Practically off the grid!

Whether your making plans to harvest and save your own rain water or are just practicing frugal and environmentally conscious living, careful water use is a must.  In 2001, the average Canadian used 335 litres of water each day in their home (Shrubsole and Draper, 2007).  This is a huge sum that does not even begin to account for the water use associated with our lifestyle but it is a number I will use for now to keep things simple.  I will also just focus on water consumption in the shower in this article even though there are many other areas in which to consider water conservation.

Let us begin by estimating the water use for a typical shower with a typical shower head.  A common shower head will have a flow rate close to 10 litres/minute and let’s assume a typical person showers for 5 minutes. A simple calculation shows us a 5 minute shower with a standard shower head will use about 50 litres of water.

Next let’s figure out how much water we could save with a low flow shower head.  A photo of my shower head is shown below.  It is called the Lowest Flow Shower Head and has an impressive flow rate.  At 80 psi it delivers 2.25 gpm as a maximum flow rate but under average conditions it will deliver more like 1.2 gpm.  I wanted to know the exact flow rate of my shower head so I measured it myself by turning on the shower for 30 seconds and measuring the volume of water I collected in a pail in that time.  In 30 seconds I collected 1.3 litres so that is a flow rate of 2.6 lpm or 0.7 gpm.  Assuming I only buy the shower head and make no changes to my showering habits I have just reduced my water consumption by 75% to 13 litres/minute!

In addition to the low flow rate, this shower head also features a cut off valve.  This allows to really scrimp and save by cutting off your water supply to soap up.  Because the valve is right on the shower head you can turn the water on and off without having to adjust the water to the right temperature every time.  Using this feature it is easy to shower at a relaxed pace with 2 minutes or less of water usage.  With that low flow rate this feature and this shower head cut off valve I can have a comfortable shower with only 5.2 litres of water.  I’d be hard pressed to sponge bath with less than that.

So it’s obvious that the water savings are possible but does this also save us a significant amount of money.  My local cost for water usage is 0.036 cents/cu.ft. or 0.0013 cents/litre. If I use a standard shower head for a 5 minute shower every day for 1 year I would use 18,250 litres at a cost of $23.  If I use my low flow shower head for a 5 minute shower every day for 1 year I would only use 4745 litres at a cost of $6.  I bought this low flow shower head a few years ago for something like $8 so it has easily paid for itself and has been saving me money each day.  

Wait! There are even more savings to consider.  That water that was not used does not need to be heated now so there is also a savings of energy.  The difference in water use for a year was 13,505 litres and each of those litres must be heated from an average ground temperature of about 7 degrees celsius to about 45 degrees celsius.  It takes 4.2 KJ of energy to heat 1 litre of water by 1 degree celsius and let’s be generous and imagine you have a 100% efficient water heater.  The heating of 13,505 litres of water from 7 to 45 degrees celsius would require 2,155,398 KJ of energy or 2,042,923 BTUs or 600kWh.  I pay 11 cents/kwh here so that would mean a total cost savings of $66/year and bring the total cost savings to $83/year.  Alternatively, heating the water with a 100% efficient natural gas boiler would mean paying 0.024 cents/kWh of natural gas for a lower cost savings of $14/year and a total savings of $31/year.  The money saved for one person per year with relatively short showers may not be that remarkable to you but consider the savings with a family of 4 and with and perhaps with more generous 10 minute showers.  The savings of water, energy and money begin to add up significantly. 

Low flow shower heads did not seem to be very common even just a few years ago in Canada but even then they were easy to find online.  Today, they are much more common.  I recently saw a few low flow shower head models equipped with stop valves at Canadian Tire and if a product is at Canadian Tire you know it’s accepted as mainstream so you should not have any trouble finding one of these shower heads at your local plumbing or hardware store.  Pick one up and try it out!

If you are considering building a solar air heater yourself you may be interested in the tools needed and the approximate budget for the air heater I have built for my house.  I have described the construction of the heater in earlier posts which you can find here: Trial 1, Trial 2, Completed

My research told me that a collector should be about 1/10th of the floor area you wish to heat and my main floor is 440 square feet so that is how I determined the size of the heater area.  I also wanted to be sensitive to the integration of the heater into the house facade and that limited its size.  The next time I build a solar air heater it will be bigger.  Why not really?  You can always get rid of excess heat but you can get more heat from an undersized collector. Anyway, I ended up building a 43 square foot collector and this post is about the tools and expenses needed to build a collector of this size.  

I have listed the equipment and materials that I used for the project.   You could easily complete the project without all of the equipment in the list but the materials are all pretty essential.  The one area of variation in the materials section might be the absorber.  Some studies I have seen of felt and screen absorbers show potential.  Other than that element though you should really have everything on the list.  You especially don’t want to skimp on the fan and solar panel because they will be driving the whole system.  The upfront cost of this solar panel/ DC fan combo is high but will save energy and headaches in the future.  The alternative would be to hook up a grid tied AC fan with a thermostat but an AC fan will use a lot more power and you’ll be paying for it.  I guess you could also use an inverter to hook up a grid tied DC fan but again that is just more equipment, wiring and power you will be paying for.  The simplicity and long term economics of the solar panel and DC fan are just too attractive to ignore I think.

