I was in Labrador for two weeks for work, so it has been a little while since I last wrote; however, I am now inspired to write about heating, insulation and all things warm (Goosebay was cold!). Going into this, I had a fairly good understanding of options for heating, but very little knowledge about insulation. I have memories of my grandfather installing big panels of the fluffy pink stuff, and that’s about it. But of course, if you’re going to be paying to heat a space, you’ll end up wasting a lot of money and energy if your space isn’t properly insulated. So for those of you who are in the same boat as I was before my research, I will try to lay out what I’ve learned in a straight forward way.
Before I go into explanations, I want to present a few definitions which will make things easier when trying to wrap your head around this stuff- I relied heavily on wikipedia here for sure. If you’re currently completing a grade 8 science course, you can skip this section. Disclaimer: I realize this isn’t a very fun thing to be talking about, but in order to make an informed decision, and be able to back it up, I needed to go right back to basics. This stuff will also be really helpful when I write a post about wiring the tiny house, with the help of my super handy electrician brother.
- JOULE (J): Unit measurement of energy, work, or heat, defined as Newton metres. It is equal to the energy transferred (or work done) when applying a force of one newton through a distance of one metre. Also equal to passing an electric current of one amp through a resistance of one ohm for one second.
- WATT (w): Unit measurement of power, defined as joules per second. Rate of energy conversion or transfer with respect to time. Significant orders of magnitude include kilowatts, megawatts, and gigawatts
- KILOWATT HOUR (kw.h): The amount of energy equivalent to a steady power of 1 kilowatt running for 1 hour. As an aside, one terawatt hour is equal to a sustained power of approximately 114 megawatts for a period of one year. So when discussing the energy generation by a major corporation, terawatt hours would be more appropriate.
- BTU: British Thermal Unit. Equivalent to about 1055 joules. This is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. I don’t like this unit because it’s imperial, but it is the most widely used unit when talking about the capabilities of heating units. It’s also very easy to picture- one four inch, wooden match completely burned generates 1 BTU.
- R-VALUE (m2·°C/W): Measures thermal resistance. It is the ratio of temperature difference across an insulator and the heat flux (heat transfer per unit area per unit time) through it. The R-value of a material varies with temperature but it is common practice to treat it as a constant value. Simply put, the more the material restricts the flow of heat, the higher its R-value. Important note- in the states, R-values are given in units of ft2·°F·hr/Btu and often don’t actually state the units. Therefore, if reading about an American manufactured material, it’s likely in imperial, and you should divide by 6 to get the metric value.
The interwebs tell me that there are four main types of insulation:
- Loose Fill
- Batt (Pink fiberglass)
- Spray Foam
I know you’re all dying for me to write up in-depth descriptions of the pros and cons on each one (and all the alternatives like sheep’s wool, recycled denim, and cellulose)…kidding. I’ll spare you that, even though I think it’s pretty interesting stuff, and just give you the low-down on our preferred route. Another reason for the abridged version is that options for fancy recycled or natural materials are very limited in Newfoundland, like a lot of other cool products mainlanders get to enjoy. So even if I wanted to fill our walls and ceilings with wool, it would likely not even be possible. Island living has its drawbacks.
Because rigid polystyrene is such a great insulator, is readily available, and will add structural integrity to walls, it was a no-brainer to choose this as our main insulator. One website I saw quoted that it ranges from R-3.6 to R-6.7 per inch of thickness. I know some people really don’t like it because it’s a petroleum based product, which makes me think twice as well, but it can be recycled. And the energy it saves compared to other insulators is a fair trade off for the potential cons it has.
I’d like to nerd out and touch on closed-cell soybean spray foam insulation. My initial thought was that we could use this as supplementary insulation in case there are areas where rigid board won’t fit/work, or if it turns out that we can’t find recycled rigid boards. If it is affordable for us, we could use it exclusively, especially since we would need so little of it to completely insulate the tiny house. Here are two great articles about it, in case it’s a new concept for anyone (it was for me!) http://www.hgtv.com/remodel/mechanical-systems/soy-spray-foam-insulation and http://www.thegreenestdollar.com/2009/02/soy-based-foam-insulation-what-it-is-and-why-you-should-use-it/.
Soybean-based products claim to contain no urea or formaldehyde (which other spray foams contain lots of), and they release no volatile chemicals or other toxic emissions. They expand and fill gaps like a regular spray foam for a tight seal, and they’re resistant to mold and mildew. Apparently closed-cell foam is around R-5.5 to R-6 per inch, and like rigid boards, contributes greatly to the structural strength of a building, increasing shear strength by 300% (according to http://www.ewinginsolutions.com/FAQ.html). I need to do more investigating on how easy it is to get here in St. John’s, but it seems that soybean popularity has been really ramping up recently, so here’s hoping. If anyone has any experience with alternative/new insulation options, or any insight, please weigh in!
