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Canada’s Greenest Home Lowers Embodied Energy by 50%

In an Endeavour post about a year ago, I examined the concept of embodied energy in buildings. You can see that post here. To quote the summary of that article:

“Choosing high EE materials is willfully neglectful, and in my experience the choice is often due to sheer laziness or an unwillingness to alter choices simply because that’s what has always been done. A builder doesn’t need to dabble on the fringes of the natural building world to drastically reduce EE. Many mainstream choices offer vastly lower EE than others. It’s just a matter of putting the effort into knowing what the EE impacts will be.”

While building our Canada’s Greenest Home project, we made conscious decisions to choose low embodied energy materials, but only recently have we taken the time to do a full embodied energy analysis on the shell of the house. While doing this, we also did the same analysis for a conventional home built to the same dimensions and specifications.

The results of this study (using the Inventory of Carbon and Energy (ICE) 2.0 and the book Making Better Buildings) showed that our home used 138,052 megajoules (MJ) of energy embodied in its construction materials, while a similar conventional build would have used 277,544 MJ. That means that our home used just less than 50% of the embodied energy of a conventional home!

Embodied energy of building materialsWhat does this mean? Let’s look at the difference in terms of energy use in the house. In a recent post, we discovered that after one year in the home, our annual energy consumption was 31.92 gigajoules (GJ). The embodied energy difference of 139,492 MJ (converted to gigajoules is 139.5 GJ) is enough to completely heat and power our home for 4.37 years. This means that even if the conventional home had the same level of energy performance, it would always carry a 4+ year deficit compared to our home.

In reality, the comparison is even more dramatic. The majority (68%) of the energy being used in Canada’s Greenest Home is renewably generated on site. The remainder is renewably generated via a Bullfrog Power contract. Whereas the energy embodied in the materials is almost certainly not renewably generated, and comes with carbon emissions and environmental impacts far higher than our home energy use.

The point I made in my embodied energy article is: Why not pay attention to this? The choices we made are easy ones to make, and there are equally easy choices within conventional options that also dramatically lower embodied energy. If it’s possible to cut overall energy use by the construction materials sector by 50%, why aren’t we making that choice? Seen as a choice made by one builder, it’s a small impact, but extended over the entire sector, it is a vast and radical change.

 

Canada’s Greenest Home uses 71% less energy!

We set out with some pretty lofty goals for our Canada’s Greenest Home project. The idea was to use only the healthiest, most ecologically friendly building materials and use them to create a home with outstanding energy performance. And we wanted to do it in a way that would be cost-comparative and easily achievable for other contractors. We finally have the data to show our results on the energy performance side.

From modelling to the real world

Much is made during the design process of “green” homes of energy modelling figures and estimates of consumption and/or savings based on the design. However, in few cases do we ever get to see an accurate portrayal of the actual consumption figures as compared to the models.

Obtaining real-world performance data was one of the key reasons we wanted to spend at least a year living in Canada’s Greenest Home. And now that we have been living here for a year, the results are in!

Energy produced compared to energy used at Canada's Greenest Home

Energy produced compared to energy used at Canada’s Greenest Home

Canada’s Greenest Home components

To recap, the home has a 5kw PV array, that is grid-tied using Ontario’s MicroFIT program. This means that there are two electricity meters on the house, one recording power going out to the grid via MicroFIT, and one recording power coming into the home. These figures allow us to see a clear picture of our consumption versus our production. There is no other fuel source in the home, as our heating system is powered electrically, via a Mitsubishi Zuba air source heat pump.

The results!

Our total annual consumption (including heat, refrigeration, cooking and all other plug loads) was 8,867 kilowatt hours, and our total production was 6,075 kilowatt hours. So we were 2,792 kw/h short of being net zero energy. Some of this can be attributed to the fact that the winter of 2013/2014 was quite a bit colder than average, and ice covered our panels for much of January and February (the output numbers are typically higher than December, but are quite a bit lower). In a different year, we would be quite a bit closer to net zero.