Equipment:

tin snips

drill

skill saw

paint brush

staple gun

hand saw

(a jig saw or reciprocating saw would have been nice for the holes in the wall)

 

Materials:

bubble foil radiant barrier:  $30

4 salvaged double pane windows: $80

aluminum flashing: $60

flat black high temp. spray paint:  $20

aluminum tape: $10

12 inch DC fan: $150

25 watt solar panel: $200

Other: silicon, screws, stain, wood for frame, staples, wire: $50

Total:  $540

That total is trivial compared to the cost of a well known commercial model like the Cansolair Solar Max 240 which retails for $2695.  That purchase would also require taxes and shipping so the total is really more like $3000 to get the unit to your door.  That collector only has an area of 28 square feet and mine covers an area of 43 square feet so a cost per square foot would be even more telling of the economy of building your own collector.  A simple calculation reveals that my collector has a cost per square foot of $ 12.50 and the cost for the Solar Max 240 is around $100 per square foot!   In an field where size is king and low tech possibilities are plentiful why not build a collector yourself for a tenth of the cost.  Depending on your access to materials you may sacrifice a bit in terms of efficiency but that is a difference you can make up easily in collector size.  In addition you will enjoy the pride that comes with doing the project yourself and can integrated the collector more appropriately into the design of your home.

 I have made a number of energy saving changes to my home in recent years and one of the changes I have been most happy with is the radiant heating system.   It was easy to install, has operated efficiently,  and creates a very comfortable living space.

A radiant heating systems work by heating a large mass within a home and allowing that mass to radiate its heat throughout the building.  Most commonly the mass chosen is the floor of the house but I have also seen radiant walls and ceilings.  The old style cast iron radiators are a form of radiant heat but they are a bit more intrusive because of their placement right in the living spaces and their higher operating temperatures.  When the entire floor surface is used to radiate heat, that surface does not need to be as hot as the old style radiators and the heat distribution system is tucked away neatly inside the floor.

The installation of the radiant heating system was simple.  I have a fairly small house of only 440 square feet so I appreciated that the job was greatly simplified compared to what it would have been in a much larger home.  I chose to install the radiant heating pipes underneath my main floor between all of the floor joists.  This was mostly because my house was already built.  Had it been a system for a new house I might have opted to install the piping above the subfloor but in my case an underfloor application was the simplest and had been shown to be effective so that was my choice.  My research told me that I should keep my loops around 200-400 feet in length so as not to overpower the pumps and still have even heat distribution.  To meet this requirement I decided to use two radiant heating loops about 300 feet long.  One loop included both bedrooms and the bathroom and the other loop included the living area and kitchen.  There are AC pumps available that could drive both loops of this system but I chose to use one smaller DC pump for each loop.  The DC pumps I bought from WSE Technologies are simpler and more efficient than AC pumps and having one pump for each loop also makes it easy to add a second thermostat to the system later on if I want to have different temperature settings for each heating zone.  As for now, I have one programmable thermostat powering both 12V DC pumps.  The pumps are on an independent circuit hooked up to a 12V battery and charger temporarily until I invest in more PV panels to power the whole system.  So those are the radiant system essentials: hot water source, heating loops, manifold, pumps, and thermostat. 

 

Once I had the delivery of the heat sorted out I needed to make sure that heat is transfered efficiently from the pipes to the floor.  Air is not a great conductor so first I fastened right against the bottom of the floor.  In addition to this, I stapled aluminum heat transfer plates over the piping to increase heat conduction bewteen the pipes and the floor.  The plates will extract more heat from your pipes and save you energy because you will not need to circulate as much water.  Your pumps will also last longer because they will not run as often.   I also stapled reflective bubble foil between the floor joists to reflect radiated heat back up to the floor.  I started using the system without the foil at first and found that the basement became uncomfortably hot.  The addition of the foil between the joists made a huge difference.  My basement now stays at a comfortable temperature but is still often a degree or two warmer than the main floor in the heating season.

 

 

This is my second winter with this radiant heating system installed and I have observed some significant improvements in the energy efficiency over my older forced air heating system.  The most noticeable improvement was actually the drop in my electrical bill because the DC pumps draw much less power than the fan in the old furnace.  I have also observed a large drop in my gas bill.  Radiant heating has a reputation of being more efficient than forced air systems but I can’t attribute the decrease of my gas bill to the radiant system alone.  The switch to radiant heat meant using a gas boiler (also a bit old) for the grid tied heat source which is probably a bit more efficient than the old furnace.  The radiant heating system also allows the contribution of heat from my solar water heating system.  What I can say is that all of these factors combined have slashed my heating bill by half and that is pretty significant!  

As if the energy savings were not enough of a reason to celebrate, the new radiant heating system has also made my living spaces more comfortable.  Because the floor is always warm, I now have the pleasure of walking around with warm and even bare feet in the middle of winter.  I used to be awoken in the night from the abrupt start of the old furnace fan but the new pumps quietly deliver the heat without any disturbance.  I also have enjoyed the absence of my furnace in my basement.  It was a monster of a thing that took up a lot of space and I now get to decide what else I could do with that space.  The spider like furnace ducting is also gone and that cleared up even more space in the basement.  Oh yeah and my old chimney is also gone because my water heater can be vented out a side wall.  So not only have I experienced an increase in comfort I now have significantly more space and in my small home that amount of space makes a noticeable difference.

To summarize my experience with radiant heating, I have been impressed with the ease of installation, the simplicity and efficiency of the working system and the improved comfort in my home.  I recommend radiant heating to everyone who asks me about it.