There are two camps for heating (and all powered resources) in the tiny house world: on grid and off grid. I initially found myself torn about which I would like to align myself with, since there are very good reasons for both.
On grid implies electricity, which is provided by a crown corporation under provincial government leadership- in Newfoundland’s case, Nalcor Energy. As an exercise to become more comfortable with energy terminology and units, I did some digging on this. The net generating capacity for the island interconnected system is about 2000 MW. 92% of that electricity is produced by Nalcor’s daughter company, Newfoundland Hydro. As the primary generator of electricity, more than 80% of Hydro’s energy is clean, hydroelectric generation. The remaining electricity is supplied by Newfoundland Power’s 23 small hydroelectric plants, which again are considered clean energy sources as they are renewable. Because Newfoundland’s grid electricity is mostly renewable and ‘clean’, and will only increase its proportion and reliability of renewable sources once the Lower Churchill mega-hydroelectric dam comes online, we feel comfortable relying at least partially on the grid, with an electric space heater. If I was living in a different part of the world where the grid relied more heavily on fossil fuels, I would be leaning much more heavily towards being completely off-grid. Fortunately for us, the system in Newfoundland allows me to connect to the grid relatively guilt-free.
The negative side of connecting to the grid is that you become more stationary than mobile. Also, if you’re planning on setting up on your own land, you need to initiate your very own connection through your municipality. If you’re planning on setting up on someone else’s property adjacent to an existing fixed-foundation home, you need to ensure there is sufficient space in their panel box to accommodate the amperage required to run the tiny house. More on this later when I bring my brother in to educate me on how to tackle the electrical side of things.
Off grid opens up a lot more doors in terms of options:
- Solar (with a 12 volt battery system…$$$)
- Propane (with storage tanks fixed to the outside of your tiny house)
- Your very own tiny wind turbine
- Tiny geothermal wells
Ok let’s be real, the wind turbine and geothermal options are not realistic, and kind of defeat the purpose of going off grid for a tiny house. The main reason you’d want to hook up solar panels on your roof and buy a very expensive battery system, or buy all propane powered appliances would be so that you can go wherever you want, whenever you want, without having to rely on anyone else for your needs. This is very cool. A lot of tiny housers combine solar and propane for an efficient off grid solution to all their energy needs. Since we have already decided that we want to have on grid capability, the most sensible and awesome off grid option to combine with in our minds is wood. This allows us to cut as many ties with fossil fuels as possible. Wood is also extremely plentiful in Newfoundland, making it a great choice for us.
The newest concept overall for me with regard to this topic was actually calculating our thermal needs based on our space dimensions, climate, and insulation efficiency. Determining this allows us to choose which specific products we’ll be installing in the tiny house. We want a heating unit(s) that will be as cost effective as possible while still providing the heat we need if we want to walk around in shorts and tank tops in the winter like I shamelessly do. Enter the Goldilocks principle (juuuuust right :P). Likewise, we’d prefer insulation that has the highest R-value to cost ratio.
The easiest way to do this is to use an online BTU calculator, like this one: http://www.calculator.net/btu-calculator.html or this one: http://www.bestheating.com/btu-calculator which is kind of crude, but a good approximation. Using these tools, I calculated that we will need between 7,274 BTU/hour and 12,960 BTU/hour or 2131 to 3798 watt. The first calculator takes into account the width, length and height of the room, the insulation condition, and the temperature increase required (i.e. the average temperature in winter in St. John’s is around -10ºC, which means you’d need an increase of around 30ºC to be comfy). In addition to these parameters, the second calculator takes into account the square footage of windows, type of windows, what is above and below the room, the type of wall framing, and how many outside walls are included in the room. Unfortunately 4 walls wasn’t an option, since the thought of having a one room house in North America is not common outside the tiny house (and other alternative living concepts) world, but I picked 3. Strangely, the more detailed calculator gave me the lower heating requirement. I may or may not seek out a mathematical equation and do this manually, but I think perhaps having a chat with someone at Home Hardware or Kent might be even better, since they’ll be knowledgeable of the typical BTU/hour per square foot requirements here in Newfoundland.
Now that everything is laid out, I’m all set up to reveal to you the actual heating units we’re thinking of purchasing for the tiny house. The next post will have lots of pictures and probably be more fun, since there will be real tangible things I’ll be discussing and not just concepts and options. But hopefully this was even a little useful to those of you interested in learning about this topic, and that I haven’t gone and included any misinformation. Again, any suggestions or eye-openers are very welcomed 🙂