Point of Use Water Heating

Imagine going to the kitchen sink and dialing in the water temperature you want.  Then open the single tap and voila - water at the temperature you want, at any volume.  When you close the tap and re-open it, the water is at the same temperature.  Again and again.  No having to adjust to the right temperature every time you open the tap.  Wouldn't that be luxurious?  The technology to do this was available decades ago, but we keep doing things the old way...

Achieving this is simple.  One need only provide a single water line to the faucet.  In that line is a point of use (electric) water heater with a remote control.  The remote control is mounted near the faucet (EcoSmart makes this kind of unit).  The heater is somewhere nearby, but out of sight.  The only issue with implementing this is that the efficiency of water heating is always just 100%. However, one advantage is that there is no hot water anywhere in the system - just at the last two feet of water tubing before the faucet.  No standby losses, although these days they are small in better tanks.

Consider the shower.  Imagine again, only one water line supplying the shower, with an inline point of use water heater with remote.  In the shower, we dial in on the digital display the water temperature we want.  Shower water comes out of the spout at precisely that temperature.  The warm water leaves the shower via the drain, but here, we have a heat recovery device which is some 80% effective.  We give most of the waste heat to the incoming cold water stream just before it contacts the POU heater.  Then the heater finds it very easy to raise the water temperature just the last say 10 degrees Celsius.  In this way, we minimize the heat that leaves the house and the energy and power needed to heat shower water.  If we want a bath, things are quite a different story, and I haven't really thought about what I'll do in that case.

The drain water heat recovery devices out there right now are only some 50 to 60 percent efficient.  Even that is saving half our energy to heat the water, so yay, but for some untold reason, none of these devices take advantage of heat pipes, which I plan to experiment with.

Energy Efficient Lighting for Passive Houses

Been looking long and hard at energy efficient and sensible topologies for wiring a house or a building.
Here are the needs:

1. Other than power outlets, we need very little energy for everything else - so why wire them with the 14ga Romex?  I'd like to see a new style of wiring for this stuff.  One that more closely reflects the realities of today - very small loads, and more demand for flexibility.
2. Long term flexibility:  It is really nuts that we wire the whole house and then hide everything behind drywall - it makes it so hard to make adjustments and changes.  Why can't we have a wiring and control scheme that is modular, flexible, and not expensive?
3. Every CFL or LED light works on voltages not related to household voltages of 120 or 240V.  All these silly LED lights we buy that fit into regular 115V sockets come with power supplies built-in.  While the bulbs can last 50,000 hrs, the power supplies die after 2000 or whatever.  Why not have a central LED light control/power supply to distribute low voltage to our lights and a host of other things like USB charging jacks, clocks, etc.
4. We need some low voltage lights for our exposed beam ceiling.  Ever notice the exposed beam ceilings in magazines?  Most of them don't seem to have effective solutions for their lighting.  That's because there is no joist space for them to hide pot lights or wiring or electrical boxes.  A lot of times you see the light is run using a metal conduit (EMT) along the joist, and then to chandelier.  These days I always look for this when I see exposed beam ceilings in magazines.  This can be a vexing problem.  Our solution is to use low voltage (hence few electrical code issues).  The wire is small, and we hope to bury it above the plywood subfloor - this should be easy because we are looking at adding acoustic layers to the subfloor top side anyway (another vexing issue).  Then each wire will enter a surface mounted, hopefully very small light fixture  - something like an under-the-cabinet light.  The trick is finding lights like this that are small, beautiful, and give off tons of light on very little power.

Well, it looks like Lumencache is a product that addresses most of these needs, if not all.  Other than the duplex power outlets, everything is wired with CAT5 ethernet cable.  All devices are wired with home-runs to a central box.  This means every light and every switch, and every other point wired with CAT5 is a potential data node.  It also means the house's wiring is highly flexible and adaptable to future changes - 3-way wiring is done in the central cabinet, rather than in the walls.  A switch can control any light, and this can be changed, and it can control any number of lights, or it can control something other than lights. A light fixture can be changed to be (theoretically for now - not sure if any product yet exists) a smoke alarm, or it can be both, or perhaps a motion sensor with light, or a WiFi Hotspot....

