gun, etc.  So the interesting point here is that if one must use urethane foam as a DIY, consider buying it in the liquid phase - that's what contractors do.  If you don't need to spray it on walls, but can pour it into a cavity, this is really the way to go.  In our case, we could have poured it into our walls - just like we will be 'pouring' the cellulose.

PS - We are purchasing larger amounts of mineral wool for our project as well, and Winroc has also given us excellent pricing on the material - again, to do their part to support 'green' projects.  Our cost for this material worked out to about $0.034/sf-R - about 4.7 x the cost of cellulose, not accounting for installation labour, which would reduce the cost advantage of cellulose, probably bringing it nearly even with the Roxul.