Financially, the picture is quite rosy. At our MicroFIT rate of 54.9 cents per kilowatt hour, our earnings from the PV system were $2,028.07 higher than our utility costs. Not many homes earn money for the owners, rather than costing them! That surplus goes a long way to putting a dent in the mortgage costs.

Comparing to other homes in Ontario

Comparing our energy usage to averages for Ontario (using the most recent StatsCan figures) is also illuminating. The average home of this size (2,000-2,500 square feet) built since 1996 uses 107 gigajoules of total energy (GJ is used to be able to compare measurements between different fuel sources like natural gas, oil, and electricity). Converting our kilowatt hours to gigajoules shows that we used 31.92 GJ, or just under 30% of the comparable average home! By square meters, we used 0.15 GJ per meter squared of floor area.

Passive House modelling slightly off

Interestingly, the energy modelling done in the Passive House software (PHPP) showed that our heating demand should have been 11,529 kw/h for the year, but our total usage including all non-heating loads was 8,867 kw/h, a substantial difference. As a guess, I would say that it is low R-value figures given for straw bale walls that accounts for this difference. Tested R-values and real world performance are always different beasts, but seem to be even more so for straw bale wall systems.

Doing better isn’t hard

We are very proud of these results. Considering that the costs for the shell of the home were very comparable to “conventional” construction (the majority of our additional costs were for mechanical systems like rainwater harvesting, composting toilets and solar hot water, as well as the PV), it bodes well to show that with small, achievable, and affordable changes in construction, vast improvements in performance can be achieved.

In our case, these improvements were made using locally-sourced, low-impact and mostly renewable resources, showing that eco-friendliness has many facets, and that being good for the planet when choosing materials can also mean being good for the planet in long-term impacts.

Anybody can build a home like this, with very low environmental impacts and great performance. The question is, why don’t more people do it?

Paperstone countertops at Canada’s Greenest Home

We spent a lot of time considering our countertop choices for Canada’s Greenest Home. It’s an area with many options, and many factors to weigh when trying to make an environmentally sound choice. Ideally, the countertop material must be durable, aesthetically pleasing, stable, renewable and/or recyclable and not off gas any chemicals into the home.

After much deliberation, we chose to go with a material called Paperstone. This type of countertop is made from 100% recycled paper fibers (complete with FSC certification), bound with a phenolic resin to create a solid, dense material that is certified food safe by NSF and resistant to high temperatures and abrasion/scratching.

One of the main attractions to Paperstone is its workability. It can be cut with typical woodworking tools, allowing us to do our own installation. We were able to shape the pieces we needed, make the sink cut-outs and bevel the edges of the material easily.

Paperstone came in a range of attractive colours, and can be finished with natural sealants and waxes.

The phenolic resin binder gave us some cause for concern. While the material does not contain any petro chemicals or off gas in the home, the resin ingredients are not environmentally benign. However, the company documents its handling practices very convincingly and has received numerous awards for its sustainability initiatives. We would like to see the company apply for Greenguard certification to ensure its claims of zero off gassing are confirmed by a trusted third party.

We obtained our Paperstone from Living Rooms in Kingston, Ontario, allowing us to work with a supplier we know and trust. This is always an important part of any product decision. The material comes in large slabs, and we bought a 5×12 foot slab from which we cut the pieces we needed.

After a lot of use (and abuse), we have been extremely pleased with the performance of the Paperstone. We gave it an initial waxing prior to use, and have not refinished it after 10 months. It is impervious to water, easy to clean, and very scratch and dent resistant. The dark charcoal colour we chose has a nice depth to it, and doesn’t show any signs of staining or wear. Areas around the sink, where many countertops begin to show signs of failure quite quickly, don’t seem vulnerable to deterioration at this point.

The countertop draws compliments from almost everybody who sees it. It looks and feels unique and attractive. While it is not inexpensive, the initial workability of the Paperstone allowed us to do the installation ourselves, saving money. And its apparent durability means that its an investment that will last a very long time. If you can afford it, we would recommend it as a good choice.

 

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