The possibilities are endless.  That is why I am wiring the house with CAT5 instead of Romex.

We will be having CAT5 at every window opening, every door, every light fixture, every switch, and every thermostat, HVAC component, sensor, etc.  In addition, every data point and telephone point - the data and lighting use the same wire, after all.  Sometimes 2.  This makes it all so simple, and I would say very future friendly.

The only thing which I might wire with different cable is the in-wall speakers.  Ethernet connected speakers might be OK, but from what I hear, not quite that good as yet, so we'll probably wire them with 18gauge or something like that.

There are other developments in the home automation field which are exciting.  OpenHAB is an open-source software framework for home and building automation.  Just appeared on the internet last year.  I hope everyone who makes automation gear pays attention to that standard....

These days, the way to go seems to be to control the house with a small PC, powered by an atom processor.  These are inexpensive and consume very little energy - something like the EEEBox 1033.  On this you can run a home automation software like Mcontrol V3.  Only $170 or so online.  Apparently very open and has drivers for hundreds of different protocols so can connect to and talk to virtually everything from your smartphone.

Link to the Passive House news on Global TV

Here is the link to the Passive House video that was aired tonight on Global news: 

http://www.globalnews.ca/video/passive+housing/video.html?v=2337457041&p=1&s=dd#video

We didn't appear much in the piece, but there were lots of footage of our house, which is most of the construction in this video.  The workers are our crew members, doing actual work two weeks ago.  They used a lot of the information supplied by us, but Lyndon only said one sentence 'on air'.  The filming was supposed to be included in an episode about innovative things happening in construction across Canada, but it is presented in this news piece instead. Hopefully, this will lead to more people knowing about the possibility of passive houses in Canada!

Our Passive House on TV

Global TV recently approached us for an interview for their upcoming 'The National" news show.  The episode will air this Thursday, Feb 21, 6:30pm on Global TV (channel 3 in Toronto).  They were interested in what Passive House was, and they took some footage of our project, showing the spaces, the double walls, etc.  I hope we don't look too silly!

Thought I would post some of the older  photos.

Lovely attic space will be a sea of cellulose soon.

Solar panel installation.

A view between the double wall frames.

Stainless Steel Exterior Post Anchors

Look around and you will see many exterior columns on residential buildings suffering from corrosion at their bases.  At least I do.  A major reason for this is because pressure treated lumber is frequently used for exterior columns, and the preservative is not compatible with the steel column bases and screws you can get from the lumber store.

One of my beefs with exterior columns is how there is no easy and accessible solution to mount them properly at their bases.  Most of the column bases seem inadequate to me, and in addition they are cheap looking.  Often they are set with their bottom plates in contact with the concrete - an invitation for crevice corrosion.  I looked and looked for solutions, but found them hard to come by.  Finally, I decided to go with steel columns set off the concrete with stainless threaded rod anchors (5/8").  Here are some pics:

Columns offset from concrete SOG about 45mm

5/8" (15mm) stainless steel threaded rod anchors.

That is a temporary door in pic.  Just showing the steel columns and how they're not in contact with the concrete.  Stainless anchors and nuts.

Steel Balcony Frame:  Designed beyond code minimum so as to be strong enough to support a crowd overlooking whatever is happening below.  The frame is completely isolated from the interior of the building which avoids what would be very significant thermal bridging.  this is easy to do when the building is made with a double wall system.  Note the offset joist/outrigger at the far left:  the little 4" x 4" void is to accommodate a concealed downspout.

The floor will be made from 1/8" thick stainless plate welded to the steel.  Probably have wood slats on top of the smooth stainless.

Snow Melt for a Passive House and Recent Photos

Well, we finally poured our slabs on grade and front steps - in Nov. and Dec.  We decided to place snow melt heating loops in the slabs, and it does seem a bit extravagant, but if we actually use it, it means no application of salt to melt ice, and clean, safe entries to the building, especially for the front steps.  As we plan to eliminate the gas service, there will not be any strong heat source to service these snow melt areas -unless we use a wood boiler!

So the idea is to simply run the wood boiler at times when we are expecting significant snow and we need to clear ice from the front steps.  In working out the heat inputs and hydronic flow rates for glycol, etc, I realized a big lesson for exterior snow melt applications.  Normally, radiant slabs are assumed to benefit from high thermal mass - that is when they are indoors, one wants a constant temperature, and heavy massive slabs help to regulate and temper any significant fluctuations such as high solar loads, etc.  Thus, the hydronic heating pipes are frequently installed submerged in slabs of concrete or gypcrete, etc.  However, snow melt works in reverse, in a sense.  In a snow melt application, one wants LOW thermal mass to avoid heating up a big, massive concrete slab just to melt off a thin layer of snow or ice.  Doing the calculations, one finds that it is actually easy to spend more energy bringing the slab to temperature than melting the snow or ice, even when the slab is insulated underneath.  Wish I knew this before I did mine, but for all you guys and gals out there thinking of snow melt, consider this.  Unfortunately, I don't know of any practical solutions to this whole issue at this time, though I have some ideas - we must keep the slab as thin as possible, insulate well underneath, and insulate the edges as well, if practical.  The idea I have been toying with is using a stainless steel or steel plate as the top surface of the slab - or even building the top of the 'slab with a series of rectangular stainless steel tubes and run the heating fluid through these.  This would place the fluid in nearly direct contact with the snow/ice, and diminish heat transfer to the concrete.  The plate would need to have a traction surface, which is an issue because I don't like diamond plate (there is a company 'Algrip' making beautifully dimpled surfaces via laser deposition of metal - no idea of price).  And stainless steel is very cheap right now - just about twice the price of steel.  But it does seem extravagant....

On another note, snow melt components are priced into the thin air of the mountains.  Companies such as Uponor and Viega make the snow sensors, and they are absolutely ridiculous - I cannot understand why.  An ABS plastic housing that holds the sensor (needed during rough-in/casting of the slab) which should cost maybe $20 (perhaps for lack of volume in production), instead commands some $150 in the plumbing/mechanical supply store.  See pic;

This little kit of parts is $150 (contractor price).  The black plastic disc/cover is discarded when the snow melt sensor is installed.  The tube-like thing is made of steel and the temperature sensor is to go into that tube, which sits inside the slab.  The sensor itself is about $1000 contractor price (retail is $1700).

The sensor is just a couple of plates of brass separated by a space.  The resistance between these plates is reduced in the presence of snow and this change triggers a signal which becomes the snow melt system's demand for heat.  Very simple, but the darn sensor is about $1000.  I say it's worth $50 at most.  Since we are no longer at the beginning of the project and money is getting more expensive, we opted to make our own plastic housing and later, when the house is finished and there is more time, we will make our own snow sensor, if needed.  After all, a manual system is not much of an issue - in any case, it is often desirable to heat the slab well before snow appears.

Look closely and you'll see we placed some pipe insulation around the pex tubing where it enters the building.  This is to cushion the tubing in case the slab moves relative to the building.  We also agonized over where to enter the building.  In the end we opted to drill through the wall inside the slab volume, but we drilled the hole with a significant slope so any water from rain or snow will find it harder to flow into the building through those holes.

Add caption

Here is our rough-in:

DIY Rough-in for snow melt sensor made from common plumbing parts - 4" clean-out - we would have to make an adaptor plate to adapt the actual sensor to this bolt pattern, or make our own sensor, which is more likely.

Below are some photos of our snow-melt piping installation.  BTW, I mentioned this to a contractor and he told me they never install 1/2" pex for snow melt - they use 5/8" minimum.  I double-checked my calculations and feel very comfortable with the 1/2" pex - but we'll see if it performs when the time comes.  He is probably thinking of larger areas like driveways.  In our case, it is only on three little concrete slabs.

Solid Lumber Sheathing

Recent Photos:
We opted for solid lumber sheathing, right from design.  It is a fairly vapour-open sheathing, due in large part to the gaps, which is what we wanted.  It is also strong - allowing us to apply a wide variety of finishes, and place strapping anywhere we want.  The lumber used was good one side 1x10 (22 x 235mm) pine/spruce, gotten for a really good price.  It was actually 7/8" (22mm) thick.

Basement window install.  The peel and stick flashing on the bottom covers shaped rigid foam.  It will be covered with a metal flashing as well.  There is a good 1" space between the window and the concrete, which was formed to overlap the window on 3 sides.  The window sits in a 3/4" (19mm) plywood box cantilevered out from the inner wood frame, but is supported by the rigid foam at the concrete.

Note the concrete drip edge cast into the window opening.

Article in The Varsity

Thanks to Simon Bromberg for writing an informative article about our house.  Here is the link to the article: http://thevarsity.ca/2012/08/25/from-bungalow-to-solar-house/

Rainwater Harvesting With Solar PV Panels

A Marriage Made in Heaven!

As the project progresses, we've been blessed with making connections with some excellent contributors:

I've mentioned some of them before, but most recently we've been connected to DTE Solar as well as Boss Solar, and Trevor at EcoInsulation, Reiner (the Reno Coach) all excellent people.

One connection was with John Paul from DTE Solar, who has put me onto rainwater collection as an energy-related component of our project.  He's written an excellent article on the topic, discussing rainwater collection's potential impact on the City of Toronto's energy, waste, environmental and financial costs.  It certainly opened my eyes to the amazing, yet highly under-appreciated costs of water treatment, distribution to and from, etc.  These are costs easily offset by rainwater collection if implemented ubiquitously.  Not to mention water costs in Toronto have increased about 8% per year for some time now.

After some discussion we've together arrived at tantalizing possibilities for our own project.  The fact that PV panels are glass-clad means they present a premium surface for rainwater collection.  The trouble is that they are not designed for this task - which I certainly feel they should be.  In fact, I would like to see PV panels made as large interlinking panels that shed water - This way they can be installed on the roof without plywood (so using PV panels, one eliminates not only the shingles but also the plywood layer, although the roof shape must be planned with this in mind), perhaps directly to the rafters or purlins.  The benefit is they can be wired or accessed from the backside (from inside the attic), they can serve as the roof, and shedding water all the way down the roof, rainwater collection becomes a breeze - not to mention the quality of the collected water is also improved.  In any case, given the current, less-perfect situation of panels on rails on shingle roof, JP's thought was to add troughs underneath the panel gaps to collect the water - in our case 3 long troughs, and direct it to the collection reservoir.  However, what if we also introduced pipes onto the roof to pump that rainwater from the holding tank onto the solar panels?  I believe by dousing the panels with rainwater we can cool them dramatically, increasing electricity yields significantly - perhaps as much as 10%, even after pumping losses.  Some of the water will evaporate, but much of it will just flow back into the collection system, where the heat may again be made use of - a heat pump can take the heat from the rainwater collection tank and port it to the DHW (domestic hot water) system.  Even if not, an un-insulated rainwater tank in the ground is constantly being cooled by the soil, so that over the hot summer season, there will be a significant cooling capacity available for the solar panels.  This cooling action will also lengthen the lifespan of the solar panels.
This is in a way similar to the new techniques appearing whereby the heat from the solar panels is being captured by flowing air over/under the panel backsides.  The heated air is then used in the building.  I've read this can increase by some 90% the energy harvested via electricity alone.  But air is generally a lesser medium than water - which is compact and easily filtered and transported in pipes.  Air carries dust, and requires larger ducts to move it.  And the fact that it is a (compressible) gas means there are a lot more losses related to its handling (pumping).
Mike at Boss Solar has devised a water coil to attach to the backs of solar PV panels to both cool them and capture their heat - but this seems a lot more difficult and costly than the 'rainwater collection' idea, - which appears to be - a marriage made in heaven!
Notice how there are no photos or sketches here.  The ideas are very simple.  This seems to be the reality of rainwater collection as it is with other aspects of super energy efficient houses - not glamorous - just important.